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Short-term Forecasting and WRF Case Study

Explore a detailed case study on short-term forecasting using WRF data assimilation and additional forecast interests from NASA Marshall Space Flight Center. Learn about dynamics, radar retrievals, nowcasting, and NWP forecast rules.

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Short-term Forecasting and WRF Case Study

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  1. Short-term Forecasting and WRF Case Study Steven J. Goodman, W. Lapenta, K. La Casse, E. McCaul, and W. Petersen NASA Marshall Space Flight Center Earth and Planetary Science Branch Huntsville, Alabama, USA SPoRT Science Advisory Committee Meeting 21 November 2005 Photo, David Blankenship Guntersville, Alabama

  2. NWS STIP Solutions (Science and Technology Infusion Plan) Weather Research and Forecast, WRF Data Assimilation, DA Additional Forecast Interests CI - convective initiation Ti - First lightning (35 dbZ at -15C, glaciation) Tp – Peak flash rate a VIL (Mass) Tf - Final lightning

  3. 0 oC Flash Rate Coupled to Mass in the Mixed Phase Region Cecil et al., Mon. Wea. Rev. 2005 (from TRMM Observations)

  4. Lightning Connection to Thunderstorm Updraft, Storm Growth and Decay • Total Lightning —responds to updraft velocity and concentration, phase, type of hydrometeors, integrated flux of particles • WX Radar — responds to concentration, size, phase, and type of hydrometeors- integrated over small volumes • Microwave Radiometer — responds to concentration, size, phase, and type of hydrometeors — integrated over depth of storm (85 GHz ice scattering) • VIS / IR — cloud top height and temperature, texture, optical depth

  5. Extrapolation Statistical Model derived forecast fields Convergence line Detection & characterization Radar retrievals Data Fusion System Nowcast NWP Forecast Rules Forecast rules e.q boundary collision storm initiation likely Forecaster Input e.q. convergence line Input, meteorological situation Courtesy, Jim Wilson NCAR WWRP/Tom Keenan

  6. Enhanced Thunder 19 July 2005 2000Z – 2012Z SPC Experimental Product NCEP SPC/Schaefer

  7. SPC Experimental Product - Pr (CPTP) >= 1 x Pr (PCPN) >= .01” Uncalibrated probability of lightning F15 SREF 3-hr COMBINED PROBABILITY OF LIGHTNING

  8. North Alabama Nowcasting Short-term Forecasting Test Bed

  9. WRF Thunderstorm and Lightning Forecasts:10 December 2004

  10. 4km horizontal resolution 37 vertical levels Dynamics and physics Eulerian mass core Dudhia SW radiation RRTM LW radiation YSU PBL scheme Noah LSM WSM 6-class microphysics scheme Explicit convection 24h forecast initialized at 00 UTC 10 December 2004 with AWIP212 NCEP EDAS analysis Eta 3-h forecasts used for LBC’s WRF Configuration10 December 2004 Case Study Cloud cover 18h forecast valid at 18 UTC 10 Dec. 2004

  11. Observed Thunderstorm Precipitation and Lightning10 December 2004, 1700-2125 UTC KHTX NEXRAD, LMA, NLDN

  12. WRF Surface Based CAPE 18h fcst valid 18 UTC Dec 10

  13. WRF Sounding ~ 800 J/kg CAPE

  14. MIPS Sounding ~ 761 J/kg CAPE • Low level lapse rates and low freezing level efficient for converting CAPE to kinetic energy • Surface T=15C, Td=10C • Max w= 19 m/s UAH MIPS, Kevin Knupp

  15. WRF 3h Precipitation 18h fcst valid 18 UTC Dec 10

  16. WRF 3h Precipitation 21h fcst valid 21 UTC Dec 10

  17. WRF 3h Precipitation 21h fcst valid 21 UTC Dec 10 Question: Any lightning, when was it, What was WRF reflectivity at -15 C?

