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Hurricane season's peak: Why we see more active Atlantic now

8 weeks of the 6-month Atlantic season are more active

The number of tropical storm and hurricane days for the Atlantic Basin (the Atlantic Ocean, the Caribbean Sea, and the Gulf of Mexico) jumps markedly by mid-August  (NOAA)
The number of tropical storm and hurricane days for the Atlantic Basin (the Atlantic Ocean, the Caribbean Sea, and the Gulf of Mexico) jumps markedly by mid-August (NOAA)

JACKSONVILLE, Fla. – Hurricane season for the Atlantic Ocean begins on June 1st and ends on November 30th, but 8 weeks in particular are the peak for tropical activity.  

According to the NOAA, 78% of the tropical storm days, 87% of the category one and category two hurricane days, and an impressive 96% of the category 3, 4, and 5 days occur in the time period from mid-August to mid-October.   

Statistically, the highest number of tropical depressions and tropical storms within a week in the Atlantic Ocean falls on the second week of September.  

The statistical peak day of the hurricane season, the day you are most likely to find a tropical cyclone in the Atlantic Ocean

NOAA explains why this time period is so much more active despite the fact that tropical waves (where most hurricanes get their start) roll off of the coastline of Africa, on average, every three days throughout the entire six month hurricane season.

The difference lies in the environment that these tropical waves enter after leaving the coastline of Africa, and involves wind factors, temperature, and moisture factors. 

NOAA explains that in May, wind shear (which tears tropical disturbances apart before they can intensify,) is strong, and slowly weakens and fades throughout June and July.

Wind shear reaches its minimum in mid-August. Low wind shear coupled with warmer air temperatures and warmer seas surface temperatures and an increase in atmospheric moisture makes for a more ideal environment for tropical waves to become better organized and intensify.  

With all three factors in sync, which they often are during the peak of the season (mid-August- late-October) the tropical waves sweeping into the Atlantic can easily become organized and intensify into a Tropical Depression or a Tropical Storm. 

According to NOAA, wind shear builds across the Atlantic basin due to strong upper level winds by mid-October, which limits the potential for tropical waves to intensify.

Also this time of the year, air temperatures and sea surface temperatures also start to fall, inhibiting the potential for tropical development as well.

The cooler seas surface temperatures also limit areas of the ocean where tropical formation is possible. 


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