Session 10.5 How upper-level shear can promote organized convective systems

Wednesday, 6 October 2004: 2:30 PM
Michael C. Coniglio, NOAA/NSSL/University of Oklahoma, Norman, OK; and D. J. Stensrud and L. J. Wicker

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This study examines the role of positive mid-and upper-level vertical wind shear on the lifting of environmental air along cold pools. Observations of strong, linear convective systems within relatively weak low-lever shear and significant mid- and upper-level shear that may not fit past conceptual models of cold pool/shear interactions will be presented. By using a numerical cloud model in a 2D dry, nuetral state, it is found that increasing the shear above the cold pool can promote much deeper lifting than an environment with only weak to moderate low-level shear. As suggested in previous analytical studies, vertical parcel displacements are increased, despite a decrease in vertical velocity along the leading edge of the cold pool. Positive wind shear in the 5-10 km layer can promote deeper lifting by this same mechanism for parcels originating in the 1-2 km layer. Moist 2D and 3D simulations that include ice microphysics also suggest this mechansim can significantly influence the maintenance and structure of convective systems.
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