Gray and Colorado State Team Increase Seasonal Forecast

William Gray and the Colorado State University hurricane forecast team, Fort Collins, CO, have slightly increased their predictions for the 2003 hurricane season. In their latest forecast update, issued before the official beginning of hurricane season on June 1, Gray and his colleagues continue to predict Atlantic basin storm activity to be well above average in 2003. They expect twice as many hurricanes as in 2002 and an increased probability of landfalling hurricanes.

“The dissipation of El Niño and the anticipated formation of a La Niña in the Pacific are factors leading to the increase in our May update of two more tropical storms,” said Gray. “The amount of hurricane activity remains identical to our earlier December 6 and April 4 forecasts (see HP, Spring 2003, page 37). Overall, we anticipate the 2003 Atlantic basin hurricane season to be very active.”

Gray and his colleagues call for a total of 14 named storms to form in the Atlantic basin this year, two more than the team’s early December and April forecasts. Of the 14 storms, eight are predicted to become hurricanes and three are anticipated to evolve into intense hurricanes (Saffir/Simpson category 3, 4, 5) with sustained winds of 111 mph or greater. The long-term average is 9.6 named storms, 5.9 hurricanes and 2.3 intense hurricanes per year. Last year there were 12 named storms but only four hurricanes and two intense hurricanes formed.

The El Niño in the Pacific, which played a role in suppressing 2002 hurricane activity, has now dissipated. The team foresees La Niña, or cold-water conditions, to be established in the Pacific by the beginning of the most active part of the hurricane season in mid-August.

Additionally, the Colorado State forecasters cite anomalously warm sea surface temperatures and lower than normal sea level pressure in the Atlantic as other factors that are expected to contribute to making 2003 an above-average hurricane season.

The Colorado State forecast team also stresses a higher than average probability of at least one intense hurricane making landfall in the United States this year. According to the latest forecast, there is a 69 percent chance of a major hurricane hitting somewhere along the U.S. coastline in 2003 (the long-term average is 52 percent). For the U.S. East Coast, including the Florida Peninsula, the probability of an intense hurricane making landfall is 49 percent (the long-term average is 31 percent). For the Gulf Coast from the Florida Panhandle westward to Brownsville, TX, the probability is 39 percent (the long-term average is 30 percent). The team also expects an above-average major hurricane landfall risk in the Caribbean.