JP5J.13 WRF Simulations of a Severe Squall Line: Comparisons against High Resolution BAMEX Observations

Tuesday, 25 October 2005
Alvarado F and Atria (Hotel Albuquerque at Old Town)
Bryan A. Guarente, Univ. of Illlinois, Urbana, IL; and B. F. Jewett, G. McFarquhar, and R. M. Rauber

Latent cooling plays an essential role in forcing the rear inflow jet that frequently occurs behind a squall line, yet the specific contributions of sublimation, melting, and evaporation to this process at various stages of MCS development are not fully known. A severe squall line sampled during the Bow Echo and Mesoscale Convective Vortex Experiment (BAMEX) is simulated using the Weather Research and Forecasting model using high resolution (1 km) on the innermost grid. Simulations are compared against high-resolution radar and in-situ microphysics observations acquired during BAMEX to quantify the ability of WRF to adequately predict the liquid and ice mass contents that critically impact predictions of latent cooling. Sensitivity experiments are carried out to quantify the effects of evaporation, melting, and sublimation to latent cooling and hence to the structure and intensity of the rear inflow jet. Additional tests are performed by changing the amount of latent cooling (0%, 50%, 200%) in our control experiment at certain stages of the evolution (initial growth, pre-bow, mature bow with trailing stratiform precipitation, and decay) to quantify how latent cooling impacts the structure and dynamics of the MCS.
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