Category 6™

Controlling hurricanes

By: JeffMasters, 6:09 AM GMT on April 28, 2006

In a talk presented Monday at the 27th annual meeting of the American Meteorological Society's conference on Hurricanes and Tropical Meteorology, Philip Kithil of Atmocean, Inc. presented a radical idea to reduce the intensity of hurricanes approaching the coast: deploy an array of wave-activated deep ocean pumps in front of an approaching storm. These pumps would each be attached to a 1000 meter long, 1.5 meter diameter flexible tube moored to the ocean bottom. Since the water at 1 kilometer depth is up to 15 degrees C cooler than the surface water, these pumps could quickly pump enough cold water to the surface to significantly cool the surface waters. Assuming a typical 2-meter high wave, the pumps, which operate at 30% efficiency, would be able to able to pump enough cold water to the surface in a day or two to cool a 50 meter deep layer by 1 degree C. In a field test conducted near Bermuda last year, Atmocean lowered the surface temperature of ocean water by 4 degrees C using a test pump attached to a 25 cm wide, 160 meter long tube.

Figure 1. Diagram of the deep ocean pump with flexible tube attached proposed by Atmocean to reduce hurricane intensity.

Could such a scheme work? Yes, but you would need a lot of these pumps. Kithil estimated that 6000 of these units would be needed, deployed in a 100 km wide band stretching across the Gulf of Mexico, each pump spaced 50-100 meters apart. The pumps would all be tethered to each other and anchored to the bottom to slow any drift that might occur from ocean currents. The pumps and flexible tubes cost about $2800 each, so we're talking a total cost of $2.4 billion for a single array stretched across the Gulf of Mexico. Additional arrays located off the Florida Atlantic coast and near the Lesser Antilles Islands would cost $2 billion or more, each. The yearly cost of maintenance and operation would be another 20% of the installation cost.

That's a pretty steep price, and makes this scheme a difficult sell. In addition to the major financial issues to overcome, the plan also has serious technical, environmental, political, and legal problems to consider.

Environmental concerns
Kithil acknowledged that an evaluation of the ecological effects of injecting a large amount of cold water to the surface needs to be done. Such a large change to a significant region of the ocean is bound to have major and possibly negative consequences to fisheries and wildlife. Since the pumps can be turned off when there is no hurricane threat, it is possible that these effects will be minimal.

Technical problems
It is not clear how long the cold water pumped to the surface will stay there--the cold water pumped to the surface is more dense than the water beneath it, and so will tend to sink, allowing warmer water beneath to replace it and warm the surface waters again. Modeling studies and field studies are needed to determine if the cold water can stay at the surface long enough to significantly affect a hurricane. The modeling studies Atmocean did do of a Hurricane Ivan case showed a 10 mb increase in pressure when the storm crossed the cold wake, followed by a re-intensification of the storm after it crossed back into warm waters. In some cases, this will be a worthwhile expenditure of money, since such a reduction in storm strength would save billions. However, in other cases, the storm would simply re-intensify and grow even stronger after encountering the cold pool, and nothing would be gained.

Political issues
The array of pumps will lie across some very busy shipping lanes. Companies that operate deep draft vessels such as oil tankers are not going to be too happy about their ships having to take longer and more costly routes around the array. It will take some considerable political clout to convince Congress into authorizing the money for this project.

Legal problems
Another major obstacle to clear will be a legal one. While Mr. Kithil pointed out that none of their numerical model simulations of hurricanes hitting pools of cold water showed the hurricanes changing course, it is inevitable that sooner or later such a course change would occur, since hurricanes naturally make sudden unpredictable course shifts. Residents on the coast hit by the modified storm will want to sue, and there will be many lawyers more than happy to take their case. I asked Dave Moran, Professor of Law at Wayne State University about this this, and he assured me that those suing would have a very good case. Atmocean would have to get special legislation passed to protect it from lawsuits, such as was recently passed to protect the gun industry from lawsuits.

Despite all these negatives, Atmocean appears to be determined to pull this off. They appear to have some venture capital money to work with, which they are applying this year to the twin tasks of doing more computer model simulations and field tests. I wouldn't be surprised if they hire a lobbyist to work the corridors of power in Washington D.C., as well. I am dubious that given all the obstacles involved that they can pull this off, but I wish them luck in their creative effort to do so.

Jeff Masters

Hurricane scientists divided on global warming issue

By: JeffMasters, 4:15 AM GMT on April 27, 2006

Greetings from Monterey, California, where the 27th annual meeting of the American Meteorological Society's conference on Hurricanes and Tropical Meteorology is taking place. It's been a feast of information for the 500-plus hurricane buffs here this week! I'm having trouble choosing between attending any of four simultaneous scientific talks offered--or catching up with old friends outside the sessions. Fortunately, the weather has been rather dreary, so I feel no guilt about being a troglodyte and hiding in dark rooms watching slides of awesome hurricanes of years gone by. There have been some fantastic talks, and I've learned an enormous amount of new information that I will share with you in blogs over the coming weeks.

There have been a number of sharp debates on the hurricane/global warming issue, and this controversy has really been difficult for the hurricane science community. There were some rather uncomfortable arguments between some of the scientists at talks on Monday, but a more civilized debate last night during a panel discussion featuring four of the experts who've published papers on the subject. The discussion lasted nearly three hours, and could have lasted much longer, as only about 20 of the 60 questions posed by the audience of over 300 were answered. I'll have a detailed look at what was said in a blog next week. Contrary to what one might expect from the headline of yesterday's CNN story from Reuters (Experts: Global warming behind 2005 hurricanes), hurricane experts at this conference are very divided about this issue. There is a lot of very confusing and conflicting information to consider, and the science is a long way from being settled.

My next blog from Monterey will be Friday morning, when I plan to discuss a radical hurricane modification proposal presented at the meeting. Is it feasible to tame the next Katrina with modern technology?

Jeff Masters

Climate Change

How strong was Monica?

By: JeffMasters, 4:48 AM GMT on April 25, 2006

Cyclone Monica has come and gone. Fortunately, the storm hit a very sparsely populated area. There no reports of deaths or injuries, and damage was light. Darwin, the capital of the Northern Territory, received just tropical storm-force winds. With Monica's departure, we are left puzzling over an important question--how strong was she? The Navy Research Lab, using a satellite intensity estimation technique called the "Dvorak Technique", rated Monica as the strongest cyclone ever recorded in the Southern Hemisphere, with a central pressure of 879 mb and 180 mph sustained winds. However, the Australian Bureau of Meteorology (BOM) rated Monica a much weaker storm, with a central pressure of 915 mb at that time. Curiously, the BOM give Monica a 905 mb pressure 12 hours earlier, at a time when the Navy Research Lab had her much weaker--892 mb.

Figure 1. Cyclone Monica at peak intensity at 0130 GMT April 24, 2006, the strongest storm in Southern Hemisphere history--180 mph sustatined winds, and a 879 mb pressure. Or was she 915 mb?? Image credit: Navy Research Lab.

