Above normal sea-surface temperatures and expected reduced vertical shear in the tropical Atlantic, combined with near-neutral El Nino-Southern Oscillation (ENSO) conditions, will likely contribute to an above-average hurricane season. The hurricane forecast team at Colorado State University predicts 16 named storms with nine of the 16 becoming hurricanes in the Atlantic basin between June 1 and Nov. 30. Five are expected to develop into major hurricanes (Saffir/Simpson category 3-4-5) with sustained winds of 111 mph or greater.

Forecasters estimate the 2011 season will have roughly as much activity as was experienced in five similar years: 1951, 1981, 1989, 1996 and 2008.

“Based on our historical analysis along with our current forecast, the probability of a major hurricane making landfall along the U.S. coastline is approximately 72%,” says lead forecaster Phil Klotzbach. “These probabilities are based on the idea that more active seasons tend to have more landfalls, but coastal residents should prepare the same way every year for landfall, regardless of how active or inactive the forecast might be.”

Other probabilities for a major hurricane making landfall on various portions of the U.S. coast:

  • A 48% 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 47% chance that a major hurricane will make landfall on the Gulf Coast from the Florida Panhandle west to Brownsville, TX (the long-term average is 30%).
  • A 61% change of a major hurricane tracking into the Caribbean (average for the last century 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 within a variety of time periods are listed on the forecast team's Landfall Probability web site at www.e-transit.org/hurricane. The site provides U.S. landfall probabilities for 11 regions and 205 individual counties along the U.S. coastline from Brownsville, TX to Eastport, ME.

The hurricane forecast team predicts tropical cyclone activity in 2011 will be approximately 175% of the average season. By comparison, 2010 witnessed tropical cyclone activity that was about 196% of the average season.

A full copy of the 2011 hurricane season report may be found at http://hurricane.atmos.colostate.edu/.