The Colorado State University Hurricane Forecast Team slightly increased its overall seasonal forecast today, while still calling for a slightly below-average remainder of the season due to the likely development of El Nino.
The team of Phil Klotzbach and William Gray are now predicting a total of 14 named storms with six becoming hurricanes and two becoming major hurricanes (Saffir/Simpson category 3-4-5) with sustained winds of 111 mph or greater. In June, the team had predicted 13 named storms with five of the 13 expected to become hurricanes and two of those expected to become major hurricanes.
The 14 named storms and six hurricanes in the latest forecast includes the four named storms and one hurricane that formed in May and June.
We have increased our seasonal forecast from early April and early June, due to a combination of uncertainty in El Nino as well as slightly more favorable tropical Atlantic conditions, Klotzbach said. Still, the probability of U.S. major hurricane landfall and Caribbean major hurricane activity for the remainder of the 2012 season is estimated to be slightly below its long-period average.
The last four years of CSU's hurricane forecasts have been largely successful. To view the four-year verification, go to tropical.atmos.colostate.edu/Includes/Documents/Publications/verification.pdf.
CSU is in its 29th year of issuing Atlantic basin seasonal hurricane forecasts.
For the remainder of the season, Klotzbach also recalculated probabilities for a major hurricane making landfall on the U.S. coast after July 31:
A 48 percent chance that a major hurricane will make landfall on the U.S. coastline (full-season average for the last century is 52 percent)
A 28 percent chance for the East Coast, including the Florida Peninsula (full-season average for the last century is 31 percent).
A 28 percent chance for the Gulf Coast from the Florida Panhandle west to Brownsville (full-season average for the last century is 30 percent).
The probability for at least one major hurricane making landfall in the Caribbean is 39 percent (full-season average for the last century is 42 percent).
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 Web site. 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. Individual state probabilities are also available. Gray and Klotzbach recommend that coastal residents consult this website to learn of their local hurricane impact probabilities on multiple timescales.
The website, available to the public at www.e-transit.org/hurricane, is the first publicly accessible internet tool that adjusts landfall probabilities for regions, states 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 University in Massachusetts. In addition, probabilities for various islands in the Caribbean and landmasses in Central America are now available on the Landfall Probability Web site.
The Colorado State team predicts that tropical cyclone activity for the remainder of 2012 will be about 90 percent of the average season. By comparison, 2011 witnessed tropical cyclone activity that was about 145 percent of the average season.
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.
CSU RESEARCH TEAM
2012 EXTENDED RANGE ATLANTIC BASIN HURRICANE FORECAST
-Released Aug. 3, 2012-
Tropical Cyclone Parameters Extended Range
(1981-2010 Climatological Averages Forecast for 2012)
Named Storms (12.0)* 14
Named Storm Days (60.1) 52
Hurricanes (6.5) 6
Hurricane Days (21.3) 20
Major Hurricanes (2.0) 2
Major Hurricane Days (3.9) 5
Accumulated Cyclone Energy (92) 99
Net Tropical Cyclone
Activity (103%) 105
* Numbers in ( ) represent average year totals based on 1981-2010 data. These numbers include the four named storms and one hurricane that formed prior to August 1.
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More information: A full copy of the forecast is available at news.colostate.edu and at typhoon.atmos.colostate.edu/.