On
Friday, March 12, 1993, a strong low pressure system formed in
the Gulf of Mexico. This low pressure system continued to strengthen
dramatically and moved northeast to the mid Atlantic coastal
region by Saturday evening, March 13th. Besides producing a record
snowstorm over the eastern United States, this low pressure system
was accompanied by an intense squall line with embedded bow echoes
ahead of the system's cold front. The squall line produced a serial
derecho as it swept across the Florida peninsula, Cuba, and adjacent
waters. The squall line reached the northern part of Florida's west
coast and western Cuba between 11 PM and midnight EST on the
evening of the 12th. After causing much damage and producing many
casualties, the storm line moved off the southeastern coast of
Florida around 5 AM EST on the 13th, and departed central Cuba
after sunrise.
As
is shown in Figure 1, much wind damage occurred across Florida,
with measured wind gusts reaching a maximum of 96 mph in the Tampa
Bay area. Supercells embedded in the squall line produced
tornadoes over the northern half of the Florida peninsula, with some
reaching F2 intensity.
As
the derecho-producing squall line raced through Florida, seven people
were killed and 79 were injured from the strong derecho winds
and embedded tornadoes. The storm system winds blew down many
trees, power poles, and power lines, tore roofs off homes, severely
damaged mobile homes, and overturned large trucks.
As the derecho
was moving through Florida, it also was passing through Cuba.
The event caused ten deaths and many injuries in western
and central Cuba. Economic losses in Cuba exceeded one billion U.S.
dollars. More about the derecho in Cuba may be found in Figs. 2 and 3
and the associated text below.
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Figure
1. Severe weather reports in Georgia and Florida (south of blue
shaded line) associated with the derecho of March 12-13, 1993.
Measured gusts in mph are plotted (blue numbers); "+"
symbols indicate the locations of wind damage or estimated wind
gusts above severe limits (58 mph or greater). Red dots and paths
indicate tornado events. Small red numbers indicate tornado intensities
in F-scale. The approximate location of the squall line "gust
front" is shown in two-hour increments (curved purple lines).
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