Category 6â„¢

Bill Gray's latest hurricane season forecast

By: JeffMasters, 3:15 PM GMT on May 31, 2006

The latest 2006 Atlantic hurricane season forecast from the forecast team at Colorado State University (CSU) was issued today. Phil Klotzbach and Dr. Bill Gray's forecast is unchanged from their earlier April 4 and December 6 forecasts, predicting 17 named storms (10 is average), nine hurricanes (six is average), and five intense hurricanes (2.3 is average). This is the highest level of activity they have forecast in their 23 years of making these predictions. They put the odds of a major (Category 3-4-5) hurricane crossing the U.S. coast at 82% (average for last century is 52%). The U.S. East Coast (including Florida) has a 69% chance of a major hurricane strike (31% is average), and the Gulf Coast, 38% (30% is average). In addition, there is an above-average risk of major hurricanes in the Caribbean.

The CSU team identified four years that had similar weather patterns in May compared to this year, and all four of these years had much above levels of hurricane activity: 2004 (six major hurricanes, three of which made landfall in the U.S.), 2001 (no hurricanes made landfall in the U.S., but there were two major hurricanes); 1996 (six major hurricanes, one of which hit the U.S.--Fran); and 1961 (seven major hurricanes, one of which hit the U.S.--Carla).

What the other hurricane forecasting groups are predicting for 2006:
NOAA forecast issued May 22, 2006:

13-16 named storms
8-10 hurricanes
4-6 intense hurricanes

Cuba's National Weather Institute prediction from May 2, 2006:

15 named storms
9 hurricanes

Tropical Storm Risk, Inc. May 5, 2006 forecast:

15 named storms
8 hurricanes

The CSU forecasters cite three main reasons to expect a very busy season:

1) Weaker trade winds than usual have led to anomalous warming of the tropical Atlantic since the early part of April. Sea surface temperatures remain much warmer than average, and are expected to be much warmer than average during the August-October peak of hurricane season.

2) No El Niño is expected to be present during August-October 2006. When the tropical Atlantic is warm, and no El Niño is present, Atlantic basin hurricane activity is greatly enhanced.

3) We continue to be in the positive phase of the Atlantic Multidecadal Oscillation (AMO), the decades-long cycle of natural hurricane activity.

The next forecast from the CSU group will be issued August 3.

Tomorrow--June 1--marks the beginning of hurricane season. I'll have a look at what we can expect for the month of June.

Jeff Masters




East Pacific hurricane season kicks off

By: JeffMasters, 2:03 PM GMT on May 30, 2006

Hurricane season has begun in the Northeastern Pacific (the region off the west coast of Mexico), with the formation of Tropical Storm Aletta over the weekend. Aletta is expected to die by Thursday, a victim of high wind shear and dry air. At its peak, Aletta was only a weak tropical storm with top winds of 45 mph. The storm brought over two inches of beneficial rain to Acapulco, and ten inches to the surrounding mountains. Aletta is now moving away to the west over open ocean, bringing an end to the rains over Mexico.


Figure 1. Latest image of Aletta.

NOAA's 2006 forecast for the Northeastern Pacific hurricane season calls for a less active than usual year, with 12-16 named storms, 6-8 hurricanes, and 1-3 major Category 3 and stronger storms. On average, the Northeastern Pacific has 16 named storms, 9 hurricanes, and 4.5 major hurricanes. The pattern of upper level winds that favors an active hurricane season in the Atlantic typically brings high wind shear and low hurricane activity to the Northeastern Pacific. Last year's record breaking year in the Atlantic was balanced by a slightly below-average year in the Northeastern Pacific, which had 15 named storms, seven hurricanes, and two major hurricanes. The last three east Pacific hurricane seasons have been below normal, following an overall trend of lower activity since 1995. This is exactly the opposite of what has been observed in the Atlantic. "Since 1995, despite the trend to warmer waters in the tropical east Pacific, higher wind shear has contributed to fewer tropical storms, hurricanes, and major hurricanes," noted Muthuvel Chelliah, NOAA's Climate Prediction Center lead scientist on the east Pacific hurricane season outlook.

The Northeast Pacific basin hurricane season officially began May 15. The season has a broader peak than the Atlantic. Activity usually begins in late May or early June, and lasts until late October or early November. Peak storminess occurs in late August/early September. Only three Eastern Pacific hurricanes have had their names retired--Hurricane Ismael of 1995, Hurricane Pauline of 1997, and Hurricane Kenna of 2002, all of which hit Mexico. In addition, Adolph and Israel of 2001 had their names retired for political reasons.

I'll be back Wednesday with a look at Bill Gray's latest Atlantic hurricane season forecast, due to be issued tomorrow.

Jeff Masters

High wind shear over the Gulf of Mexico

By: JeffMasters, 2:01 PM GMT on May 26, 2006

April 2006 was the warmest April on record in the U.S. since record keeping began in 1895. The U.S. has now had two "warmest ever" months this year, January and April. The nationally averaged April temperature was 56.5°F (13.6°C), which was 4.5°F (2.5°C) above the 1901-2000 (20th century) mean. Globally, April ranked as the 7th warmest April on record, and the period January through April ranks as the 6th warmest such period on record globally. From Figure 1, we can see that the entire tropical Atlantic region where hurricane formation occurs was warmer than average during April, and this region has remained about .5 - 1.5 degrees C above normal over the past few months.


Figure 1. Temperature Anomalies (difference of temperature from normal) for April 2006.

With all this warmer than normal water over the Atlantic, one might expect that hurricane season could have an earlier than normal start. However, that will not be the case this year, because high levels of wind shear will dominate the regions where June tropical cyclones typically form--the Gulf of Mexico. The Gulf is the primary genesis region in June because that is typically the only region where we get initial disturbances that can set a tropical storm spinning up. These initial disturbances in June are usually the remains of an old cold front or upper-level trough that stalls out over the Gulf and festers for a few days, gradually developing deep convection and spinning up into a tropical depression. June is too soon to get a tropical storm in the Caribbean or tropical Atlantic, since the tropical waves that typically serve as the initial seed for a storm are still too far south. The tropical waves coming off of Africa right now are at about six degrees latitude, and they need to be at nine degrees latitude or higher before they are far enough from the equator to serve as a seed for a tropical storm.

For the start of this year's hurricane season next week, the GFS model (Figure 2) is forecasting that there will be strong upper-level winds over the Gulf of Mexico. These winds are part of the so-called Subtropical jet stream. The jet stream--the band of high velocity winds that circles the globe--always has at least one branch, the polar jet. As its name implies, the polar jet lies close to the pole, and circles it entirely. Sometimes the jet splits, and a branch called the Subtropical jet blows across subtropical latitudes, where the Gulf of Mexico lies. As we can see from the GFS forecast for June 3 in Figure 2, both the polar and subtropical jets are apparent where the color coding indicates strong winds at the 300 millibar level (the jet stream occurs at an altitude in the atmosphere where the pressure ranges between 300 mb and 200 mb). The strong winds of the Subtropical jet will create too much wind shear for a tropical storm to form in the Gulf of Mexico next week, and the jet is expected to remain strong for at least the next two weeks. So, an early start to hurricane season looks unlikely this year.


Figure 2. GFS forecast for June 3 2006 at 300 millibars, the altitude where the jet stream is found. The polar and subtropical branches of the jet stream are clearly visible where upper-level wind speeds are highest. An area of light upper level winds and low wind shear is forecast to develop over the southern Caribbean Sea.

