Session 7A.9 Strong and violent tornado outbreaks: Comparisons in thermodynamic and wind parameters between large hail and non large hail events

Wednesday, 27 June 2007: 4:00 PM
Summit A (The Yarrow Resort Hotel and Conference Center)
Michael P. Seaman, NOAA, Salt Lake City, UT; and R. H. Johns

Presentation PDF (71.1 kB)

Tornado outbreaks involving strong to violent tornadoes almost always include numerous reports of large hail (0.75 inches or greater), often in excess of 2 inches in diameter. Tornadoes which develop during these outbreaks nearly always evolve from parent thunderstorms with associated mesocyclones (supercells). A popular misconception in the past has been that supercell thunderstorms always produce large hail. However, there have been instances, primarily in the southeastern U.S., where strong and violent tornado outbreaks have occurred without producing large hail. Previous work in this area has focused on the frequency and distribution of these “no large hail” events. This study will build on this previous work, and focus on differences in thermodynamic and wind parameters between tornado events in which no large hail was reported (NLH), and tornado events in which large hail did occur (LH). Instability, freezing level, and shear parameters from proximity soundings will all be examined, in order to identify differences between NLH and LH environments. The dataset used covers a 30 year period ending in 2005. Cases associated with tropical systems are not included in the study, except for comparison purposes.
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