HURRICANE CENTRAL - Hurricane season starts June 1st and ends November 30th, with things really heating up late summer.
There are three main reasons why tropical activity is greater in the summer months. First, the ocean get warmer. Second, we see an increase in tropical moisture. Third, the wind in the upper atmosphere weakens, which is referred to as low wind shear.
In the month of June, we generally see little activity, with an average of about one tropical system every two years. Tropical systems usually form in the Gulf of Mexico or off the east coast of the United States.
Not much tropical activity occurs during the month of July. Most hurricane seasons see the formation of one tropical system during July. Formation usually occurs in the eastern Caribbean Sea around the Lesser Antilles, in the Gulf of Mexico, near the Bahamas, and off the coast of the Carolinas in the Atlantic.
A decrease in wind shear from July to August leads to a significant increase in tropical activity. An average of three tropical storms develop annually in August. By the end of the month, four named systems and one hurricane typically form. Tropical activity develops in the Gulf of Mexico, off the East Coast, in the Caribbean Sea and now we see activity out in the central Atlantic Ocean.
The peak of hurricane season occurs in September and corresponds to the lowest wind shear and the warmest ocean temperatures. By the end of September, an average of seven named storms have formed, including four hurricanes and two major hurricanes. Activity occurs from the Gulf of Mexico, off the East Coast, in the Caribbean Sea, and the Atlantic Ocean.
The favorable conditions found during September begin to decay in October. The main reason for the decrease in activity is increasing wind shear, and ocean temperatures are cooler. The areas for tropical formation shift westward to the Caribbean Sea, the Gulf of Mexico, and off the East Coast.
Wind shear from the westerly wind increases through November, generally preventing storm formation. Some activity occurs in the Atlantic north of the Bahamas.
Hurricane season ends November 30th. It's rare that we see any tropical activity in the month of December, but in 2005, which was a record year of 28 named storms, we had a tropical storm which formed December 30th and dissipated on January 6th.