2011 Hurricane Season - Above-Normally Active!
By William P. Roeder, 45th Weather Squadron
/ Published June 03, 2011
PATRICK AFB, Fla. -- The 2011 hurricane season is expected to be well above average. The NOAA Climate Prediction Center is predicting 12-18 tropical cyclones, 6-10 hurricanes, and 3-6 major hurricanes of Category-3 strength or higher (111 mph or higher). An average season has just 11 tropical storms, six hurricanes, and two major hurricanes. NOAA is predicting the overall season to be 105-200% of average according to the Accumulated Cyclone Energy index (a method used to account for the intensity and duration of named storms and hurricanes).
Three important ingredients have combined to produce this year's active hurricane forecast. First, water temperatures in the Atlantic are above normal. Warm water is the fuel for tropical cyclones.
Second, the current weak La Nina (indicated by cooler than average water temperature in the equatorial Pacific Ocean) is expected to dissipate by June. However, the reduced wind shear over the Atlantic Ocean associated with the La Nina are expected to persist through much of the hurricane season. Less wind shear aids tropical cyclone development by ensuring the storms are not torn apart by winds aloft, and is critical to a storm's long-term survival.
Third, we remain in a multidecade cycle of above average activity that began in 1995.
The NOAA forecast does not consider landfall. We could have an extremely active hurricane season where most of the activity stays over water and has little impact on land. However, the more tropical cyclones that occur, the larger the chance that some will affect land.
Remember, it only takes one land-falling hurricane to cause a disaster. You are warned - BE PREPARED!