IMPACTS: Weather 2007

2.5

The 2007 U.S. Tornado Season: Large Outbreaks Scattered Throughout the Year, Most Fatalities in Eight Years

Joseph T. Schaefer, NOAA/NWS/NCEP/SPC, Norman, OK; and G. W. Carbin

Several notable tornado outbreaks occurred during the late winter and early spring of 2007. For instance, in the early morning hours of February 2nd two F3 tornadoes killed 21 people in central Florida. Illustrating that tornadoes do not differentiate among species, 18 endangered whooping cranes (25 percent of a semi-captive breeding program) were also killed when one of the tornadoes struck near Crystal River. This event highlights the warning and public response challenges associated with nocturnal tornadoes. A month later, on March 1st, a widespread outbreak of at least 49 confirmed tornadoes struck the Southeast. Twenty fatalities, including nine students who were killed at the high school in Enterprise, Alabama, occurred during this outbreak. In addition, damage on March 1st topped $580 million, making this the 4th costliest tornado outbreak behind the May 1999 Oklahoma City outbreak, the East St. Louis/St Louis Tornado of 1896, and the Tri-State Tornado of 1925. On May 4th, the most violent tornado of the year occurred at Greensburg, KS resulting in 10 deaths. This was the first tornado to be rated as a 5 since 1999.

After the early May activity, the weather pattern across the country changed markedly and more widespread tornado events were generally suppressed going into and through the summer months (including the latter part of the climatological tornado season). The dearth of tornado events ended in mid-October when possibly the largest tornado outbreak on record for the month occurred from the 17th-19th. A preliminary count of 87 tornadoes occurred over a large portion of the central U.S., from southwestern Missouri to middle Tennessee, and from central Mississippi through Lower Michigan. These storms came from two simultaneously occurring, but geographically separated synoptic systems. A low pressure system in the Gulf of Mexico was the primary cause of storms that produced at least six tornadoes in the coastal regions of Texas, Louisiana, Mississippi and the Florida Panhandle. Another 81 tornadoes occurred from southwestern Missouri to middle Tennessee, and from central Mississippi through Lower Michigan, in association with a classic frontal system that developed under an upper level trough from the Central Plains through the Great Lakes. These tornados occurred in two distinct groups. The earlier ones were spawned by isolated supercells that developed in the warm sector, while a second round of storms developed as the dry line/front surged east late in the day on the 18th. Because of the complexity of this situation, several service issues arose. The meteorology, impacts, and implications of these and other tornado outbreaks that occurred during 2007 will be explored during this presentation.

wrf recording  Recorded presentation

Session 2, High Impact 2007 US Weather
Tuesday, 22 January 2008, 3:30 PM-5:00 PM, R08-R09

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