Category 6™

Stratospheric water vapor decline credited with slowing global warming

By: JeffMasters, 6:18 PM GMT on January 29, 2010

After a steep rise in global average temperatures in the 1990s, the 2000s have seen relatively flat temperatures, despite increasing levels of CO2 emissions by humans. This reduced warming may be partially due to a sharp decrease in stratospheric water vapor that began after 2000, according to research published yesterday in Science by a team of researchers led by Dr. Susan Solomon of NOAA's Earth System Research Laboratory in Boulder. Water vapor is a potent greenhouse gas capable of significantly warming the planet, and its potency is much higher when it is located in the lower stratosphere where temperatures are extremely cold. Greenhouse gases located in cold regions of the atmosphere are more effective at heating the planet because they absorb heat radiation from the Earth's relatively warm surface, but then re-emit energy at a much colder temperature, resulting in less heat energy lost to space. Even though stratospheric water vapor can exist at concentrations more than 100 times lower than at the surface, the 10% drop in stratospheric water vapor since 2000 noted by Solomon et al. acted to slow down global warming by 25% between 2000 - 2009, compared to that which would have occurred due only to carbon dioxide and other greenhouse gases.


Figure 1. Stratospheric water vapor in the tropics, between 5°S - 5°N, as measured by the HALOE instrument on the Upper Atmosphere Research Satellite (UARS), between 1993 - 2005. The bottom portion of the plot shows the lower stratosphere, just above where tall thunderstorms are able to transport water vapor into the stratosphere. A strong yearly cycle is evident in the water vapor, due to the seasonal variation in heavy thunderstorms over the tropics. Once in the lower stratosphere, the waver vapor takes about 1.2 years to travel to the upper stratosphere, as seen in the bending of the contours to the right with height. Note that beginning in 2001, very low water vapor concentrations less than 2.2 parts per million by volume (ppmv) began appearing in the lower stratosphere, due to substantial cooling. Image credit: Rosenlof, K. H., and G. C. Reid (2008), Trends in the temperature and water vapor content of the tropical lower stratosphere: Sea surface connection, J. Geophys. Res., 113, D06107, doi:10.1029/2007JD009109.

The observations
We haven't been able to observe water vapor in the stratosphere very long--accurate global measurements only go back to 1991, when the HALOE instrument aboard the Upper Atmosphere Research Satellite (UARS) began taking data (Figure 1). Stratospheric water vapor showed an increase of about 0.5 parts per million by volume (ppmv) during the 1990s. But after 2000, a sudden drop of 0.4 ppmv was observed, and this decrease has persisted into 2009. To see how these changes impacted the amount of global warming, Solomon et al. fed the observations into a specialized high-resolution model that computed the change in heat from the fluctuating water vapor levels. They found that the increase in stratospheric water vapor in the 1990s led to about a 30% increase in the amount of global warming observed during that decade, and the decrease of 0.4 ppmv since 2000 led to a 25% reduction between 2000 - 2009.

How water vapor gets into the stratosphere
The stratosphere has two main sources of water vapor: transport from the lower atmosphere (the troposphere) via tall thunderstorms, and the chemical breakdown of methane gas into water vapor and carbon dioxide. With regard to greenhouse effect warming, transport of water vapor by thunderstorms is the most important source, since this mechanism delivers water vapor to the lowest part of the stratosphere, where temperatures are coldest and greenhouse gases are more effective at warming the climate. There is a limit as to how much water vapor that can enter the stratosphere via thunderstorms, though. Temperature decreases with altitude from the surface to the bottom of the stratosphere, where they begin to rise with height due to the solar energy-absorbing effect of the stratospheric ozone layer. As moisture-laden air rises in thunderstorms towards the lower stratosphere, it encounters the atmosphere's "cold point"--the coldest point in the lower atmosphere, at the base of the stratosphere. Since the amount of water vapor that can be present in the atmosphere decreases as the temperature gets colder, and moisture being transported to the stratosphere must traverse through the "cold point" of the atmosphere, the air gets "freeze dried" and loses most of its moisture.


Figure 2. The departure from average of tropopause temperature (dark line) and Sea Surface Temperature (light dashed line) for the tropical Pacific Ocean between 10°S - 10°N, from 1981 - 2007. The tropopause is the bottom boundary of the stratosphere. The SST data is for 139°W - 171°W longitude, and is from the NOAA Optimal Interpolation v2 data set. The tropopause data is from balloon soundings, for the region 171°W - 200°W. The SST is plotted so that the anomalies increase as one looks down. Note that prior to about 2000, tropopause temperatures and SSTs increased and decreased together, but that beginning in 2000 - 2001, a sharp climate shift occurred, and the two quantities became anti-correlated. The sudden drop in tropopause temperature in 2000 - 2001 caused a sharp drop in stratospheric water vapor. Image credit: Rosenlof, K. H., and G. C. Reid (2008), Trends in the temperature and water vapor content of the tropical lower stratosphere: Sea surface connection, J. Geophys. Res., 113, D06107, doi:10.1029/2007JD009109.

Why did stratospheric water vapor drop in 2000?
Tall thunderstorms capable of delivering water vapor into the stratosphere occur primarily in the tropics, particularly over the Western Pacific, where a huge warm pool with very high Sea Surface Temperatures (SSTs) exists. In 2000, this region experienced a sharp increase in SST of 0.25°C, which has remained consistent though the 2000s (Figure 2). Coincident with this increase in SST came a sharp drop in the "cold point" temperature of the tropopause--the lower boundary of the stratosphere. This reduction in "cold point" temperature meant that less water vapor could make it into the stratosphere over the Tropical Pacific, since more thunderstorm water was getting "freeze dried" out. Did global warming trigger this increase in Pacific SST, resulting in cooling of the "cold point" and less water vapor in the stratosphere? Or was it random variation due to some decades-long natural cycle? This key question was left unanswered by the Solomon et al. study, and observations of stratospheric water vapor don't go back far enough to offer a reasonable guess. One factor arguing against global warming having triggered a negative feedback of this nature is that prior to 2000, increases in Western Pacific SST caused increases in "cold point" temperatures--behavior opposite of what has been seen since 2000.

If global warming has triggered the decrease in stratospheric water vapor seen since 2000, it could mean that the climate models have predicted too much global warming, since they don't predict that such a negative feedback exists. On the other hand, if this is a natural cycle, we can expect the recent flattening in global temperatures to average out in the long run, with a return to steeper increases in temperature in the coming decades. Climate models currently do a poor job modeling the complex dynamics of water vapor in the stratosphere, and are not much help figuring out what's going on. Complicating the issue is the fact that about 15% of all thunderstorms capable of delivering water vapor into the stratosphere are generated by tropical cyclones (Rosenlof and Reid, 2008), and tropical cyclones are not well-treated by climate models. We also have to factor in the impact of stratospheric ozone loss, which acts to cool the lower stratosphere. This effect should gradually decrease in future decades as CFC levels decline, though. The stratosphere is a devilishly complicated place that can have a significant impact on global climate change, and we are many years from understanding what is going on there.

References
Romps, D.M., and Z. Kuang, "Overshooting convection in tropical cyclones", Geophysical Research Letters, 2009; 36 (9): L09804 DOI: 10.1029/2009GL037396

Rosenlof, K. H., and G. C. Reid (2008), Trends in the temperature and water vapor content of the tropical lower stratosphere: Sea surface connection, J. Geophys. Res., 113, D06107, doi:10.1029/2007JD009109.

Portlight Haiti update
Paul Timmons, who directs the Portlight.org disaster-relief charity that has sprung up from the hard work and dedication of many members of the wunderground.com community, was interviewed by NBC yesterday. The reporter doing the story is planning to follow the Portlight-donated goods to Haiti and interview the people with disabilities that receive the donations. It is uncertain when the story will be aired, but I'll try to give everyone a heads-up.

Next post
My next post will probably be Tuesday (Groundhog's Day), when I plan to discuss Phil's forecast for the rest of winter. I'll throw in my two cents worth, too.

Jeff Masters

Climate Change

A new world record wind gust: 253 mph in Australia's Tropical Cyclone Olivia

By: JeffMasters, 5:34 PM GMT on January 27, 2010

The 6,288-foot peak of New Hampshire's Mount Washington is a forbidding landscape of wind-swept barren rock, home to some of planet Earth's fiercest winds. As a 5-year old boy, I remember being blown over by a terrific gust of wind on the summit, and rolling out of control towards a dangerous drop-off before a fortuitously-placed rock saved me. Perusing the Guinness Book of World Records as a kid, three iconic world weather records always held a particular mystique and fascination for me: the incredible 136°F (57.8°C) at El Azizia, Libya in 1922, the -128.5°F (-89.2°C) at the "Pole of Cold" in Vostok, Antarctica in 1983, and the amazing 231 mph wind gust (103.3 m/s) recorded in 1934 on the summit of Mount Washington, New Hampshire. Well, the legendary winds of Mount Washington have to take second place now, next to the tropical waters of northwest Australia. The World Meteorological Organization (WMO) has announced that the new world wind speed record at the surface is a 253 mph (113.2 m/s) wind gust measured on Barrow Island, Australia. The gust occurred on April 10, 1996, during passage of the eyewall of Category 4 Tropical Cyclone Olivia.


Figure 1. Instruments coated with rime ice on the summit of Mt. Washington, New Hampshire. Image credit: Mike Theiss.

Tropical Cyclone Olivia
Tropical Cyclone Olivia was a Category 4 storm on the U.S. Saffir-Simpson scale, and generated sustained winds of 145 mph (1-minute average) as it crossed over Barrow Island off the northwest coast of Australia on April 10, 1996. Olivia had a central pressure of 927 mb and an eye 45 miles in diameter at the time, and generated waves 21 meters (69 feet) high offshore. According to Black et al. (1999), the eyewall likely had a tornado-scale mesovortex embedded in it that caused the extreme wind gust of 253 mph. The gust was measured at the standard measuring height of 10 meters above ground, on ground at an elevation of 64 meters (210 feet). A similar mesovortex was encountered by a Hurricane Hunter aircraft in Hurricane Hugo of 1989, and a mesovortex was also believed to be responsible for the 239 mph wind gust measured at 1400 meters by a dropsonde in Hurricane Isabel in 2003. For reference, 200 mph is the threshold for the strongest category of tornado, the EF-5, and any gusts of this strength are capable of causing catastrophic damage.


Figure 2. Visible satellite image of Tropical Cyclone Olivia a few hours before it crossed Barrow Island, Australia, setting a new world-record wind gust of 253 mph. Image credit: Japan Meteorological Agency.


Figure 3. Wind trace taken at Barrow Island, Australia during Tropical Cyclone Olivia. Image credit: Buchan, S.J., P.G. Black, and R.L. Cohen, 1999, "The Impact of Tropical Cyclone Olivia on Australia's Northwest Shelf", paper presented at the 1999 Offshore Technology Conference in Houston, Texas, 3-6 May, 1999.

Why did it take so long for the new record to be announced?
The instrument used to take the world record wind gust was funded by a private company, Chevron, and Chevron's data was not made available to forecasters at Australia's Bureau of Meteorology (BOM) during the storm. After the storm, the tropical cyclone experts at BOM were made aware of the data, but it was viewed as suspect, since the gusts were so extreme and the data was taken with equipment of unknown accuracy. Hence, the observations were not included in the post-storm report. Steve Buchan from RPS MetOcean believed in the accuracy of the observations, and coauthored a paper on the record gust, presented at the 1999 Offshore Technology Conference in Houston (Buchan et al., 1999). The data lay dormant until 2009, when Joe Courtney of the Australian Bureau of Meteorology was made aware of it. Courtney wrote up a report, coauthored with Steve Buchan, and presented this to the WMO extremes committee for ratification. The report has not been made public yet, and is awaiting approval by Chevron. The verified data will be released next month at a World Meteorological Organization meeting in Turkey, when the new world wind record will become official.

