The Colorado State University forecast team in April predicted a below-average 2012 Atlantic basin hurricane season due to a cooling of the tropical Atlantic and the potential development of El Nino conditions.
The CSU team calls for 10 named storms during the hurricane season, which falls between June 1 and Nov. 30. Four of those are expected to become hurricanes and two of those major hurricanes (Saffir/Simpson category 3-4-5) with sustained winds of 111 mph or greater.
CSU is in its 29th year of issuing Atlantic basin seasonal hurricane forecasts.
Despite the prediction for a less active season based on data analysis of about 30 years, the scientists warned that it only takes one hurricane to make it an active season for U.S. coastal residents.
"We have witnessed cooling of the tropical Atlantic during this past winter, and there is a fairly high likelihood that an El Nino event will develop this summer. Typically, El Nino is associated with stronger vertical shear across the tropical Atlantic, creating conditions less conducive for storm formation," said Phil Klotzbach of the CSU Tropical Meteorology Project in a press release issued by the university. "Still, all vulnerable coastal residents should make the same hurricane preparations every year, regardless of how active or inactive the seasonal forecast is. It takes only one landfall event near you to make this an active season."
The hurricane forecast team made this early April forecast based on a new forecast scheme that relies on 29 years of historical data. The forecasts are based on the premise that global oceanic and atmospheric conditions - such as El Nino, Atlantic basin sea surface temperatures, sea level pressures, etc. - that preceded active or inactive hurricane seasons in the past provide meaningful information about similar conditions that will likely occur in the current year.
The team's annual predictions are intended to provide a best estimate of activity to be experienced during the upcoming season, not an exact measure.
Four years since 1949 exhibited February-March characteristics most similar to the oceanic and atmospheric features observed during February-March 2012: 1957, 1965, 2001 and 2009. Three of these four years had below-average Atlantic basin hurricane activity.
"Despite this below-average forecast, we remain - since 1995 - in a favorable multi-decadal period for enhanced Atlantic Basin hurricane activity, which is expected to continue for the next 10-15 years or so," said William Gray, founder of the Tropical Meteorology Project.
The team predicts that tropical cyclone activity in 2012 will be about 75 percent of the average season.
By comparison, 2011 witnessed tropical cyclone activity that was 145 percent of the average season.
The hurricane forecast team's probabilities for a major hurricane making landfall on U.S. soil in 2012 are:
- A 42 percent chance that at least one major hurricane will make landfall on the U.S. coastline (the long-term average probability is 52 percent).
- A 24 percent chance that a major hurricane will make landfall on the U.S. East Coast, including the Florida Peninsula (the long-term average is 31 percent).
- A 24 percent chance that a major hurricane will make landfall on the Gulf Coast from the Florida Panhandle west to Brownsville (the long-term average is 30 percent).
The team also predicts a 34 percent chance of a major hurricane tracking into the Caribbean (the long-term average 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 are listed on the forecast team's Landfall Probability website at www.e-transit.org/hurricane. The site provides U.S. landfall probabilities for all coastal states as well as 11 regions and 205 individual counties along the U.S. coastline from Brownsville, Texas, to Eastport, Maine. Landfall probabilities for regions and counties are adjusted based on the current climate and its projected effects on the upcoming hurricane season. Probabilities are also available for the Caribbean and Central America. Klotzbach and Gray update the site regularly with assistance from the GeoGraphics Laboratory at Bridgewater State University in Massachusetts.
The next report is due June 1.
Source: Colorado State University