Symposium on the Challenges of Severe Convective Storms


Analysis of a hook echo and rear flank downdraft from a simulated supercell on 8 May 2003

Lewis Grasso, Cooperative Institute for Research in the Atmosphere, Fort Collins, CO; and D. T. Lindsey

First efforts to simulate thunderstorms used an idealized framework with horizontal domains about 100 km on a side and horizontal grid spacings of 1 to 2 km. Further, the initial domain was horizontally homogeneous. A warm bubble was then used to trigger a single storm for study. Today, computer capabilities allow for more detailed simulations. We have initialized the CSU-RAMS model with observations from 8 May 2003. With multiple, non-moving nested grids, a right-moving storm was captured within the fourth grid. This grid was about 400 km on a side and had horizontal grid spacing of 400 m. With relatively small horizontal grid spacings, we have an opportunity to study the evolution of a hook echo that developed. This can help our understanding of the role of storm rotation and falling hydrometeors in the development of the hook appendage. Further, the development of both a warm rear flank downdraft and other warm regions within the downdraft can be examined. Even though 400 m is too large to resolve a tornado, closed surface rotation exists in the expected position for tornado development. We will show the evolution of the hook echo, warm rear flank downdraft, and surface rotation of this storm. In addition, a synthetic polar orbiting satellite image at 11.02 microns of the storms in grid 4 will be shown.

extended abstract  Extended Abstract (1.8M)

Poster Session 1, The Observation, Modeling, Theory, and Prediction of Severe Convective Storms and Their Attendant Hazards
Wednesday, 1 February 2006, 2:30 PM-4:00 PM, Exhibit Hall A2

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