New Hampshire residents are not happy
Residents of New Hampshire are understandably not too happy about losing their cherished claim to fame. The current home page of the Mount Washington Observatory reads, "For once, the big news on Mount Washington isn't our extreme weather. Sadly, it's about how our extreme weather--our world record wind speed, to be exact--was outdone by that of a warm, tropical island".

Comparison with other wind records
Top wind in an Atlantic hurricane: 239 mph (107 m/s) at an altitude of 1400 meters, measured by dropsonde in Hurricane Isabel (2003).
Top surface wind in an Atlantic hurricane: 211 mph (94.4 m/s), Hurricane Gustav, Paso Real de San Diego meteorological station in the western Cuban province of Pinar del Rio, Cuba, on the afternoon of August 30, 2008.
Top wind in a tornado: 302 mph (135 m/s), measured via Doppler radar at an altitude of 100 meters (330 feet), in the Bridge Creek, Oklahoma tornado of May 3, 1999.
Top surface wind not associated with a tropical cyclone or tornado: 231 mph (103.3 m/s), April 12, 1934 on the summit of Mount Washington, New Hampshire.
Top wind in a typhoon: 191 mph (85.4 m/s) on Taiwanese Island of Lanyu, Super Typhoon Ryan, Sep 22, 1995; also on island of Miyakojima, Super Typhoon Cora, Sep 5, 1966.
Top surface wind not measured on a mountain or in a tropical cyclone: 207 mph (92.5 m/s) measured in Greenland at Thule Air Force Base on March 6, 1972.
Top wind measured in a U.S. hurricane: 186 mph (83.1 m/s) measured at Blue Hill Observatory, Massachusetts, during the 1938 New England Hurricane.

References
Buchan, S.J., P.G. Black, and R.L. Cohen, 1999, "The Impact of Tropical Cyclone Olivia on Australia's Northwest Shelf", paper presented at the 1999 Offshore Technology Conference in Houston, Texas, 3-6 May, 1999.

Black, P.G., Buchan, S.J., and R.L. Cohen, 1999, "The Tropical Cyclone Eyewall Mesovortex: A Physical Mechanism Explaining Extreme Peak Gust Occurrence in TC Olivia, 4 April 1996 on Barrow Island, Australia", paper presented at the 1999 Offshore Technology Conference in Houston, Texas, 3-6 May, 1999.

Jeff Masters

Hurricane

Poorly sited U.S. temperature instruments not responsible for artificial warming

By: JeffMasters, 5:57 PM GMT on January 25, 2010

Former TV weatherman Anthony Watts, who runs the popular global warming contrarian website, "Watts Up With That", was convinced that many of the U.S. network of surface weather stations had serious flaws in their siting that was causing an artificial warm bias in the observed increase in U.S. temperatures of 1.1°F over the past century. To address this concern, Watts established the website surfacestations.org in 2007, which enlisted an army of volunteers to travel the U.S. to obtain photographic evidence of poor siting of weather stations. The goal was to document cases where "microclimate" influence was important, and could be contaminating temperature measurements. (Note that this is a separate issue from the Urban Heat Island, the phenomenon where a metropolitan area in general is warmer than surrounding rural areas). Watts' volunteers--650 strong--documented the siting of 865 of the 1,218 stations used in the National Climatic Data Center's U.S. Historical Climatology Network (USHCN) for tracking climate change. As reported in Watt's 2009 publication put out by the Heartland Institute, the volunteers "found stations located next to the exhaust fans of air conditioning units, surrounded by asphalt parking lots and roads, on blistering-hot rooftops, and near sidewalks and buildings that absorb and radiate heat." Watts surmised that these poorly-sited stations were responsible for much of the increase in U.S. temperatures over the past century, due to "a bias trend that likely results from the thermometers being closer to buildings, asphalt, etc." Watts concluded, "the U.S. temperature record is unreliable. And since the U.S. record is thought to be the best in the world, it follows that the global database is likely similarly compromised and unreliable".


Figure 1. A poorly sited temperature sensor in Marysville, California, used for the USHCN. The sensor is situation right next to an asphalt parking lot, instead in the middle of a grassy field, as it is supposed to be. The sensor is also adjacent to several several air conditioners that blow their exhaust into the air nearby. Image credit: surfacestation.org.

Analysis of the data disagrees with Watts' conclusion
While Watts' publication by the Heartland Institute is a valuable source of information on siting problems of the U.S. network of weather stations, the publication did not undergo peer-review--the process whereby three anonymous scientists who are experts in the field review a manuscript submitted for publication, and offer criticisms on the scientific validity of the results, resulting in revisions to the original paper or outright rejection. The Heartland Institute is an advocacy organization that accepts money from corporate benefactors such as the tobacco industry and fossil fuel industry, and publishes non-peer reviewed science that inevitably supports the interests of the groups paying for the studies. Watts did not actually analyze the data to see if taking out the poorly sited surface stations would have a significant impact on the observed 1.1°F increase in U.S. temperatures over the past century. His study would never have been publishable in a peer-reviewed scientific journal.


Figure 2. Annual average maximum and minimum unadjusted temperature change calculated using (c) maximum and (d) minimum temperatures from good and poor exposure sites (Menne 2010). Poor sites showed a cooler maximum temperature compared to good sites. For minimum temperature, the poor sites were slightly warmer. The net effect was a cool bias in poorly sited stations. The dashed lines are for stations ranked by NOAA, while the solid lines are for the stations ranked by surfacestations.org.

Fortunately, a proper analysis of the impact of these poorly-sited surface stations on the U.S. historical temperature record has now been done by Dr. Matthew Menne and co-authors at NOAA's National Climatic Data Center (NCDC). In a talk at last week's 90th Annual Meeting of the American Meteorological Society, Dr. Menne reported the results of their new paper just accepted for publication in the Journal of Geophysical Research titled, On the reliability of the U.S. Surface Temperature Record. Dr. Menne's study split the U.S. surface stations into two categories: good (rating 1 or 2) and bad (ratings 3, 4 or 5). They performed the analysis using both the rating provided by surfacestations.org, and from an independent rating provided by NOAA personnel. In general, the NOAA-provided ratings coincided with the ratings given by surfacestations.org. Of the NOAA-rated stations, only 71 stations fell into the "good" siting category, while 454 fell into the "bad" category. According to the authors, though, "the sites with good exposure, though small in number, are reasonably well distributed across the country and, as shown by Vose and Menne [2004], are of sufficient density to obtain a robust estimate of the CONUS average". Dr. Menne's study computed the average daily minimum and maximum temperatures from the good sites and poor sites. The results were surprising. While the poor sites had a slightly warmer average minimum temperature than the good sites (by 0.03°C), the average maximum temperature measured at the poor sites was significantly cooler (by 0.14°C) than the good sites. As a result, overall average temperatures measured at the poor sites were cooler than the good sites. This is the opposite of the conclusion reached by Anthony Watts in his 2009 Heartland Institute publication.

Why did the poorly sited stations measure cooler temperatures?
The reason why the poorly-sites stations measured cooler temperatures lies in the predominant types of thermometers used at the two types of sites. An electronic Maximum/Minimum Temperature System (MMTS) is used at 75% of the poor sites. These MMTS sensors are attached by cable to an indoor readout device, and are consequently limited by cable length as to how far they can be sited from the building housing the indoor readout device. As a result, they are often located close to heated buildings, paved surfaces, air conditioner exhausts, etc. It turns out that these MMTS thermometers have a flaw that causes them to measure minimum temperatures that are slightly too warm, and maximum temperatures that are considerably too cool, leading to an overall cool bias in measured average temperatures. In contrast, only 30% of the "good" sites used the MMTS sensors. The "good" sites predominantly used Liquid in Glass (LiG) thermometers housed in wooden shelters that were more easily located further from the buildings where the observers worked. Since the poorly-sites stations were dominantly equipped with MMTS thermometers, they tended to measure temperatures that were too cool, despite their poor siting.


Figure 3. Comparison of U.S. average annual (a) maximum and (b) minimum temperatures calculated using USHCN version 2 temperatures. Temperatures were adjusted to correct for changes in instrumentation, station relocations, and changes in the time of observation, making the trend from good sites show close agreement with poor sites. Good and poor site ratings are based on surfacestations.org. For comparison, the data between 2004 - 2008 taken by the new high-quality U.S. Climate Reference Network (USCRN, black dashed line) is shown, and displays excellent agreement for that time period. Image credit: Menne 2010.

Independent verification of recent USHCN annual temperatures
Clearly, the siting of many of the surface stations used to track climate change in the U.S. is not good. To address this issue, in 2004 NOAA created the U.S. Climate Reference Network, a collection of 114 stations in the continental United States for the express purpose of detecting the national signal of climate change. The stations were sited and instrumented with climate studies in mind, and can provide an extremely high-quality independent check on the old USHCN network. Each of 114 stations at 107 locations (some stations were installed as nearby pairs) is equipped with very accurate instruments in a triplicate configuration so that each measurement can be checked for internal consistency. As shown in Figure 3, the USCRN air temperature departures for 2004 - 2008 are extremely well aligned with those derived from the USHCN version 2 temperature data. For these five years, the the difference between the mean annual temperatures measured by the old USHCN compared to the new USCRN was just 0.03°C, with a mathematical correlation coefficient (r-squared) of 0.997. Menne et al. concluded, "This finding provides independent verification that the USHCN version 2 data are consistent with research-quality measurements taken at pristine locations and do not contain spurious trends during the recent past even if sampled exclusively at poorly sited stations. While admittedly this period of coincident observations between the networks is rather brief, the value of the USCRN as a benchmark for reducing the uncertainty of historic observations from the USHCN and other networks will only increase with time". The authors finally concluded, "we find no evidence that the CONUS temperature trends are inflated due to poor siting".

Crediting Anthony Watts
The surfacestations.org effort coordinated by Anthony Watts has made a valuable contribution to science, helping us better understand the nature of the errors in the U.S. historical temperature data set. In his talk last week at the AMS conference, and in the credits of his paper, Dr. Menne had some genuinely grateful comments on the efforts of Anthony Watts and the volunteers of surfacestations.org. However, as of this writing, Watts has made no mention on surfacestations.org or on wattsupwiththat.com of Dr. Menne's study.

I'll have a new post Wednesday or Thursday.

Jeff Masters

Climate Change

Strongest winter storm in at least 140 years whallops Southwest U.S.

By: JeffMasters, 4:18 PM GMT on January 22, 2010

The most powerful low pressure system in 140 years of record keeping swept through the Southwest U.S. yesterday, bringing deadly flooding, tornadoes, hail, hurricane force winds, and blizzard conditions. We expect to get powerful winter storms affecting the Southwest U.S. during strong El Niño events, but yesterday's storm was truly epic in its size and intensity. The storm set all-time low pressure records over roughly 10 - 15% of the U.S.--over southern Oregon, and most of California, Nevada, Arizona, and Utah. Old records were broken by a wide margin in many locations, most notably in Los Angeles, where the old record of 29.25" set January 17, 1988, was shattered by .18" (6 mb). Bakersfield broke its record by .30" (10 mb). The record-setting low spawned an extremely intense cold front that rumbled thought the Southwest, and winds ahead of the cold front reached sustained speeds of hurricane force--74 mph--last night at Apache Junction, 40 miles east of Phoenix. Wind gusts as high as 94 mph were recorded in Ajo, Arizona, and a Personal Weather Station in Summerhaven (on top of Mt. Lemmon next to Tucson) recorded sustained winds of 67 mph, gusting to 86 mph, before the power failed. Prescott recorded sustained winds at 52 mph, gusting to 67 as the cold front passed, and high winds plunged visibility to zero in blowing dust on I-10 connecting Phoenix and Tucson. The storm spawned one possible tornado in Arizona, which touched down at 8:32 pm MST in Phoenix near Desert Ridge Mall. No damage or injuries were reported. If verified, it would be only the 7th January tornado in Arizona since record keeping began in 1950.