What about the southern Caribbean Sea, where the GFS model is predicting very light upper level winds, and where wind shear is likely to be low? Well, we will have to watch this area for tropical storm formation, but as I indicated before, the tropical waves one needs to act as the seed for a storm are usually too far south in June. Tropical waves usually do not start entering the Caribbean until July.

Have a worry-free weekend, everyone!

Jeff Masters

Is carbon dioxide a pollutant?

By: JeffMasters, 3:26 PM GMT on May 24, 2006

"Carbon dioxide: they call it pollution, we call it life!" That's the slogan of two 60-second TV ads airing in 14 U.S. cities May 14-28. The ads are being run by the Competitive Enterprise Institute (CEI). According to their web site, CEI is a non-profit public policy organization dedicated to advancing the principles of free enterprise and limited government. They tout a Wall Street Journal article which calls CEI "the best environmental think tank in the country".

Who funds the Competitive Enterprise Institute?
A variety of businesses fund CEI, but the fossil-fuel industry is one of their main contributors. Exxon documents show that the company gave $270,000 to CEI in 2004 alone. $180,000 of that was earmarked for "global climate change and global climate change outreach." Exxon has contributed over $1.6 million to CEI since 1998. Other oil companies, such as Amoco and Texaco, also contribute to CEI, through the American Petroleum Institute. So, it is safe to mentally replace the "paid for by the Competitive Enterprise Institute" tag on the ads with, "paid for by the fossil fuel industry." I speculated in an April blog that the Wall Street Journal opinion piece by Dr. Richard Lindzen of MIT (and other op-eds that appeared nationwide about the same time) were funded as part of an orchestrated public relations campaign by the fossil fuel industry. The appearance of the new TV ads are also likely part of the same PR campaign. The ads use language similar to the April op-ed pieces, using the word "alarmist" or its variations to describe those who warn that climate change presents a danger. The ads were timed to launch just before the opening of Al Gore's new film on global warming, "An Inconvenient Truth", due out today in New York City.

What do the ads say?
Here is the full transcript of the narration for the second ad, titled "Glaciers":

You've seen those headlines about global warming. The glaciers are melting, we're doomed. That's what several studies supposedly found.

But other scientific studies found exactly the opposite. Greenland's glaciers are growing, not melting. The Antarctic ice sheet is getting thicker, not thinner.

Did you see any big headlines about that? Why are they trying to scare us?

Global warming alarmists claim the glaciers are melting because of carbon dioxide from the fuels we use. Let's force people to cut back, they say. But we depend on those fuels, to grow our food, move our children, light up our lives.

And as for carbon dioxide, it isn't smog or smoke, it's what we breathe out and plants breathe in. Carbon dioxide: they call it pollution, we call it life.

What is the validity of the scientific results quoted in the ads?
When the narrator says "Greenland's glaciers are growing, not melting", the screen image is of a 2005 paper that appeared in Science magazine, "Recent Ice-Sheet Growth in the Interior of Greenland". A glowing halo appears around the word "Growth". If you go to the trouble to read the article, you'll discover that it discusses satellite measurements which show that the interior of Greenland's ice sheet has thickened by about 6 cm/year since 1999. This thickening is attributed to increased precipitation, primarily due to natural cycles. However, 25% of the increase is attributed to increased atmospheric water vapor from heightened evaporation caused by global warming. The paper also notes that the glaciers at the edge of Greenland have thinned by about 2 cm/year since 1999, and conclude that their measurements cannot be used to tell if the glaciers of Greenland are showing a net gain or loss in recent years. So, the claim that "Greenland's glaciers are growing, not melting" is a half truth. Ice in Greenland's interior is getting thicker, but the the glaciers at the edges are getting thinner. As I discussed in a blog on Greenland's Greenhouse, this is a very complicated system with many unknowns! Making a simple statement that Greenland's glaciers are not melting--or are melting--hides the very high scientific uncertainty about what is going on there. Also left out from the ads is that most of Greenland's glaciers have shown a marked increase in flow rate in recent years.

Is the Antarctic ice sheet getting thicker?
When the CEI ad claims, "The Antarctic ice sheet is getting thicker, not thinner", an image of another 2005 Science paper appears, Snowfall-Driven Growth in East Antarctic Ice Sheet Mitigates Recent Sea-Level Rise. Another halo of light appears around the word "Growth". Again, we are being subjected to a partial truth. Antarctica is divided into two ice sheets, and East and West Antarctic ice sheets, and this paper is only talking about one of the ice sheets. As I discussed in my March 7 blog, Antarctica Melting?, the question of whether Antarctica is undergoing a significant net melting or mass gain is not known--this is another very complicated system that we do not understand very well. In the words of the lead author of the paper, Professor Curt H. Davis, Director of the Center for Geospatial Intelligence at the University of Missouri:

"Our result is only for East Antarctica. Moreover, we make it clear that our results are for the interior and it is well known that the edges are losing mass." In a University of Missouri press release issued May 19, Dr. Davis states: "These television ads are a deliberate effort to confuse and mislead the public about the global warming debate. They are selectively using only parts of my previous research to support their claims. They are not telling the entire story to the public."

Is Carbon Dioxide a pollutant?
The fossil fuel industry points out in their ads that carbon dioxide it essential for both plant life and human life. Is it wrong, then, to label carbon dioxide as a pollutant? The definition of pollution in Webster's dictionary is "to make physically impure or unclean: Befoul, dirty." By that definition, carbon dioxide is not pollution. However, Webster's also has the definition: "to contaminate (an environment) esp. with man-made waste." Carbon dioxide is a waste gas produced by fossil fuel combustion, so can be classified as man-made waste. One can also make the case that carbon dioxide is contaminating the environment, since increased CO2 from burning fossil fuels has already harmed sea life. Carbon dioxide, when dissolved in sea water, is deadly to shell-building microorganisms that form an important part of the food chain in some cold ocean regions. The extra CO2 lowers the pH and make the water too acidic for these organisms to build their shells. As I reported in my blog on Acidifying the Oceans, the observed increase in acidity of 0.1 pH units during the past century due to fossil fuel burning, and expected continued acidification in the coming decades, could cause a massive die off of marine life and collapse of the food chain in these ocean areas. Based on these arguments, the fossil fuel industry's slogan, "Carbon dioxide: they call it pollution, we call it life!" could just as truthfully be phrased, "Carbon dioxide. We call it pollution, and we call it death." One need only look at our sister planet, Venus, to see that too much "life" can be a bad thing. There, an atmosphere of 96% carbon dioxide has created a hellish greenhouse effect. The temperatures of 860 F at the surface are hot enough to melt lead. There's not too much life there!

Crediting fossil fuels for our economic prosperity
The fossil fuel industry ads point out that the burning of fossil fuels has brought dramatic increases in wealth and prosperity to the world. This is a good point, and we should not seriously damage the basis of the world economy through reckless efforts to cut CO2 emissions. We can credit a good portion of the marvels of modern civilization to the availability of cheap fossil fuels to power our technological revolution. However, we shouldn't get all misty-eyed about the wondrous things we've accomplished by using this ready source of energy left for us by the fossilized plants of Earth's past. Any technology can bring about terrible suffering if used unwisely. Consider that fossil fuels have also made possible the horrors of modern warfare. The tanks of Hitler's blitzkrieg--and the aircraft that have dropped the bombs that have killed millions of innocent people this past century--were all powered by fossil fuels. Air pollution from fossil fuel burning has killed millions as well. We need to be honest about both the importance of fossil fuels, and the dangers they pose if used unwisely. The threat of climate change due to burning fossil fuels needs to be addressed truthfully, so that we can make wise decisions about the future of our energy technology. The untruthful new ad campaign by the fossil fuel industry is harmful to this end.

