S68 Difficulties with Classifying and Analyzing the Low Level Jet in a Convection Allowing Ensemble

Sunday, 7 January 2018
Exhibit Hall 5 (ACC) (Austin, Texas)
Emily N. Tinney, NWC REU, Norman, OK; and J. Correia Jr.

Common in the Great Plains, the low level jet can have important implications for storms and convective systems as it can increase heat, moisture, and vertical wind shear after sunset. Criteria created by William Bonner in 1968 have been used in numerous studies in the past five decades, and are still commonly used today. As convection allowing models become more accurate and more important in forecasting today, the relationship between the LLJ and storms can be analyzed to provide further knowledge into the impacts the LLJ may have on severe weather. This study used data from the NSSL Experimental Warn-on-Forecast System for ensembles for May 16th, 2017 to see if the Bonner criteria would be a suitable classification method for a typical severe weather event in the Great Plains. Results show that for cases with a strong background wind field such as the one examined in this study, the use of Bonner’s criteria prevents a spatially coherent jet from being classified due to a lack of wind shear. Therefore, a different method of classifying the low level jet is required to analyze the low level jet and storms in a convection allowing ensemble.
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