The Rapid Weakening of Hurricane Fred (2009)

Date of Award

Spring 5-2020

Document Type

Honors Thesis

Degree Name

Bachelor of Science


Atmospheric and Environmental Sciences

Advisor/Committee Chair

Kristen Corbosiero, Ph.D.


This research project discusses the rapid weakening of Hurricane Fred, a major Category 3 hurricane that occurred in the Atlantic basin during the 2009 Atlantic hurricane season. Between the days of 9 September and 13 September, Fred remained stationary off the coast of Africa in the Atlantic Ocean and never made landfall, all the while consistently weakening over open ocean from a major Category 3 hurricane to a tropical storm. In the Atlantic basin, I will define the rapid weakening, or RW, of a tropical cyclone as a decrease in the storm’s maximum sustained winds by 10.3 m s⁻¹ in a continuous 24-hour period. In the continuous 24-hour period between 0600 UTC 11 September and 0600 UTC 12 September, Hurricane Fred weakened most significantly from a Category 1 hurricane to a tropical storm, and its maximum sustained winds decreased by 17.9 m s⁻¹. This decrease in tropical cyclone intensity clearly meets and exceeds the threshold requirements for a tropical cyclone that underwent rapid weakening. Multiple environmentally driven factors were analyzed within this case study in order to observe these changes in tropical cyclone intensity, and to aid in determining the major causes leading up to and inducing the rapid weakening of Hurricane Fred.

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