  18. x2 x1 WRF Reflectivity (dBZ)at -15 C (4.0 km) 1200 UTC forecast valid at 18:50 UTC 10 Dec. 2004

  19. x1: Reflectivity (dBZ), Temperature (°C), and Pressure (hPa) 1200 UTC forecast valid at 18:50 UTC 10 Dec. 2004 Max dBZ< 40 dBZ

  20. x2: Reflectivity (dBZ), Temperature (°C), and Pressure (hPa) 6h 50m forecast valid at 18:50 UTC 10 Dec. 2004 Max dBZ~50 dBZ

  21. Ground-truth Report of Dime-Size Hail Owens Crossroads, Alabama

  22. 10 December Hail Case ARMOR collected data! First time ZDR used on television! • Cold upper-low • GOES 2057 J/kg CAPE in a layer about 7.5 km deep • GOES sounding too warm and moist near surface, likely cloud contaminated • Dime to quarter-sized hail reported in SE Madison county and in S. Tennessee

  23. NCAR HYDRO-ID REFLECTIVITY Cloud Drizzle Lt. Rain Mod. Rain Heavy Rain Hail Hail/Rain Small Hail Rain/Sm. Hail Dry Snow Wet Snow Ice Crys. 5 12 20 28 35 43 50 57 HAIL SMALL HAIL RAIN ARMOR 1.3 degree PPI scan at 17:55 UTC on 10 Dec. 04 Particle Identification Reflectivity [dBZ]

  24. Rain/Hail -0.5 to 2 dB ARMOR: 12/10/04 17:55:06 EL=1.3o Rain/Hail 40-55 dBZ dBZ ZDR Hail -1.5 to 0.5 dB Hail 50-55 dBZ Rain 2 to 3.5 dB Rain 55+ dBZ -1.8 -0.9 0.1 1.0 1.9 2.9 3.6 -15 - 5 5 15 25 35 45 Hail 55+ dBZ Hail -1 to 0.5 dB LMA S. Cell 17:52:30 – 17:57:30 At 17:55 IC fl. rate ~ 3/minute in southern cell No IC’s in northern cell at 17:55 No CG’s in either cell for 20 minutes centered on 17:55 Only 3 CG’s detected for duration of storms

  25. LMA Observed Flashes Precede Hail Report

  26. RAMS Configuration • 500 m horizontal resolution • Height, Dz is variable, from 250 m at bottom to 750 m at 20 km height • Domain 75 km x 75 km x 24.5 km • Time, Dt = 4 s, five acoustic steps between • Smagorinsky subgrid mixing scheme • 5-class precipitating hydrometeors: • Rain, snow, aggregates, graupel, hail • Initialized with 3K warm bubble, radius=12 km at z=0 • 120 min simulation, initiation effects dominate until t=60 min

  27. RAMS Configuration Graupel • 500 m horizontal resolution • Height, Dz is variable, from 250 m at bottom to 750 m at 20 km height • Domain 75 km x 75 km x 24.5 km • Time, Dt = 4 s, five acoustic steps between • Smagorinsky subgrid mixing scheme • 5-class precipitating hydrometeors: • Rain, snow, aggregates, graupel, hail • Initialized with 3K warm bubble, radius=12 km at z=0 • 120 min simulation, initiation effects dominate until t=60 min

  28. RAMS Configuration Hail • 500 m horizontal resolution • Height, Dz is variable, from 250 m at bottom to 750 m at 20 km height • Domain 75 km x 75 km x 24.5 km • Time, Dt = 4 s, five acoustic steps between • Smagorinsky subgrid mixing scheme • 5-class precipitating hydrometeors: • Rain, snow, aggregates, graupel, hail • Initialized with 3K warm bubble, radius=12 km at z=0 • 120 min simulation, initiation effects dominate until t=60 min

  29. WRF Thunderstorm and Lightning Forecasts:1 May 2004

  30. 1h WRF forecast valid at 01 UTC 1 May 2004 using MODIS SSTs A B

  31. Cross-section of reflectivity on sigma levels 1h WRF forecast valid at 01 UTC 1 May 2004 A B

  32. LIS Ground Truth - Florida 1May 2004 (Day 122) 03:03 UTC

  33. NLDN Observed Lightning, 1 May 2004

  34. High resolution 2 km WRF database Validation of convective processes with TRMM LIS and ancillary data sets Examine the “Warn on Forecast” framework for lightning threat: WRF-Nowcaster-LMA WRF Thunderstorm and Lightning Forecasts:Motivations to study the 1-3 May 2004 Florida Cases

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