Session 4.2 Cool season significant (F2-F5) tornadoes in the Gulf Coast states

Tuesday, 7 November 2006: 8:45 AM
St. Louis AB (Adam's Mark Hotel)
Jared L. Guyer, NOAA/NWS, Norman, OK; and A. K. Kis, K. N. Venable, and D. A. Imy

Presentation PDF (656.1 kB)

Significant tornado (F2 and greater) cases were examined from 20 cool seasons across a geographic area including far eastern Texas, southern Arkansas, Louisiana, Mississippi, Alabama, Georgia, and northern Florida. These cases included 100 significant tornado event days between October 15-February 15 from 1984-1985 to 2003-2004. For each tornado event, analysis sources included observed surface data, North American Regional Reanalysis (NARR), as well as observed upper air observations and sounding data.

While strong ambient wind fields/vertical shear are relatively common during the cool season, the occurrence of significant tornadoes in the Gulf Coast states appears to be highly sensitive to boundary layer moisture (surface dewpoints 60-65°F or higher in nearly all cases) and relatively subtle changes in available buoyancy. This study will further incorporate composite synoptic patterns, sounding/thermodynamic analysis, and examination of convective mode in an effort to help improve operational forecasting of significant cool season tornadoes in the Gulf Coast states. Student participation was funded by the NOAA Hollings Scholarship program and 2005 Research Experiences for Undergraduates (REU).

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