So who's right? Well, today I was in the right place to find out! I am attending the American Meteorological Society's 27th annual conference on hurricanes in Monterey, California all week, and I had the opportunity to talk to an Australian hurricane expert. Bruce Harper of Systems Engineering Australia Pty Ltd in Brisbane, Australia, gave a talk titled, "On the importance of reviewing historical tropical cyclone intensities," and I had the opportunity after his talk to ask him about Monica. He told me that hurricane forecasters in eastern Australia, the North Pacific, and Atlantic all use a uniform technique for estimating pressure of tropical cyclones from satellite imagery, but the western Australian forecasters use a different set of equations for that ocean region. These region-specific equations were developed to better model the small and intense cyclones that typically affect the area, such as Tropical Cyclone Tracy of 1974. The equations were not developed with much data from large and intense Category 5 storms, and so the 915 mb pressure estimate for Monica is suspect.

In reality, we will never know just how strong Monica was. There are no hurricane hunter airplanes anywhere but the Atlantic. Satellite estimation techniques are getting better each year, but are still subject to large errors. Scientists who are researching the link between hurricanes and global warming are free to use either intensity estimate for Monica's lowest pressure. This underscores the difficulty of assigning much credence to the reported 80% increase in Category 4 and 5 hurricanes globally since 1970 reported by Peter Webster and Greg Holland last year in their controversial article in Science. While I do believe there has been some increase in these storms, the estimation of maximum cyclone intensities is so fraught with uncertainties that I do not believe a reliable estimate of how significant this increase can be done until a full re-analysis of all historical tropical cyclones is completed. Even then, I think we need at least another ten years of data, since our data set covers such a short period of time.

Jeff Masters

Southern Hemisphere's strongest hurricane ever slams Australia

By: JeffMasters, 3:09 PM GMT on April 24, 2006

Cyclone Monica slammed ashore as a Category 4 hurricane on a sparsely populated region of Australia's north coast today, missing major population centers and sparing that country from serious damage as was experienced in Cylone Larry earlier this season. For a time yesterday, Monica was the most intense tropical cyclone in Southern Hemisphere history--sustatained winds of 180 mph, and a central pressure of 879 mb. This is not far from the world record of 870 mb set in Super Typhoon Tip in 1979, and Monica ranks as the 14th most intense tropical cyclone in world history, and is tied with Cyclone Zoe of 2003 as the strongest Southern Hemisphere cyclone on record. Curiously, the Australian Bureau of Meteorology put Monica's pressure at 915 mb at the same time the Navy Research Lab was reporting 879 mb, so I'm not sure what Monica's final "official" pressure will be. Reliable records of cyclone intensity only go back to the mid-1980s in the Southern Hemisphere, but two of top five strongest hurricanes ever recorded there have occurred this year--Tropical Cyclone Glenda (898 mb) from March, and now Monica. What's really extraordinary about Monica is that she came so late in the season--tropical cyclone season is usually over by late April in the Southern Hemisphere.

Figure 1. Cyclone Monica at peak intensity at 0130 GMT April 24, 2006, the strongest storm in Southern Hemisphere history--180 mph sustatined winds, and a 879 mb pressure. Image credit: Navy Research Lab.

Monica has weakened considerably due to interaction with land, and now has a pressure of 935 mb estimated by the Australian Bureau of Meteorology. Monica probably came ashore as a Category 4 storm. Monica has missed major population centers, and has done little damage. The mining town of Nhulunbuy, on north-east Arnhem Land was thought to be in Monica's path, but the storm veered to the north, limiting the damage in the town to mostly downed trees. It now apears that Darwin, capital of the Northern Territory and a city of 110,000 inhabitants, will not receive a direct hit from Monica.In addition, Monica is expected to weaken as it interacts with the islands and peninsulas surrounging Darwin, so it is unlikely Monica will cause death and destruction similar to what Darwin experienced on Christmas Eve 1974, when Cyclone Tracy smashed the city with Category 4 force winds. Tracy was Australia's worst ever natural disaster. The storm killed at least 65, did over $4 billion in damage, destroyed 80% of Darwin's buildings, and left 20,000 homeless. The city was since rebuilt with stronger building codes.

Figure 2. Damage to Darwin, Australia, after the passage of Cyclone Tracy on Chrismas Eve, 1974. Photo courtesy of the National Archives of Australia.

Jeff Masters

Another extreme Australian hurricane

By: JeffMasters, 4:45 PM GMT on April 23, 2006

Australia's hurricane season continues its parade of unusually intense storms this year with the intensification of Cyclone Monica today into a huge Category 5 storm. The 12 GMT advisory this morning from the Joint Typhoon Warning Center put Monica at 165 mph sustained winds and a 892 mb pressure, making it second most intense hurricane ever recorded in the Southern Hemisphere. The most intense Southern Hemisphere cyclone on record was Cyclone Zoe of 2003, which had a 879 mb pressure. The Australian Bureau of Meteorology puts Monica's pressure at 905 mb, which would make it the fifth strongest cyclone on record. Reliable records of cyclone intensity only go back to the mid-1980s in the Southern Hemisphere, but two of top five strongest hurricanes ever recorded there have occurred this year--Tropical Cyclone Glenda (898 mb) from March, and now Monica. What's really extraordinary about Monica is that she came so late in the season--tropical cyclone season is usually over by late April in the Southern Hemisphere. Monica's formation echoes what happened in the Atlantic last year, with the intensification of Hurricane Wilma to a record 882 mb pressure very late in the hurricane season--October 19. When one adds in the $1 billion in devastation wrought in Queensland by Category 4 Cyclone Larry (915 mb) in March, Australians must feel like residents of hurricane alley in the Atlantic did last year, when three of the six strongest hurricanes on record occurred, causing the most damage ever--what's going on with the weather? However, be reminded that the Northern Hemisphere Pacific Ocean had a very below-normal tropical cyclone season last year, and the Indian Ocean also had below normal activity.

Figure 1. Visible satellite image of Cyclone Monica at peak intensity, 165 mph sustained winds and a 892 mb central pressure. Image taken at 7:30 GMT April 23, 2006 by the GMS satellite. Image courtest of the Navy Research Lab

Monica is expected to track just offshore the sparsely populated north coast of Australia today as it moves slowly westward. Darwin, the most heavily populated city in the region, will begin to feel Monica's wind later today, and a direct hit is possible on Tuesday. Monica should slowly weaken before she gets to Darwin, since much of the circulation will be over land, and the eye will have to cross land as well. Still, Monica could still be a formidable Category 3 or 4 hurricane by then, and a direct hit on Darwin would likely cause severe damage.

Jeff Masters

Earth Day

By: JeffMasters, 3:34 PM GMT on April 21, 2006

This week marks the 1-year anniversary of my first blog, and what a year it's been! I had no idea when this blogging project started last year on Earth Day that it would grow to the levels it has. A big Thanks goes to everybody who reads the blog, and for those who post comments and wunderphotos and write your own blogs--thanks for your participation in this awesome experiment to explore the immense potential of this strange and wonderful new communication medium we've invented, the Internet. While at times the comments section of my blog may lapse into irrelevant anarchy, these comments helps me understand what subjects people find important to talk about . Many of the links and comments you've posted I've used to help formulate my blogs. This blog is a collaborative effort! I particulary want to thank the great people at the National Weather Service, National Hurricane Center, Storm Prediction Center, and Climate Prediction Center, whom I rely on very heavily for my blog material.

