Session 2.5 An examination of severe thunderstorm discrimination skills from traditional Doppler radar parameters and near storm environment (NSE) factors at large radar range

Monday, 4 October 2004: 2:30 PM
William E. Togstad, NOAA/NWS, Chanhassen, MN; and S. J. Taylor and J. L. Peters

Presentation PDF (1.1 MB)

We explore the utility of traditional Doppler radar parameters such as VIL (vertically integrated liquid) and (STD) storm top divergence when used alone or in combination with near storm environment (NSE) factors such as 0-3 km VGP (vorticity generation potential), CIN (convective inhibition), 0-1 km vertical wind shear and the lifted condensation level (LCL) in discrimination of severe storm type at range distances in excess of 80 km. For purposes of this study, storm type is broken down into two categories; the storm is either a tornado of F2 strength or greater or the storm is some other severe weather report such as large hail, damaging straight line surface winds or a combination of the two. Tornadoes of F0 or F1 strength are not considered in this study.

The data sample we drew on included a minimal F4 tornado at Granite Falls Minnesota on 25 July 2000, the F2 tornado at Glenville, Minnesota on 01 May 2001 and the F3 tornado at Ladysmith, Wisconsin on 02 September, 2002. The major research goal for this study is to determine if a useful discrimination function can be derived for severe thunderstorms at larger distances from Doppler radar sites. The discrimination function to be derived will be based on multiple linear regression of radar and NSE parameters. With the three above mentioned tornado cases serving as dependent data sample, we will attempt to discriminate severe storm type for the Agency, Iowa tornado case of 11 April 2001.

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