Figure 1. Radar reflectivity from the Phoenix Doppler radar at the time of the Phoenix tornado. The tornado touched down under the circle with a "+" inside it. The Doppler velocity image did not show any rotation to the clouds in the vicinity.

Some of the all-time low pressure records set in yesterday's storm:
Los Angeles, CA: 29.07", Old Record: 29.25", January 17, 1988
Eureka, CA: 28.90", Old Record: 28.91", February 1891
San Diego, CA: 29.15", Old Record, 29.37", March 3, 1983
Fresno, CA: 28.94", Old Record, 29.10", January 27, 1916
Bakersfield, CA: 28.94", Old Record, 29.24", February 3, 1998

Salt Lake City, UT: 28.94", Old Record, 29.00" April 2002

Reno, NV: 28.94", Old Record, 29.00", January 27, 1916
Las Vegas, NV: 29.03" Old Record: 29.17", December 1949

Phoenix, AZ: 29.22", Old Record: 29.32", May 18, 1902
Flagstaff, AZ: 29.13", Old Record: 29.15", February 7, 1937
Yuma, AZ: 29.15", Old Record: 29.37", September 12, 1927

Three tornadoes in California
Three tornadoes were reported in California yesterday. A small EF0 twister hit the east side of Ventura, leaving a 1.5 mile damage path. Another tornado hit Santa Barbara, downing trees and power poles. The most damaging California tornado yesterday touched down just west of Blythe, on the Arizona-California border, at 4:31 pm MST. The twister crossed I-10, blowing three semi trucks over, ripping the roofs off houses, and downing power lines. I-10 was closed for several hours to clear the debris and toppled trucks.

Two tornadoes also hit Southern California on Tuesday. A sheriff's deputy spotted a possible tornado in Goleta that caused some roof damage, and another tornado hit Huntington Beach, damaging boats and buildings and flipping cars.

If all five tornadoes are confirmed as genuine by the National Weather Service, it will tie the record of most January California tornadoes. The all-time record for most California tornadoes in a single day is seven, set on April 1, 1996, and November 9, 1982.


Figure 2. Radar reflectivity from the Los Angeles Doppler radar at the time of the Santa Barbara tornado.

Figure 3. Storm-relative radial velocity from the Los Angeles Doppler radar at the time of the Santa Barbara tornado. The area of yellow and orange colors, lying right next to a region of blues and greens just west of Santa Barbara shows that the winds in that region were moving towards and away from the radar in a very tight area, signifying the presence of a rotating thunderstorm and possible tornado.

The storm will continue to bring heavy rain and snow to many portions the Southwest today, then wind down on Saturday. A new storm is expected to move ashore over Northern California on Sunday night, but this storm will not be as intense. Another storm is also possible next Friday, January 29, but it appears that a renewed battering by a long succession of storms like we had this week will not occur next week.

Selected storm total snowfalls (in inches) from 7 am Sunday January 17, through 7 am PST Friday January 22:
...ARIZONA...
FLAGSTAFF 3.2 NNW 36.5
SUNRISE MOUNTAIN 29.0
FOREST LAKES 26.0
HEBER 21.0
PINETOP/LAKESIDE 4 ESE 20.4
ALPINE 20.0
CLAY SPRINGS 20.0
CLINTS WELL 19.0
KACHINA VILLAGE 18.6
WILLIAMS 16.5
PRESCOTT 7.0

...CALIFORNIA...
CHAGOOPA PLATEAU 73.6
SODA SPRINGS 63.0
SUGAR BOWL 61.0
LWR RELIEF VALLEY 50.6
KIRKWOOD 48.0
SQUAW VALLEY 47.0
SIERRA AT TAHOE 38.0
BIG BEAR CITY 37.0

...COLORADO...
DURANGO 24.0
PAGOSA SPRINGS 9 NW 24.0
SILVERTON 24.0
WOLF CREEK PASS 1 SSE 24.0
ABAJO 19.0
TELLURIDE 15.0
COAL BANK PASS 14.5
RED MTN 12.3
CREEDE 10 SW 12.0
SOUTH FORK 4 SW 12.0
MOLAS PASS 10.0

...NEW MEXICO...
JEMEZ SPRINGS 14.0
CHAMA 12.0
FARMINGTON 7 NE 10.5
AZTEC 8.0
BLUEWATER LAKE 11 WSW 8.0
BONITO LAKE 5 SW 8.0
FARMINGTON 7 NE 8.0
LUNA 8.0
KIRTLAND 2 ESE 6.0
MOGOLLON 6 ESE 6.0
RAMAH 6.0
BLOOMFIELD 3 SW 5.5
LOS ALAMOS 5.5

...NEVADA...
YUCCA FLAT 20.0
BERRY CREEK 19.0
BIG CREEK SUMMIT 16.0
DRAW CREEK 13.0
POLE CREEK R.S. 13.0
MT. POTOSI 12.0
ELY 8.3
WARD MOUNTAIN 8.0
CHARLESTON 6.0

...UTAH...
BRIGHTON CREST 35.0
ALTA/COLLINS 33.5
DEER VALLEY DALY WEST 28.0
PARK CITY JUPITER PEAK 28.0
BIG COTTONWOOD SPRUCES 19.0
SOLITUDE 17.5
SNOWBIRD 13.5

Selected storm total precipitation (in inches) from 7 am Sunday January 17, through 7 am PST Friday January 22:
...ARIZONA...
DAVIS-MONTHAN AFB/TUCSON 10.23
BLACK CANYON CITY 10 N 6.57
CROWN KING 6.50
SURPRISE 1 ESE 5.58
SUN CITY WEST 2 NNE 4.78
COTTONWOOD 1 WSW 4.63
SCOTTSDALE 5.5 NNW 4.21
NEW RIVER 5 ESE 4.05
WITTMAN 5 SW 4.05
PAYSON 4.01
PINE 1 SW 4.00
SIERRA VISTA 3.83
LUKE AFB/PHOENIX 3.58
CASTLE HOT SPRINGS 3.55
FLAGSTAFF PULLIAM AP 3.41
CLIFTON 2.96
WINSLOW 2.84
GILBERT 4 NW 2.74
CHANDLER 4 WNW 2.72
YUMA MCAF 2.43
PRESCOTT/ERNEST A LOVE FIELD AP 2.28
PHOENIX AIRPORT 2.21
TUCSON AIRPORT 0.52

...CALIFORNIA...
LOS GATOS 4 SW 14.70
CAZADERO 13.46
LYTLE CREEK 13.39
MINING RIDGE 13.14
PETROLIA 7 SE 12.17
BARTLETT SPRINGS 11.23
LAKE ARROWHEAD 11.23
ALTADENA 1 ESE 11.14
CLOVERDALE 1 S 10.30
CRESTLINE 10.27
DEVORE 9.58
DESERT HOT SPRINGS 8.04
UKIAH MUNI ARPT 7.58
NEWHALL 7.08
SANTA ROSA/SONOMA CO ARPT 6.55
SAN LUIS OBISPO ARPT 5.37
SAN DIEGO/MONTGOMERY FIELD 4.32
SAN FRANCISCO INTL ARPT 4.30
LOS ANGELES-USC 3.89
PALM SPRINGS RGNL ARPT 3.75
SACRAMENTO METRO ARPT 3.65
SAN JOSE INTL ARPT 3.19

...NEVADA...
NORTH LAS VEGAS AIRPORT 1.50
HENDERSON AIRPORT 1.17
MERCURY/DESERT ROCK ARPT 1.06

...OREGON...
AGNESS 6.4 NE 3.90
PORT ORFORD 5.0 E 3.52
BROOKINGS 4.2 ENE 2.83
BANDON 11.4 S 2.67
ASTORIA 1.45

...WASHINGTON...
HOQUIAM/BOWERMAN AIRPORT 2.01

Tornadoes, severe weather in the South
Severe weather associated with a separate storm brought damaging winds, hail, and tornadoes to portions of Kentucky, Tennessee, Georgia, Alabama, and Florida last night. Two tornadoes were reported, one in Tennessee, and one in Alabama, near Huntsville. The Huntsville tornado injured approximately six people, and cut power to 10,000 people. The storm responsible for the severe weather has moved out to sea, and no further severe weather is expected today. A slight chance of severe weather is expected Saturday over Arkansas and Mississippi, and there is also a severe weather threat for Georgia and surrounding states on Sunday.


Figure 4. Last night's Huntsville, Alabama tornado was captured by wunderphotographer Southampton.

Portlight's Paul Timmons to appear on NBC and CNN
Portlight.org, the disaster-relief charity that has sprung up from the hard work and dedication of many members of the wunderground.com community, has successfully shipped medical equipment and a water filtration unit capable of supplying the needs of 3,500 people per day to the Dominican Republic. The relief supplies were trucked to Haiti via road, and have made it to the earthquake zone. The supplies have been targeted to go to those with disabilities, or to those who are living in areas where the main aid efforts have been inadequate. Portlight is working through the local Catholic Church, which is probably best positioned to deliver private aid donations to those in need. Paul Timmons, leader of the Portlight relief efforts, is scheduled to appear on NBC news later today, and on CNN news tomorrow, to discuss Portlight's efforts.


Figure 5. Walkers and medical supplies for Haiti getting ready to ship from the Portlight warehouse in Atlanta.

Please visit the Portlight.org blog to learn more. Floodman's blog has the latest info on Portlight's plan for Haitian relief. The Reeve Foundation, founded by Christopher and Dana Reeve has awarded Portlight Strategies a $10,000 Quality of of Life grant to assist in the relief efforts in Haiti. This is very big and will allow Portlight to pursue more aggressive relief efforts over the course of the next few weeks.

For those of you more interested in helping out with the long-term rebuilding of Haiti's shattered infrastructure from the quake, I recommend a contribution to Lambi Fund of Haiti, a charity that is very active in promoting reforestation efforts, use of alternative fuels, and infrastructure improvements at a grass-roots level in Haiti. I've developed a great respect for the work they do in the country in the five years I've been a supporter.

Next post
My next post will be Monday.

Jeff Masters

Winter Weather

A wild weather night in Arizona

By: JeffMasters, 3:08 AM GMT on January 22, 2010

The most powerful low pressure system in Arizona history is generating havoc in the state tonight, as a powerful cold front sweeps through. Prescott last hour recorded sustained winds at 52 mph, gusting to 67 as the cold front passed. Visibility was zero in blowing dust on I-10 connecting Phoenix and Tucson, and a cooperative observer in Apache Junction between Phoenix and Tucson reported sustained winds of hurricane force, 74 mph. A tornado touched down just west of Blythe, on the Arizona California border, at 4:31 pm MST. The twister crossed I-10, blowing three semi trucks over, blowing the roofs off houses, and downing power lines. I-10 has been closed until further notice, according to media reports.


Figure 1. Radar image of Arizona's nastiest cold front in recorded history approaching Phoenix.

This past hour, Phoenix obliterated their all-time record low pressure, set in 1902. The old record was 29.32", and they are now at 29.22", with the pressure still falling. Flagstaff has also beaten their all-time low pressure record, which was 29.15", set in 1937. The pressure has fallen to 29.13" so far. Yuma also set a new record, 29.15", compared to the old record of 29.37". At 4:41 PM today, Las Vegas set a new record of 29.03 inches. This crushed the all-time record low sea level pressure of 29.17 inches set in December 1949. Fresno, Bakersfield, Eureka, and San Diego have also set new all-time low pressure records today.