Jeff Masters

PS, my next blog will be Friday, when I'll probably review the global weather for April and give an update on the tropics. In a later blog, I'll be sure to review Al Gore's new movie, and comment on its truthfulness. However, I don't think the movie is playing until mid-June here in Michigan. BTW, most of us will never get to see the "we call it life" ads on TV. They are only playing in Albany, Albuquerque, Anchorage, Austin, Charleston WV, Dallas, Dayton, Denver, Harrisburg, Phoenix, Sacramento, Santa Barbara, Springfield IL, and Washington DC. I guess the fossil fuel industry wanted to run them in some test markets to see how they did before attempting a more widespread release.

Climate Change

Hurricane Katrina death toll raised to 1823

By: JeffMasters, 10:09 PM GMT on May 23, 2006

Louisiana raised its official death toll from Hurricane Katrina by 281 to 1,577, according to an Associated Press article from May 19. The Louisiana Department of Health and Hospitals decided decided that deaths caused by the stress and trauma associated with relocating or an accidental injury during travel should be counted as a Katrina-related death. This would bring the death toll from Katrina to 1823, when including the 228 deaths in Mississippi, 14 in Florida, 2 in Georgia, and 2 in Alabama. It is unlikely that the National Hurricane Center will consider these deaths part of the official death toll, but regardless, Katrina is the third deadliest hurricane ever to hit the U.S.

Low pressure in the Gulf of Mexico
Extensive cloudiness and thunderstorm activity continue in the Gulf of Mexico, where an upper-level area of low pressure sits. Wind shear is too high in the Gulf to allow tropical development of this system, and wind shear is expected to stay high for at least the next week over the Gulf. Tropical storm formation is not likely in the Atlantic for at least the next week, and probably longer. The GFS model is indicating that a stong subtropical jet stream will blow across the Gulf for the next two weeks, which should create too much shear for a tropical storm to develop.

I'll be back tomorrow with my article on the new global warming ads being aired by the fossil fuel industry.

Jeff Masters

NOAA hurricane season forecast issued

By: JeffMasters, 4:16 PM GMT on May 22, 2006

NOAA released its not-very-cheerful 2006 Atlantic hurricane season forecast today. The outlook calls for a very active 2006 season, with 13-16 named storms, 8-10 hurricanes, and 4-6 major hurricanes. An average season has 10 named storms, 6 hurricanes, with 2.3 of them being major hurricanes. However, since an active period of hurricane activity began in 1995, the Atlantic has averaged 15 named storms, 8.5 hurricanes, and 4 major hurricanes (Figure 1). NOAA expects an 80% chance of an above normal season, 15% chance near normal, and a 5% chance below normal. They note that 2006 may turn out to be the 4th hyperactive Atlantic hurricane season in a row. A repeat of last year's record season is not expected, though, because tropical Atlantic SSTs are not presently as warm as last spring. They also note that some of the other factors that contributed to last year's record season are not predictable at this time--an amplified upper-level ridge of high pressure over the eastern U.S., long periods of low thunderstorm activity in the central Pacific, and exceptionally low pressures in the Gulf and Caribbean Sea region.


Figure 1. NOAA's 2006 Atlantic hurricane season forecast, compared to the historical record.

NOAA does not make any forecast of where this season's storms are likely to hit, stating, "Historically, very active seasons have averaged 2-4 landfalling hurricanes in the continental United States and 2-3 hurricanes in the region around the Caribbean Sea. However, it is currently not possible to confidently predict at these extended ranges the number or intensity of landfalling hurricanes, and whether or not a given locality will be impacted by a hurricane this season."

For comparison, here is what the other hurricane forecasting groups are predicting for 2006:

Colorado State team (Phil Klotzbach and Bill Gray, updated April 4 2006, with a new update scheduled for Wednesday, May 31):

17 named storms
9 hurricanes
5 intense hurricanes

Cuba's National Weather Institute prediction from May 2, 2006:

15 named storms
9 hurricanes

Tropical Storm Risk, Inc. May 5, 2006 forecast:

15 named storms
8 hurricanes
3.6 intense hurricanes

So, if you live on the Atlantic or Gulf coast, it's time to get your hurricane supplies ready, perhaps buy that generator you've been thinking about getting, and make whatever other preparations you've been putting off. Hurricane season starts next week, and it looks like it'll be another significant one!

Jeff Masters

I'll be back tomorrow afternoon with an analysis of the new TV ads being run by the Competive Enterprise Institute procaiming that "Greenland's glaciers are growing, not melting", and "the Antarctic Ice sheet is getting thicker, not thinner." We'll see that these statements are dubious half-truths, at best.

Texas air pollution study gets help from the Hurricane Hunters

By: JeffMasters, 2:52 PM GMT on May 19, 2006

Houston and Los Angeles rank as the two most polluted or cities in the U.S. To address the problem in Houston, a series of air pollution field studies have been run over the past decade in Texas to help understand the what is going on, and come up with the best emission control strategies needed to reduce ozone pollution levels. The TexAQS II Air Quality Field Study is that latest effort to do so. The field study, slated to run through September of this year, will take a broad number of surface based and airborne air pollution and meteorology measurements. A key tool in the study is one of NOAA's P-3 weather research aircraft, which will be specially outfitted as a state-of-the-art air pollution sampling platform. I flew on the NOAA P-3s in a number of such air pollution field studies during my stint with the hurricane hunters. My most memorable project came in 1989, when we flew over the Arctic Ice Cap to track "Arctic Haze". It was unbelievable to be flying over what should have been one of the cleanest places in the world, only to find visibility reduced to three miles in thick haze, due to pollution blown over the North Pole from industrial sources in Eastern Europe.


Figure 1. Areas of the U.S. in violation of the EPA standards for ozone pollution.

The data collected in the Texas study will be used to develop a variety of computer models needed to understand what is going on, and thereby recommend pollution control strategies. Ozone is not emitted directly, but is formed in a very complicated way from the "precursor" pollutants, Nitrogen Oxides (NOx) and Volatile Organic Compounds (VOC). It turns out that this formation process is extremely non-linear--which means that in some cases, reducing emissions of one of the "precursor" pollutants will actually increase ozone. As a result, you really have to understand the problem thoroughly before going to the expense of implementing emission controls of NOx or VOC in an effort to reduce ozone pollution.

Computer modeling efforts to understand pollution are of limited help, because we don't have a very good idea about how much pollution is being emitted. Each year, businesses are required to submit estimates of how much pollution they are emitting. These emission estimates, however, are not very accurate. For example, according to a story published May 7 in the Houston Chronicle, a British Petroleum refinery in Texas City (just south of Houston) reported that it emitted three times more formaldehyde and ammonia in 2004 than in 2003. The increase in emissions at this one plant was so large, that it distorted the data for refineries nationwide, according to the EPA. The Texas City plant accounted for the bulk of a 15 percent increase in emissions in 2004 that drove refinery pollution to its worst level since 2000. The problem is that the company likely underestimated its 2003 emissions. The emission estimates are all theoretical, and are not based on actual measurements of pollutant gases coming out of the stacks.

The article quotes Matt Fraser, an associate professor in civil and environmental engineering at Rice University, who says: "It's incredible that they were that far off. That's a huge increase in formaldehyde. It just shows you how little attention is being paid to getting emissions numbers right. And since all of our air-quality control strategies are based on that data, it makes you wonder." Well, the planners of the TexAQS II Air Quality Field Study are also wondering, which is why there is the necessity of doing this field study. The only sure way to know what's really going up into the air is to go out and measure it, and this summer's study should help the scientists and regulators figure out what the right steps are to control air pollution in one of our most polluted cities.

