Fort Collins. December 10th, 2008. An early extended-range forecast for 2009 calls for somewhat above-average Atlantic basin hurricane activity, according to a new report from the Tropical Meteorology Project at Colorado State University.
The report marks the 26th year of the CSU hurricane forecasting team, which is led by Philip Klotzbach and William Gray.
The team’s first extended-range forecast for the 2009 hurricane season anticipates 14 named storms forming in the Atlantic basin between June 1 and Nov. 30. Seven of the 14 storms are predicted to become hurricanes, and of those seven, three are expected to develop into intense or major hurricanes (Saffir/Simpson category 3-4-5) with sustained winds of 111 mph or greater.
“We’re forecasting an above-average season based on our early assessment of factors that influence an active hurricane season including warm Atlantic sea surface temperatures and the likely absence of El Nino conditions,” said Klotzbach, lead author of the forecasts. “The media and general public should realize that there is a large amount of uncertainty with our early December prediction, issued seven months prior to the start of the hurricane season.”
This forecast is based on an extended-range early December statistical prediction scheme that uses 58 years of data. This statistical model explains a considerable amount of hurricane variability in hindcasts issued from 1950-2007. Over this time period, the three-predictor scheme correctly forecast above- or below-average seasons in 45 out of 58 years. The forecast model also successfully predicted an above-average season in 2008.
The entire forecast report is available on the Web at http://hurricane.atmos.colostate.edu.
“We are currently in an active period for Atlantic hurricane activity. This active cycle in the Atlantic basin is expected to continue for another decade or two at which time we should enter a quieter Atlantic major hurricane period like we experienced during the periods from 1970-1994 and 1901-1925,” Gray said.
The CSU hurricane forecast team also predicts a 63 percent chance that at least one major hurricane will make landfall on the U.S. coastline in 2009. The long-term average probability is 52 percent.
For the U.S. East Coast, including the Florida Peninsula, the probability of a major hurricane making landfall is 39 percent (the long-term average is 31 percent). For the Gulf Coast from the Florida Panhandle west to Brownsville, the probability is 38 percent (the long-term average is 30 percent).
The team predicts above-average major hurricane landfall risk in the Caribbean.
Along with today’s report, the team has updated the Landfall Probability Web site that provides probabilities of tropical storm-force, hurricane-force and major hurricane-force winds making landfall at specific locations along the U.S. East and Gulf Coasts within a variety of time periods. U.S. landfall probabilities are available for 11 regions and 205 individual counties along the U.S. coastline from Brownsville, Texas, to Eastport, Maine.
The Web site, available to the public at http://www.e-transit.org/hurricane, 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.
The hurricane team’s forecasts are based on the premise that global oceanic and atmospheric conditions – such as El Nino and tropical Atlantic sea surface temperatures – that preceded active or inactive hurricane seasons in the past provide meaningful information about similar trends in future seasons.
For 2009, Gray and the hurricane forecast team expect continued warm tropical and north Atlantic sea surface temperatures, prevalent in most years since 1995, as well as the absence of El Nino conditions – a recipe for enhanced Atlantic basin hurricane activity.
The team will issue seasonal updates of its 2009 Atlantic basin hurricane activity forecast on April 7, June 2, Aug. 4, Sept. 2 and Oct. 1. The August, September and October forecasts will include separate forecasts for August, September and October activity.
GRAY RESEARCH TEAM
EXTENDED RANGE ATLANTIC BASIN HURRICANE FORECAST FOR 2009
-Released Dec. 10, 2008-
Tropical Cyclone Parameters Extended Range
(1950-2000 Averages in parentheses) Forecast for 2009
Named Storms (9.6)* 14
Named Storm Days (49.1) 70
Hurricanes (5.9) 7
Hurricane Days (24.5) 30
Intense Hurricanes (2.3) 3
Intense Hurricane Days (5.0) 7
Accumulated Cyclone Energy (96.7) 125
Net Tropical Cyclone Activity (100%) 135
* Numbers in ( ) represent average year totals based on 1950-2000 data.