I tend to focus a lot on the violence and destruction our weather brings, as well as the dangers posed human-caused climate change and pollution. While these issues are critical to our survival, we also need to focus on just what an amazing and beautiful creation the atmosphere is. The air we breathe and the water it gives us, sustain all life. We all share the atmosphere, and are all touched by it, for we all breathe the same air. The best thing you can do tomorrow to honor Earth Day is to go outside, take a few deep breaths and feel how the air in your lungs sustains you, look at the beauty of the atmosphere surrounding you, and appreciate this great gift we have.

I'll post a few of the many awesome wunderphotos you've submitted over the past year, that I've used as my screensavers. Thank you all for sharing these!

Jeff Masters

Atmospheric Phenomena

Climate of Fear

By: JeffMasters, 4:15 PM GMT on April 18, 2006

An opinion piece titled, "Climate of Fear: Global-Warming Alarmists Intimidate Scientists Into Silence" appeared in the Wall Street Journal on Wednesday, criticizing the "iron triangle" of of climate scientists, advocates and policymakers responsible for raising the alarm over the threat posed by global warming. The article's two main points:

1) Climate scientists who are raising alarms over global warming are exaggerating the danger in order to get funding.

2) "Scientists who dissent from the alarmism have seen their grant funds disappear, their work derided, and themselves libeled as industry stooges, scientific hacks or worse. Consequently, lies about climate change gain credence even when they fly in the face of the science that supposedly is their basis."

I'm not familiar with the scientists Dr. Lindzen discusses who have lost their funding because they are greenhouse skeptics, and he does not provide any quotes or references to support this point. So, to keep this discussion shorter, I will only focus on his first argument--that climate scientists are exaggerating the threat of global warming in order to get funding.

Who is Richard Lindzen?
First, a little background on the author. Dr. Richard Lindzen is Professor of Atmospheric Science at MIT, a member of the National Academy of Sciences panel of experts that advises the President on climate change science, and was a lead author of the most recent UN-sponsored Climate Assessment report of the Intergovernmental Panel on Climate Change (IPCC) that is used as the "official" benchmark of the expected amount of climate change this century. He has written many excellent and highly regarded peer-reviewed scientific papers during a career spanning over 40 years.

Much of his recent work has focused on climate change. Dr. Lindzen hypothesizes that global warming will not increase Earth's temperature significantly because increases in upper-level cloud cover will result from increased thunderstorm activity, and this increased cloud cover will act to reflect away more incoming sunlight, cooling the planet. This "Iris Effect" is named after the ability of the human eye to control the amount of light entering the eye by changing the diameter of its iris. His theory is difficult to prove or disprove, as the water vapor-cloud feedback is one of the hardest things to get right in climate models, and is a key source of uncertainty in them. To my knowledge, his Iris theory has not been disproven, but is thought to be incorrect by most climate scientists.

Dr. Lindzen continues to champion his Iris Effect theory, and has been one of about ten famous outspoken "greenhouse skeptics" who are skeptical of the dangers posed by climate change. He opposes the Kyoto Protocol and efforts to curb greenhouse gas emissions. He has testified in front of Congress multiple times, authored many opinion pieces on the matter, and been a paid consultant for major oil and coal companies. In Ross Gelbspan's 1998 book, The Heat is On, the author discusses a 2-hour interview he did with Lindzen. In the interview, Lindzen estimated that he made $10,000 per year doing consulting work, and typically charged $2500 per day to fossil fuel interests. For example, a trip to Washington D.C. in 1991 to testify in front of a Senate committee was paid for by Western Fuels, a $400 million coal consortium. Gelbspan describes Dr. Lindzen as "exceedingly gracious and hospitable" in person, but relates several instances of unwarranted attacks he has made on scientific opponents.

Some good points
Dr. Lindzen's essay is a typical example of greenhouse skeptic writing, which unfortunately for me, I've read a lot of. Intermingled are scientific truths, scientific distortions, difficult to verify accusations, and some legitimate nuggets of complaint, all wrapped in a fiercely emotional tirade intended to sway the emotions of the reader. Several of Dr. Lindzen's concerns in his article are valid ones. For instance, he complains of "repeated claims that this past year's hurricane activity was another sign of human-induced climate change", which is a concern of mine, as well. A single extreme weather event, or an even a series of extreme hurricanes in one ocean basin during a single year, are not valid indicators of climate change. Lindzen also criticizes the world's most prestigious scientific journals, Science and Nature, for bias against papers by global warming skeptics. This bias is difficult to prove or disprove, but I believe there is probably some substance to this claim. I've seen a number of complaints that ring true about this from the greenhouse skeptic scientists.

Some bad points
While Dr. Lindzen is an excellent scientist, the piece he wrote for the Wall Street Journal is written in emotional, not scientific language. The article contains oversimplifications, distortions, and errors, and would fail the scientific peer review process needed to be published in a scientific journal. Let's look at three of these problems:

1) Dr. Lindzen refers to the "barely discernible, one-degree increase in the recorded global mean temperature since the late 19th century." I would hardly characterize our recent warming as "barely discernible." By measures such as the significant warming of the Arctic in recent decades, the several-week increase in the growing season and early arrival of Spring over most of the globe in recent years, the widespread retreat of glaciers worldwide, and the significant die-off of coral reefs worldwide due in part to record warm sea surface temperatures, a one-degree increase in global temperature is very discernible.

2) Dr. Lindzen says that global warming will lead to a decrease in extratropical cyclones. However, this is not a consensus view among climate scientists. Some model results have shown a decrease, but other models show that global warming will increase the intensity and frequency of El Nino events, which would lead to an increase in extratropical storms over the North Pacific and western U.S. Global warming may also increase the positive phase of the North Atlantic Oscillation (NAO) pattern, creating increased extratropical storms in the North Atlantic and Western Europe.

3) Lindzen criticizes arguments by other researchers that global warming will increase hurricane intensities thusly:

"The problem with this is that the ability of evaporation to drive tropical storms relies not only on temperature but humidity as well, and calls for drier, less humid air. Claims for starkly higher temperatures are based upon there being more humidity, not less--hardly a case for more
storminess with global warming."

I asked Dr. Andrew Dessler, a professor at Texas A&M University whose research focuses on climate change and water vapor, to comment on this. He responded:

The rate of evaporation from the surface, which is one determinant of the strength of a hurricane, is determined by (q*-q), the difference between saturation specific humidity and the specific humidity. You can convince yourself that this makes sense by thinking of the two limits: if the air is saturated, then q*=q and evaporation is zero, which makes sense since saturated air cannot hold any more molecules. If the air is extremely dry, then q is about 0 and evaporation
is at a maximum, again as you'd expect.

The climate, on the other hand, is sensitive to q in the mid-troposphere. There's not really a simple explanation for this. I can give you a few good references if you want to check this out further (e.g., Held, I. M., and B. J. Soden, 2000: Water vapor feedback and global warming. Ann. Rev. Energy Environ., 25, 441-475).