Unfortunately, the participation of NOAA's P-3 in the Texas study means that only one P-3 will be available for hurricane hunting this hurricane season. This worries me, because the P-3s are the best tool we have for hurricane reconnaissance. The Air Force C-130s do not have the state-of-the-art radar systems like the P-3s carry, nor the new SFMR Stepped Frequency Microwave Radiometer instrument that can measure surface winds speeds anywhere in a storm. Will participation of the P-3 in this air pollution study save more lives and property than if the aircraft participated in hurricane hunting this Fall? I think that is probably the case, but it is definitely a gamble that I'm uncomfortable with.

Jeff Masters

Air and Water Pollution

AIr pollution forecasting

By: JeffMasters, 2:49 PM GMT on May 18, 2006

Over the past decade, more state and local agencies have begun air quality forecasting for their communities. Today, about 300 cities nationwide are issuing air quality alerts based on forecast concentrations of known pollutants such as ozone and particle pollution, but have been doing so without the benefit of the kind of high-powered national forecasting technology and guidance that supports local weather forecasts. However, this is changing this year, with the arrival of new NOAA forecasting guidance to improve forecasters� ability to predict the onset, severity, and duration of poor air quality. For communities in most of the country, this will be the first time that comprehensive air quality predictions, with hour-by-hour information for cities, suburbs and rural communities alike will be available.

Figure 1. Ozone pollution forecast for 7pm EDT May 18, 2006, generated by NOAA's new air pollution forecasting system. With a major push of clean Canadian air over the eastern half of the country, the usual pattern of pollution over the Northeast and Midwest is absent today.

NOAA, in partnership with EPA, has implemented the first stages of an air quality forecast (AQF) capability. Now providing ozone forecast guidance for the eastern U.S. (predictions available at http://www.nws.noaa.gov/aq), the AQF capability uses the National Weather Service�s most advanced operational computer weather models at NOAA�s National Centers for Environmental Prediction (NCEP) coupled with a community multi-scale air quality (CMAQ) chemical transport model to produce daily forecast guidance for surface ozone. Meteorological information such as current and predicted temperature, humidity, winds, cloudiness, and precipitation, combined with pollutant emissions data supplied by EPA, are input to CMAQ to predict ozone concentrations through the next day. In summer, 2006 an experimental version of the AQF capability will cover the lower 48 states. Currently, the AQF capability covers the eastern US from the Atlantic Seaboard to the Mississippi Valley, with hourly and 8-hourly forecast ozone concentrations out to midnight, next day, at 12 km (about 7 miles) grid resolution. This information, converted to EPA�s health-based Air Quality Index (AQI) is also available on EPA�s AIRNow website.

In the next few years, the operational ozone prediction domain will be expanded still further to include Alaska and Hawaii and the forecast range will be extended out to several days. Also in development are predictions of airborne particulate matter (PM). As a component of the eventual PM forecast capability, a daily smoke forecast tool is being tested experimentally. For this tool, NOAA�s National Environmental Satellite and Data Information Service provides fire locations of active fires from complex satellite-based imaging techniques. Smoke transported from these fires is simulated with a computer transport model called HYSPLIT linked to NWS� operational weather forecast models. Predictions of the smoke are updated each morning and provided on a web site at http://www.nws.noaa.gov/aq-expr. State and local air quality forecasters will be able to use the expanding guidance when they prepare their forecasts or issue local alerts for their communities. The public, especially those with greater sensitivity to poor air quality, will be able to see hour-by-hour trends for the entire Nation and take appropriate actions.

I'll conclude my series on air pollution tomorrow, with a look at why one of NOAA's P-3 weather research aircraft will be flying an air pollution research project this summer in Texas instead of chasing hurricanes.

Jeff Masters

Air and Water Pollution

Tropical outlook, NE flooding, and more on air pollution progress and challenges

By: JeffMasters, 2:45 PM GMT on May 17, 2006

The flooding in the Northeastern U.S. is easing today, with most of the rivers in flood stage expected to drop below flood stage by Thursday afternoon. No new rain is expected across the region today or Thursday, but some light to moderate rains Friday may slow the recovery efforts. A series of modest rain systems should then cross through the region into early next week. By mid-week, the jet stream is forecast to move poleward and being a more summerlike pattern to North America.

Tropical outlook for the next week
With the coming of a more summerlike pattern next week, we will need to start watching the Western Caribbean for some possible tropical development; wind shear values there are starting to fall to levels where tropical development is possible again. Wind shear is quite low (5-10 knots) over the waters just north of Panama today and will stay low the next few days, but at present the clouds there are sparse and disorganized, and I am not expecting anything to develop this week. Next week things may be more favorable, when the remains of a cold front that pushes off the coast could provide enough of an initial disurbance to kick something off--if the front can push far enough south, where wind shear is lower. Again, I am not really expecting anything to develop, wind shear should still be high enough to make tropical development marginal.

Air pollution progress and health effects
Let's continue our dicussion of air pollution this week, focusing on the health effects. Significant progress has been made in recent years in cleaning the nation's air. Between 1970 and 2004, total emissions of the six major air pollutants regulated by the Environmental Protection Agency (EPA) dropped by 54 percent. This is particularly impressive when noting that the gross domestic product increased 187 percent, energy consumption increased 47 percent, and U.S. population grew by 40 percent during the same time--proof that economic growth and environmental protection do go hand in hand. However, air pollution remains a serious threat to public health and the environment. Outdoor air pollution in the U.S. due to particulate pollution alone was estimated by the EPA in 1997 to cause at least 20,000 premature deaths each year. Other estimates place this number at 50,000 to 100,000 deaths per year. A study in Southern California found that living near major roadways increases the risk of childhood asthma. Among those long-term kids studied that had no parental history of asthma who lived within 75 meters of a major road, 59% of asthma was attributable to residential proximity to the road. The annual costs of air pollution per person in the Los Angeles area were estimated at $3000-$4000 per person back in the 1970s. This cost has dropped significantly, and is now estimated at about $1000 per person. This $1000 per person amounts to $3 billion per year just for the Los Angeles area, and further efforts to control air pollution need to be looked at to see if this cost--and the human suffering that accompanies it--can be further reduced. Of course, the costs to businesses will also have to be factored in--for example, emissions control equipment can add over $1000 to the cost of a vehicle.

How to protect yourself when air pollution is high
You're exposed to air contamination any time you breathe polluted air. But when you exercise, work in the yard, or do other strenuous activities that make you breathe harder and faster, you take more polluted air into your lungs. Exposure to ozone and particle pollution is linked with a number of significant health problems. Children, people with lung disease, older adults and people with heart disease tend to be more vulnerable.

You can help protect yourself simply by changing the time or intensity of your exercise, yard work or other strenuous activities. Use the Air Quality Index (AQI) and daily air quality forecasts to help you determine when you need to make changes. These are posted on the Weather Underground web site for most major cities in the U.S., or you can get them from www.airnow.gov.

The AQI is a color-coded scale that tells you who needs to take steps to reduce their exposure to ozone or particle pollution and when. If you have heart disease, for example, pay close attention when particle pollution reaches Code Orange levels. If you have asthma, youll want to pay attention at Code Orange for particle pollution and for ozone.

Ozone pollution tends to be more of a problem in the warm summer months. Levels of this colorless, odorless gas can increase during the day, peaking in the late afternoon to early evening. At elevated levels, ozone is a threat to everyones health, but those who are most susceptible are people with lung diseases such as asthma, children, older adults and healthy people who are active outdoors.