Links to follow tonight:

Severe Weather Page.
Interactive Tornado Map.
Arizona Current Conditions.

I'll have a full update on Friday morning.

Jeff Masters

Winter Weather

Storm battering California sets record low pressure mark

By: JeffMasters, 3:53 PM GMT on January 21, 2010

One of the most powerful low pressure systems since record keeping began in the 1800s slammed the West Coast yesterday with hurricane-force wind gusts, large hail, and torrential rains that have created flash floods and dangerous debris flows. The storm, centered just offshore near the Oregon/California border this morning, set an all-time record for the lowest pressure ever recorded along the southern Oregon coast yesterday. Medford, Oregon hit a pressure of 978 mb (28.88") yesterday afternoon, beating their old lowest ever pressure of 28.93" set in 1995. Northern California came close to setting a new record for lowest pressure as well, as Eureka, California hit 980 mb (28.93"), nearly matching the old record of 979 mb (28.91") set on Feb 22, 1891.


Figure 1. Huge waves up to fifteen feet high slam ashore yesterday on Agate Beach, in Northern California. Image credit: wunderphotographer Tsurai.

The storm, the latest and strongest of a series of El Niño-fueled storms to assault California this week, is expected to bring heavy rains of 1 - 3 inches over much of of the state today, wind gusts of up to 45 mph near the coast, and heavy snows of 1 - 2 feet to the Sierras. Arizona is expected to receive heavy rains of up to five inches from the storm. The storm will wind down by Friday, and California will have brief respite Saturday, before the next storm hits on Sunday and Monday. Sunday's storm should be much weaker, and the state will get a chance to dry out Wednesday and Thursday. However, another parade of storm is forecast to impact the state beginning on Friday the 29th, according to the latest long-range forecasts of the GFS and ECMWF models.

Severe weather in central California
The cold front associated with the strong low swept inland yesterday afternoon over central California, triggering heavy thunderstorms that brought hail and heavy rains in excess of two inches to some locations. A rare tornado warning was issued for Morgan Hill in the San Francisco Bay area at 2:02pm, when Doppler radar revealed a rotating thunderstorm. No touchdown of a tornado occurred, though 1-inch hail was observed in Morgan Hill. The Storm Prediction Center (SPC) has placed Los Angeles and San Diego in the "Slight Risk" region for severe weather today. The primary severe weather risk will be damaging thunderstorm winds, though a few tornadoes and waterspouts may also occur.

Snowfall amounts of 1 - 2 feet were recorded in the Sierra Mountains yesterday, with up to 4 1/2 feet of snow expected to fall by the time the storm ends on Saturday. Some precipitation amounts from the storm, for the 4-day period ending at 4am PST today:

Major Cities:

Los Angeles 2.80
San Francisco 3.49
Sacramento 2.35
Eureka 2.78
San Diego 1.65
Fresno 1.33

Sierra Nevada sites:

Chilkoot Meadow 7.08
Kaiser Point 6.60
Tenaya Lake 6.54
Graveyard Meadow 5.64
Tamarack Summit 5.36
Yosemite Village 4.04

Tornadoes, severe weather in the South
Tornadoes tore through Texas and Louisiana yesterday, with one twister destroying several homes and businesses near in Waskom, Texas, near the Louisiana border. Fourteen tornado reports were received yesterday by the Storm Prediction Center (SPC). SPC has placed portions of Alabama, Georgia, Mississippi, Tennessee, and Florida under their "Slight Risk" region for severe weather today. Already, there have been tornado warnings posted this morning for the Florida Panhandle, and southern Georgia.


Figure 2. Radar reflectivity from the Shreveport, LA radar last night shows the classic hook echo of the tornado that tore through Waskom, Texas.

Portlight successfully gets much-needed water filtration systems and medical supplies into Haiti
Portlight.org, the disaster-relief charity that has sprung up from the hard work and dedication of many members of the wunderground.com community, has successfully shipped medical equipment and a water filtration unit capable of supplying the needs of 3,500 people per day to the Dominican Republic, where was trucked to Haiti via road. These supplies have now made it to the earthquake zone, and have been targeted to go to those with disabilities, or who are living in areas where the main aid efforts have forgotten. Portlight is working through the local Catholic Church, which is probably best positioned to deliver private aid donations to those in need. Paul Timmons, leader of the Portlight relief efforts, wrote this to me yesterday:

Thanks to Wunderground blogger Dak Simonton (Dakster) we were made aware of Richard Lamarque, a Haitian expatriate and 15 year veteran of the Miami Police Department who was planning to go back to Haiti this week to look for family members and to help with recovery efforts. Our on scene coordinator, Richard Lamarque, will be leaving for Haiti in a few days. He is from there, is well connected there, and has a skill set and life experiences which will be invaluable to our work there.

We want this to be a uniquely Weather Underground community initiative. We will place WU signage on the truck...and we will be able to post photos of it at work in Haiti.

The Weather Underground community has been the genesis of our efforts. And the WU truck will be a long term, tangible symbol of the generosity of the WU community.



Figure 3. Walkers and medical supplies for Haiti getting ready to ship from the Portlight warehouse in Atlanta.

Thanks to the generosity of its donors, Portlight has been able to fund purchase of the truck for Richard Lamarque. Please visit the Portlight.org blog to learn more. Floodman's blog has the latest info on Portlight's plan for Haitian relief. The Reeve Foundation, founded by Christopher and Dana Reeve has awarded Portlight Strategies a $10,000 Quality of of Life grant to assist in the relief efforts in Haiti. This is very big and will allow Portlight to pursue more aggressive relief efforts over the course of the next few weeks.

For those of you more interested in helping out with the long-term rebuilding of Haiti's shattered infrastructure from the quake, I recommend a contribution to Lambi Fund of Haiti, a charity that is very active in promoting reforestation efforts, use of alternative fuels, and infrastructure improvements at a grass-roots level in Haiti. I've developed a great respect for the work they do in the country in the five years I've been a supporter.

Next post
My next post will be Friday.

Jeff Masters

Winter Weather

Top global weather story of 2009: drought in the Horn of Africa

By: JeffMasters, 3:44 PM GMT on January 19, 2010

I'm in Atlanta at the 90th Annual Meeting of the American Meteorological Society, and the picture I'm getting from the presentations here is that the most significant weather event of 2009 was the failure of the summer rains in the Horn of Africa. Rainfall over most of the Horn of Africa between February and September 2009 was 2 - 12 inches (50 - 300 mm) below average, leading to a continuation of the region's deadly 6-year drought. This drought has very likely contributed significantly to the ongoing civil wars and high levels of violence in some of the affected countries, as the affected population competes for scarce resources. The Horn of Africa has two rainy seasons, a main rainy season in April/May, and then the "short rains" of October/November. The failure of the 2009 main rainy season was the worst such failure of the past six years. The "short rains" of the secondary October/November were mostly near average over the region, fortunately, but millions of people in Kenya, Ethiopia, Somalia, Uganda and Tanzania face hunger and poverty due to withered crops, dead livestock, and dried up ponds and streams, according to the aid group Oxfam. Cattle prices have tumbled from $200 to $4 in some areas as families try to sell dying animals to buy food. Over 1.5 million animals have died in Kenya, Tanzania and Uganda, with an estimated net worth to the region of nearly $360 million, Oxfam said. Cattle represent the only wealth for many nomadic families, and the death of these animals can begin a spiral into poverty and dependency that can trap a family for generations. The those areas where the "short rains" failed--like large parts of the Turkana region of northern Kenya, which received just 12mm of rain October through December--almost one person in three is malnourished. This region of Kenya now has the opposite problem to contend with--severe flooding. Massive downpours, probably linked to El Niño conditions, hit the region December 27 - January 5, resulting in heavy flooding that killed at least 34 people and left 10,000 people homeless. The flooding was worsened by the preceding drought, which killed much of the vegetation that ordinarily would have stabilized the soil and absorbed rainwater before it could run off and create destructive floods. Thousands of cattle were killed and large areas of crops were ruined by the flooding.

The current endemic lawlessness in countries such as Somalia and Yemen are very likely due, in large part, to the extreme drought conditions that have gripped the Horn of Africa over the past six years. Thus the continuation of this drought in 2009 likely contributed to hundreds or thousands of deaths. According to the Associated Press, in addition to the war in Somalia, which has killed at least 300,000 people since 1991 and left 1/2 of the nation's 7.2 million people in need of external aid, rebel groups are battling the central government in Ethiopia, which has restricted access to aid agencies. In northern Kenya and parts of Uganda, heavily armed ethnic militias conduct cattle raids and fight over precious grazing ground and water.


Figure 1. Hydrological drought conditions over the Horn of Africa for a 1-year period (left) and 3-year period (right) as computed using the Standardized Precipitation Index (SPI). Exceptional drought on a 1-year and 3-year time scale was affecting approximately 20 million people in the Horn of Africa, according to the Global Drought Monitor.


Figure 2. Rainfall over most of the Horn of Africa between February and September 2009 was 2 - 12 inches (50 - 300 mm) below average, leading to a continuation of the deadly 6-year drought in the region. Image credit: NOAA Climate Prediction Center.

Droughts and civil war in Africa
African countries are highly dependent on rain-fed agriculture for both employment and economic production, with agriculture accounting for more than 50% of gross domestic product and up to 90% of employment across much of the continent (World Development Indicators 2009, World Bank). One third of the population of Africa lives in drought-prone areas (World Water Forum, 2000), and about 25% of the population of Africa currently experiences high water stress. Since increased drought in Africa leads to increased competition for life-giving water, and it is logical to assume that reduced rainfall will result in increases in civil war. Several scientific studies have shown this to be true. For example, Raleigh and Urdal (2007) found that "decreasing levels of freshwater are associated with higher risks on conflict". They found this relationship was compounded by higher population densities and therefore more competition for resources. Applying a similar approach, Levy et al. (2005) found that when rainfall was significantly below normal, the likelihood of conflict outbreak was higher the subsequent year. Hendrix and Glaser (2007) also found that water availability increased the chances of conflict, but that large year-to-year changes in rainfall were more important in triggering war. For example, a dry year immediately following a wet year was more likely to cause conflict than two dry years in a row, since societies have trouble adjusting to large changes in water availability.

However, we should not just be looking at precipitation, but temperature as well, since higher temperatures also contribute to drought. Higher temperatures increase crop evapotranspiration and accelerate crop development. The combined effect of these two mechanisms is predicted to reduce the yield of African staple crops by 10% - 30% per °C of warming (Lobell et al., 2008). A 2009 study by Burke et al. titled, "Warming increases the risk of civil war in Africa", found a correlation between rising temperatures and civil war in Africa. The researchers found that a 1°C warming--the amount of warming that is expected for Africa by 2030 under some of the typical IPCC climate change scenarios--has historically caused a remarkable 49% relative increase in the incidence of civil war. The authors concluded "this historical response to temperature suggests a roughly 54% increase in armed conflict incidence by 2030, or an additional 393,000 battle deaths if future wars are as deadly as recent wars". While a 1°C warming of temperature will have little impact to societies in many parts of the world, this research suggests that Africa will be very sensitive to global warming. More than two-thirds of the countries in sub-Saharan Africa have experienced civil conflict since 1960, resulting in millions of deaths and monumental human suffering. A 3°C warming by 2100 could kill an additional million people in Africa, if the conclusions of this research are correct. It's easy to think of climate change as a long way off, the researchers said in a press release, but their study shows how sensitive many human systems are to small increases in temperature, and how fast the negative impacts of climate change could be felt. "Our findings provide strong impetus to ramp up investments in African adaptation to climate change, for instance by developing crop varieties less sensitive to extreme heat and promoting insurance plans to help protect farmers from adverse effects of the hotter climate," said lead author Marshall Burke of Stanford's Program on Food Security and the Environment. One promising research development is the recent isolation of a "thermometer gene" that helps plants sense temperature. The discovery could lead to the development of food plants able to flower in much higher temperatures.


