65 Comparison of Nocturnal Supercells Environments of Hail and Wind to Hail Only Events across the Central and Northern Plains

Monday, 5 November 2012
Symphony III and Foyer (Loews Vanderbilt Hotel)
Joshua M. Boustead, NOAA/NWS, Omaha, NE; and P. N. Schumacher

Environments associated with nocturnal supercells that are not attendant to larger-scale convective complexes will be presented. Nocturnal reports from supercells for parts of the central and northern Plains were gathered from 2008 through 2011. These reports were grouped into two categories: supercell events with severe hail and those that produce severe hail and wind. Rapid Update Cycle model data was obtained and analyzed to assess the convective environment associated with each dataset. Archived Level 2 radar data is used to analyze radar characteristics of the supercells such as rotation velocity, storm-top divergence, and reflectivity structure. It was found that nocturnal supercells that produce both damaging winds and large hail are associated with environments that have stronger mid- and upper-level winds, leading to a stronger effective bulk wind difference. The hail and wind events were associated with a drier sub-cloud layer that may allow for additional evaporation and downward momentum transfer, but also exhibited more moisture aloft than the hail-only supercells. Finally, analysis of a select number of these events will be presented utilizing a high-resolution convection-resolving model to assess to what degree these events can be forecast.
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