Ozone causes cells in the lungs to swell and get inflamed similar to what happens to your skin cells when you get sunburned. Repeated episodes of this kind of inflammation may cause permanent damage to the lungs. Ozone aggravates asthma and other lung diseases, leading to increased medication use, visits to doctors and emergency rooms, and hospital admissions. Recent studies have also linked ozone exposure with premature death.

Can you tell if ozone is affecting you? You may experience symptoms like coughing, a burning sensation when you breathe, chest tightness, or shortness of breath. If you have asthma, you may find yourself needing to use medicine more frequently, or you may have asthma attacks requiring a doctor's attention.

Particle pollution can occur at any time of year. If you live in an area with high woodstove use, for example, particle pollution may be higher in your community in winter. In many areas of the eastern U.S., particle pollution may also be high in the summertime, often accompanied by high levels of ozone. People with heart or lung disease, older adults, and children are considered at greater risk from particle pollution than other people, especially when they are physically active.

Particle pollution can aggravate lung disease, causing asthma attacks and acute bronchitis, and may also increase susceptibility to respiratory infections. Particle pollution has been linked to heart attacks and arrhythmias in people with heart disease, and also to premature death in people with heart or lung disease.

If you or your children are healthy, you're not likely to suffer serious effects from short-term, peak exposures to particle pollution. But when particle pollution is elevated, you may experience irritation of the eyes, nose and throat, coughing, chest tightness, and shortness of breath.

Reducing your exposure to ozone and particle pollution isn't hard. Just take it a little easier. If pollution is forecast to be high in your area, cut back or change the time of your strenuous activities: go for a for a walk instead of a jog, or reschedule for times when the air quality is expected to be better. If you have asthma, be sure to follow your asthma action plan with air pollution levels are high. And don't exercise near busy roads; particle levels generally are higher in these areas.

Particle levels can be elevated indoors too, especially when outdoor particle levels are high, such as during an inversion or when there's a lot of smoke outside (such as from a wildfire). Certain filters and room air cleaners can help reduce indoor particle levels. You can also reduce particle levels indoors by not smoking inside or vacuuming, and by reducing your use of other particle sources such as candles, wood-burning stoves, and fireplaces. Go to http://www.epa.gov/iaq/homes/index.html for more information.

My next blog will be Thursday.
Jeff Masters

Air and Water Pollution Flood

Northeast flooding continues; Hong Hong breathing easier

By: JeffMasters, 2:12 PM GMT on May 16, 2006

Major flooding continues across New Hampshire, southwest Maine, and northeast Massachussetts today, where an additional 1-3 inches of rain has fallen in the past day and another inch is expected today. The culprit "cut off low"--a large low pressure system that got separated from the jet stream--is drifting slowly northeastward, and is expected to leave the area tonight, bringing an end to the heavy rains and the worst of the flooding. However, an active jet stream pattern over the next seven days will continue to bring occasional rain to the area, and area rivers--which are generally five to eight feet above flood stage--will be slow to fall. By next Tuesday, the GFS model is indicating that a more summer-like weather pattern may emerge, with the jet stream retreating northwards and warmer, dryer air moving in.


Figure 1. Rainfall amounts for New England estimated by radar, ending at 10am EDT Monday May 16.

Typhoon Chanchu
The season's first typhoon has continued to weaken, and was a Category 3 storm with 125 mph sustained winds at 8am EDT this morning. Chanchu (which means "pearl" in Chinese), is expected to continue to weaken over the next day due to dry air, cooler ocean temperatures in its path, and interaction with land. The typhoon is expected to spare Hong Kong a direct hit, and come ashore over the Guangdong province on China's eastern coast on Wednesday as a Category 2 storm. This is a far cry from last Friday's intensity forecast, which projected that Chanchu would strike as a Category 5 supertyphoon! Chanchu is yet another example of our poor ability to make accurate long-range hurricane intensity forecasts.

Chanchu delivered a serious blow to the Philippines over the weekend, killing at least 37 and leaving thousands homeless.


Figure 2. Typhoon Chanchu at 5:30 am EDT Tuesday, with 125 mph sustained winds.

My next blog will be Wednesday, when I'll talk more about air pollution, plus the Northeast flooding and Typhoon Chanchu.

Jeff Masters

Flood

New England flooding, air pollution, and the season's first typhoon

By: JeffMasters, 2:05 PM GMT on May 15, 2006

Major flooding has hit southern New Hampshire, southwest Maine, and northeast Massachussetts today, where more than 10 inches of rain has fallen in the past four days. The culprit is a "cut off low", a large low pressure system over the Great Lakes that got separated from the jet stream on Thursday, and has stayed almost stationary since since then, with no upper level winds to push it along. The counter-clockwise flow of air around the low has drawn copious amounts of moist oceanic air over New England. The rains from this moisture have brought the Warner river at Davisville and the Smith River at Bristol to flood stage this morning. With another 1-2 inches of rain expected across the region today, these rivers should crest several feet above flood stage, with moderate to major flooding. The cut-off low is expected to drift slowly northeastward today and get re-absorbed by the jet stream on Tuesday, which will finally bring an end to the worst of the rains. Howver, the weather pattern over the next week is expected to remain wet over the eastern half of the U.S., and more rain is expected in the Northeast later this week as the jet stream continues to remain in a typical Springtime active pattern.


Figure 1. Rainfall amounts for New England estimated by radar, ending at 8:30am EDT Monday May 15.

Air pollution season is here
May marks the beginning of air pollution season in the U.S., when summertime brings the hot temperatures, high amounts of UV radiation, and stagnant air that can trigger air pollution "Action Days". This week marks the annual observance of Air Pollution Awareness week, and at EPA's request, I will be writing several blogs highlighting air pollution. In particular, I'll discuss why one of NOAA's P-3 hurricane hunter airplanes will be in Texas for air pollution research this hurricane season, instead of flying hurricanes.

Quick intro on air pollution
Today, I'll present a quick summary of what pollutants we're concerned about. The Environmental Protection Agency (EPA) calculates the Air Quality Index (AQI) for five major air pollutants regulated by the Clean Air Act: ground-level ozone, particle pollution, carbon monoxide, sulfur dioxide, and nitrogen dioxide. Ozone and particle pollution are the two most serious pollutants in the U.S. Particle pollution alone has been estimated to cause over 20,000 premature deaths the U.S. each year, and 800,000 worldwide (although the exact mortality numbers and definition of "premature deaths" is controversial).

Ozone is a colorless gas composed of three atoms of oxygen. Ozone forms both in the Earth's upper atmosphere and at the surface. Where ozone forms determines whether it is helpful or harmful to your health.

Good ozone naturally forms in the stratosphere, a layer of air about 10 - 30 miles (16 - 48 km) above Earth's
surface. This protective layer shields us from the sun's harmful ultraviolet rays. Without this layer, we would all be blinded and sunburned. Unfortunately, human-created chemicals are destroying this beneficial layer of ozone. Over the South Pole in springtime, the ozone loss is so severe that an "Ozone Hole" forms, letting significant amounts of harmful ultraviolet light reach the surface.

Ozone from the stratosphere sometimes gets transported to the surface, particularly in high mountainous regions. Hikers on Mt. Everest who don't use bottled oxygen can be at risk of death from breathing poisonous levels of ozone near the mountain's summit in some weather conditions.

