Method behind storm outlook
Two climatologists from Colorado State University, who have been scorned and respected for their hurricane season forecasts, took to the podium last week to discuss their predictions for 2009: Twelve named storms, six hurricanes and two major hurricanes of Category 3 or worse.
“Basically, an average hurricane season,” Philip Klotzbach told attendees at the Governor’s Hurricane Conference in the Broward County Convention Center.
Klotzbach and colleague William Gray issue periodic prognostications before and during the six-month hurricane season, which begins June 1. Some years, the pair’s forecasts have been spot-on; other seasons, their figures have skewed sharply from the actual number of tropical storms that developed.
According to Klotzbach and Gray, Florida and the East Coast of the United States have a 32% chance of experiencing a hurricane landfall this year. The odds are 31% for the states along the Gulf of Mexico, and 54% for the entire U.S. coastline.
Klotzbach explained to conference attendees, mostly scientists and emergency management professionals, how he and Gray use “hindcasting,” the study of past weather activity, to predict the future.
“You don’t see the dartboard model,” he joked, pointing to a projected chart. “We do actually use science in our forecasts.” The Colorado-based researchers examine ocean temperature, barometric pressure and wind shear to forecast the number and strength of the coming season’s storms.
Warmer water, for example, fuels stronger hurricanes. This year, Klotzbach said, the Atlantic Ocean has been its coolest temperature in decades. But he said it could warm up during storm season.
El Nino, a large atmospheric condition that affects weather patterns, can cause an increase in wind shear, which inhibits a storm’s intensity, Klotzbach said.
“We have a bit of a challenge ahead of us because we don’t know what El Nino will do,” he said.
Regardless of the overall seasonal prediction, the researchers urged Americans at risk to be prepared for a hurricane.
“If you have one storm and it comes over you,” Gray said, “it’s a very active season.”
--
