A Composite Climatological Study of the Frequency and Distribution of Severe Weather Associated with Spring Season Colorado Cyclogenesis.
AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH
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A composite approach is used to investigate the evolution and distribution of severe weather events for 39 cases of spring season Colorado cyclogenesis. The study also examined the incidence of severe weather during a jet streak subsample of 15 cases, based on the presence of a 300 mb wind maximum over the New Mexico-Texas area on the day of cyclogenesis, and a complement subsample of the cyclogenetic cases not included in the jet streak subsample. Composites were constructed of the normalized frequency of 1 tornadoes, 2 high winds,3 large hail, 4 funnel clouds and 5 total severe weather events for the total sample of 39 cases and the two subsamples for three 24 hour intervals with the first interval coinciding with the day of cyclogenesis. Distribution and frequency of severe weather for the three days was consistent with the mean synoptic features as the composite cyclone developed and moved away from its lee side development site in the southern Rockies. The area where severe weather occurred significantly broadened and moved northeastward on the two days following cyclogenesis. For each of the three samples, the maximum frequency of total severe storm events was highest on the day after cyclogenesis. Theses