Bad ozone forms near Earth's surface when the ultraviolet light in sunlight triggers a chemical reaction with "precursor pollutants" emitted by cars, power plants, and industrial sources. These precursor pollutants consist of nitrogen oxides (NOx) and volatile organic hydrocarbons (VOC). Ozone near ground level is a harmful pollutant. Ozone pollution isn't limited to big cities like Los Angeles, Houston and New York. It's also found in smaller cities like Raleigh, NC and Cincinnati, OH. It can be a problem in rural areas, including some national parks. Ozone and the pollutants that react to form it (NOx and VOCs) can also be carried on the wind to affect air quality in urban and rural areas hundreds of miles away.

Particle pollution is a mixture of microscopic solids and liquid droplets suspended in air. This pollution, also known as particulate matter, is made up of a number of components, including acids (such as nitrates and sulfates), organic chemicals, metals, soil or dust particles, and allergens (such as fragments of pollen or mold spores). Unlike summertime ozone, particle pollution can occur year-round. It is worst in summer, though, when winds are lighter and the air becomes more stagnant.

Particles come in a wide range of sizes. Fine particles are less than 2.5 micrometers in diameter. How small is that? About 1/30th the diameter of the average human hair--so small, you'd need an electron microscope to see them.

Some fine particles can be emitted directly (think of smoke from a woodstove). But most are formed secondarily from complex atmospheric reactions of gases such as NOx and sulfur dioxide (SO2), that are emitted from power plants, industries, cars, buses and trucks. These fine particles are the worst for your health, since their small size allows then to penetrate deep into your lungs.

Inhalable coarse particles are larger than 2.5 and up to 10 micrometers in diameter. Sources of coarse particles include crushing or grinding operations and dust stirred up by vehicles traveling on roads. These particles are not as injurious to your health, as their large size allows them to be filtered out more readily by your nose before they reach your lungs.

Typhoon Chanchu
The season's first typhoon, a Category 4 storm with 140 mph winds named Chanchu, has turned north, and is now threatening to strike Hong Hong on Wednesday. Chanchu briefly made it to supertyphoon status on Sunday, when it had 150 mph sustained winds and a 910 mb central pressure. This was good enough for a Category 4 rating on the U.S. Saffir-Simpson scale, but not Category 5--which starts at 156 mph. A supertyphoon is defined as any tropical cyclone in the Western Pacific that attains maximum sustained winds of 150 mph. It is not unusual to get a supertyphoon in May, and this last happened in 2004, when Supertyphoon Nida reached Category 5 status with sustained winds of 160 mph. I'll have more on Typhoon Chanchu tomorrow.


Figure 2. Typhoon Chanchu at peak intensity Sunday, with 150 mph sustained winds and a 910 mb pressure.

Jeff Masters

Air and Water Pollution

La Niña is gone

By: JeffMasters, 3:13 PM GMT on May 11, 2006

The La Niña of 2006 proved to be short-lived. Sea Surface Temperatures (SSTs) in the eastern Pacific near the Equator have returned to near-normal values over the past month, according to the latest El Niño advisory issued today by the Climate Prediction Center (CPC). We are now in what is characterized as ENSO-neutral conditions (or El Niño-neutral conditions), which means that there is neither an El Niño nor a La Niña occurring. This is the case about 45% of the time, and was true for March through December of 2005. The CPC expects El Niño-neutral conditions to continue for at least the next 3-6 months, which means for all of hurricane season. The 2006 La Niña was an unusual one, because it started very late--no La Niña of similar magnitude has ever formed in the middle of winter, as this one did. However, the demise of this year's La Niña came at the usual time such events end--April and May are the typical months for the demise of both La Niña and El Niño.

How will this affect the hurricane season of 2006?
So, what does all this portend for the upcoming hurricane season? It is well-known that the presence of a La Niña usually means more Atlantic hurricanes, and stronger hurricanes, too. This is because the large-scale wind circulation that develops during a La Niña keeps wind shear levels relatively low over the main development region for hurricanes in the tropical Atlantic. So, the demise of La Niña is good news for those of you living in Hurricane Alley. However, before we get too cheerful about this, it is worth remembering that the unbelievable Hurricane Season of 2005 occurred in El Niño-neutral conditions, and El Niño-neutral conditions are expected for this hurricane season, too. So, let's look at some other factors that will influence this year's hurricane season.


Figure 1. Comparison of this year's May SST anomalies with last year's. Image credit: NOAA.

SST comparison--this year vs. last year
Let's compare last year's SST anomalies (the difference in temperature between observed and normal) with this year's, to see how things have changed (Figure 1). The key things to look at are the SSTs in the Caribbean and the tropical Atlantic between Africa and the Antilles Islands, since this is where 85% of all major hurricanes form. While SSTs are .5 to 1.5 degrees above normal--which is a lot!--SSTs are a full degree Centigrade cooler this year than last year at this time. This reduction in SSTs should keep this year's hurricane season from producing early major hurricanes, like Dennis and Emily of July 2005. However, once we enter the prime hurricane months of August through October, expect another above normal year for hurricanes and intense hurricanes. My worst-case scenario for 2006 is a year similar to 2004, which was awful, but modest compared to 2005. My best-case scenario is a year like 1995, which was still very active, but the Bermuda High set up much farther east and recurved most storms before they hit land. Of course, this would be bad for the northeastern Leeward Islands, which got pounded in 1995.

The Gulf of Mexico SSTs are much warmer this year than last, due in part to the record warm temperatures the U.S. experienced in January and April. This may allow for more intense that normal June systems to develop in the Gulf this year. However, remember that systems that develop in the Gulf usually only last a day or two, which doesn't give them much time to strengthen before they hit land. There has only ever been one major hurricane in June (Audrey of 1957).

The other item of interest is that the pattern of SSTs over the eastern Pacific is much different this year versus last year. Waters near the Equator were much warmer last year, thanks to the lingering effect of the El Niño event early in the year. There is also a much warmer pool of water north of Hawaii this year. These differences may end up having a significant influence on this year's jet stream pattern, and where the Bermuda high ultimately sets up camp. The jet stream and Bermuda high determine how hurricanes are steered, but unfortunately we don't know enough about long-range influences of unusual SST patterns on the weather to be able to predict where this year's hurricanes are likely to be steered. The bottom line is that SSTs are cooler and have a much different pattern this year compared to last year, and thus we should not expect a continuation of last year's ridiculously hyperactive, once-in-a-lifetime hurricane season.

Outlook for the rest of May
SSTs are already warm enough to support hurricane formation in the Gulf of Mexico, and the entire tropical Atlantic. What is saving us are the strong upper level winds of the jet stream, which has been dipping far to the south and creating lots of wind shear. The jet stream is forecast to remain active and fairly far south for at least the next two weeks, which should maintain unfavorable levels of wind shear over the Atlantic for the remainder of May. As long as we're talking about tornado outbreaks in the southern U.S., such as we've experienced this week, we don't have to worry about hurricane formation in the Gulf of Mexico. Tornado outbreaks require a stong jet stream, which is the bane of a hurricane trying to form.

The other missing ingredient--at least in the Caribbean and tropical Atlantic--has been the lack of an initial disturbance to get a hurricane started. Africa has just begun to produce its usual summer parade of tropical waves, which frequently serve as the nucleus for a tropical storm. These tropical waves are coming off of Africa at about 2 degrees North Latitude, which is too close to the Equator to allow a hurricane to spin up. I'm not expecting any tropical development for the rest of May in the Atlantic due to high wind shear and the lack of proper initial disturbances.

It's another story in the Eastern Pacific, where wind shear is less and the remains of an old cold front coming off of North America could serve to trigger tropical storm formation as early as next week. The hurricane specialists at the National Hurricane Center begin rotating shift work on Monday May 15, which marks the official beginning of the Eastern Pacific hurricane season.

My next blog will be on Monday. I'll talk about air pollution some next week, since May marks the beginning of air pollution season, and next week is EPA's Air Pollution Awareness Week.