Lindzen's argument ignores the differences and suggests that if q*-q decreases at the surface, then q must decrease in the mid-troposphere. That argument is so far outside the realm of scientific reasonability or common sense, that it's my opinion that Lindzen is acting as a policy advocate rather than a scientist. Like most advocates, he takes advantage of the lenient rules of policy debates (e.g., no peer review or other vetting mechanism to test for scientific accuracy of arguments), to make patently false scientific arguments as a way to advance his preferred policy position (he opposes any policy to reduce greenhouse-gas emissions).

Dr. Lindzen claims that "Ambiguous scientific statements about climate are hyped by those with a vested interest in alarm, thus raising the political stakes for policy makers who provide funds for more science research to feed more alarm to increase the political stakes." The words "alarm" or "alarmist" or "anti-alarmist" appear 16 times in the editorial, and Dr. Lindzen is clearly trying to provoke an emotional reaction against those Chicken Littles guilty of raising the alarm.

Speaking as an atmospheric scientist, I can tell you from long experience that we are not the wild-eyed, alarmist lot that Dr. Lindzen makes us out to be. This makes for some very dull parties (if you're not excited about discussing quasi-geostrophic theory), when we get together for a big bash. Very little alarming behavior takes place. (In fact, after I dragged my wife to three straight devastatingly dull departmental Christmas parties while I was in graduate school, she forbade me from ever requiring her to go to another.) Atmospheric scientists are not an alarmist lot--put us in quiet room with a window and give us a computer and pile of data to analyze, and we'll be as happy as a clam at high tide. Atmospheric scientists are generally not motivated by money--they selected science as a career out of a genuine curiosity about how the world works, plus a desire to help understand the significant dangers posed by pollution and climate change. If more money to do research really was a primary concern, wouldn't these scientists stop calling for action against global warming, and instead emphasize the uncertainties and claim that more research is needed?

Dr. Gavin Schmidt, a climate modeler at the NASA Goddard Institute for Space Studies in New York, posted this response to Dr. Lindzen's accusations that scientists feed alarmism to get funding: "Lindzen has frequently claimed that within the scientific community "alarm is felt to be essential to the maintenance of funding". I have yet to see any empirical evidence of this, and a brief perusal of active NSF grants related to climate change reveals a lot of interesting projects but none that jump out as being 'alarmist'. Having sat on panels that decide on funding allocations and as a reviewer of proposals for both US and international agencies, my experience has been that these panels actually do a very good job at deciding which proposals are interesting, tractable and achievable. I have not seen even one example of where the degree of 'alarmism' was ever a criteria in whether funding was given. (NB. I don't regard my own grants (viewable here) as remotely 'alarmist' and I don't have too much trouble getting funding (fingers crossed!))"

Environmental scientists have in the past issued false alarms over environmental problems that did not materialize as expected. However, we should expect and tolerate some degree of false alarms, given the uncertainty in forecasting these events. If our scientists never issue a false alarm, then the tolerance for issuing alarms is not correct. Would you expect the National Weather Service to stop issuing tornado warnings when a possible tornado signature is spotted on Doppler radar, since less than half of these signatures result in in an actual tornado touchdown? No, some degree of false alarms must be tolerated. The NWS forecasters are dedicated public servants, doing their job of warning the public when their best scientific judgment indicates that there might be a significant threat. It is no different with our climate scientists who issue warnings on the dangers of climate change.

Skeptics commonly like to claim that atmospheric scientist "Chicken Littles" in the 1970s warned that the next ice age was coming. While there were some articles in the popular press about this, the scientific literature never made such a claim. This is one of the myths perpetuated by the greenhouse skeptics that crumbles under analysis.

A Public Relations Campaign?
Dr. Lindzen's article appeared at about the same time as similar op-ed pieces by syndicated columnists Robert Novak (April 3) and George Will (April 2). A large number of additional anti-global global warming editorials have appeared in the opinion pages of many newspapers in the past week, including the Washington Times, Detroit News, and Arizona Star. Given Dr. Lindzen's history of accepting consulting money from the fossil fuel industry, it would be no surprise if his article was paid for by the fossil fuel industry as part of an orchestrated public relations campaign that included the appearance of all these op-ed articles. I am sure the industry is very concerned about the recent media attention on global warming that has hurt their position. Scientific studies published this year showed unexpectedly large amounts of melting of the Greenland and Antarctic ice sheets. A cover story last month in Time magazine headlined, "Be Worried. Be Very Worried", warned that we may be at the "tipping point" for uncorrectable climate change. A episode of 60 Minutes reported that scientific reports on climate change written for Congress were being modified by a White House chief of staff, who changed key phrases of the reports to make climate change appear less threatening (the staffer in question has since resigned to go work for Exxon Mobil). James Hansen of NASA and many scientists working for NOAA and NASA have complained of being gagged by the Bush Administration on climate change issues in recent months. It would be an obvious move for the fossil fuel industry to mount a PR campaign this month to try to push back.

The fossil fuel industry has spent tens of millions of dollars on many such campaigns in the past. The most notorious of these campaigns was launched in 1991, when the Information Council on the Environment (ICE), a creation of a group of utility and coal companies, launched a PR campaign whose goal was to "reposition global warming as theory rather than fact". The campaign targeted "older, less-educated men" and "young, low-income women" in electoral districts who had a congressperson on the House Energy Committee. The PR campaign hired four "greenhouse skeptic" scientists--Patrick Michaels, Fred Singer, Robert Balling, and Sherwood Idso--to generate op-ed pieces, broadcast appearances, and newspaper interviews. Gelbspan writes: "The plan was clever if not accurate. One newspaper advertisement prepared by the ICE, for example, was headlined: 'If the earth is getting warmer, why is Minneapolis getting colder?' (Data indicate that Minneapolis has actually warmed between 1 and 1.5 degrees Celsius in the last century.)" Another print ad featured a cowering chicken under the headline "Who Told You the Earth Was Warming...Chicken Little?"

Environmental groups do their share of public relations campaigns, as well. One recent estimate I saw put the spending of the five major environmental groups on climate issues at about $2.1 million per year (Environmental Defense Fund, NRDC, Sierra Club, Union of Concerned Scientists, and the World Wildlife Federation). Exxon Mobil alone spends over $1 milion per year to fund think tanks like the Competive Enterprise Institute and the George C. Marshal Foundation that generate frequent anti-global warming reports (Gelbspan, 2004).

Flashback to 1974
On June 28, 1974, Sherry Rowland and Mario Molina, chemists at the University of California, Irvine, published the first scientific paper warning that human-generated chlorofluorocarbons (CFCs) could cause serious harm to Earth's protective ozone layer. They calculated that if CFC production continued to increase at the going rate of 10%/year until 1990, then remain steady, CFCs would cause a global 5 to 7 percent ozone loss by 1995 and 30-50% loss by 2050.

