Colloquium, October 28, 2008, 3:00 pm, EN6085A

On May 22, 2008, a slow moving, meridional trough led to widespread severe weather across the Great Plains, Front Range of Colorado and Laramie Ridge/Mountains of Wyoming. The most damaging storm developed near the Denver International Airport and quickly became tornadic. A large tornado occurred with this storm in Weld county Colorado that was responsible for EF3 damage in the town of Windsor, CO.  After some weakening, the storm intensified and produced tornado(es) and large hail from the Wyoming-Colorado border to Laramie, WY.  The elevation in this region varies from 7500 to 8700 ft., which makes this event particularly interesting and rare.  Relatively high potential temperatures resulted in moderate surface-based CAPE despite modest mixing ratios (compared to the low plains). The presence of potentially “warm” air on the high terrain of Wyoming, despite the low clouds, “cold” surface temperatures and dense fog, will be explained in detail. The key synoptic scale features, as well as shear and instability parameters, are presented, with an emphasis on observational data.  There is a need for documenting this case in detail due to the low frequency of high-end severe weather events in this region.