Poster Session P3.6 An investigation of the significant tornado outbreak in southern South Carolina and northern coastal Georgia on March 15, 2008

Monday, 27 October 2008
Madison Ballroom (Hilton DeSoto)
Frank Alsheimer, NOAA/NWSFO, North Charleston, SC; and R. Bright, J. Jelsema, W. Moen, J. Quagliariello, and D. Berry

Handout (2.5 MB)

On March 15, 2008, a significant tornado outbreak occurred across southern South Carolina and portions of north coastal Georgia within the county warning area (CWA) of the National Weather Service (NWS) Forecast Office in Charleston, SC (CHS). During the afternoon, the area was placed under a high risk of severe weather by the National Weather Service's Storm Prediction Center (SPC), and later a Particularly Dangerous Situation (PDS) Tornado Watch was issued. Six EF1 or greater tornadoes occurred in the CHS CWA during that afternoon and evening. This event marked the first such occurrence of as many tornadoes for a non-tropical outbreak since 1984.

This study will describe the state of the atmosphere during 15 March 2008, which led to an unusually large outbreak of tornadoes for this part of the country. The ability of numerical models to handle both the synoptic scale features leading up to the event and the mesoscale features present during the event, which aided in the development of multiple classic supercells and associated tornadoes, will be presented. In addition, the shortcomings of the numerical models in depicting the proper location of the convection, due to errors in the low level mass, wind, and moisture fields, will also be explored.

Further, a full radar investigation will take place emphasizing supercell genesis and maintenance, as well as the transition from a tornado-dominated event to a hail-dominated event. Three-dimensional structures of select supercells will be shown in detail to aid in visualization of the supercell's regime transition.

Lastly, the strengths and cautions of the NWS polygon warning initiative as related to this event will be discussed. This will include warning strategies that proved effective as well as lessons learned in handling an event with multiple supercells and multiple threats over the same location.

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