Posted: 12:16 pm Thursday, May 24th, 2012

NOAA: Average hurricane season 

By Eliot Kleinberg

Posted 12:15 p.m., May 24, 2012

On the 20th anniversary of a below-average season that produced a catastrophic hurricane, federal forecasters today predicted a near normal year.

The National Oceanic and Atmospheric Administration’s Climate Prediction Center called for a 70 percent chance that the season will produce nine to 15 storms of at least tropical storm strength, with four to eight becoming hurricanes and one to three becoming major hurricanes, of at least Category 3 on the Saffir-Simpson scale.

NOAA’s 1981-2010 average is 12, six and three.

This year’s factors: the region still is in a period of above-average storms that started back in 1995, and temperatures remain warm in the parts of the Atlantic Ocean and Caribbean Sea where hurricanes are prone to form.

Two factors now in place could help limit storm development — if they’re still around when the season really gets going. They’re a strong wind shear, which tends to tear apart storm circulation, and cooler surface temperatures in the far east Atlantic, where the monster storms are inclined to form.

Then there’s El Niño, the Pacific Ocean warm-water phenomenon that tends to hinder tropical storms and hurricanes. It would be good news for Florida if it develops by the the late summer and early fall, the peak storm months, “possibly shifting the activity toward the lower end of the predicted range,” Gerry Bell, lead seasonal hurricane forecaster at the Climate Prediction Center, said Thursday at a press conference.

During the summer, the “Bermuda High,” which sits over the Atlantic Ocean, can extend into the eastern quarter of North America, and block the natural tendency of storms to curve north into the open Atlantic, steering them to land. The last two years, a persistent trough of low pressure eroded the western edge of the “High” and created an alley that let the storms shoot north.

It’s still too early to predict where those patterns will be later this summer, and even then, they can stay in place for weeks or months or change from one day to next, National Hurricane center spokesman Dennis Feltgen said today.

Forecasters and emergency managers have practically pounded their fists on the table over the years in stressing that these seasonal forecasts do not say how many storms will strike land or where, and that people need to prepare every year as if that one storm will strike them.

On Thursday, NOAA Administrator Jane Lubchenco repeated the grave concerns forecasters and meteorological scholars have had for decades: in the two decades since Category 5 Hurricane Andrew smashed South Florida in August 1992, the improvement in the tracking of storm paths “has been remarkable,” but it is woefully inadequate when it comes to predicting changes in storms’ strength.

“We’re stepping up to meet this challenge through our Hurricane Forecast Improvement Project, which has already demonstrated exciting early progress toward improving storm intensity forecasts,” she said Thursday.

NOAA will issue an updated seasonal outlook for the Atlantic hurricane season in early August.

HURRICANE SEASON PREDICTIONS:      
  Trop Storms Hurrs. Major hurrs
NOAA 2012 Prediction (May 24)      
(70 pct chance of:) 9-15 4-8 1-3
Colo State 2012 Prediction (April 4) 10 4 2
Colo St. 2011 Prediction 16 9 5
NOAA 2011 Prediction 12-18 6-10 3-6
2011 Actual 19 7 4
Historical Average (1981-2010) 12 6 3