Dynamical Downscaling of Major US Tornado Outbreaks

Dynamical Downscaling of Major U.S. Tornado Outbreaks @wx_pythonista Kimberly A. Hoogewind Victor A. Gensini Purdue University West LafayeFe, IN College of DuPage Glen Ellyn, IL
Introduction
1920 Palm Sunday # 1 @gensiniwx 1965 Palm Sunday # 2 Discussion H i g h -­‐ r e s o l u @ o n , d y n a m i c a l l y downscaled output from the 20th Century Reanalysis Project admirably replicates outbreaks of severe weather that have historical significance. Westward spa@al shiLs are noted in some of the downscaled events, likely due to the coarse resoluXon of the iniXal and lateral boundary condiXons. Verifica@on of events with synthe@c severe weather reports suggests that more recent cases perform beZer, likely due to a denser network of surface observaXons. Performance also appears to be linked to strongly forced synopXc outbreaks (e.g., 3 May 1999 performed poorly). Dynamical downscaling has been tested on historical U.S. tornado outbreaks using data from the 20th Century Reanalysis Project. This reanalysis has been used in previous research to examine other historical extreme weather events (e.g., drought and hurricanes), but no study has inves@gated its use for small-­‐scale hazardous convecXve weather events. This par@cular reanalysis dataset is desired due to its unique temporal length (1871-­‐present) that spans nearly all documented U.S. tornado outbreaks. Learn More About the 20th Century Reanalysis 1925 Tri-­‐State 2011 QLCS Severe Event Data & Methods
Cases: •  27 May 1896 (St. Louis Cyclone) •  28 March 1920 (Palm Sunday #1) •  18 March 1925 (Tri-­‐State) •  11 April 1965 (Palm Sunday #2) •  3 April 1974 (Super Outbreak #1) •  3 May 1999 (Moore #1) •  19 April 2011 (QLCS All Severe) •  27 April 2011 (Super Outbreak #2) • Ini@al and boundary condi@ons provided by 20th Century Reanalysis, Version 2 dataset 1974 Super-­‐Outbreak Similar to observa@ons, both April 27th, 2011 and April 3, 1974 exhibited the most impressive tornado environments as depicted by STP. DOWNSCALED 1974 & 2011 Super-­‐Outbreak Environment Comparison Future Work 2011 Super-­‐Outbreak WRF-­‐ARW configuraXon VerYcal Levels Time Step Microphysics RadiaYon Land Surface Surface Layer PBL Cumulus 50 AdapYve Thompson RRTM/Dudhia (10 min) 0000 UTC 28 April 2011 KBMX OBSERVED NOAH LSM Revised Monin-­‐
Obukhov YSU None •  Process more cases! •  Synthe@c severe weather climatology •  Other historical extreme mesoscale events •  Objec@ve verifica@on •  Test mul@ple PBL and Microphysics schemes •  Compare results to other reanalyses •  Merge with current socioeconomic data to examine change in exposure •  Interannual changes in environments/proxy 4-­‐km Grid Spacing # Points 749 Y, 1149 X WRF 30s Topography Corresponding Author
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