1983 Atlantic Hurricane Season - Seasonal Forecasts and Activity

Seasonal Forecasts and Activity

Forecasts of hurricane activity are issued before each hurricane season by noted hurricane experts like Dr. William M. Gray, and his associates at Colorado State University. A normal season, as defined by NOAA, has six to fourteen named storms, with four to eight of those reaching hurricane strength, and one to three major hurricanes. The July 23, 1983 forecast predicted that after the slow start to the season, that a total of eight storms would form, and five of the storms would reach hurricane status. The forecast did not specify how many of the hurricanes would reach major hurricane status. However, the predictions proved to be too high, with only four named storms forming by the end of the season and three of those reaching hurricane status.

The season, which began on June 1 and ended on November 30, was very inactive because of strong upper-level wind shear. The wind shear was unusually strong throughout the Caribbean and open Atlantic, and disrupted convection in areas of disturbed weather so they could not develop. Over sixty African systems had formed and made it westward, but when they reached the Lesser Antilles, they were dissolved easily. The only area where the shear was minimal—a region encompassing the Gulf of Mexico and the Atlantic north of the Bahamas and east of Florida—was where the four named storms developed. This makes the 1983 season the least active season since the 1930 Atlantic hurricane season which had only two storms. 1983 and the prior season became the first example of two consecutive years to have no storms form in the Caribbean Sea since 1871, when reliable record began. 1983 also proved to be the first season since 1871 that a storm did not form south of 25°N latitude.

1983 was the first season for which the National Hurricane Center issued numeric landfall probabilities. Probabilities had been calculated for prior storms for use in the issuing of hurricane watches and warnings, but this was the first time the raw numeric probabilities were released to the public. The probabilities issued were accurate during Alicia, indicating that Galveston and surrounding portions of the upper Texas coast were the most likely area to be struck.

The season's activity was reflected with a low cumulative accumulated cyclone energy (ACE) rating of 17, which is classified as "below normal". ACE is, broadly speaking, a measure of the power of the hurricane multiplied by the length of time it existed, so storms that last a long time, as well as particularly strong hurricanes, have high ACEs. ACE is only calculated for full advisories on tropical systems at or exceeding 34 knots (39 mph, 63 km/h) or tropical storm strength. Subtropical cyclones are excluded from the total.