They warned that the loss of ozone would significantly increase the amount of skin-damaging ultraviolet UV-B light reaching the surface, greatly increasing skin cancer and cataracts. The loss of stratospheric ozone could also significantly cool the stratosphere, potentially causing destructive climate change. Although no stratospheric ozone loss had been observed yet, CFCs should be banned, they said. At the time, the CFC industry was worth about $8 billion in the U.S., employed over 600,000 people directly, and 1.4 million people indirectly (Roan, 1989).

Critics and skeptics--primarily industry spokespeople and scientists paid by conservative think tanks--immediately attacked the theory. Despite the fact that Molina and Rowland's theory had wide support in the scientific community, these handful of skeptics, their voices greatly amplified by the public relations machines of powerful corporations and politicians sympathetic to them, succeeded in delaying imposition of controls on CFCs for over a decade. Scientists who advocated CFC controls were accused of being alarmists out to get research funding. One CFC industry magazine stated in 1975, "The whole area of research grants and the competition among scientists to get them must be considered a factor in the politics of ozone" (Roan, 1989).

DuPont, which made 1/4 of the world's CFCs, spent millions of dollars running full-page newspaper advertisements defending CFCs in 1975, claiming there was no proof that CFCs were harming the ozone layer. The chairman of DuPont commented that the ozone depletion theory was "a science fiction tale...a load of rubbish...utter nonsense." (Chemical Week, 16 July 1975). The aerosol industry also launched a PR blitz, issuing a press release stating that the ozone destruction by CFCs was a theory, and not fact. This press release, and many other 'news stories' favorable to industry, were generated by the aerosol industry and printed by the New York Times, Wall Street Journal, Fortune magazine, Business Week, and the London Observer (Blysky and Blysky, 1985). The symbol of Chicken Little claiming that "The sky is falling!" was used with great effect by the PR campaign, and appeared in various newspaper headlines.

The CFC industry companies hired the world's largest public relations firm, Hill & Knowlton, who organized a month-long U.S. speaking tour in 1975 for noted British scientist Richard Scorer, a former editor of the International Journal of Air Pollution and author of several books on pollution. Scorer blasted Molina and Rowland, calling them "doomsayers", and remarking, "The only thing that has been accumulated so far is a number of theories."

Sound familiar?

In a 1984 interview in The New Yorker, Rowland concluded, "Nothing will be done about this problem until there is further evidence that a significant loss of ozone has occurred. Unfortunately, this means that if there is a disaster in the making in the stratosphere we are probably not going to avoid it." The very next year, all the "Chicken Little" scientists were proved right, when the Antarctic ozone hole was discovered. Human-generated CFCs were indeed destroying Earth's protective ozone layer. In fact, the ozone depletion was far worse than Molina and Roland had predicted. No one had imagined that ozone depletions like the 50% losses being observed by 1987 over Antarctica were possible so soon. Despite the continued opposition of many of the skeptics, the Montreal Protocol, an international agreement to phase out ozone-destroying chemicals, was hurriedly approved in 1987 to address the threat. By 2003, it appeared that the ozone hole had stopped growing, thanks to the quick action. Molina and Rowland were awarded the Nobel Prize in 1995. The citation from the Nobel committee credited them with helping to deliver the Earth from a potential environmental disaster.

According to Wikipedia's biography of Richard Lindzen:

The November 10, 2004 online version of Reason magazine reported that Lindzen is "willing to take bets that global average temperatures in 20 years will in fact be lower than they are now." Climatologist James Annan, who has offered multiple bets that global temperatures will increase, contacted Lindzen to arrange a bet. Annan offered to pay 2:1 odds in Lindzen's favor if temperatures declined, but said that Lindzen would only accept a bet if the payout was 50:1 or better in his favor. No bet occurred.

I would agree with Dr. Lindzen, there is about a 50:1 chance that global average temperatures in 20 years will in fact be lower than they are now. This would most likely occur as a result of a major volcanic eruption that would put up enough stratospheric aerosol dust to cool the climate for a few years. The effect would be temporary, and the Earth would go on warming as before once the dust dissipates.

Climate scientists are not alarmists out to get research funding. They are raising the alarm because they see a genuine major threat to the planet. Dr. Lindzen's voice needs to be considered, because he is a good scientist looking at the same data as the "alarmist" scientists, and is coming up with a different conclusion. But consider that his voice, and voices of the 10 or so famous "greenhouse skeptics", are in the extreme minority. Their voices are greatly amplified by the public relations machinery of the fossil fuel industry, and the politicians sympathetic to them. Thus, it seems like there is more of a scientific controversy than there really is. As a society, we need to decide--do we do the same thing we did for the ozone depletion crisis? Do we take the 50:1 odds, betting on the dark horse because some very loud voices are urging us to do so? Or is it smarter to bet on the favorite?

We got very lucky with the ozone hole. The lifetime of CFCs in the atmosphere is a few tens of years, and the quick action to eliminate emissions has kept ozone destruction from reaching severe levels. Carbon dioxide stays in the atmosphere hundreds of years, and 25% of what we add stays there essentially forever. By the time it is obvious we are severely damaging the planet, it will be too late to avoid much of the damage.

Jeff Masters

My next blog will be Thursday or Friday, to give people time to comment on this one.

For further reading
The climate scientists who run have an interesting discussion on the op-ed piece by Dr. Lindzen, as well the one by George Will and Robert Novak. I also wrote an opinion piece titled, The Skeptics vs. the Ozone Hole, which presents a more complete comparison of how the skeptics attacked the science of ozone depletion and succeeded in delaying CFC emission controls for many years.


Blyskal, J., and M. Blyskal, "PR: How the public relations industry writes the news", William Morrow and Co., New York, 1985.

Gelbspan, Ross, The Heat is On, Perseus Books, Cambridge, MA, 1998.

Gelbspan, Ross, Boiling Point, Perseus Books, Cambridge, MA, 2004.

Roan, Sharon L., Ozone Crisis: The 15-year Evolution of a Sudden Global Emergency, John Wiley & Sons, Inc., New York, 1989.

Climate Change

Weather Channel arrests

By: JeffMasters, 1:54 PM GMT on April 17, 2006

Three members of a Weather Channel camera crew were arrested Wednesday after repeatedly trespassing on the property of a tornado victim killed by a tornado in Tennessee. Edward John Lazano Jr., Bradley Reynolds, and Jorma Brandon Duran were freed on $500 bail each after their arrests. The Weather Channel has not released any comments on the matter. According to the press release from the Associated Press:

"There are eight no trespassing signs posted on the property," Bruce's brother-in-law, Lynn Boren, wrote in warrants filed against the video team. "They were asked at least six times over 30 minutes to leave."

Sheriff Jackie Matheny denied reports that he gave them permission to be on the property.

"If they say they were given permission by me, they are telling a big one. Plus I'd have no authority to tell them that since it's private property," Matheny said.

I hope this incident will encourage all media to be respectful of the victims of tragedy. With the recent explosion of dramatic prime-time coverage of disasters, such as offered by the Weather Channel, Discovery Channel, and other news programs, the media needs to be sensitive in their disaster coverage to prevent the perception that sensationalist journalism is exploiting death and tragedy for the sake of profit.

