Rather active hurricane-season is expected in the Atlantic
This year’s North Atlantic hurricane season officially began on June 1st, and will last until November 30th. According to the latest forecasts there is a definite risk it could become more intense than usual.
Copyright 2010 EUMETSAT
The latest ECMWF numerical forecast is projecting a total of 14.4 tropical storms during the whole of the 2011 hurricane-season. Out of these 8.3 are expected to develop into actual hurricanes, with winds of at least 33m/s. This should be compared to the 1990-2005 average of 12.6 tropical storms, and 7.3 hurricanes. (The decimal in the forecasted value may seem a bit confusing, but is a result of the way the forecast is made, by combining the results of many individual forecasts.)
USA’s National Oceanographic and Atmospheric Administration (NOAA) issued its official forecast on May 19th, and they also expect a rather active season this year with 12-18 tropical storms, out of which 6-10 are expected to reach hurricane-status.
We are still waiting for the first system of the season that is strong enough to be given a name, but when it comes it will be named “Arlene”. Tropical cyclones in the North Atlantic are named by the WMO when they reach a sustained wind-speed of 17m/s. The cyclones are then named according to a pre-made list containing 22 names each beginning with a different letter of the alphabet, from A to W. If in a season more than 22 named storms should develop, Greek letters are used as a contingency plan. This actually became necessary in 2005, one of the worst hurricane-seasons ever, when we witnessed the formation of no less than six storms after “Wilma”, which was the last name on that years list. The following storms were consequently named “Alpha”, “Beta”, “Gamma”, “Delta”, “Epsilon” and “Zeta”. The last one “Zeta” actually formed after the end of the official hurricane-season.
While there are no immediate signs that this years hurricane-season will be as bad as 2005 warmer than normal waters in the Caribbean, and the lingering effects of a La Niña earlier this year suggest that we can expect a rather active hurricane-season.