Figure 3. The forecast change in precipitation for the period 2090 - 2100, as predicted by 21 climate models used to formulate the 2007 IPCC report on climate change. The "A1B Scenario" results here are for a moderate-case warming, with a best estimate temperature rise of 2.8°C with a likely range of 1.7 - 4.4°C (5.0°F with a likely range of 3.1 - 7.9°F). Blue areas show where more than 90% of the 21 models agree that precipitation increases are likely, while orange areas show where more than 90% of the 21 models agree that precipitation decreases are likely. Image credit: Intergovernmental Panel on Climate Change (IPCC) 2007 Report.

The future of drought in Africa
Global warming theory predicts that although global precipitation should increase in a warmer climate, droughts will also increase in intensity, areal coverage, and frequency (Dai et al., 2004). This occurs because when the normal variability of weather patterns brings a period of dry weather to a region, the increased temperatures due to global warming will intensify drought conditions by causing more evaporation and drying up of vegetation. However, the models used in the 2007 IPCC report on climate change mostly predict an increase in rainfall over the Horn of Africa and the Sahel region of Africa (the southern boundary of the Sahara Desert) by the end of this century (Figure 3). The increased precipitation may act to limit the length and areal extent of droughts in these regions in coming decades. The droughts that do occur may increase in intensity, though, since temperature are predicted to increase by several degrees Centigrade. Could increased rainfall lead to a re-greening of the Sahara towards the lush conditions that existed 12,000 years ago? It is possible, argues Stefan Kropelin of the Institute of Prehistoric Archaeology at the University of Cologne in Germany. Satellite imagery has shown a greening of some southern portions of the Sahara (the Sahel) in recent years, he points out. However, some climate models show lower precipitation in coming decades for the Sahel and Horn of Africa, leading architect Magnus Lasson to propose building a 6,000 km long wall across the Sahara Desert to stop the spread of the desert. The wall would effectively be made by "freezing" the shifting sand dunes, turning them into sandstone using a bacterium called Bacillus pasteurii commonly found in wetlands. The microorganism chemically produces calcite--a kind of natural cement.

What the future ultimately holds for African climate is highly uncertain at this point. While the models used to formulate the 2007 IPCC report do a reasonable job simulating the the current climate over most of the world, they do a poor job of simulating Africa's current climate. The models put too much precipitation in southern Africa, and displace the band of heavy thunderstorms called the Intertropical Convergence Zone (ITCZ) too far south. The 2007 IPCC report concludes, "the absence of realistic variability in the Sahel in most 20th-century simulations casts some doubt on the reliability of models". In other words, since these models do a poor job simulating the current climate of the Sahel region of Africa, we shouldn't trust their predictions for the future climate.

References
Burke, M.B., Miguel, E., Satyanath, S., Dykema, J.A., and D. B. Lobell, "Warming increases the risk of civil war in Africa", PNAS 2009 106: 20670-20674.

Dai A., K.E. Trenberth, and T. Qian, 2004: A global data set of Palmer Drought Severity Index for 1870-2002: Relationship with soil moisture and effects of surface warming", J. Hydrometeorol., 5, 11171130.

Hendrix, C.S., and S.M. Glaser (2007), "Trends and triggers: Climate, climate change and civil conflict in sub-Saharan Africa". Political Geography 26:695-715.

Levy, M. A., Thorkelson, C., Vörösmarty, C., Douglas, E., and M. Humphreys (2005), "Freshwater availability anomalies and outbreak of internal war: results from a global spatial time series analysis". Paper presented at the International Workshop on Climate Change and Human Security, Oslo, Norway, June 21-23.

Lobell, D.B. et al. (2008), "Prioritizing climate change adaptation needs for food security in 2030", Science 319:607-610.

Raleigh and Urdal, 2007, "Climate change, environmental degradation and armed conflict", Political Geography 26 (6) (2007), pp. 674-694.

Sheffield, J., K. M. Andreadis, E. F. Wood, and D. P. Lettenmaier, 2009, "Global and continental drought in the second half of the 20th century: severity-area-duration analysis and temporal variability of large-scale events", J. Climate 22, pp 1962-1981.

Portlight successfully gets much-needed water filtration systems and medical supplies into Haiti
Portlight.org, the disaster-relief charity that has sprung up from the hard work and dedication of many members of the wunderground.com community, has successfully shipped medical equipment and a water filtration unit capable of supplying the needs of 3,500 people per day to the Dominican Republic. The supplies were loaded on trucks and driven into Haiti, and have reached the earthquake zone. These supplies are targeted to go to those with disabilities, or to those who are living in areas forgotten by the main aid efforts. Portlight is working through the local Catholic Church in Haiti, which is probably best positioned to deliver private aid donations to those in need. Paul Timmons, leader of the Portlight relief efforts, wrote this yesterday:

Thanks to Wunderground blogger Dak Simonton (Dakster) we were made aware of Richard Lamarque, a Haitian expatriate and 15 year veteran of the Miami Police Department who was planning to go back to Haiti this week to look for family members and to help with recovery efforts. Our on scene coordinator, Richard Lamarque, will be leaving for Haiti in a few days. He is from there, is well connected there, and has a skill set and life experiences which will be invaluable to our work there.

He will be traveling by ship. We have committed to purchasing for him a small truck to take with him. The truck will be loaded with supplies. Upon arrival, the benefits of having a vehicle on site are self evident. The truck will cost roughly $3,000 - $5,000. We have already earmarked $2000.00 for this.

We want this to be a uniquely Weather Underground community initiative. We will place WU signage on the truck...and we will be able to post photos of it at work in Haiti.

The Weather Underground community has been the genesis of our efforts. And the WU truck will be a long term, tangible symbol of the generosity of the WU community.

The next $3000 we receive will be earmarked for the WU truck. Please post this announcement to blogs...and forward it to all your WU friends.

So, please visit the Portlight.org blog to learn more and to donate. Floodman's blog has the latest info on Portlight's plan for Haitian relief. The Reeve Foundation, founded by Christopher and Dana Reeve has awarded Portlight Strategies a $10,000 Quality of of Life grant to assist in the relief efforts in Haiti. This is very big and will allow Portlight to pursue more aggressive relief efforts over the course of the next few weeks.

For those of you more interested in helping out with the long-term rebuilding of Haiti's shattered infrastructure from the quake, I recommend a contribution to Lambi Fund of Haiti, a charity that is very active in promoting reforestation efforts, use of alternative fuels, and infrastructure improvements at a grass-roots level in Haiti. I've developed a great respect for the work they do in the country in the five years I've been a supporter.

Next post
My next post will be Thursday.

Jeff Masters

Climate Change Drought Climate Summaries

December 2009: 4th or 8th warmest December on record

By: JeffMasters, 2:38 AM GMT on January 17, 2010

The globe recorded its eighth warmest December since record keeping began in 1880, and 2009 tied with 2006 as the fifth warmest year on record, according to NOAA's National Climatic Data Center. NASA's Goddard Institute for Space Studies rated December 2009 as the 4th warmest December on record, and the year 2009 tied with 2007 as the second warmest year on record. NOAA rated December 2009 ocean temperatures as the 2nd warmest on record, next to 1997, and land temperatures as the 31st warmest on record. The anomalously cool conditions over much of northern Asian and North American land areas may be associated with the near record December snow cover extent over Northern Hemisphere land areas--2nd most on record, behind 1985. Snow cover records go back to 1967. The December global satellite-measured temperatures for the lowest 8 km of the atmosphere were the 7th warmest on record, according to the University of Alabama Huntsville and RSS data sets.


Figure 1. Departure of temperature from average for December, 2009. Image credit: National Climatic Data Center.

One interesting note: the NASA global average temperature for 2009 was .57°C above average. NOAA's was .56°C above average. These temperatures were just .06°C below the all-time hottest year on record, 2005. The 11-year global sunspot cycle causes a variation of 0.1°C between the maximum and minimum of the solar cycle. We are currently at a deep minimum of the solar cycle, so we would have set a new global temperature record had we been at the maximum of the solar cycle. The other global temperature data set, the UK HadCRUT3 data, is not yet available for 2009. This data set is the one most often quoted by global warming skeptics, since it says that 1998 was the warmest year on record. However, HadCRUT3 fills in a huge area of missing data in the Arctic with the average temperature from the rest of the globe. This is bound to cause an underestimate of the global temperature, since the Arctic has warmed much more than the rest of the globe. The NASA and NOAA data sets fill in the missing data in the Arctic with data interpolated from the nearest stations in the Arctic, a procedure which is less likely to underestimate the global temperature.

December 2009: 14th coolest December on record for the U.S.
For the contiguous U.S., the average December temperature was 3.2°F below average, making it the 14th coolest December in the 115-year record, according to the National Climatic Data Center. The U.S. has been on quite a roller coaster of temperatures over the past three months--the nation recorded its third coldest October on record, followed by its third warmest November, followed by its 14th coolest December. The coolest December weather was in the Central U.S., where Nebraska had its eighth coolest December; Texas, Nevada, and Wyoming their ninth; and Montana and Utah their tenth coolest.

December 2009 was the 11th wettest December in U.S. history. It was a record wet month for Georgia, South Carolina, Virginia, and Maryland; 2nd wettest month on record for New Jersey; and the third wettest month on record for South Dakota, North Carolina, and Alabama. The Northwest U.S. was dry, with Washington experiencing its 11th driest December on record.

The year 2009: 35th warmest for the U.S.
For the entire year of 2009, it was the 35th warmest year in the contiguous U.S during the 115-year record. The coolest state was Nebraska, which had its 19th coolest year on record, and the warmest state was California, with its 16th warmest year on record. The driest state was Arizona, where 2009 ranked as the 4th driest year on record, while the wettest states were Illinois, Alabama, and Arkansas, who all had their 2nd wettest year on record.

U.S. tornado deaths: 2nd lowest on record
The year 2009 was below average for number of tornadoes, with a final tally around 1120 expected, compared to the 3-year average of 1297, according to the Storm Prediction Center. The 21 tornado deaths in 2009 was the 2nd lowest death toll in the 60-year record. Only 1986, with its 15 tornado deaths, saw fewer fatalities. The 60-year average annual death toll is 84.

U.S. drought
At the end of December, 6% of the contiguous United States was in severe-to-exceptional drought, which is well below average. The U.S. Drought Monitor shows no areas in the highest classification of drought--exceptional drought, and U.S. drought extent is close to its lowest value for the past ten years. The second highest category of drought, extreme drought, covers only a small region of northeast Arizona, and this will shrink over the remainder of January as much-needed rain falls across Arizona. About 43 percent of the contiguous United States had moderately-to-extremely wet conditions at the end of December, according to the Palmer Index (a well-known index that measures both drought intensity and wet spell intensity). This footprint is significantly larger than the long-term average.

Average U.S. fire activity in 2009
Significant fire activity occurred early in 2009, but wetter conditions across many parts of the nation as the year progressed, coupled with effective fire management, helped to restrain fire activity by mid-year. Despite the largest fire in Los Angeles County's (California) recorded history (Station fire), by the end of August the nationwide acreage burned by wildfire was very near the 2000 - 2009 average, and thereafter declined below average. Based upon data provided by the National Interagency Fire Center (NIFC), fire activity in 2009 ranked fifth highest (sixth lowest) out of the past decade in terms of number of fires, about 1 percent below the 2000 - 2008 average. Acres burned in 2009 were 14.5 percent below the 2000 - 2008 average, ranking seventh highest (fourth lowest) since 2000. Average fire size also ranked seventh highest out of the 2000 - 2009 period, at about 14 percent below average.

