S231 Mid-South Tornado Pattern Classification, Synoptic Scale

Sunday, 6 January 2019
Hall 4 (Phoenix Convention Center - West and North Buildings)
Anna Wanless, NOAA, Silver Spring, MD

The Mid-South region, which consists of west Tennessee, northeast Arkansas, north Mississippi, and the Missouri bootheel, is one of many areas in the United States that frequently faces the threats to life and property posed by tornadoes. Forecasting the occurrence of tornadoes is arguably the biggest challenge for meteorologists responsible for the region. This study analyzes synoptic scale weather conditions associated with tornadoes in the Mid-South with the hopes of identifying patterns conducive to tornadic activity and that these patterns can be used to better forecast potential tornado days. It was hypothesized that patterns associated with tornado formation would be identified and that certain patterns would be more favorable to stronger tornadoes or tornado outbreaks than others.

To find these patterns, surface and upper air features were analyzed on days where multiple tornadoes occurred from January 1999 to March 2018. Specifically, the surface low pressure, 500mb trough, and 850 and 300mb jets were analyzed. Using a floating nine point grid system, the location of the Mid-South in relation to the feature was identified. In the end, eight patterns of similar grid locations were identified to be related to tornado days. For example, the Mid-South was frequently to the southeast of the surface low. Yet, there did not seem to be any correlation between the patterns and the number or intensity of tornadoes. It is recommended that in the future these patterns be tested as a forecast method and/or compared to non-tornado days to verify that they are valid tools.

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