1998 Kissimmee Tornado Outbreak - Storm Overview

Storm Overview

During the night of February 22 and the very early parts of February 23, some very unusual weather formed over central Florida. Three supercell thunderstorms produced seven tornadoes between about 11 pm on Feb. 22nd and 2:30 am on Feb. 23rd. As these storms swept through Central Florida, the tornadoes killed 42 people and seriously injured more than 260 other. This was the deadliest tornado related storm in Florida’s history after the storm that occurred on March 31, 1962, in Santa Rosa County, FL. These tornadoes were unusually strong due to the atmospheric conditions over central Florida. Weather was strangely warm, humid, and the jet stream was blowing unusually hard (140 knots), because of the combined effects of El Nino. A tornado from the northern supercell touched town in Sumter County, FL just before 10 pm. This tornado was an F2 (based on the Fujita Tornado Intensity Scale), had winds between 113-157 mph and killed one, injured 3, and damaged/destroyed about 600 structures. As the storm moved southwest, a larger stronger F3 tornado with winds between 158-206 mph touched down in Volusia County, FL near Daytona Beach about 55 minutes later. The central supercell produced three more tornadoes. The first hit Orange County, FL at 11:37 pm, severely hitting Winter Garden and Ocoee and was rated at an F3 (winds between 158-206 mph). This tornado was approximately 18 miles long, produced 3 fatalities, 70 injuries, and damaged/destroyed 500 structures. The next tornado formed in Seminole County, FL at 12:10 am and was also an F3 with winds between 158-206 mph. This tornado traveled for about 14 miles killing 13, injuring 36, and damaging/destroying 625 structures. The last tornado from the central supercell hit Volusia County, FL at about 12:45 am. This tornado was an F2 (winds between 113-157 mph), and had no casualties reported. The southern supercell produced the final three tornadoes. The first was an F3 with winds between 158-206 mph and touched down at 12:40 am in northwest Osceola County, FL. This tornado was on the ground the longest; it tracked northeastward for about 38 miles. At 12:50 am the tornado went straight through the Ponderosa RV Park, killing 12. Overall this tornado killed 25, injured 150, and damaged/destroyed more than 1,000 structures. The next tornado from this supercell was produced at 1:38 am; it was a smaller F1 with winds between 73-112 mph. This tornado had no reported deaths, but damaged/destroyed 100 structures. The final tornado was produced around 2:30 am in Brevard County, FL. This tornado was also a smaller F1; it had no reported deaths, and damaged/destroyed only 30 structures.

The tornadoes were strong due to an abnormally strong jet stream with warm, humid air out ahead of the cold front. This is common in the El Niño phase of the El Niño-Southern Oscillation (ENSO) during the Florida dry season (November 1 - April 30). During EL Nino the jet stream is typically stronger and further south near or over Florida in the winter and spring. This greatly increases the odds that conditions will be favorable for strong tornado development. The controversy surrounding this outbreak resulted from attempts to try to correlate specific tornadoes with El Nino. There are a number of reasons why a tornado may or may not occur, or be reported, that have nothing to do with Pacific SSTs. A better approach is to focus on the development of atmospheric conditions that might produce tornadoes and severe weather. A novel approach to enhancing El Nino preparedness in Florida is to concentrate on "storminess" or the increase in extratropical cyclones affecting Florida that might spawn severe weather in El Nino dry seasons. An experimental forecast of Florida storminess based on Pacific SST's has been developed. Studies that look at yearly tornado reports and Pacific SST's show no relationship between El Niño and United States tornado activity and a weak relationship for Florida.