Jeff Masters

Major severe weather outbreak possible today

By: JeffMasters, 2:25 PM GMT on May 10, 2006

A relative lull in the Spring severe weather season is over, as killer tornadoes have once again struck the southern U.S. At least three people were killed and ten injured last night when a tornado swept through Winchester and Anna, Texas, an area about 45 miles northeast of Dallas. The tornado struck at about 10:30 pm local time, and was part of an intense squall line that you can see in this radar animation. Tornadoes have also touched down in Oklahoma, Arkansas, Missouri, Mississippi, and Alabama in the past 24 hours, as you can see from our Storm Report Map.


Figure 1. The Storm Prediction Center is forecasting a moderate risk of a major severe weather outbreak today across the lower Misssissippi Valley and central Gulf states, and northward across portions of the Tennessee Valley.

The significant severe weather event is expected to continue today across the lower Misssissippi Valley and central Gulf states, and northward across portions of the Tennessee Valley today. Strong tornadoes of up to F3 intensity, plus thunderstorms with damaging winds and very large hail are possible prior to the passage of a strong cold front today across the region. Flooding is also a concern in Missouri and Arkansas, where drought had been a major concern until recently.

My next blog will be Thursday.
Jeff Masters

Tornado

2006 Gulf of Mexico Loop Current outlook

By: JeffMasters, 2:41 PM GMT on May 08, 2006

The Loop Current is an ocean current that transports warm Caribbean water through the Yucatan Channel between Cuba and Mexico. The current flows northward into the Gulf of Mexico, then loops southeastward through the Florida Keys (where it is called the Florida Current), and into the Bahamas. Here, the waters of the Loop Current flow northward along the U.S. coast and become the Gulf Stream. With current speeds of about 0.8 m/s, the Loop Current is one of the fastest currents in the Atlantic Ocean. The current is about 200-300 km (125 -190 miles) wide, and 800 meters (2600 feet) deep, and is present in the Gulf of Mexico about 95% of the time. During summer and fall, the Loop Current provides a deep (80 - 150 meter) layer of vary warm water that can provide a huge energy source for any lucky hurricanes that might cross over.


Figure 1. The Loop Current flow northwards into the Gulf of Mexico. Every 6 - 11 months, a bulge in the current cuts off into a clockwise-rotating eddy that then drifts slowly west-southwestward towards Texas. Image credit: NOAA.

The Loop Current commonly bulges out in the northern Gulf of Mexico and sometimes will shed a clockwise rotating ring of warm water that separates from the main current (Figure 1). This ring of warm water slowly drifts west-southwestward towards Texas or Mexico at about 3-5 km per day. This feature is called a "Loop Current Ring", "Loop Current Eddy", or "Warm Core Ring", and can provide a key source of energy to fuel rapid intensification of hurricanes that cross the Gulf, in addition to the Loop Current itself. The Loop Current pulsates in a quasi-regular fashion and sheds rings every 6 to 11 months. When a Loop Current Eddy breaks off in the Gulf of Mexico at the height of hurricane season, it can lead to a dangerous situation where a vast reservoir of energy is available to any hurricane that might cross over. This occurred in 2005, when a Loop Current Eddy separated in July, just before Hurricane Katrina passed over and "bombed" into a Category 5 hurricane. The eddy remained in the Gulf and slowly drifted westward during September. Hurricane Rita passed over the same Loop Current Eddy three weeks after Katrina, and also explosively deepened to a Category 5 storm.


Figure 2. Current position of the Loop Current and Loop Current Eddy that cut off in March 2006. Image credit: Navy Research Lab.

So, a key question to ask this hurricane season, is when will the next Loop Current Eddy break off, creating a ready-made high-octane energy source for any hurricane that might pass by? Well, the behavior of the Loop Current over the past year can be viewed at Navy Research Lab's web site (51 Mb). This movie has arrows showing the direction of the current, plus a color coding that represents the height of the sea surface above mean level. The higher the height, the warmer the water (since warm water expands and thus raises the sea level where it is at). One can see near the beginning of the animation that the Loop Current Eddy that fueled Katrina and Rita breaks off from the Loop Current in July 2005, then slowly moves west-southwest to a point off the Texas coast by November, where it gradually dissipates. Another Loop Current Eddy breaks off eight months later in March, and lies south of Louisiana in early May. If the Loop Current maintains its 6 - 11 month periodicity shedding these eddies, the next eddy is due sometime between September and February. Oceanographic models can't forecast these events realiably, so we don't know when the most likely time is. Let's hope that this doesn't occur in September or October--we could do without another big eddy of warm water in the Gulf at the height of hurricane season, fueling explosive hurricane intensification!

The Navy web site offers a 1-month forecast of the Loop Current in the Gulf of Mexico. The current forecast hints that the Loop Current may shed an eddy at the beginning of June. I don't know how reliable these forecasts are, but keep in mind that currents are driven by winds, and wind forecasts are not reliable out more than about 10 days. Given that the Loop Current just shed an eddy in March, I'd be surprised if a new eddy comes off in June.

My next blog will be Wednesday.
Jeff Masters

Global warming a hoax no longer

By: JeffMasters, 12:44 PM GMT on May 05, 2006

Are the climate models that form the foundation of greenhouse warming predictions fundamentally flawed? That has been the argument of some scientists and "greenhouse skeptics" over the past few decades. The main issue has been the inability of the climate models to reproduce the relatively low amount of warming observed by satellites and weather balloon instruments in the troposphere (the lower portion of the atmosphere that extends up to elevations of about 40,000 feet.) This discrepancy was a prime argument Senator James Inhofe (R-Oklahoma) used in his famed 2003 speech when he referred to the threat of catastrophic global warming as the "greatest hoax ever perpetrated on the American people." Greenhouse skeptic S. Fred Singer, who has probably more Congressional testimony about global warming under his belt than any other scientist, headlines his website with the quote, "Computer models forecast rapidly rising global temperatures, but data from weather satellites and balloon instruments show no warming whatsoever. Nevertheless, these same unreliable computer models underpin the Global Climate Treaty." Michael Crichton also used the tropospheric warming discrepancy to give climate models a bad rap in his State of Fear novel. (Incredibily, Crichton--a science fiction writer--was summoned by Sen. Inhofe in September of 2005 to testify before Congress on the issue of climate change.) However, the arguments of these global warming skeptics were dealt a major blow with the issuance this week of a press release by NOAA's Climate Change Science Program refuting their main argument.



The Climate Change Science Program study, which was commissioned by the Bush Administration in 2002 to help answer unresolved questions on climate, found that it was the measurements, not the models, that were in error. Their report, issued on Wednesday, stated, "there is no longer a discrepancy in the rate of global average temperature increase for the surface compared with higher levels in the atmosphere." They cautioned, however, that discrepancies still existed in some regions, particularly the tropics. Greenhouse skeptics will undoubtedly point to this smaller remaining discrepancy as evidence that climate models cannot be trusted, but the authors of the report thought it more likely that the measurements were flawed. Chief Editor Dr. Thomas Karl, director of NOAA's National Climatic Data Center, concluded in the report: "Discrepancies between the data sets and the models have been reduced and our understanding of observed climate changes and their causes have increased. The evidence continues to support a substantial human impact on global temperature increases."

The satellite measurements that were found to be in error were taken beginning in 1978 by Microwave Sounding Units (MSU) operating on NOAA polar-orbiting satellites. According to a description of the MSU data available on the web site where the data is archived,

"The instruments in the MSU series were intended for day to day operational use in weather forecasting and thus are not calibrated to the precision needed for climate studies. A climate quality dataset can be extracted from their measurements only by careful intercalibration of the nine distinct MSU instruments."