Strong El Niño conditions continue
Strong El Niño conditions continue over the tropical Eastern Pacific. Ocean temperatures in the area 5°N - 5°S, 120°W - 170°W, also called the "Niña 3.4 region", were at 1.6°C above average on January 10, just above the 1.5°C threshold for a strong El Niño, according to the Australian Bureau of Meteorology. The strength of El Niño has been roughly constant for the 9 weeks ending January 10. NOAA's Climate Prediction Center is maintaining an El Niño Advisory. Most of the El Niño models forecast that El Niño has peaked and will gradually weaken. Most of the models predict that El Niño conditions will last into early summer, but cross the threshold into neutral territory by the height of hurricane season.

December sea ice extent in the Arctic 4th lowest on record
December 2009 Northern Hemisphere sea ice extent was the 4th lowest since satellite measurements began in 1979 and slightly below December 2008 levels, according to the National Snow and Ice Data Center (NSIDC). Only 2005, 2006, and 2007 saw lower December arctic sea ice extent. The weather pattern over the Arctic in December 2009 featured a strongly negative Arctic Oscillation (AO). This pattern tends to slow the winds that typically flush large amounts of sea ice out of the Arctic between Greenland and Iceland. In this way, a negative AO could help retain some the second- and third-year ice through the winter, and potentially rebuild some of the older, multi-year ice that has been lost over the past few years. However, the AO has increased significantly in January, and it is unclear what the net effect of the AO on sea ice transported out of the Arctic this winter will be.

Next post
I'm at the 90th Annual Meeting of the American Meteorological Society in Atlanta, Georgia, and will be making my next post from Atlanta on Tuesday.

Jeff Masters

Climate Summaries

Haiti's tragic hurricane history

By: JeffMasters, 3:15 PM GMT on January 15, 2010

The catastrophic earthquake of 2010 is only the latest--and worst--natural disaster to devastate the nation of Haiti. Up until the quake, the hurricane season of 2008 was the cruelest natural disaster ever experienced in Haiti. Four storms--Fay, Gustav, Hanna, and Ike--dumped heavy rains on the impoverished nation. The rugged hillsides, stripped bare of 98% of their forest cover thanks to deforestation, let flood waters rampage into large areas of the country. Particularly hard-hit was Gonaives, the fourth largest city. According to reliefweb.org, Haiti suffered 793 killed, with 310 missing and another 593 injured. The hurricanes destroyed 22,702 homes and damaged another 84,625. About 800,000 people were affected--8% of Haiti's total population. The flood wiped out 70% of Haiti's crops, resulting in dozens of deaths of children due to malnutrition in the months following the storms. Damage was estimated at over $1 billion, the costliest natural disaster in Haitian history. The damage amounted to over 5% of the country's $17 billion GDP, a staggering blow for a nation so poor.


Figure 1. The flooded city of Gonaives after Hurricane Hanna, September 3, 2008. Image credit: Lambi Fund of Haiti.

The year 2008 was only one of many years hurricane have brought untold misery to Haiti. Hurricane Jeanne of 2004 passed just north of the country as a tropical storm, dumping 13 inches of rains on the nation's northern mountains. The resulting floods killed over 3,000 people, mostly in the town of Gonaives. Jeanne ranks as the 12th deadliest hurricane of all time on the list of the 30 most deadly Atlantic hurricanes . Unfortunately for Haiti, its name appears several times on this list. Hurricane Flora killed over 8,000 people in 1963, making it the 6th most deadly hurricane ever. An unnamed 1935 storm killed over 2,000, and Hurricane Hazel killed over 1,000 in 1954. More recently, Hurricane Gordon killed over 1,000 Haitians in 1994, and in 1998, Hurricane Georges killed over 400 while destroying 80% of all the crops in the country.


Figure 2. Hurricane Georges Approaching Haiti: September 22, 1998

Why does Haiti suffer a seemingly disproportionate number of natural disasters? The answer in that in large part, these are not natural disasters--they are human-caused disasters. Haiti is the poorest nation in the Western Hemisphere. With oil too expensive for the impoverished nation, charcoal from burnt trees has provided 85% or more of the energy in Haiti for decades. As a result, Haiti's 9 million poor have relentlessly hunted and chopped down huge amounts of forest, leaving denuded mountain slopes that rainwater washes down unimpeded. Back in 1980, Haiti still had 25% of its forests, allowing the nation to withstand heavy rain events like 1987's Category 3 Hurricane Emily, without loss of life. But as of 2004, only 1.4% of Haiti's forests remained. Jeanne and Gordon were not even hurricanes--merely strong tropical storms--when they stuck Haiti, but the almost total lack of tree cover contributed to the devastating floods that killed thousands. And it doesn't even take a tropical storm to devastate Haiti--in May of 2004, three days of heavy rains from a tropical disturbance dumped more than 18 inches of rain in the mountains, triggering floods that killed over 2,600 people.

What can be done to reduce these human-worsened natural disasters? Education and poverty eradication are critical to improving things. In addition, reforestation efforts and promotion of alternative fuels are needed. In the past two decades, the U.S. Agency for International Development has planted some 60 million trees, while an estimated 10 to 20 million of these are cut down each year, according to the USAID director in Haiti, David Adams. If you're looking for a promising way to make a charitable donation to help Haitian flood victims, considering sending a check to the Lambi Fund of Haiti, which is very active in promoting reforestation efforts, use of alternative fuels, and infrastructure improvements at a grass-roots level to help avert future flood disasters.

Portlight delivers much-needed water filtration systems and medical supplies to Haiti
Portlight.org, the disaster-relief charity that has sprung up from the hard work and dedication of many members of the wunderground.com community, has successfully shipped medical equipment and a water filtration unit capable of supplying the needs of 3,800 people per day to the Dominican Republic, where it will be trucked to Haiti via road. Portlight is working through the local Catholic Church, which is probably best positioned to deliver private aid donations to those in need. Paul Timmons, leader of the Portlight relief efforts, wrote this to me today:

This is important:
We are now accepting donations of medical equipment and clinical supplies...

Please forward this info as far and wide as you can. Any groups collecting or with access to this kind of stuff can ship it to our Atlanta warehouse:

Portlight Strategies, Inc.
4900 Lewis Road
Stone Mountain, GA 30083

We have good contacts on Hispaniola who are able to get this stuff where it's needed.

We are also still in need of funds!


So, please visit the Portlight.org blog to learn more and to donate. Floodman's blog has the latest info on Portlight's plan for Haitian relief. If you're interested in sponsoring an Honor Walk to help raise funds for the Haitians, please contact Paul Timmons of Portlight, via the Portlight.org blog. Portlight's Haitian relief efforts got a nice write-up in the Odessa American Online, a Texas newspaper, yesterday. Also, last night, Portlight booster Ron "Floodman" Myers was on the Barometer Bob Internet radio show.

For those of you more interested in helping out with the long-term rebuilding of Haiti's shattered infrastructure from the quake, I recommend a contribution to Lambi Fund of Haiti, a charity that is very active in promoting reforestation efforts, use of alternative fuels, and infrastructure improvements at a grass-roots level in Haiti. I've developed a great respect for the work they do in the country in the five years I've been a supporter.

I'll have a new post on Monday, when I'll be blogging from the 90th Annual Meeting of the American Meteorological Society, in Atlanta, Georgia.

Jeff Masters

Hurricane

Catastophic earthquake rocks Haiti

By: JeffMasters, 3:45 PM GMT on January 13, 2010

After making it through the hurricane season of 2009 without a scratch, Haiti's terrible earthquake of January 12, 2010 has brought a catastrophe of unfathomable magnitude to the impoverished people of Haiti, the poorest nation in the Western Hemisphere. The magnitude 7.0 earthquake was centered just ten miles southwest of the capital of Port-au-Prince, at a shallow depth of 6.2 miles, according to the U.S. Geological Survey. The shock occurred in the boundary region separating the Caribbean plate and the North America plate. The two plates slide past each other at a rate of about 0.8 inches (20 mm) per year, with the Caribbean plate moving eastward with respect to the North America plate. The fault that produced the quake is called the Enriquillo-Plaintain Garden fault system, and last produced a major earthquake in 1860. According to the USGS (Figure 1), 238,000 people near the quake's epicenter experienced violent to extreme shaking, capable of causing very heavy damage. A further 3.2 million people experienced very strong to severe shaking, capable of causing moderate to heavy damage. Another 1.3 million people experienced strong shaking, capable of causing moderate damage. Haiti's total population is just 9 million, so half the country's population lived in areas that received moderate to very heavy damage from the earthquake. The quake did not generate a large tsunami, though a tsunami of 5 inches (12 cm) was recorded at Santo Domingo in the Dominican Republic. It is possible that a local scale, moderately destructive tsunami was generated close to the shores of Port-au-Prince.


Figure 1. Earthquake shaking map for the January 12, 2010 Haitian earthquake, from the USGS. According to the USGS, 238,000 people near the quake's epicenter experienced violent to extreme shaking, capable of causing very heavy damage. A further 3.2 million people experienced very strong to severe shaking, capable of causing moderate to heavy damage. Another 1.3 million people experienced strong shaking, capable of causing moderate damage. Haiti's total population is just 9 million, so half the country's population lived in areas that received moderate to very heavy damage from the earthquake.

One of the greatest natural disasters in Haitian history
In many ways, the hurricane season of 2008 was the cruelest ever experienced in Haiti. Four storms--Fay, Gustav, Hanna, and Ike--dumped heavy rains on the impoverished nation. The rugged hillsides, stripped bare of 98% of their forest cover thanks to deforestation, let flood waters rampage into large areas of the country. Particularly hard-hit was Gonaives, the fourth largest city. According to reliefweb.org, Haiti suffered 793 killed, with 310 missing and another 593 injured. The hurricanes destroyed 22,702 homes and damaged another 84,625. About 800,000 people were affected--8% of Haiti's total population. The flood wiped out 70% of Haiti's crops, resulting in dozens of deaths of children due to malnutrition in the months following the storms. Damage was estimated at over $1 billion, the costliest natural disaster in Haitian history. The damage amounted to over 5% of the country's $17 billion GDP, a massive blow for a nation so poor.

Thus when it became clear that the hurricane season of 2009 would spare Haiti further misery, I was delighted that our suffering neighbors would get a chance to regroup and rebuild. But the unimaginable destruction wrought by yesterday's quake is a staggering blow for a nation so poor. When the damage is tallied and compared to Haiti's GDP of $17 billion, the earthquake of 2010 could well prove to be one of the most devastating disasters in world history. Further, Haiti's population is only 9 million, and the number of people killed, injured, and made homeless will make up a huge fraction of the Haitian population.


Figure 2. An earthquake hazard map for the Caribbean reveals that yesterday's quake occurred in a relatively low-risk portion of the Caribbean. Image credit: USGS.

Haitian earthquake history
The western portion of Haiti where yesterday's quake occurred is in a relatively low seismic risk region of the Caribbean (Figure 2). Large quakes are uncommon in Haiti. The worst quake in Haitian history was probably the May 7, 1842 magnitude 7.7 Cap-Haitien earthquake. This massive tremor hit a fault on the northern portion of the island, killing 10,000; three hundred of these deaths were from a large tsunami generated by the quake. One of the largest cities in Haiti--Cap-Haitien, with a population of 60,000--was destroyed, with the loss of 6,000 lives.

