977 Efficient Tornado-Producing QLCS Events: Challenges and Best Practices for Damage Surveys

Tuesday, 14 January 2020
Hall B (Boston Convention and Exhibition Center)
Thomas Winesett, NWS, Jackson, MS; and D. Lamb and C. Entremont

Quasi-Linear Convective Systems (QLCS) frequently occur across the National Weather Service (NWS) Jackson Mississippi (JAN) County Warning Area (CWA) during the cool season (October - May). These QLCSs often produce embedded tornadoes when conditions are favorable for mesovortex generation. Depending on the governing parameter space (i.e. strong synoptic scale forcing and orientation of low-level shear vectors), some of these QLCSs produce very few or even no tornadoes, while others are prolific tornado producers. In addition to the inherent forecast challenges, these QLCS tornadoes can prove difficult to assess during post-storm damage surveys. The majority of QLCS tornadoes are brief and weak with subtle damage indicators, which poses a challenge for surveys. This is especially true when the tornado occurs at a significant distance from the nearest radar site, where the radar beam often overshoots the low-level circulation, making the radar data less useful in aiding the damage survey process. This presentation will discuss the myriad of challenges that NWS JAN staff face when conducting damage surveys for QLCS tornadoes with a focus on several recent QLCS tornado outbreaks, including the record setting 18 April 2019 event in which 44 tornadoes were confirmed in the JAN CWA. Storm damage survey techniques, strategies and best practices will also be discussed.
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