Colorado State Team Predicts Very Mild Hurricane Season

HurricaneTalk about going out not with a bang but a whimper!

William M. Gray of the Colorado State University Tropical Meteorology Project, the dean of long-range hurricane forecasts, is retiring from that field to concentrate on the issues of climate change and global warming.

His timing may be perfect. Gray made his first seasonal forecast in 1984. Five of the 10 busiest years – in number of hurricanes since records began in 1851 – took place while Gray was on watch, including the record-busting 2005 season that featured 15 hurricanes and the infamous Katrina. No less than 11 of the 15 busiest seasons in terms of named storms took place during Gray’s tenure, led once again by 2005 with an incredible 28. (The runner up, 1933, had 20.) No wonder the press and the public eagerly awaited Gray’s annual forecasts.

But tropical activity in the Atlantic Basin seems to be in a slow cycle. Only two hurricanes developed during the 2013 season and for the first time since 1994, there were no major (Category 3 or above) blows. Then in 2014, there were six hurricanes, including two that breached the major threshold, but only eight named storms, the fewest since 1997. Gray expects more of the same this year:

“We anticipate that the 2015 Atlantic Basin hurricane season will be one of the least active seasons since the middle of the 20th century,” read the introduction of this year’s CSU preseason forecast, the last that will bear Gray’s name. “It appears quite likely that an El Niño (atmospheric wind current) of at least moderate strength will develop this summer and fall. The tropical and subtropical Atlantic is also quite cool at present. We anticipate a below-average probability for major hurricanes making landfall along the United States coastline and in the Caribbean.”

Indeed, his team’s forecast is calling for nothing short of a stunningly mild hurricane season. Gray and Co. expect just seven named storms to develop in the Atlantic this season, which runs from June 1 through Nov. 30. The average between 1981 and 2010 was a dozen. The scientists predict only three hurricanes, as compared to a 1981-2010 average of 6½ per year. One of those hurricanes, said the Colorado State meteorologists, will be a major one, Category 3 or higher. Two such monster storms typically formed each year between 1981 and 2010.

The CSU’s prediction for a major hurricane landfall in the U.S. is also on the decidedly low side. The scientists said there is a 28 percent possibility of a Category 3 or above hurricane hitting this country’s coastline. The average for the last century was 52 percent.

Gray, the octogenarian pioneer of long-range hurricane forecasts, has been weaning himself from the predictions for a decade, giving more responsibility to his protégé, Philip J. Klotzbach. Now Gray is saying, in a self-deprecating way, that he’s bowing out of the hurricane prediction biz altogether.

“Klotzbach became lead author of the CSU forecasts in 2006,” Gray wrote, “and in recent years has expended most of his efforts in researching and writing up these forecasts and their post-season evaluation. We still talk nearly every day on climate-hurricane matters, and no forecast has been released without my detailed comments. Phil has been making all the final forecast decisions in recent years. He has, nevertheless, appointed me to serve in the important role of taking the blame for any and all forecast busts, with all credit for successful forecasts going to him. I have fully embraced this special arrangement.

“Although I still come to my office every working day and remain quite active, I am now devoting more of my research efforts to the climate change and global warming issue. For this reason I will be discontinuing my formal association with these seasonal hurricane forecasts at the end of this year. But I will remain as a special personal advisor to Phil in all of his future CSU hurricane forecasts as long as I am able.”

Gray was controversial when he started making his long-range forecasts. The meteorologists of the time feared gazing into a figurative crystal ball months ahead of time. Gray, however, developed a system of hurricane prediction called “hindcasting.” Gray looked at the atmospheric-oceanic conditions during the winter and spring of prior years since 1950 and recorded the number of storms and hurricanes that ended up developing. He then looked at the current year’s conditions and, after finding similar patterns in the past, predicted a comparable season.

This winter, for example, the CSU team looked for years that were generally characterized by at least moderate El Niño conditions and cool temperature in the tropical Atlantic. Five stood out: 1957, 1987, 1991, 1993 and 2014. They averaged 7.8 named storms and 4 hurricanes, including 1.6 of the major variety. Thus the prediction for a mild hurricane season for 2015.

Since Gray’s groundbreaking efforts, other meteorologists and climatologists have started making their own long-range hurricane forecasts, even the conservative folks at the National Weather Service Climate Prediction Center who release theirs in late May. A public consortium named Tropical Storm Risk, based at University College London, released a report on April 9 – the same day as CSU – which called for 11 named storms and five hurricanes, including two majors. On April 13 North Carolina State University chipped in, predicting four to six named storms and just one to three hurricanes, including one major. The Weather Channel, on April 22, called for nine storms and five hurricanes, including one Category 3 or above.

So there will be plenty of people, including Klotzbach, making long-range hurricane forecasts in the future. But with Gray’s announced retirement, an era has definitely ended.

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