Forecasters predict a below-average 2012 Atlantic basin hurricane season, due to a cooling of the tropical Atlantic and the potential development of El Niño conditions.

The forecast 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, with two of those major hurricanes providing sustained winds of 111 mph or greater, according to Colorado State University (CSU) scientists who are in their 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 warn 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 Niño event will develop this summer. Typically, El Niño is associated with stronger vertical shear across the tropical Atlantic, creating conditions less conducive for storm formation,” says Phil Klotzbach of CSU’s Tropical Meteorology Project.

“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.”

Since 1949, four years exhibited February-March characteristics most similar to the oceanic and atmospheric features observed during February-March 2012; these were 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% of the average season.

By comparison, 2011 witnessed tropical cyclone activity that was 145% 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% chance that at least one major hurricane will make landfall on the U.S. coastline (the long-term average probability is 52%).

• A 24% chance that a major hurricane will make landfall on the U.S. East Coast, including the Florida Peninsula (the long-term average is 31%).

• A 24% 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%).

• The team also predicts a 34% chance of a major hurricane tracking into the Caribbean (the long-term average is 42%).

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 http://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, TX, to Eastport, ME.

The full report is available at http://typhoon.atmos.colostate.edu/.