The Colorado State University tropical storm research team has lowered its hurricane development forecast for the 2009 North Atlantic season and now foresees “average activity.” Researchers Philip Klotzbach and William Gray decreased their forecast from their initial December prediction and now expect 12 named tropical storms to develop in the North Atlantic basin between June 1, 2009 and November 30, 2009. Of these, six are predicted to become hurricanes and two intense hurricanes with sustained winds of 111 mph or greater (Category 3 and above on the Saffir-Simpson Scale). In December, the Colorado State University predicted an above-average season with 14 named storms, seven hurricanes and three major hurricanes.
The latest 2009 forecast was cut because of expected weak La Niña conditions that could transition to neutral and perhaps weak El Niño conditions by this year’s hurricane season, Klotzbach said. El Niño, a phenomenon marked by a warming of equatorial Pacific waters, tends to increase levels of vertical wind shear that can prevent the formation of tropical storms. Klotzbach added that Atlantic tropical sea surface temperatures are the lowest they have been since 1994, meaning less fuel for hurricane development.
Klotzbach and Gray said that the chances of at least one intense hurricane making landfall in the United States in 2009 is 54 percent, lower than the 63 percent predicted in December and just above the long-term average of 52 percent. For the United States east coast, including the Florida Peninsula, the probability of an intense hurricane making landfall is 32 percent, again down from the 39 percent forecast in December and close to the average of 31 percent. For the Gulf Coast, from the Florida Panhandle west to Brownsville, the probability is 31 percent, compared with a long-term average of 30 percent.
The North Atlantic tropical cyclone names for 2009 are: Ana, Bill, Claudette, Danny, Erika, Fred, Grace, Henri, Ida, Joaquin, Kate, Larry, Mindy, Nicholas, Odette, Peter, Rose, Sam, Teresa, Victor, Wanda.
The next Philip Klotzbach and William Gray forecast is due to be released on 2 June 2009.
Sources: NOAA, Associated Press Newswires, Reuters News, Platts Commodity News, Bloomberg, http://tropical.atmos.colostate.edu/forecasts/2009/april2009/apr2009.pdf
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