Interactions Between Mesoscale Convective systems, Cold Pools, and the Low Level Jet on 23-24 May 2011 over the Southern Great Plain Region

This study investigates the complicated interactions among mesoscale convective systems (MCS), cold pools (CP), and the low level jet (LLJ) for a case on 23-24 May, 2011 over the Southern Great Plain Region using the mesoscale community Weather Research and Forecasting (WRF) model. It is found that the numerical simulations of each of these components are sensitive to the microphysics, planetary boundary layer, and land surface parameterizations as well as the grid spacing, initial time, and initial conditions of the model.

During the study period, significant severe weather occurred first along the dry line in central Oklahoma, and later in the form of back building super cells over northeastern Oklahoma and a forward propagating band into Arkansas. This sequence of mesoscale convective events, including the timing, intensity, and location was highly sensitive to the strength and timing of the initial dry line convection, the convection over northeast Oklahoma, as well as the respective CPs associated with each event.

The LLJ modified the MCS and CP it interacted with, but its strength, position, and orientation were also affected by the MCS and CP. Specifically, the LLJ strengthens the MCS through the transport of warm and moist air and convergence, after which the stronger MCS dynamically strengthens the LLJ through latent heat release and lowering pressure. This feedback allowed for a divergence in the simulations based primarily on their strength of the initial dry line convection and associated CP. Only simulations which accurately depicted the dry line convection could capture the back-building convection, which developed several hours later. Details will be presented in the conference.