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Tropical Storm Isaias - August 1-2, 2020


Tropical Storm Isaias formed in the eastern Caribbean Sea on Wednesday evening, July 29th, and moved NW across Hispaniola on Thursday, July 30th. Isaias continued on a NW track and became a hurricane at Midnight on July 31st near Great Inagua Island, then moved over Andros Island on Saturday, August 1st when it was then downgraded to a Tropical Storm with maximum sustained winds of 70 mph. TS Isaias then made a gradual turn to the N-NW as the center passed about 30-40 miles east of the Palm Beach County coast (its closest approach to the SE Florida coast) on Sunday, August 2nd.

Isaias did not regain hurricane strength as it passed just east of the SE Florida coast for what appeared to be two main reasons: 1) strong W upper level winds which caused the thunderstorms near the center of the storm to be sheared off to the east and not around the surface circulation, and 2) relative dry tropospheric air over Florida to the west of the storm. This caused Isaias to have a highly asymmetrical structure with the strongest winds and heaviest rainfall well to the east over the Bahamas, with limited extent of tropical storm force winds and rainfall on the west side. Isaias eventually regained hurricane strength just before landfall near Wilmington, NC on August 3rd, then continued NE over the U.S. eastern seaboard as a fast-moving tropical storm. 

                                                         Track image courtesy of Hurrevac