To their credit, the Weather Channel did offer a public apology on Thursday:

"While we cannot comment on legal proceedings, we are upset and saddened this family suffered the loss of one of its members," Weather Channel spokeswoman Kathleen Lane said.

Jeff Masters



By: JeffMasters, 1:02 PM GMT on April 14, 2006

Well, we need to re-write the record books--again--for the amazing Hurricane Season of 2005. The season added another named storm to its near-unassailable record for number of named storms, which now stands at 28. NHC announced this week that previously unrecognized subtropical storm formed over the Atlantic near the Azores Islands on October 4, 2005. In the National Hurricane Center's report on the unnamed storm, the authors comment that on rare occasions, routine post-season review reveals the existence of tropical or subtropical storms that should have been given a name. The last time this happened was for 1997's first storm. In the case of the unnamed 2005 storm (which I'll call Should-have-been-Tammy, since that was the next name on the list when it formed), the storm started off as a non-tropical low pressure system. However, on October 4, microwave satellite data from the AMSU instrument on NOAA's polar-orbiting satellite revealed the presence of a warm core in the storm . Additionally, when Should-have-been-Tammy passed through the Azores Islands on Ocotber 5, no change of temperature was noted, as would have been the case if this storm was extratropical in nature. Extratropical storms derive their energy from temperature differences within them, and one should always see some sort of frontal passage and temperature change when these non-tropical storm pass by. Should-have-been-Tammy was not fully tropical, though, since its warm core did not extend all the way to the top of the lower atmosphere, and there was no upper-level anticyclone on top of the system. Thus, Should-have-been-Tammy will forever be called "Unnamed subtropical storm 4-5 October 2005."

Figure 1. METEOSAT-8 visible image of Should-have-been-Tammy taken at 15 UTC October 4, 2005. Surface observations are overlaid on the satellite image, and a cold front is analyzed to the west.

The existence of Should-have-been-Tammy raises an interesting point--if the storm had been correctly identified at the time and given a name, Hurricane Wilma would have been given the name Hurricane Alpha. This would have raised the question of what to do about replacing the name Alpha in the list of Greek names, since Alpha would have had to be retired. I've heard rumor that the list of Greek names is going to be ditched in favor of an alternate naming system, but I haven't heard anything official on this yet.

Severe weather outbreak today and Saturday
After a one-week break, severe weather returned to the central U.S. again last night, when tornadoes struck Iowa, killing one, and causing extensive damage to the University of Iowa campus. The Storm Prediction Center has put Indiana, Ohio, Illinois, and Iowa in its "Moderate Risk" bullseye for today, and western Iowa and eastern Nebraska on Saturday.

Next week: I'll comment on the Wall Street Journal opinion piece by noted MIT atmospheric scientist Dr. Richard Lindzen accusing climate scientists of alarmism intended to generate research funding.

Jeff Masters

Stronger SST-intense hurricane link?

By: JeffMasters, 2:53 PM GMT on April 12, 2006

A link between global warming and increased intense hurricane activity is a very hot topic in hurricane research right now, and many new papers on the subject will be published this year. The latest paper, published March 15 in the on-line version of Science, Science Express, finds stronger evidence that the increasing number of Category 4 and 5 hurricanes globally since 1970 is directly linked to increases in Sea Surface Temperature (SST). The paper by Hoyos et al. was called, "Deconvolution of the Factors Contributing to the Increase in Global Hurricane Intensity". Two of the co-authors--Peter Webster and Judith Curry of Georgia Tech--were also authors of a paper published in Science magazine in 2005 that reported a worldwide increase in the number of Category 4 and 5 hurricanes of 80% in the past 30 years. The paper, (Webster et al., 2005), titled "Changes in Tropical Cyclone Number, Duration, and Intensity in a Warming Environment", linked the rise in storms to increasing sea surface temperatures and concluded that "global data indicate a 30-year trend toward more frequent and intense hurricanes." As I reported in my blog on the subject, their findings should be considered as preliminary evidence that the global incidence of Category 4 and 5 hurricanes may be increasing. There are some severe problems with the quality of the data set used to, and there are good reasons to believe that the actual increase in Category 4 and 5 hurricanes is far lower than the 80% increase found by Webster et al.

The new paper by Hoyos et al. uses a mathematical technique called information theory to study the relative effects of SST, wind shear, humidity, and wind patterns on global incidence of Category 4 and 5 hurricanes. The study found that only SST can explain the observed increase in these storms. One thing I like about the new study is that it directly addesses the issue of data quality in the record of Category 4 and 5 hurricanes, something the authors neglected to do in their previous paper. The authors write, "Recently, the quality of the hurricane data has been questioned and even a reanalysis of the tropical cyclone databses has been suggested in order to ratify that the results of recent studies are not due to problems in the data." The authors go on to say that they performed their analysis without using suspect data from the North Indian Ocean, and found no difference in their results. Well, that's not too surprising, since the number of Category 4 and 5 hurricanes in that ocean basin represents only about 2% of the global total. What I would have liked to have seen was the analysis re-done using the latest reanalyzed results for typhoons from the Western Pacific, which accounts for 48% of global Category 4 and 5 hurricanes. In a paper accepted for publication but not yet finalized, Knaff and Zehr (2006) make convincing arguments that typhoon intensities during the 1973-1986 period were too low due to measurement error, and the number of Category 4 and 5 storms in the region have been roughly constant for the past 50 years. Dr. Knaff and Charles Sampson have performed a preliminary re-analysis of maximum typhoon intensities for the period 1966-1987 based on the Knaff and Zehr (2006) results. In a paper to be presented at the upcoming 27th Conference on Hurricanes and Tropical Meteorology (April 24-28, 2006), they show that after correcting for the measurement errors, the number of Category 4 and 5 typhoons during the 1966-1987 period increased by 1.5 per year, leaving only a slight upward trend in Category 4 and 5 typhoons during the period 1970 - 2004. The 16% increase in Category 4 and 5 typhoons found by Webster et al. during the past 15-year period is reduced to just 3%. I suspect that if the information theory techniques of Hoyos et al. were applied to this modified data set, the connection between SST and an increase in global Category 4 and 5 hurricanes would be much weaker.

The blog has more information on the paper, along with links to quotes in the media from many of the scientists involved in the hurricanes/global warming debate.

My next blog will be on Friday. Apparently, NHC has "found" a new Atlantic subtropical storm that formed in 2005, bringing the total for the season to 28 named storms. If the final report on this new storm has been issued, I'll discuss that.

Jeff Masters

Hoyos, C.D., P.A. Agudelo, P.J. Webster, and J.A. Curry, "Deconvolution of the Factors Contributing to the Increase in Global Hurricane Intensity",, 16 March 2006, 10.1126/science.1123560.

Knaff, J.A., and R.M. Zehr, "Reexamination of Tropical Cyclone Wind-Pressure Relationships", accepted to Weather and Forecasting, 2006.

Webster, P.J., G.J. Holland, J.A. Curry, and H.-R. Chang, "Changes in Tropical Cyclone Number, Duration, and Intensity in a Warming Environment", Science, 309, 1844,1846, 16 September 2005.

