The Role of Low-Level Convergence and Latent Heating in a Simulation of Observed Squall Line Formation

Abstract

Abstract The effects of mesoscale forcing and diabatic heating on the development of convective systems have been investigated using a simplified numerical model to simulate the squall line and the convective system preceding it that occurred over Texas and Oklahoma on 10– 11 April 1979. A simulation run without including latent but showed both systems to be initiated and maintained by convergence produced by larger-scale forcing. The first cloud system formed downwind of the convergence zone that was produced by the confluence of airstreams along a dryline. A cloud front approaching from the west then merged with this dryline, destroying its horizontal gradients through diffusive effects and replacing it with a frontal convergence line that was alinged with the low-level flow. This new configuration was then favorable for the formation of the squall line that developed in the simulation. When latent heat was included the continuous cloud in the first convective system broke down into isolated cells which...