1.3 The dependence of high-precipitation supercells on preexisting airmass boundaries: a targeted modeling study

Monday, 17 August 2009: 9:30 AM
The Canyons (Sheraton Salt Lake City Hotel)
Jenni Laflin, NOAA/NWS, Sioux Falls, SD; and A. L. Houston

It is theorized that high-precipitation (HP) supercells are the most commonly observed supercell morphology in the United States; in addition to their abundance, HP supercells pose the threat of flash flooding and large amounts of significantly severe (diameter ≥ 5 cm) hail, both of which are significant hazards to life and property. It is not generally known how and where HP supercells tend to form, due to their sparse appearance in the literature. Since HP supercells may comprise a significant portion of supercells, which are assumed to account for the majority of significantly severe convective weather, it is necessary that a method for recognizing a pattern for the HP morphology is created.

This study examines the influence of preexisting airmass boundaries on HP supercell morphology through a series of idealized simulations. These simulations are based on an HP supercell which formed along an outflow boundary in the panhandle of Texas on 25 May 1999, and involve both homogeneous environments from the warm and cool sides of the boundary, as well as a representation of the actual environment with a boundary present. Detailed analyses of these simulations are then performed to determine the specific influence of the preexisting airmass boundary on supercell formation and morphology. In this presentation, preliminary results, analysis techniques, and future work will be discussed.

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