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Experiences with 0-36 h Explicit Convective Forecasting with the WRF-ARW Model

Experiences with 0-36 h Explicit Convective Forecasting with the WRF-ARW Model. Morris Weisman (Wei Wang, Chris Davis) NCAR/MMM WSN05 September 8, 2005. Composite NEXRAD Radar 00 UTC 6/10/03 - 12 UTC 6/11/03. WRF Realtime Convective Forecasting. May 1 – July 31 4 km 00 UTC -- 36h.

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Experiences with 0-36 h Explicit Convective Forecasting with the WRF-ARW Model

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  1. Experiences with 0-36 h Explicit Convective Forecasting with the WRF-ARW Model Morris Weisman (Wei Wang, Chris Davis) NCAR/MMM WSN05 September 8, 2005

  2. Composite NEXRAD Radar 00 UTC 6/10/03 - 12 UTC 6/11/03

  3. WRF Realtime Convective Forecasting May 1 – July 31 4 km 00 UTC -- 36h 2003, 2004, 2005

  4. WRF Real-time Forecasts: 2004, 2005 • 4-km from 0000 UTC - 36 h • Version 1.3 (2.0.3.1) • Eta initial and boundary conditions (40 km) • Physics: • Lin et al. (5 cat.) microphysics (WSM6) • YSU PBL (first-order closure) • Noah LSM (HRLDAS) • 2000 km X 2000 km domain / 2800 km X 2600 km domain • 5.0h (6.5h) on 128 (192) IBM Power-4 processors

  5. Real-time WRF 4 km Forecast Initialized 00 UTC 9 June 03 Reflectivity forecast Composite NEXRAD Radar

  6. Real-time WRF 4 km Forecast Initialized 00 UTC 10 June 03 Reflectivity forecast Composite NEXRAD Radar

  7. Consider the 24-30 h forecast challenge(i.e., the next diurnal cycle). How does the 4 km WRF-ARW ‘’guidance’’ compare to the 12 km operational ETA?

  8. May 30, 2004 Radar 03 GMT 4 km WRF-ARW 12 km ETA 03 GMT 27 hr 06 GMT prec. 30 hr

  9. Overall Forecast WRF RADAR Good: OK: Bad:

  10. How well does 4-km WRF represent the climatological behavior of convection? (e.g., diurnal cycle, episodes)

  11. Longitudinal 1 hr Precip. May 10-31, 2004 Stage IV WRF

  12. Diurnal Average Frequency: May 10-July 31 2004 Stage IV 4 km WRF

  13. Diurnal Average 3 hr Precip. Stage IV 4 km WRF 12 km ETA

  14. Initialized 04 June 2005 00 UTC Composite NEXRAD Radar Reflectivity forecast

  15. 24 h forecast Valid 00 UTC 06/05/05 4-km NMM 4-km ARW Nexrad 2-km ARW

  16. ARW4 NMM4 ARW2 BREF 0500 UTC 29 April 2005: 1 km model reflectivity, NEXRAD BREF

  17. Progress 4 km WRF-ARW simulations exhibit: • A surprising ability to forecast mesoscale convective systems (MCS) out to 36 h ( strongly controlled by 12-km ETA forcing) • A demonstrated skill at depicting MCS mode(bow echoes, mesoscale convective vortices, supercell lines) • A more accurate depiction of diurnal cycle and precipitation episodes • An ability to spin-up convective systems within 3-4 h from a cold start.

  18. Challenge: • QPF problematic (too much convective precip) • Stratiform regions appear too small (microphysics?) • Convective systems often fail to decay (BL evolution?) • Initialization (data assimilation) • Verification methods

  19. WRF-ARW 2005 real-time forecasts can be found at: http://box.mmm.ucar.edu/projects/wrf_spring/ http://rain.mmm.ucar.edu/mm5/ Also archived at: http://www.joss.ucar.edu/wrf-2004/catalog/ http://www.joss.ucar.edu/wrf-2005/catalog/

  20. OBS 24 hr precipitation verification Valid 6/10/03 12 UTC 4 km WRF 10 km WRF 12 km ETA

  21. 4 km WRF 12 h Precipitation Forecast Valid 10 June 2003 12 Z WSM - 6 Scheme Lin, et al. Scheme NCEP Stage 4 Data Total Precipitation (mm) (Axel Seifert, 2004) Reisner Scheme SB2004 Scheme

  22. WSM - 6 Scheme Lin, et al. Scheme NEXRAD Composite Reisner Scheme SB2004 Scheme 4 km WRF 12 h Reflectivity Forecast Valid 10 June 2003 12 Z Column Max Reflectivity ( dBZ ) (Axel Seifert, 2004)

  23. Lin WSM-6 12 h Surface Theta Reisner SB2004

  24. Sounding comparison: 24h forecast valid 00Z 24 May at DDC ARW4 Good forecast… NMM4 PBL too shallow, cold, & moist… clouds just broke up! Model Raob Model Raob

  25. Sounding comparison: 24h forecast valid 00Z 18 May at DDC ARW4 Too dry in PBL, too moist above; Where is the PBL top? NMM4 Good forecast… Model Raob Raob Model

  26. Sounding comparison: 24h forecast valid 00Z 28 April at OUN ARW4 Good in PBL, but CIN layer is washed out NMM4 PBL too shallow and moist, but CIN layer looks good Raob Model Raob Model

  27. 24 h Reflectivity Forecast valid 4-30-05 00Z 4 km WRF-ARW 4 km WRF-NMM 2 km WRF-ARW Radar

  28. Diurnal Average (2003) 4 km 10 km

  29. 1 10 100 km Resolved Convection Cumulus Parameterization 3-D Radiation Two Stream Radiation LES PBL Parameterization Model Physics in High Resolution NWP Physics “No Man’s Land”

  30. Convective Mode/Intensity WRF ETA CAT 3:severe, well organized (> 1 in) CAT 2: some organization (.25-1.0 in) CAT 1:weak,disorganized (< .25 in)

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