On Friday March 12, 1993 a strong low pressure system developed in the Gulf of Mexico. This low pressure system continued to strengthen dramatically and moved northeastward into the mid Atlantic coastal region by Saturday evening, March 13th. Besides producing a record snowstorm in the eastern United States, this low pressure system produced 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 portion of the west coast of Florida and western Cuba between 11 PM and midnight EST on the evening of the 12th. After creating much damage and many casualties, the storm line passed off the shore of southeastern Florida about 5 AM EST on the morning of the 13th and pulled out of 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 within the squall line produced tornadoes in the northern half of the Florida peninsula with some reaching F2 intensity.

As the derecho producing squall line raced through Florida, 7 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 passing through Florida it was also passing through Cuba. This event resulted in 10 deaths and many injuries in western and central Cuba. Economic losses in Cuba exceed one billion U.S. dollars. More information about this derecho storm system in Cuba can be found in the Figs. 2 and 3 and the associated text below.

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).

Figure 2. Measured wind gusts in mph associated with the March 12-13, 1993 serial derecho as it crossed western and central Cuba. The colored areas on the map indicate where the wind gusts ranged from 65 to 75 mph (green), 75-100 mph (light red) and 100 mph or greater (dark red). (Modified from Alfonso and Naranjo 1996)

As the derecho producing squall line crossed Cuba and adjacent waters during the morning hours of March 13th, there were two bands of very intense wind gusts (Fig. 2) associated with bow echoes embedded within the squall line. The eastern band extended from east of the Isle of Pines across central Cuba. The western band extended from the western tip of Cuba along the north coast and through the Havana area. Gusts over 100 mph were measured in the Havana area and a survey conducted by a research team from the Institute of Meteorology of Cuba suggests that the maximum wind speeds may have reached 130 mph. Figure 3 (below) shows the bow echo associated with the western band of intense winds as it was approaching Havana.

Figure 3. Reflectivity image (green) of the derecho producing squall line and associated bow echo recorded by the Havana radar at 2:59 AM EST on March 13, 1993. The bow echo was approaching Havana and winds above 100 mph were occurring. The red arrow is pointed towards what might be an embedded supercell which is adding to the strength of the bow echo winds. (From Alfonso and Naranjo 1996)

(References....Alfonso and Naranjo 1996; Storm Data for March 1993)

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