Tropical Storm Fred - August 10-19, 2021
A series of tropicals moved off the coast of Africa on July 29th, 31st, and
August 2nd. A broad surface low formed on the 3rd
across the eastern and central tropical Atlantic. It moved westward without
further definition. By the 7th, a cluster of storms
formed about 1000 miles east of the Windward Islands. Organization increased
while the system picked up the pace to the west-
northwest. Its center crossed between Dominica and Martinique on the 10th with
what appeared to be a well-defined circulation,
but its surface wind circulation was not closed. By that evening, the system
was producing tropical storm-force winds and a
well-defined center finally emerged. Fred formed just to the south-southeast
of Ponce, Puerto Rico. It moved west-northwest
and made landfall in the Dominican Republic on the 11th, exiting the north coast
of Haiti early on the 12th. Its circulation was
disrupted and reconnaisance found a well-defined surface circulation between
the southeast Bahamas and Cuba, even while thunderstorm
activity, though disorganized, focused more across the northwest Caribbean sea.
Late on the 12th, Fred regained tropical storm strength
just east of Cuba. Strong westerly shear exposed the circulation center again
before it made landfall on Cayo Romano, Cuba on the
morning of the 13th as a tropical depression. Microwave imagery and surface
observations indicated that the Fred's low which
entered southeast Cuba slipped back into the northwest Caribbean, with westerly
wind shear displacing convection off to its east.
The system slowly organized as it moved into the Yucatan Channel late on the 14th.
Fred turned north-northwest, and winds increased
to tropical storm force across the Keys. Fred was redesignated a tropical storm
on the morning of the 15th west of Naples. Wind
shear became more southwest and Fred continued to strengthen while recurving on
the 15th and 16th. Fred made landfall just northwest
of Cape San Blas on the afternoon of the 16th. By the morning of the 17th, Fred
regained tropical depression status over Alabama.
Accelerating north-northeast, Fred lost its well defined center and deep convection
that evening over eastern Tennessee. Its center
moved up the Appalachians and became post-tropical across central Pennsylvania
on the evening of the 18th. Turning east-northeast,
Fred moved offshore southern New England on the morning of the 20th.
The graphics below show the storm total rainfall for Fred, which used
rain gage information from the National Weather
Service River Forecast Centers, Forecast Offices, and CoCoRAHS.