Preliminary analysis of a severe winter storm in central Oklahoma using data from the CASA, dual-polarization, Doppler-radar network

From 29 - 30 Nov. 2006, a severe winter storm struck central Oklahoma. Mesoscale bands of ice pellets with thunder and lightning were observed during the evening of 29 Nov. During the afternoon of 30 Nov., heavy snow fell within the” wrap-around” region of the mesoscale precipitation area associated with a deep synoptic-scale cyclone and upper-level trough. Both distinctly different winter weather events were sampled by two or more of the dual-polarization, X-band, CASA (Center for Collaborative Adaptive Sensing of the Atmosphere) radars in its mesoscale network.

The following scientific questions are addressed on the basis of single and dual-Doppler analysis of the CASA data and of data from nearby WSR-88D radars, the Oklahoma Mesonet, the Doppler wind profiler network in the central U. S., and the operational sounding network: 1. What were the airflow kinematics in the thunder – ice pellet storms? Were there individual cells? Were there bands? To what extent were the motions 2D? 3D? 2. What were/was the nature of the dynamics of the thunder – ice pellet storms? Was there upright convection? Was there slantwise convection? Were there ducted gravity waves? Was there frontal lift? Was there lift over a cold pool? 3. Were the dual-pol data able to identify hydrometeors as ice pellets? Snow? Rain? 4. What were the airflow kinematics in the wrap-around snow band? 5. What was the nature of the dynamics in the wrap-around snow area?

Although the CASA radars were set up in central Oklahoma primarily for improving tornado warnings in severe convective storms during the warm season, it is shown here how they can also be used also for research of dynamical and microphysical processes in severe winter storms