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Research / Discovery

Forecast teams predicts above-average 2010 hurricane season

April 7, 2010

The Colorado State University forecast team predicts an above-average 2010 Atlantic basin hurricane season based on the premise that El Nino conditions will dissipate by this summer and that anomalously warm tropical Atlantic sea surface temperatures will persist.

Team predicts 15 named storms

William Gray, professor of atmospheric science and Phil Klotzbach, lead forecaster on the CSU Hurricane Forecast Team.

The team predicts 15 named storms to form in the Atlantic basin between June 1 and Nov. 30 with eight expected to be hurricanes and four developing into major hurricanes (Saffir/Simpson category 3-4-5) with sustained winds of 111 mph or greater.

Long-term averages are 9.6 named storms, 5.9 hurricanes and 2.3 major hurricanes per year.

Moderate El Nino conditions

“We expect current moderate El Nino conditions to transition to neutral conditions by this year’s hurricane season,” said Phil Klotzbach, lead forecaster on the CSU Hurricane Forecast Team. “The dissipating El Nino, along with the expected anomalously warm Atlantic ocean sea surface temperatures, will lead to favorable dynamic and thermodynamic conditions for hurricane formation and intensification.”

The 2010 forecast marks 27 years of hurricane forecasting at Colorado State, led by William Gray. The hurricane forecast team makes its predictions based on 58 years of historical data.

Probability of major hurricane making landfall is above-average

“Based on our latest forecast, the probability of a major hurricane making landfall along the U.S. coastline is 69 percent compared with the last-century average of 52 percent,” Gray said. “While patterns may change before the start of hurricane season, we believe current conditions warrant concern for an above-average season.”

Precursor factors to this year have a number of similarities to early April conditions that preceded the hurricane years of 1958, 1966, 1969, 1998, and 2005. All five of these seasons had above-average activity, especially the seasons of 1969, 1998 and 2005. Klotzbach and Gray predict the 2010 season will have slightly less activity than the average of these five earlier years.

The team predicts tropical cyclone activity in 2010 will be 160 percent of the average season. By comparison, 2009 witnessed tropical cyclone activity that was about 70 percent of the average season.

Forecast probabilities

The hurricane forecast team's probabilities for a major hurricane making landfall on U.S. soil are as follows:

- A 69 percent chance that at least one major hurricane will make landfall on the U.S. coastline in 2010 (the long-term average probability is 52 percent).

- A 45 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 44 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).

The team also predicts a 58 percent chance of a major hurricane tracking into the Caribbean (the long-term average is 42 percent).

Forecasts based on global oceanic and atmospheric conditions

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 began using a new early April statistical model in 2008.

“We have found that using two late-winter predictors and our early December hindcast, we can obtain early April predictions that show considerable hindcast skill over the period from 1950-2007,” said Klotzbach. “This new forecast model also provided a very accurate prediction over the past few seasons.”

New forecast model has led to very accurate predictions

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 website. 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.

The website, 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. Probabilities are also available for all islands in the Caribbean and countries in Central America. Klotzbach and Gray update the site regularly with assistance from the GeoGraphics Laboratory at Bridgewater State College in Massachusetts.

The team will issue forecast updates on June 2 and Aug. 4.


Contact: Emily Wilmsen
E-mail: Emily.Wilmsen@colostate.edu
Phone: (970) 491-2336