Caribbean earthquake history
The Eastern Caribbean is no stranger to devastating earthquakes. The Caribbean Plate slides against the North American Plate along a line running through most of the islands in the Eastern Caribbean, generating frequent earthquakes. According to the University of the West Indies Seismic Research Center, the most severe quake to hit the region occurred on February 8, 1843, when a tremor estimated at 8.0 - 8.5 on the Richter Scale struck the Lesser Antilles Islands. Heavy damage was reported from St. Maarten to Dominica. In Antigua, the English Harbour sank. In Point-a-Pitre, Guadeloupe, all masonry construction was destroyed, and a fire broke out that burned down the remaining wooden structures. One third of the population, estimated at 4,000 - 6,000 persons, perished. The event was felt as far south as Caracas and British Guiana and was even felt 2,000 km away in Washington D.C., Vermont, and Charlestown, South Carolina. The largest Eastern Caribbean earthquake recorded by modern seismographs was the El Cibao earthquake in the Dominican Republic in 1946. The earthquake was of magnitude 8.1 and generated a tsunami which caused 75 deaths and rendered 20,000 homeless.


Figure 3. Smoke and dust rise from the rubble of Port-au-Prince a few minutes after the catastrophic earthquake of January 12, 2010. Image is from an anonymous YouTube video taken from a house overlooking Port-au-Prince.

Lambi Fund of Haiti and Portlight mobilize to help out
For the past five years, I've been a contributor and booster of the Lambi Fund of Haiti, a charity that is very active in promoting reforestation efforts, use of alternative fuels, and infrastructure improvements at a grass-roots level in Haiti. I've developed a great respect for the work they do in the country, and have gotten to know Karen Ashmore, the executive director of the charity, and have written articles for their newsletter. Karen wrote me last night with this plea for help: "Most buildings in Port-Au-Prince have been damaged or have collapsed, which would include homes of staff and families we work with, as well as the grain mills, sugar cane mills, and sites for community economic development. And cisterns and latrines we have supported for safe drinking water and sanitation. Major rebuilding effort needed. Please post on your blog".

To help the Lambi Fund rebuild what was destroyed, visit their on-line donation page. Keep in mind that they are second responders--their aim is not to provide for the immediate needs of food, water, and medicine, but to rebuild the Haitian infrastructure and economy.

Portlight.org, the remarkable disaster-relief charity that has sprung up from the hard work and dedication of many members of the wunderground.com community, has also mobilized to help out the victims of the Haitian earthquake. As Paul Timmons writes in the Portlight blog this morning,

Portlight's focus in this is going to be on people with disabilities in Haiti...providing medical equipment, shelter, and food for them...there is an article below about the treatment of this population in the best of times...and this ain't the best of times...

We have a "Go" container in Atlanta which will ship out in a few days...and an ongoing relationship with a community of Catholic sisters in Port au Prince who will be opening shelters...

Any funds we raise will be used to defray shipping costs of medical and clinical equipment...and for the purchase of food and other shelter supplies...Haiti is our neighbor...and Haitians are certainly forgotten people...people with disabilities in Haiti are frequently barely seen as human...

Anyone interested in going to Haiti to help staff one or more shelters for Haitians with disabilities please WU mail us...


So, please visit the Portlight.org blog to learn more and to donate. Portlight is acting as a first responder, to answer the immediate needs of the Haitian people for water, food, and medical equipment. Portlight is exploring ways they can work together with the Lambi Fund of Haiti to put the materials donated where they are most needed. If you're interested in sponsoring an Honor Walk to help raise funds for the Haitians, please contact Paul Timmons of Portlight, via the Portlight.org blog. Thank you.

There are two things Haiti does have going for it in the wake of this horrible tragedy. Firstly, it is not hurricane season, so the Haitians have six months to rebuild and shelter their homeless before the storms of summer arrive. There is a large mass of dry air over the Caribbean at present, so there will be dry weather for relief operations for at least the next few days. Secondly, former President Bill Clinton was appointed the UN Special Envoy to Haiti last year, and he brings an important visible face to the needs of Haiti's suffering people. A huge amount of aid will be needed for this tragedy.

My thoughts and prayers are with all the victims and relatives of those affected by the earthquake.

I'll have a new post on Friday.

Jeff Masters

Cold wave of 2010 wanes; major jet stream pattern change coming

By: JeffMasters, 3:18 PM GMT on January 12, 2010

The worst of the cold wave of 2010 is over for the Southern U.S. Temperatures this morning across the southern tier of states rebounded substantially from the lows observed Saturday through Monday, and the citrus growing region of Florida did not receive sustained periods of temperatures below 28°--the critical threshold for fruit damage. Only one record low for the day has been reported so far this morning by the National Weather Service, a 25°F low at Melbourne, Florida, beating the old record of 26° for the date set in 1982. For comparison, 11 low temperature records were set Monday morning in Florida. Temperatures will continue to recover throughout the week as a major re-orientation of the jet stream takes place. By next week, a significant January thaw will occur over the Eastern U.S., and a period of stormy weather and heavy precipitation will impact the Western U.S.

Key West's temperature bottomed out at 51° this morning, breaking its string of 5 consecutive days with temperatures below 50°--the second longest such stretch on record there. However, the damage is done in the citrus growing regions of Florida, where four nights of extremely cold temperatures over the past week may have killed 7.5% of this year's citrus crop.

Here's a list of the number of daily minimum low temperature records set at major airports during the cold wave of January, 2010, in the South:--Texas, Louisiana, Arkansas, Mississippi, Alabama, Georgia, South Carolina, and Florida:

January 2: 1 FL
January 3: 1 SC
January 4: 4 FL, 2 GA
January 5: 1 AR, 1 FL, 1 TX
January 6: 5 AL, 1 AR, 17 FL, 1 GA, 1 LA
January 7: 15 FL, 1 GA
January 8: 2 FL, 2 TX
January 9: 2 FL, 17 TX
January 10: 7 FL, 4 TX
January 11: 11 FL, 1 TX
January 12: 1 FL (data not all in yet)


Figure 1. Ice encases tangerines in Altoona, Florida. Image taken Sunday, January 10, 2010 by wunderphotographer CAVU.

A major jet stream pattern shift coming
As I noted in my post on Thursday, a sharp kink in the jet stream and a strong negative phase of the North Atlantic Oscillation was responsible for this winter's cold blast over eastern North America and Europe. However, the ridge of high pressure that has been blocking the west-to-east motion of weather systems over the past ten days is weakening and progressing eastwards, which will allow a jet stream pattern more typical of an El Niño winter to set up next week. The jet stream will dive southward over California, bringing a strong flow of moist, Pacific air to the West Coast. A series of powerful storms is expected to begin battering California Sunday, and these storms should bring significant drought relief--and flooding rains--to most of California and portions of Arizona. The stormy period will likely last at least a week.

A strong low pressure system will also bring heavy rain to the Gulf Coast this Friday and Saturday. It currently appears that the large amount of cold, stable air this weekend's cold wave has delivered to the Gulf will prevent the storm from generating a significant tornado outbreak. Some isolated severe thunderstorms are possible with this storm, and we may see the Storm Prediction Center issue a "Slight" risk area of severe weather for this storm, late this week.


Figure 2. Surface pressure and precipitation forecast for next Wednesday, January 20, from this morning's 00Z run of the GFS model. A strong low pressure system is expected to impact the West Coast and Desert Southwest, bringing large areas of rainfall in excess of 1/2 inch (green colors) during a 12-hour period. While the timing and areal coverage of this precipitation event will no doubt be different than this, given that 8-day forecasts are pretty unreliable, we can expect a very wet and stormy period of weather for the Western U.S. next week. In the Eastern U.S., a surface high pressure system will set up over the East Coast, pumping warm air northwards and bringing a significant January thaw to the Midwest and much of the Eastern U.S.

I'll have an update on Wednesday.

Jeff Masters

Winter Weather

Deep freeze in the South continues

By: JeffMasters, 3:17 PM GMT on January 11, 2010

The Deep South shivered through a ridiculously frigid weekend, with low temperature records crumbling over much of Florida, Texas, and Louisiana. This morning, record lows for the date fell in Miami, West Palm Beach, Tampa, Fort Myers, Lakeland, Tallahassee, and St. Petersburg. The most extreme low temperature record this morning was set in Key West, where the mercury fell to 42°F at 5am--the second coldest temperature ever observed in Key West. This is just 1° warmer than the all-time coldest temperature observed in Key West--41° in January of 1981 and 1873. Widespread reports of sleet and snow flurries accompanied the cold blast across Central Florida on Saturday, the eighth snow event in Florida since 2000, according to Wikipedia. It remains to be seen how much damage the $9.3 billion Florida citrus industry will see because of the cold blast, which is the most severe in Florida since the December 1989 cold wave that devastated the citrus industry. Temperatures below the 28° that causes fruit damage affected some citrus-growing areas again this morning, for the third consecutive morning.


Figure 1. Ice encases citrus in Altoona, Florida. Image taken Sunday, January 10, 2010 by wunderphotographer CAVU.

Intense and long-lasting cold
In Texas, two airports tied all-time January low temperature records on Saturday morning--Hondo, who's 12°F tied the record set January 11, 1982, and Cotulla La Salle, which hit 16°F, tying the record set January 13, 1975. Most of Texas' airports set daily low temperature records on Saturday morning. Saturday's low in Waco of 8°F broke the previous record of 15° for the date, and was the first time Waco has been in the single digits since the -4°F reading on December 23, 1989. Not only has the South's cold been intense, it has been exceptionally long-lasting. Montgomery, Alabama has had a low temperature below 25° nine consecutive days, breaking the old mark of seven straight days set in January 2001. With the cold snap only grudgingly scheduled to release its grip on the South, Montgomery can expect to run their streak of sub-25° lows to at least eleven straight days this week. Mobile, Alabama and Pensacola, Florida now have their second longest streak of days with a minimum temperature below freezing, at nine and eight days, respectively. Pensacola may equal or top their record of eleven straight days (set in January 1940) later this week, but Mobile is unlikely to break their record of fifteen straight days (set in February 1940). Also of note is that Key West has seen five consecutive days with low temperatures below 50 degrees (January 7th - 11th). This is the second longest such streak recorded in Key West, one day short of the record six-day streak on December 1 - 6, 1876. Key West has a decent chance of tying that record on Tuesday morning, when the low should fall to 50 or below.

A nicer beach weekend in Antarctica than Central Florida
Saturday's high and low temperatures in Orlando and Daytona Beach, Florida were 40° and 30°F. Tampa's high and low were 42°F and 29°F. Under sunny skies and light winds less than 10 mph, Saturday's high and low temperature at San Martin Base, Antarctica were 44° and 34°F. Gray, cloudy skies with winds gusting to 16 - 21 mph greeted beach goers at the beaches near Daytona Beach and Tampa, so it was a much nicer day at the beach in the Antarctic Peninsula than in Central Florida on Saturday (the Florida Chamber of Commerce loves stats like that!) Nice beach weather in Antarctica continued through Sunday, with sunny San Martin, Antarctica (high 41°, low 35°) recording an average temperature warmer than most stations in Central Florida. In all fairness, it is summer in Antarctica, and the ocean temperatures in Florida were a bit warmer than in Antarctica.

A major pattern shift coming
As I noted in my previous post, a sharp kink in the jet stream and a strong negative phase of the North Atlantic Oscillation is responsible for this winter's cold blast over eastern North America and Europe. The ridge of high pressure that has been blocking the west-to-east motion of weather systems over the past ten days is weakening, though, and a major shift in the winter weather pattern is in store for the Northern Hemisphere by late this week. A more typical El Niño pattern will set up, with the jet stream diving southward over California, bringing a strong flow of moist, Pacific air to the West Coast. A strong low pressure system will also bring heavy rain to the Gulf Coast on Friday and Saturday. Temperatures will slowly moderate across Europe and the Midwest and Eastern U.S. this week as the pattern gradually shifts, and more ordinary winter weather can be expected in these regions by next weekend.


