8A.6 The morphology of Multiple Simulated Supercells: Sensitivity experiments to timing and spacing of cell initiation and microphysics

Wednesday, 6 October 2004: 9:15 AM
Lee M. Cronce, University of Illinois, Urbana, IL; and R. B. Wilhelmson

Outbreaks of significant severe weather are often associated with organized lines of supercell thunderstorms. As such, gaining a further understanding of the characteristics and morphology of these lines would greatly benefit forecasters. Observations of supercell thunderstorm lines often show variable thunderstorm initiation times as well as variable spacing between cells, yet few studies have examined this. Subsequently, the importance of this temporal and spatial variability to ensuing threat and type of severe weather is still not well established. Further, previous numerical investigations have shown that the addition of ice phase to microphysics affects storm cold pools. However, among numerical studies of lines of supercell storms within the literature, the role of microphysical sensitivity to line behavior has not been determined. This project aims to address some of these key uncertainties.

We will conduct numerical simulations of lines of discrete cells using a homogeneous environment favorable for the development of supercell thunderstorms. Unlike previous studies, here we initialize cells using variable thermal bubble spacing and timing. In addition, simulations with higher order microphysics will be compared with simple warm rain cases demonstrated in prior studies of these phenomena. The impact of sequential storm development, storm separation, and ice microphysics on the morphology of a supercell line will be investigated. Further, the sensitivity to horizontal grid spacing will be shown. Preliminary results from this project will be presented at the conference, concentrating on the effect of microphysical schemes on morphology of the supercell line.

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