Dr. John Christy of the University of Alabama, Huntsville, made a series of efforts to perform the careful intercalibration needed beginning in the 1990s, and for over a decade successfully defended his conclusion that the MSU instruments were showing a much lower level of tropospheric warming than what climate models predicted. Christy was probably the most quoted scientist by the "greenhouse skeptics" during that period, and testified numerous times before Congress about his findings. However, a series of papers published in 2004 and 2005 showed that the satellite intercalibration methods used by Christy were incorrect, and Christy publicly credited the authors of the new studies with finding a real source of error. Christy is also one of the co-authors on the Climate Change Science Program study.

So can we trust the climate models now? That will remain a matter of debate, but now we know that these models have successfully performed at least one major prediction that their detractors thought was wrong. With the climate models validated by the collapse of the greenhouse skeptics' main argument against them, it is apparent that their predictions of possible catastrophic climate change are no hoax and need to be taken seriously.

For further reading: The Economist printed a easy to understand article in August 2005 summarizing the new research exposing the satellite and weather balloon measurement errors, and realclimate.org has a more technical discussion.

I'll be back next week to talk about the demise of La Nina, and other factors that may affect the coming hurricane season.

Jeff Masters

Climate Change

Hurricane help on the way

By: JeffMasters, 5:49 PM GMT on May 03, 2006

The National Hurricane Center will be getting some much-needed help this coming hurricane season. The agency has received permission to add four new hurricane forecasters, thanks to a special requisition championed by Senator Bill Nelson (D-Florida). The four new forecasters--Eric Blake, Dan Brown, Michelle Mainelli, and Jamie Rhome--all come from within the NHC's Tropical Analysis and Forecast Branch (which analyzes satellite imagery) and Technical Support Branch. They join the six Senior Hurricane Specialists--Lixion Avila, Jack Beven, James Franklin, Richard Knabb, Richard Pasch, and Stacy Stewart--to make a total of ten forecasters for this season. An eleventh forecaster--Dr. Chris Landsea, NHC's Science and Operations Officer--will also be pitching in as needed. The four new hurricane forecasters all wrote advisory packages last season under the supervision of one of the Senior Hurricane Specialists, which should speed the transition to working independently this year.

With another active hurricane season likely this summer, the NHC certainly can use the help. I talked to Senior Hurricane Specialist James Franklin at the American Meteorological Society's Conference on Hurricanes and Tropical Meteorology in Monterey, California, last week, and he confided that it was looking dicey whether or not he would finish all his work from last season before this season starts. It took until March to finish all the summaries of the 28 storms from 2005, and the task of writing the annual summary article for Monthly Weather Review and Weatherwise magazines has not been completed, nor have the official verifications of the NHC and model forecasts been done. The NHC hurricane forecasters start rotating shift work on May 15th when the Eastern Pacific hurricane season begins, so there is not a lot of time left. Additional shifts begin on June 1st, when Atlantic hurricane season officially begins.

I asked James if the National Weather Service's plan to offer early retirement to up to 1000 of its 4700 employees in order to cut costs would significantly affect the NHC. The plan, called the Voluntary
Early Out Retirement Authority (VERA) Implementation Plan
, is preliminary, and still needs approval from the Office of Personnel Management. Under the plan, 13 of the National Hurricane Center's 42 employees would be offered early retirement, and would potentially be replaced by lower-paid entry level meteorologists. James thought that if the plan was offered, few, if any, of the 13 elgible employees would take the offer, since they all enjoy what they are doing too much to retire now! With many more years of busy hurricane seasons likely to come, this is good news--along with the addition of the new hurricane forecasters.

My next blog will be Friday, when I plan to talk about the fading of La Nina, the slackening of the Atlantic trade winds, and other factors that may affect the upcoming hurricane season.

Jeff Masters

A new airplane for the hurricane hunters

By: JeffMasters, 4:45 PM GMT on May 01, 2006

If you have a copy of Google Earth, try zooming in to take a look at Davis-Monthan Air Force Base near Tucson, Arizona. Included amongst the thousands of retired airplanes in the desert is one lucky 4-engine turboprop P-3 Orion, used by the Navy for anti-submarine warfare. This sword will soon be beaten into a plowshare, for it will serve as NOAA's next weather research aircraft. Stung by criticism that neither of our top hurricane hunter aircraft--the two P-3 Orions operated by NOAA's Aircraft Operations Center (AOC)--were available to fly during 2004's Hurricane Charley, since they were off flying other weather research projects, the government has allocated $11 million to buy a new P-3 for weather research. According to Dr. Jim McFadden, head of science programs for the AOC, the new P-3 will not be used for hurricane work, but instead will be outfitted to do other weather reasearch, such as air pollution projects. This will free up the two current P-3s for the entire hurricane season, so they can concentrate exclusively on hurricane work. No funding has yet been procured to finance the additional staff required by NOAA's Aircraft Operations Center to operate the new P-3, but this funding has been promised by NOAA.


Figure 1. The NOAA P-3 Orion hurricane hunter aircraft. Image credit: NOAA's Aircraft Operations Center.

The new P-3 is scheduled to come on-line in 2008 or 2009, but we could sure use it this hurricane season! Only one P-3 is scheduled to be available for hurricane work. The other P-3 is currently in Standard Depot Level Maintainence (SDLM), a 5-month process the airplanes undergo every seven years, where they are basically gutted down to the frame and rebuilt. As part of this year's SDLM, the P-3 will also be undergoing a Special Structural Inspection (SSI), where every rivet is X-rayed and the entire frame closely inspected for stress cracks caused by the severe turbulence the aircraft flies through. When the P-3 completes SDLM, it will undergo a month-long process to outfit it with special instrumentation to perform air pollution research. The P-3 is scheduled to be ready by August to fly again, and it is slated to spend the peak months of hurricane season--August and September--in Houston for an air pollution field program. Should the other P-3 suffer some crippling mechanical problem that would put it out of hurricane flying action for an extended period, the P-3 in Houston will be summoned to fly hurricanes. This can only happen after a 3-day effort to take all the sentitive air pollution instrumentation off of the airplane, as these instruments cannot survive high turbulence.

Since only one P-3 will be available for the 2006 hurricane season, we'll have only one Stepped Frequency Microwave Radiometer (SFMR) instrument flying. The SFMR is an airborne remote sensing device that can infer surface wind speeds in a hurricane by looking at the brightness of the sea surface. The SFMR measurements were used heavily by NHC in 2005 to determine how much of the coast needed hurricane and tropical storm warnings. The U.S. Air Force Reserve's 53rd Weather Reconnaissance Squadron C-130 hurricane hunter aircraft are scheduled to receive the SFMR instruments, but this will not happen in time for the 2006 hurricane season, according to Dr. McFadden.

What's interesting about the new P-3 purchase is that no big press release about it was made--at least that I can find. It is strange that an administration concerned about its image after the Katrina disaster wouldn't emphasize its commitment spend more money to help out hurricane reconnaissance. In addition to the new P-3, the administration has also proposed in its 2006 budget to spend $1.4 million to improve hurricane data buoys and operations in the Caribbean, Gulf of Mexico, and Atlantic Oceans. Unfortunately, little new money has been approved or promised to fund more hurricane research. While I give the Bush Administration credit for these much-needed expenditures, I believe that the money proposed to fix the ailing buoys might have been better spent funding NOAA's Hurricane Research Division to do more research to improve our poor hurricane intensity forecasts.

Jeff Masters


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

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About

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