Figure 2. Departure of the surface temperature from average for the first eight days of 2010 shows much colder than average conditions were present over the Midwest and Southern U.S., much of Europe, and Central Asia. Much warmer than average temperatures were present over the Northwest U.S., Greenland, the Arctic, and Southern Asia. A sharp kink in the jet stream was responsible for the temperature anomaly pattern. Image credit: NOAA/ESRL.

Jeff Masters

Winter Weather

The U.S. and European cold blast: blame the NAO

By: JeffMasters, 4:00 PM GMT on January 07, 2010

The Deep South shivered through another frigid morning today, with low temperature records crumbling again over much of Florida. Lakeland hit 27°F, smashing the old record of 34°F; Melbourne hit 28°F, eclipsing the old record of 32°F; and West Palm Beach bottomed out at 37°F, besting the old record of 38°F. The cold wave is being driven by an unusual sharp and persistent kink in the jet stream that is being blocked from moving by a strong ridge of high pressure over Greenland. As a result, an exceptionally strong surface high pressure of 1055 mb over the North Central U.S. is pushing large amounts of cold, Arctic air southwards from Canada. No coldest January temperature records have been set yet from the cold blast, but the 500 largest U.S. cities have been averaging about 11 new daily low temperature records per day the first five days of January, according to the National Climatic Data Center. The cold will ease Friday in the Deep South, but return with a vengeance Saturday night though Monday morning, as another push of cold air descending from Canada promises to bring a cold wave that will approach the December 1989 and January 1977 cold waves in intensity, and may being some new all-time January low temperature records to the South.

Colder in Florida than Alaska and Greenland
The sharp kink in the jet stream has brought record warm temperatures to a few stations in Alaska and the Pacific Northwest this week, making much of coastal Alaska warmer than Florida. Cold Bay, Alaska, set a record high yesterday of 47°F, after recording a low temperature of 30°F. This made Cold Bay warmer than Pensacola, Florida, which had a high of 47°F and a low of 24°F. In fact, most of Florida--including Jacksonville, Tampa, Melbourne, and Tallahassee--recorded lows at or below the 27°F low recorded in Anchorage, Alaska yesterday. The jet stream kink has also brought temperatures more than 30°F above average to Greenland. The temperature in Narsarsuaq, Greenland at 10am EST today was 46°F, far warmer than most of Florida.


Figure 1. Departure of the surface temperature from average for the first three day of 2010 shows much colder than average conditions were present over the Southeast U.S., much of Europe, and Central Asia. Much warmer than average temperatures were present over the Northwest U.S., Greenland, the Arctic, and Southern Asia. A sharp kink in the jet stream was responsible for the temperature anomaly pattern. Image credit: NOAA/ESRL.

Snow in Florida?
It doesn't snow very often in Florida, and the Wikipedia list of snow events in Florida lists only seven such events over the decade of the 2000s. This weekend's cold wave may be able to generate some snow over isolated regions of Central Florida, though it appears that the odds of this happening are less than 30%. The most widespread snowfall in Florida history occurred on January 19, 1977, when snow fell over much of the state, with flurries as far south as Homestead. Snow flurries also fell on Miami Beach for the only time in recorded history.


Figure 2. North Atlantic Oscillation (NAO) index for September 9, 2009 - January 6, 2010 (black line) and forecast from the GFS model (red lines). The NAO index was strongly negative, near -2.0, for much of December and January. Image credit: NOAA/CPC.

The winter cold blast: blame the North Atlantic Oscillation (NAO)
Why has the winter been so cold over Eastern North America and northern Europe? Well, don't blame El Niño. El Niño winters are rarely this cold. Instead, blame the the North Atlantic Oscillation (NAO). The NAO is a climate pattern in the North Atlantic Ocean of fluctuations in the difference of sea-level pressure between the Icelandic Low and the Azores High. It is one of oldest known climate oscillations--seafaring Scandinavians described the pattern several centuries ago. Through east-west oscillation motions of the Icelandic Low and the Azores High,the NAO controls the strength and direction of westerly winds and storm tracks across the North Atlantic. A large difference in the pressure between Iceland and the Azores (positive NAO) leads to increased westerly winds and mild and wet winters in Europe. Positive NAO conditions also cause the Icelandic Low to draw a stronger south-westerly flow of air over eastern North America, preventing Arctic air from plunging southward. In contrast, if the difference in sea-level pressure between Iceland and the Azores is small (negative NAO), westerly winds are suppressed, allowing Arctic air to spill southwards into eastern North America more readily. Negative NAO winters tend to bring cold winters to Europe, and the prevailing storm track moves south towards the Mediterranean Sea. This brings increased storm activity and rainfall to southern Europe and North Africa.

The winter of 2009 - 2010 has seen a very strong negative NAO, causing much of our cold weather over Eastern North America and Europe. The NAO index for the month of December 2009 was -1.93, which is the third lowest NAO index since 1950 for a winter month (December, January, or February). The only winter months with a lower NAO index were February 1978 (-2.20) and January 1963 (-2.12). January 1963 was one of the coldest months on record in the UK and the Eastern U.S.. February 1978 was the coldest February on record for five U.S. states, and featured the historic blizzards in both the U.S. and UK. The NAO so far for January 2010 has continued to stay strongly negative, ranging between -1.5 and -2.1. However, the blocking ridge over Greenland is forecast to weaken next week, allowing the sharp kink in the jet stream to straighten out. This will increase the NAO index to more typical values, allowing a return of more ordinary winter weather to the U.S. and Europe.

Jeff Masters

Winter Weather

NHC increases hurricane forecast lead times

By: JeffMasters, 7:27 PM GMT on January 05, 2010

The National Hurricane Center (NHC) announced today that beginning with the 2010 hurricane season, their hurricane and tropical storm watches and warnings for the U.S. coast will be extended in time by an additional 12 hours. Warnings will now be issued 36 hours in advance instead of 24 hours, and watches will be issued 48 hours in advance, instead of 36 hours. The increase in lead time for watches and warnings has been made possible by the tremendous improvement in hurricane track forecasts, which have improved by over 50% in the past twenty years (Figure 1). "With increases in population and infrastructure along vulnerable U.S. coastlines, emergency managers need more lead time in order to make life-saving decisions regarding evacuations", said Bill Read, director of NOAA's National Hurricane Center, in today's press release.


Figure 1. Average track errors for NHC Atlantic tropical storm and hurricane forecasts issued between 1990 - 2008. Track errors have improved by over 50% in the past 20 years. Image credit: National Hurricane Center.

Commentary
NHC has been debating for a number of years how best to "invest" the gains accrued from the steady improvement in hurricane track forecasts. One obvious savings from these better hurricane forecasts has come from the reduced evacuation costs. When a hurricane warning is issued 24 hours before the expected arrival of hurricane-force winds at the coast, it costs approximately $1 million to evacuate each mile of U.S. coast warned (Aberson et al., 2006). This number will be higher for more densely populated areas of the coast, such as Miami, and may be a factor of six lower for the North Carolina coast (Whitehead, 2003). According to a 2007 presentation at the 61st Interdepartmental Hurricane Conference, the length of coast warned decreased significantly in the past decade. During the decade of the 1990s, the average length of a hurricane warning was 455 miles, but that fell to just 335 miles between 2000 - 2006. Thus, an average of 120 fewer miles of coast were warned, at an average savings of $120 million per hurricane warning issuance. During this period, 17 storms requiring 25 hurricane warnings occurred. If the costs of coastal evacuations are indeed $1 million per mile, the improved hurricane forecasts between 2000 - 2006 resulted in savings of $3 billion compared to what the forecasts of the 1990s would have cost.

However, the new increased lead times for hurricane watches and warnings will lead to an increase in the length of coast warned, due to the higher uncertainties in hurricane tracks at longer forecast lead times. Between 2004 - 2008, approximately 25% of the coast that was placed under a hurricane warning actually received hurricane force winds; this percentage was 20% for areas placed under a hurricane watch. These percentages will decline with the new increased watch and warning lead times, costing money in unnecessary evacuations, and leading to increased complacency in the warned population due to too much "crying wolf".

Balanced against these increased costs is the potential disastrous loss of life should a hurricane hit an unprepared, heavily populated shoreline. With the U.S. population continuing to increase rapidly in coastal regions, the time needed to evacuate vulnerable populated regions is increasing. For example, evacuation times for the major urban areas of Texas are 28 - 34 hours for a major hurricane. Though the costs of overwarning the coast is significant, the savings in both human lives and dollars from increased warning times should outweigh these costs. In the 2002 book, Hurricane: Coping With Disaster, Dr. Hugh Willoughby, former director of the Hurricane Research Division of NOAA's Atlantic Oceanographic and Marine Laboratory, analyzed hurricane death statistics. In 1950, about 70 U.S. residents died per year in hurricanes. In the 50 years since, the coastal population expanded by a factor of 3.2, so if we were managing the hurricane problem the way we did in 1950, we would be losing about 220 people a year. The long-term average is still about twenty per year, not including the deaths due to the levee failures during Katrina. That means we're preventing about 200 deaths per year compared with 1950. How much are these saved lives worth? A life, is, of course, priceless, but in the cold world of economics, the value of life-saving scientific research and government regulations is estimated using statistics of what people are willing to pay to avoid certain risks, and what extra money employers pay their workers to take on additional risks. This data comes primarily from payroll statistics, but opinion surveys also play a role. In 2004, the Environmental Protection Agency (EPA) valued an American life at $8 million. EPA cut the value of a life by 8% that year, and a further 3% in May 2008, making the economic value of a life $6.9 million in today's dollars. The Department of Transportation gives a lower figure of a life as being worth $5.8 million. Using this number implies a savings of about $1.2 billion per year for the 200 lives saved per year by better hurricane warnings and evacuations. Today's decision by NHC to increase warning times should continue this trend of saving lives, which will also provide considerable monetary benefit. Despite the increased costs and dangers of "crying wolf" too often due to overwarning the coast, I believe that the double value of saving lives--for both the intrinsic and monetary value of a human life--makes NHC's move of increasing warning and watch times the right call.

References
Whitehead, J.C., 2003: "One million dollars per mile? The opportunity costs of Hurricane evacuation", Ocean and Coastal Management 46, 1069.

I'll have a new post on Thursday or Friday.

Jeff Masters

Hurricane

A quiet 2009 for natural disasters

By: JeffMasters, 4:35 PM GMT on January 04, 2010

It was a relatively quiet year globally for natural disasters in 2009. According to Munich Re insurance company, the death toll from 2009 natural disasters was approximately 10,000, well below the average 75,000 deaths per year seen over the decade of the 2000s. Damage from 2009 natural disasters was about $50 billion, compared to the decadal average of $115 billion, and far below the $200 billion in destruction wrought by 2008's natural disasters. The most costly disaster of 2009 was Winter Storm Klaus, which hit northern Spain and southwest France January 23 - 25, causing $5.1 billion in damage. The deadliest weather-related disaster was Category 2 Typhoon Ketsana, which killed 694 people in the Philippines and Southeast Asia. Category 2 Typhoon Morakot was a close second, with 614 fatalities, primarily in Taiwan. The deadliest natural disaster overall was the magnitude 7.6 earthquake that shook the Indonesian island of Sumatra on 30 September, killing nearly 1,200 people.


Figure 1. Cars being swept away by Ketsana's flood waters in a still frame from a dramatic YouTube video captured by medical students at the East Ramon Magsaysay Memorial Medical Center.

I'll be back Tuesday with my selection for the top global weather event of 2009: the Horn of Africa drought.

Jeff Masters

Climate Summaries


The views of the author are his/her own and do not necessarily represent the position of The Weather Company or its parent, IBM.

Category 6™

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Cat 6 lead authors: WU cofounder Dr. Jeff Masters (right), who flew w/NOAA Hurricane Hunters 1986-1990, & WU meteorologist Bob Henson, @bhensonweather