Climate Change

Tornado season: why so active?

By: JeffMasters, 4:22 PM GMT on April 10, 2006

Friday's tornado outbreak in Tennessee featured at least 46 tornadoes across eight states. Three strong F3 tornadoes touched down (winds of 158 to 206 mph), including the Gallatin, Tennessee tornado that killed nine people and damaged or destroyed 700 to 900 homes in Sumner County. The April 2 outbreak had six F3 tornadoes among the 56 reported, and the March 9-13 outbreak had 11 F3 tornadoes and one F4 tornado among the 84 that touched down.

Figure 1. Departure of Sea Surface Temperature (SST) from normal in early April for 2005 and 2006. SSTs were near normal in 2005 in the Gulf of Mexico, but were about 1-2 degrees C warmer than normal this year. Other things of interest: the cool water signature of La Nina is obvious in the Eastern Pacific in 2006 but not 2005; water temperatures in the Caribbean and tropical Atlantic are cooler this year than last year, which may mean a delayed onset to this year's hurricane season compared to last year. Image credit: NOAA.

Why has this year's tornado season been so violent? According to NOAA,, "The difference this year is the abnormally warm temperatures and dry conditions during the winter throughout the southern and central United States that kept water temperatures warm in the Gulf of Mexico." If we look at a plot comparing this year and last year's change ino Sea Surface Temperature (SST) from normal (the anomalies, Figure 1), we see that the Gulf of Mexico is indeed significantly warmer this year. Plenty of warm moist air from the Gulf of Mexico certainly doesn't hurt, but the primary reason that this year's tornado season has been so bad is that we've had an unusually active and strong jet stream. The reasons for this are complicated and not well-understood, but have more to do with large scale global circulation patterns such the the presence of La Nina and the negative phase of the North Atlantic Oscillation (NAO) that has predominated this Spring.

The latest 2-week forecast from the GFS model shows that the jet stream is now expected to grow less active for the next 10 days, and no further major tornado outbreaks are expected during that period. A more active pattern may return late in the month, however.

Jeff Masters


Tennessee tornadoes

By: JeffMasters, 3:11 PM GMT on April 08, 2006

It was a night to huddle in the basement and cower in the face of nature's incredible fury throughout Tennessee last night, as another wave of deadly twisters swept through a state already reeling from last Sunday's 24 tornado deaths. At least 31 tornadoes touched down yesterday, killing 11 and creating tremendous destruction in the Nashville area. Sumner County, just north of Nashville, suffered eight dead. You can see the impressive line of storms that swept through the area in this 3-hour radar animation (1.4 Mb). The breadth, intensity, and duration of the storms covering the Tennessee Valley yesterday and last night was truly impressive to behold. With the peak of tornado season still a month away, the three major tornado outbreaks so far this year have already killed 49 people, compared to the average of 45 killed during the entire year each of the previous three years. Through the end of March, 286 tornadoes hit the United States, compared to an average of 70 for the January-March period in each of the past three years.

Severe thunderstorms from last night's onslaught will continue to affect Florida, Alabama, and Georgia today, but the risk of tornadoes is much reduced. It appears that the coming week will be much quieter,with no major tornado outbreaks likely. However, the jet stream pattern remains very active over the coming two weeks, and another major tornado outbreak during the week following Easter is a stong possibility. The tornado season of 2006 is more than making up for the quiet tornado seasons we've been blessed with the past three years!

Figure 1. Radar snapshot of the tornadic thunderstorms that swept through Tennessee yesterday. Note the classic hook-shaped echo from the cell southwest of Nashville, indicating a tornado.

Jeff Masters


No more Katrinas

By: JeffMasters, 1:16 PM GMT on April 07, 2006

The Hurricane Season of 2005 now has another record--the most number of names ever retired in a season, five. The World Meteorological Organization (WMO) announced yesterday that the names Dennis, Katrina, Rita, Stan, and Wilma would all be retired, due to the large loss of life and tremendous property damage these storms inflicted. For 2011, Dennis, Katrina, Rita, Stan and Wilma have been replaced with Don, Katia, Rina, Sean and Whitney, respectively. Since hurricanes were first given names in 1953, 67 names have been retired (the first being Carol and Hazel in 1954). The previous record for most retired names in a year was four in 1955, 1995 and 2004.

There is one rather amazing and ridiculous omission from the list of retired names for 2005--Hurricane Emily. Emily was the earliest-forming Category 5 hurricane on record in the Atlantic basin and the only known hurricane of that strength to occur during the month of July. Emily became a Category 5 hurricane with 160 mph winds and a 929 mb central pressure on July 17 2005, while located 115 miles southwest of Jamaica. The storm weakened somewhat before making landfall on the Mexican coast near Cozumel Island as a Category 4 storm with 135 mph winds and a storm surge of up to 15 feet. Emily went on to cross the Gulf of Mexico and slam ashore on the Mexican coast south of Brownsville, Texas, as a Category 3 hurricane. Emily killed one person on its passage over Grenada as a Category 1 hurricane, and five in Jamaica. Amazingly, no one died in Mexico as a result of Emily's two strikes as a major hurricane.

Figure 1. Emily has come and gone five times, and will be back again in 2011. Arlene, with nine appearances so far, and another scheduled in 2011, holds the record for most incarnations.

From what I understand about the process of retiring a hurricane's name, any country affected by a hurricane can request that a name be retired, and a pow-wow of big shots elected by the World Meteorological Organization (WMO) meets to consider these requests and decide which names get retired. Presumably, Haiti did not request that Hurricane Gordon of 1994 get its name retired after it killed over 1100 people there, since the country was too embroiled in civil strife and recovery from the disaster to be concerned with such matters. It is possible that Mexico did not request retiring Emily's name, since Wilma's impact on the country far overshadowed Emily's. Still, what does a storm named Emily have to do to get its name retired? Three of Emily's five appearances have been worthy of retirement. I thought Emily should have been retired when I flew through the 1987 incarnation that slammed into the Hispanolia as a Category 3 hurricane. Certainly, the Category 3 version that brushed North Carolina in 1993 was worthy of retirement, as well. I can only conclude that a dark conspiracy is at work. A member of the WMO name retirement committe must have it in for someone with the name Emily, and is determined that her name never be retired.

Severe weather threat today
Yesterday's tornado outbreak did not materialize as expected, much to the relief of those in the Central U.S. Nineteen reports of tornadoes in Kansa, Oklahoma, and MIssouri were received by the Storm Prediction Center. Most of these tornadoes crossed unpopulated farmland, although damage to several homes and 12 minor injuries were reported in Chetopa, Kansas. Residents of Alabama, Mississippi, Tennessee, and surrounding states may not be as lucky today. Conditions appear more favorable today for the appearance of violent long-track tornadoes over these states in the late afternoon today.

Figure 2. Severe weather outlook for today.

