WRAL WeatherCenter Blog

Gearing Up For Hurricane Season!

Posted May 31, 2006

Tomorrow is the start of the 2006 Atlantic Hurricane season and we are all holding our collective breath waiting and wondering what this season has in store for us. On average, the north Atlantic hurricane season produces 11 named storms, with six becoming hurricanes, including two major hurricanes.

In 2005, the Atlantic hurricane season contained a record 28 storms, including 15 hurricanes. Seven of these hurricanes were considered 'major' of which a record four hit the United States.

Even though Dr. William Gray of Colorado State University is not forecasting a season quite as rough as last year, the group says that there is an 82% chance that a major storm will strike the United States again this year( the average for the last century being 52%). A 69% chance that the East Coast and the Florida Peninsula will be struck( the average for the last century being 31%). A 38% chance that the Gulf Coast will experience a major storm( the average for the last century being 30%).

Below is a look at the satellite imagery of the Atlantic Basin take during the afternoon on Wednesday. All is quiet so far!



As we start the hurricane season it is a good idea to get an understanding of where tropical systems form during the six month period. As ocean temperatures rise and upper level winds lessen, the vicinity where these storms grow changes.

The following graphics below illustrate very well what regions of the Atlantic Basin are more prone to storm formation during certain times of the season and which areas are more prone to a landfalling cyclone.

These images and information are courtesy of NOAA and Wikipedia.

JUNE:

The beginning of the hurricane season is most closely related to the timing of increases in sea surface temperatures, convective instability, and other thermodynamical factors. Although this month marks the beginning of the hurricane season, the month of June generally still sees little activity, with an average of about 3 tropical systems per 5 years. Any tropical systems usually form in the Gulf of Mexico or off the east coast of the United States.

JULY:

July still has relatively little activity, with about one tropical cyclone a year. Climatologically speaking, half of seasons have their first tropical storm by July 11 with a second by August 8, using data from 1944 to 1996.
Formation usually occurs in the eastern Caribbean Sea around the Lesser Antilles, in the north and east parts of the Gulf of Mexico, in the northern Bahamas, and off the coast of The Carolinas and Virginia. Storms travel west through the Caribbean and then either move more northerly and curving near the eastern coast of the U.S. or southerly and entering the Gulf of Mexico.

AUGUST:

Activity increases significantly in August, with an average of about 2.8 storms per year. About half of seasons have four named systems and one hurricane total by August 30. The average season also sees one major hurricane by September 4.

SEPTEMBER:

The peak of the hurricane season in September corresponds to a time with low wind shear and high sea surface temperatures. The month of September sees an average of 3.6 storms a year. By September 24, the average season sees 7 named systems, of which 4 are hurricanes. In addition, two major hurricanes would be seen by September 28.

OCTOBER:

The favorable conditions found during September begin to decay in October. The main reason for the decrease in activity is increasing wind shear, although sea surface temperatures are also usually cooler than in September. Activity falls off markedly, with 1.8 cyclones developing in an average season. By October 21, the average season is expected to have 9 named storms with 5 hurricanes. A third major hurricane would be expected sometime between September 28 and the end of the year for half of all seasons.
Although tropical activity is lower than in September, another small peak in activity occurs around October 20.

NOVEMBER:

Wind shear from westerlies increases substantially through November, generally preventing cyclone formation. On average, one storm forms during November every other year.

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