Experiences with 0 36 h Explicit Convective Forecasting

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

Experiences with 0 -36 h Explicit Convective Forecasting with the WRF-ARW Model Morris Weisman (Wei Wang, Chris Davis) NCAR/MMM WSN 05 September 8, 2005

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

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 --

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

WRF Real-time Forecasts: 2004, 2005 § 4 -km from 0000 UTC - 36 h

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 (WSM 6) YSU PBL (first-order closure) Noah LSM (HRLDAS) § 2000 km X 2000 km domain / 2800 km X 2600 km domain § 5. 0 h (6. 5 h) on 128 (192) IBM Power-4 processors

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

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

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

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

Consider the 24 -30 h forecast challenge (i. e. , the next diurnal cycle).

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?

May 30, 2004 Radar 03 GMT 4 km WRFARW 03 GMT 27 hr 06

May 30, 2004 Radar 03 GMT 4 km WRFARW 03 GMT 27 hr 06 GMT prec. 12 km ETA 30 hr

Overall Forecast Good: OK: Bad: WRF RADAR

Overall Forecast Good: OK: Bad: WRF RADAR

How well does 4 -km WRF represent the climatological behavior of convection? (e. g.

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

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

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

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

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

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

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

Initialized 04 June 2005 00 UTC Reflectivity forecast Composite NEXRAD Radar

Initialized 04 June 2005 00 UTC Reflectivity forecast Composite NEXRAD Radar

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

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

0500 UTC 29 April 2005: 1 km model reflectivity, NEXRAD BREF ARW 4 NMM

0500 UTC 29 April 2005: 1 km model reflectivity, NEXRAD BREF ARW 4 NMM 4 ARW 2 BREF

Progress 4 km WRF-ARW simulations exhibit: § A surprising ability to forecast mesoscale convective

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.

Challenge: • QPF problematic (too much convective precip) • Stratiform regions appear too small

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

WRF-ARW 2005 real-time forecasts can be found at: http: //box. mmm. ucar. edu/projects/wrf_spring/ http:

WRF-ARW 2005 real-time forecasts can be found at: http: //box. mmm. ucar. edu/projects/wrf_spring/ http: //rain. mmm. ucar. edu/mm 5/ Also archived at: http: //www. joss. ucar. edu/wrf-2004/catalog/ http: //www. joss. ucar. edu/wrf-2005/catalog/

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

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

4 km WRF 12 h Precipitation Forecast Valid 10 June 2003 12 Z Lin,

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

4 km WRF 12 h Reflectivity Forecast Valid 10 June 2003 12 Z Lin,

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

Lin WSM-6 12 h Surface Theta Reisner SB 2004

Lin WSM-6 12 h Surface Theta Reisner SB 2004

Sounding comparison: 24 h forecast valid 00 Z 24 May at DDC ARW 4

Sounding comparison: 24 h forecast valid 00 Z 24 May at DDC ARW 4 Good forecast… Model Raob NMM 4 Model Raob PBL too shallow, cold, & moist… clouds just broke up!

Sounding comparison: 24 h forecast valid 00 Z 18 May at DDC ARW 4

Sounding comparison: 24 h forecast valid 00 Z 18 May at DDC ARW 4 Model Raob NMM 4 Too dry in PBL, too moist above; Where is the PBL top? Good forecast… Raob Model

Sounding comparison: 24 h forecast valid 00 Z 28 April at OUN ARW 4

Sounding comparison: 24 h forecast valid 00 Z 28 April at OUN ARW 4 Raob Good in PBL, but CIN layer is washed out Model NMM 4 Raob Model PBL too shallow and moist, but CIN layer looks good

24 h Reflectivity Forecast valid 4 -30 -05 00 Z 4 km WRF-ARW 4

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

Diurnal Average (2003) 4 km 10 km

Diurnal Average (2003) 4 km 10 km

Model Physics in High Resolution NWP Physics “No Man’s Land” 1 Resolved Convection 3

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

Convective Mode/Intensity CAT 3: severe, well organized (> 1 in) CAT 2: some organization

Convective Mode/Intensity CAT 3: severe, well organized (> 1 in) CAT 2: some organization (. 251. 0 in) CAT 1: weak, disorganized (<. 25 in) WRF ETA

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