Jeff Masters

Major tornado outbreak expected today

By: JeffMasters, 1:26 PM GMT on April 06, 2006

Another major severe weather outbreak is predicted for today across the central U.S. The Storm Prediction Center has just increased the risk of severe weather to the highest category across eastern Kansas and neighboring regions of Missouri and Nebraska. An extrememly potent mix of warm, moist Gulf of Mexico air, a very strong jet stream, and an intrusion of dry air at mid levels of the atmosphere is expected to trigger another major tornado outbreak over the next two days that may rival the two previous outbreaks this year for number of tornadoes. More strong F3 tornadoes are expected today, along with baseball-sized hail and damaging thunderstorm winds. Tomorrow, the action moves into Tennessee, Mississippi, Alabama, and Georgia, as the storm system responsible tracks slowly eastward.

Figure 1.Severe weather outlook for today.

The April 2-3 tornado outbreak
According to NOAA, the 68 tornado reports and 26 tornado deaths Sunday in eight states brought the totals for the year to 355 tornadoes and 38 deaths. Sunday's storms also caused two wind-related deaths and approximately 196 injuries. This is the highest total number of reports for the first three months of the year since 1999 and is a sharp contrast to last year when only 96 tornado reports and five deaths occurred by April 3. The number of deaths to date is the highest since 1998. So far, NWS damage surveys have confirmed five F3 tornadoes from the April 2-3 outbreak.

I'll be back tomorrow with a discussion of why this year's severe weather season has been so bad.

Jeff Masters


2006 hurricane season forecast; severe weather outbreak update

By: JeffMasters, 1:56 PM GMT on April 04, 2006

Today marked the release of Dr. Bill Gray's latest 2006 Atlantic hurricane season forecast, and it looks like we are in for another long and busy hurricane season. The team from Colorado State University (CSU), led by Dr. Bill Gray and Philip Klotzbach, predict 17 named storms (average is 9.6), 9 hurricanes (6 is average), and 5 intense hurricanes (average is 2.3). The net activity for the season is expected to be 95% higher than normal. The entire Caribbean and U.S. coast is at above-normal risk for a strike by a major hurricane, with the U.S. East Coast (including the Florida Peninsula) at 64% risk, and the Gulf Coast at 47% risk. There is an 81% chance that at least one major hurricane will strike the U.S. coast. However, it is statistically unlikely that this coming season will have as many major hurricane U.S. landfall events as we saw in 2004-2005.

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

1) While the Atlantic Ocean is cooler than it was at this time last year, sea surface temperatures remain warmer than average, and are expected to be warmer than average during the August-October peak of hurricane season.

2) Neutral or weak La Ni�a conditions are likely to be present during August-October 2006. A weak to moderate La Ni�a event is now occurring, with trade winds in the central Pacific anomalously strong and oceanic heat content in the tropical Pacific well below normal. These features will likely keep Eastern Pacific waters from becoming anomalously warm over the next few months and ending the La Ni�a event. In addition, most forecast models call for either neutral or La Ni�a conditions to persist for the next 4-6 months. When the tropical Atlantic is warm, and neutral or La Ni�a conditions are 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.

Accuracy of last year's April forecast
How did last year's early April hurricane forecast verify? The CSU team did forecast an above-normal year, but did not foresee the extraordinary season that would ultimately unfold. They forecasted 13 named storms (average is 9.6), 7 hurricanes (6 is average), and 3 major hurricanes (2.3 is average. In reality, there were 27 named storms, 14 hurricanes, and 7 major hurricanes. However, they did mention that a continued Atlantic Ocean warming would cause them to raise their forecast numbers for their May 31 and August 5 forecasts, which is what happened.

With this forecast, Dr. Gray hands over leadership of the forecast team to Phil Klotzbach. While Gray, 76, is at the older end of the spectrum of hurricane scientists, Klotzbach, 26, is definitely at the younger end. He earned his Bachelor's degree at age 18 from Bridgewater State College in Massachusetts, then picked up a Masters degree in Atmospheric Science from Colorado State University four years later. He has been a research associate working with Bill Gray since 2001. Dr. Gray will continue to be very involved in working on these forecasts, but prefers to concentrate on researching the connection between hurricane activity and global warming. He is a vocal opponent of theories connecting recent increases in intense hurricane activity with global warming.

Severe weather outbreak of April 2-3
At least 60 tornadoes ripped through Missouri, Arkansas, Illinois, Indiana, Ohio, and Tennessee Sunday, killing 28 people. Hardest hit was northwest Tennessee, where tornadoes claimed at least 12 lives in Dyer County. A preliminary damage survey by the NWS rated this tornado a strong F3, with winds of 200 mph. The tornado that devastated Marmaduke, Arkansas, was also a strong F3, and may have ranked as a violent F4 tornado (207-260 mph winds) on the Fujita scale. More damage surveys are being performed today to determine the exact strength of this tornado. Many other tornadoes from this outbreak also ranked as F3, and the April 2 tornado outbreak may match the March 13 outbreak for number of strong tornadoes. The March 13 outbreak had 11 strong F3 tornadoes among the 84 that touched down.

The last time we had two major tornado outbreaks killing 12 or more people was in 1998. With the peak of tornado season still a month away, we have the potential for the nastiest tornado season seen in a long time--to go along with what could also be a very long and deadly hurricane season.

Jeff Masters


Violent tornado rakes Tennessee

By: JeffMasters, 1:44 PM GMT on April 03, 2006

Tornadoes and severe thunderstorms ripped through Missouri, Arkansas, Illinois, Ohio, Tennessee, and surrounding states Sunday, killing at least 23 people. Hardest hit was northwest Tennessee, where tornadoes claimed at least 12 lives in Dyer County. Damage reports indicated that many houses in the tornado's path were completely destroyed leaving only the foundation, making it likely that the Dyer County tornado will be ranked as a violent F4 tornado (207-260 mph winds) on the Fujita scale. This would be the second F4 tornado of the year--an F4 tornado struck Monroe City, MO on March 13, as part of an 84-tornado assault on the Midwest that also featured 11 strong F3 tornadoes. There is a slight possibility that last night's Dyer County tornado was an F5--the most violent type of tornado, capable of incredible damage--but we won't know until the National Weather Service has a chance to get out today in daylight and perform a damage survey. The U.S. has not had an F5 tornado since the infamous Moore, Oklahoma tornado of 1999, which had the highest winds ever recorded in a tornado, 301 mph. The U.S. has already equalled last year total of F4 tornadoes (one), and this Spring's severe weather season is shaping up to be far more deadly and destructive than last year's unusually quiet one.

Figure 1. Damage reports for the 24 hours ending at 9am EST April 3 show the wide scope of yesterday's severe weather.

The threat for severe weather continues today. The "Moderate Risk" area in the latest outlook by the Storm Predisction Center covers a region unused to seeing tornadoes--coastal areas of North Carolina, Virginia, and Maryland. A strong cold front will push across the region this afternoon, creating a squall line with embedded supercells likely to produce tornadoes, damaging straight-line thunderstorm winds, and hail golf ball size and larger. The severe weather episode will end tonight as the cold front pushes off the coast and more tranquil weather returns to the U.S.

Tomorrow: An update on the severe weather outbreak, plus a look at Dr. Bill Gray's new forecast for the hurricane season of 2006.

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.

Category 6™


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