8A.8 The role of cell interaction on storm intensity and longevity

Wednesday, 6 October 2004: 9:30 AM
Brian F. Jewett, Univ. of Illinois, Urbana, IL; and R. B. Wilhelmson

Thunderstorms rarely form or evolve in isolation. Frequently, they form in response to mesoscale forcing which gives rise to a number of cells, whether a cluster or line. As a result, storms often are subject to the influence of nearby cells.

Our prior numerical modeling study with WRF investigated the interaction between a pair of cells, forming simultaneously in close proximity to one another. In the majority of cases, subsequent updraft intensity, near-surface rotation and storm longevity was reduced when two cells were present. Only a small fraction of the parameter space - here restricted to spatial orientation and distance between the initial storms - resulted in stronger cells, and small differences in initial conditions sometimes led to significant differences in morphology. The parameter space defining storm behavior is not smooth.

Our continuing modeling work will extend prior efforts, particularly in the realm of differences in storm timing. While observational evidence has demonstrated that storm merging can prompt tornadogenesis, the different properties - rotation, updraft intensity, cell age and propagation - between two merging cells can be important. This work is exploring and understanding the interaction of such disparate storms and the resulting behavior, contrasted with their evolution in isolation.

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