Poster Session P9.9 (Formerly poster P15.2) The 12 November 2003 Los Angeles Hailstorm

Wednesday, 6 October 2004
Robert G. Fovell, University of California, Los Angeles, CA

Handout (991.0 kB)

On 12 November 2003, a powerful yet spatially compact hail producing storm formed, and the remained quasi-stationary, over South Central LA, just east of LAX. Precipitation totals exceeding 5 inches, along with hail drifting to 6 feet, were recorded in an area encompassing just a few square kilometers. The daily operational MM5 run at UCLA captured the development and approximate location of this storm, despite rather coarse (6 km) resolution and economical microphysics being employed.

The forcing mechanisms for storm genesis and (lack of) movement are examined using still higher resolution simulations, mainly employing more sophisticated physics. Generally, the model runs suggest that a gust front generated by convection that formed earlier in the day, in the eastern portion of the LA basin, played an important role in triggering the hailstorm. Comparison will be made among runs made using MM5 and COAMPS. These simulations are not always better than the operational MM5 run; indeed, some are much worse.

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