Case study of an unforecasted mini-supercell with a high-top in Colorado

On 22 June 1995, a supercell thunderstorm developed on the Palmer Divide in east central Colorado and became tornadic. What makes this event somewhat unique is the precedent conditions were not synoptically evident for severe convection. In addition, the supercell was miniature in horizontal scale but was average in depth (a "mini high-topped" supercell). This paper will not attempt to "compartmentalize" supercell size/depth, but is designed to document that a variety of sizes exist in nature.

This poster will make an attempt to explain why convection initiated on this date. Synoptic data will be reconstructed to observe why convection developed and became severe. Preliminary data analysis indicates the KPUX VAD wind profile data at the around the time of tornadogenesis (21:40 UTC) did not favor supercell formation. The VAD profile at this time in the lowest 1.6 km showed steady east-southeast winds of 10 knots or less, then gradually shifting to the southwest reaching 25 knots at 5 km above radar level. Even though the tornadic storm was only ~60 Km from the radar, it is likely the wind fields were stronger throughout the column in the vicinity of the storm. In addition, a straight line hodograph was likely within the storms environment as a "storm split" was identified in the radar reflectivity data an hour prior to tornadogenesis. It is of interest to note that the left turning member (which did not produce a tornado) did show an anti-mesocyclone with moderate intensity at times. In addition, there is evidence in the radar data that boundaries along with topography may have played a role in supercell morphology.