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Synoptically evident event

Overview of 24 May 2011 Case & NSSL Experiments Corey Potvin 1,2 , Thomas Jones 1,2 , Dusty Wheatley 1,2 , Louis J. Wicker 2 1 Cooperative Institute for Mesoscale Meteorological Studies 2 NOAA/OAR National Severe Storms Laboratory. Synoptically evident event.

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Synoptically evident event

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  1. Overview of 24 May 2011 Case & NSSL ExperimentsCorey Potvin1,2, Thomas Jones1,2, Dusty Wheatley1,2, Louis J. Wicker21Cooperative Institute for Mesoscale Meteorological Studies2NOAA/OAR National Severe Storms Laboratory

  2. Synoptically evident event • Left exit region of jet max within negatively tilted shortwave trough  strong large-scale ascent • Advancing dryline provided additional lift • Rapid moisture advection from Gulf, aided by southerly flow induced by strong low over OK panhandle • Extreme instability (ML CAPE 3000-4000 J/kg) • Exceptional vertical wind profiles

  3. 500 hPa 0000 Z Surface 1925 Z

  4. Day 2 06 UTC (from 23 May) Day 1 13 UTC

  5. 18 UTC Norman RAOB Fig. 3, Fierro et al. (2012)

  6. Chronology • Dryline initiation ~19 UTC, rapid supercell formation • As low-level jet intensifies, 0-1 km SREH > 300 m2s-2 • Tornadoes develop 2030-2230 UTC and race NE toward OKC metro • Storms weaken as they approach I-35, possibly due to increasing convective inhibition

  7. Storm evolution – MRMS dBZ 2 km AGL 1920 Z 1950 Z 1850 Z 2050 Z 2120 Z 2020 Z

  8. Tornado Paths Canton Lake EF-3 (2015-2043) NSSL-WoF nearly suffers a “setback” Lookeba EF-3 (2031-2046) / El-Reno EF-5 (2050-2235) Goldsby EF-4 (2226-2305) Chickasha EF-4 (2209-2300) 11 fatalities, 293 injuries Adapted from http://www.srh.noaa.gov/oun/?n=events-20110524

  9. Mesoscale DA – GEFS-based NME • Dusty will give more details • WRFv3.4.1; Δ=15 km; 51 levels; 36 members • 1-way 3-km nest – used to initialize storm-scale DA

  10. Storm-scale DA • WRF v3.4.1; Δ=3km; 51 levels; Thompson microphysics • DART-EAKF or NSSL-LETKF • 36 members; 5-min cycles starting ~1845 UTC • Vr, dBZ from KTLX, KVNX, KFDR (OPAWS: Δ=6km) • Objective QC (Chris Karstens web tools) • “no-precip” obs: dBZ < 10 set to 0 • 3 m/s & 5 dBZ errors • Mesonetu, v, T, TD (errors: 1.75 m/s, 1.75 K) • Additive noise (0.5 m/s, 0.5 K) and adaptive inflation • Covariance localization cutoffs: 18 km / 6 km

  11. NSSL Projects • All use mostly the same settings • Dusty – dBZ-based dw/dt forcing • Corey – Running-In-Place • Thomas – satellite DA

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