Colorado State University Hurricane Forecast Team Increases Prediction, Calls for Very Active 2010 Hurricane Season

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The Colorado State University hurricane forecast team today increased its predictions and is now calling for a very active 2010 season in the Atlantic basin with 18 named storms predicted. The forecast was based on much warmer-than-normal tropical Atlantic sea surface temperatures and cooling tropical Pacific conditions that will likely transition into a weak La Nina by mid-season.

Of the 18 storms, the team now anticipates 10 hurricanes forming in the Atlantic basin between June 1 and Nov. 30. Five are expected to develop into major hurricanes (Saffir/Simpson category 3-4-5) with sustained winds of 111 mph or greater.

The scientists increased their forecast from April’s prediction of 15 named storms, eight hurricanes and four major hurricanes. Long-term (1950-2000) averages are 9.6 named storms, 5.9 hurricanes and 2.3 major hurricanes per year.

“We have increased our forecast from early April, due to a combination of a transition from El Nino to current neutral conditions and the continuation of unusually warm tropical Atlantic sea surface temperatures,” said William Gray, who is in his 27th year of forecasting at Colorado State. “We anticipate a well above-average probability of United States and Caribbean major hurricane landfall.”

The team also updated its U.S. landfall probabilities, which are calculated based on historical landfall statistics and then adjusted by the latest seasonal forecast.

"The probability of a major hurricane making landfall along the U.S. coastline is 76 percent compared with the last-century average of 52 percent," said lead forecaster Phil Klotzbach. “We expect that the current trend from El Nino to neutral conditions will persist and that weak La Nina conditions will develop by the most active portion of this year’s hurricane season (August-October).

“El Ninos typically increase levels of vertical wind shear in the tropical Atlantic, causing detrimental conditions for Atlantic tropical cyclone formation and intensification,” Klotzbach said.

The team’s probabilities for a major hurricane making landfall on various portions of the U.S. coast:

– A 51 percent chance that a major hurricane will make landfall on the U.S. East Coast, including the Florida Peninsula (the long-term average is 31 percent).

– A 51 percent chance that a major hurricane will make landfall on the Gulf Coast from the Florida Panhandle west to Brownsville (the long-term average is 30 percent).

-A 65 percent change of a major hurricane tracking into the Caribbean (average for the last century is 42 percent).

The team debuted a forecast for Caribbean basin activity with this prediction. The Caribbean looks to be very active in 2010, with overall tropical cyclone activity approaching levels experienced in 2004 and 2005.

Klotzbach noted this hurricane season, if it occurs as predicted, could have an impact on the cleanup of the oil spill in the Gulf.

“If the storm tracks to the west of the oil, there is the potential that the counter-clockwise circulation of the hurricane could drive some of the oil further towards the U.S. Gulf Coast,” Klotzbach said. “We do not expect that the oil slick will have much of an impact on any tropical storm or hurricane that passes over the area.”

Probabilities of tropical storm-force, hurricane-force and major hurricane-force winds occurring at specific locations along the U.S. East and Gulf Coasts within a variety of time periods are listed on the forecast team’s Landfall Probability Web site. The site provides U.S. landfall probabilities for 11 regions and 205 individual counties along the U.S. coastline from Brownsville, Texas, to Eastport, Maine. Individual state probabilities are also available on this website.

The website, available to the public at, is the first publicly accessible Internet tool that adjusts landfall probabilities for regions and counties based on the current climate and its projected effects on the upcoming hurricane season. Klotzbach and Gray update the site regularly with assistance from the GeoGraphics Laboratory at Bridgewater State College in Massachusetts. In addition, probabilities for various islands in the Caribbean and landmasses in Central America are now available on the Landfall Probability Web site

Currently observed climate factors are similar to conditions that occurred during the 1958, 1966, 1969, and 2005 seasons. The average of these four seasons had well above-average activity, and Klotzbach and Gray predict the 2010 season will have activity in line with the average of these four years.

The hurricane forecast team predicts tropical cyclone activity in 2010 will be 195 percent of the average season. By comparison, 2009 witnessed tropical cyclone activity that was about 69 percent of the average season.

The hurricane team’s forecasts are based on the premise that global oceanic and atmospheric conditions – such as El Nino, sea surface temperatures and sea level pressures – that preceded active or inactive hurricane seasons in the past provide meaningful information about similar trends in future seasons.

The team will issue a final seasonal forecast update on Wednesday, August 4.

-Released June 2, 2010-
Tropical Cyclone Parameters Extended Range
(1950-2000 Climatology Averages Forecast for 2010
in parentheses)
Named Storms (9.6)* 18
Named Storm Days (49.1) 90
Hurricanes (5.9) 10
Hurricane Days (24.5) 40
Intense Hurricanes (2.3) 5
Intense Hurricane Days (5.0) 13
Accumulated Cyclone Energy (96) 185
Net Tropical Cyclone
Activity (100%) 195
* Numbers in ( ) represent average year totals based on 1950-2000 data.