During the spring of 1991, the National Severe Storms Laboratory conducted the COPS-91 (Cooperative Oklahoma Profiler Studies-1991) field program in Oklahoma and the Texas Panhandle. Among its goals were (1) an assessment of the recently deployed National Weather Service (NWS) profiler demonstration network in observational studies of mesoscale convective systems (MCSs), (2) documentation of electrification mechanisms in MCSs, and (3) a detailed study of the dryline.On the afternoon of 26 May 1991, a thunderstorm developed along the dryline on the Texas Panhandle-Oklahoma border and began to move to the east. Within a short time, the storm had reached severe proportions and large hail and tornadoes were reported. The NOAA P-3 aircraft made multiple passes on the west and south sides of the supercell thunderstorm during and after tornado touchdown, gathering extensive pseudo-dual Doppler radar data. The thunderstorm passed close to the Vici, Oklahoma, network profiler, which was recording vertical wind profiles every 6 minutes.
This paper examines the P-3 Doppler-derived horizontal winds and compares them with the winds from the profiler at Vici. Also, some of the fine-scale circulations and storm structure observed by the P-3 are discussed in the context of current modeling results and understanding of tornadic supercells. Finally, changes in the pre-storm environmental winds are examined.