1. WMO/WWRP Workshop Use of NWP for Nowcasting 25 October 2011 Evaluation of the 3-km High Resolution Rapid Refresh (HRRR) as Nowcast Guidance NOAA/ESRL/GSD Curtis Alexander, Steve Weygandt, Stan Benjamin, David Dowell, Eric James, Patrick Hofmann, Tanya Smirnova, Ming Hu, and John Brown

2. Hourly Updated NOAA NWP Models 13km Rapid Refresh (mesoscale) 13km RUC (mesoscale) 3km HRRR (storm-scale) RUC – current oper Model, new 18h fcst every hour High-Resolution Rapid Refresh Experimental 3km nest inside RR, new 15-h fcst every hour Rapid Refresh (RR) replaces RUC at NCEP in 2011 WRF, GSI with RUC features

3. Spring 2011 Hourly HRRR Initialization from RR Hourly RR Lateral Boundary Conditions Interp to 3 km grid Hourly HRRR 15-h fcst Initial Condition Fields 11 z 12 z 13 z Time (UTC) Analysis Fields 3DVAR Obs 3DVAR Obs Back- ground Fields 18-h fcst 1-hr fcst DDFI 1-hr fcst 18-h fcst 1-hr fcst Interp to 3 km grid 15-h fcst Use 1-h old LBC to reduce latency Use most recent IC (post-DFI) to get latest radar info Reduced Latency: ~2h for 2011

4. NOAA/ESRL/GSD/AMB Models ModelVersionAssimilation Radar DFI RadiationMicrophysics Cum Param PBLLSM RUC N/A RUC-3DVARYes RRTM/Dudh ia Thompson Grell- Devenyi Burk- Thompson RUC RR WRF- ARW v3.2+ GSI-3DVARYes RRTM/Godd ard Thompson G3 + Shallow MYJRUC HRRR WRF- ARW v3.2+ None: RR I.C. No RRTM/Godd ard ThompsonNoneMYJRUC ModelRun at:Domain Grid Points Grid Spacing Vertical Levels Vertical Coordinate Boundary Conditions Initialized RUC GSD, NCO CONUS 451 x 337 13 km50 Sigma/ Isentropic NAM Hourly (cycled) RR GSD, EMC North America 758 x 567 13 km50SigmaGFS Hourly (cycled) HRRRGSDCONUS 1799 x 1059 3 km50SigmaRR Hourly (no-cycle)

5. NOAA/ESRL/GSD/AMB Models ModelVersionAssimilation Radar DFI RadiationMicrophysics Cum Param PBLLSM RUC N/A RUC-3DVARYes RRTM/Dudh ia Thompson Grell- Devenyi Burk- Thompson RUC RR WRF- ARW v3.2+ GSI-3DVARYes RRTM/Godd ard Thompson G3 + Shallow MYJRUC HRRR WRF- ARW v3.2+ Yes Multiple Radar DA Experiments RRTM/Godd ard ThompsonNoneMYJRUC ModelRun at:Domain Grid Points Grid Spacing Vertical Levels Vertical Coordinate Boundary Conditions Initialized RUC GSD, NCO CONUS 451 x 337 13 km50 Sigma/ Isentropic NAM Hourly (cycled) RR GSD, EMC North America 758 x 567 13 km50SigmaGFS Hourly (cycled) HRRRGSDCONUS 1799 x 1059 3 km50SigmaRR Hourly (no-cycle)

6. HRRR Milestones Inception over northeastern USSept 2007 Integration into CoSPA: Aviation UsersSpring 2008 Domain expansion to eastern USMar 2009 HCPF time-lagged ensemble inceptionMay 2009 HRRR WRF-ARW updated to v3.1.1Oct 2009 Domain expansion to CONUSOct 2009 HRRR WRF-ARW updated to v3.2Apr 2010 Forecast period extended to 15 hrsApr 2010 Real-time multi-scale reflect. verificationJune 2010 Parallel (shadow) retrospective systemSept 2010 Attained ~95% reliabilityJun 2010 Reduced latency to ~2 hrsDec 2010

7. HRRR (and RR) Future Milestones Conversion of all output to GRIB2 formatApr 2011 Transition from RUC to RR parent modelApr 2011 DOE-funded HRRR FTP site for energy industryMay 2011 Update to WRF-ARW v3.3.1Nov 2011 Rapid Refresh operational at NCEPDec 2011 Reflectivity data assimilation at 3 km scale2012 Incorporate SatCast products at 3 km scale2012 Assimilate Radial Velocity at 3 km scale2012 HRRR demo @ESRL improves2012-2014 Ensemble Rapid Refresh (NARRE) at NCEP2014 HRRR operational at NCEP2015? Ensemble HRRR (HRRRE) at NCEP2016?

8. Some HRRR users and applications Aviation Weather Center (AWC): 2-D grids Federal Aviation Administration (FAA) Command Center National Center for Atmospheric Research (NCAR): 2-D, 3-D, 15-min grids Operational evaluation in CoSPA Storm Prediction Center (SPC): 2-D grids Operational severe weather forecasting and evaluation National Severe Storms Laboratory (NSSL): 2-D, 3-D and 15-min grids Mesoscale analysis, Short-term precipitation forecasts National Centers for Environmental Prediction (NCEP): 15-min grids Real Time Mesoscale Analysis (RTMA) Bonneville Power Administration (BPA): 3-D grids Real-time forecasts of turbine-level wind and solar irradiance Colorado State University (CSU/CIRA): 2-D grids Verification of solar irradiance forecasts at SURFRAD sites Numerous private sector companies Air Resources Laboratory (ARL): Tiled 3-D HRRR grids Dispersion forecasts, Local wind forecasts in complex terrain National Weather Service (NWS): 2-D and 3-D grids Operational weather forecasting United States Air Force (USAF): 2-D grids Operational weather forecasting Severe Weather Aviation Renewable Energy Forecasting

9. Model Configurations HRRR Primary CoSPA NCEPESRL/GSD RR Dev RUC Dev RUC Backup RR Primary HRRR Dev RUC Oper RR EMC RR Dev2

10. Blending Radar Nowcasts and HRRR Forecasts for Aviation CoSPA: Collaborative effort: ESRL/GSD, NCAR/RAL, MIT/LL Provide 0-8 hr thunderstorm intensity and echo top guidance to aviation community HRRR 15 UTC 08 July 2011 6 hr forecast valid 21 UTC CoSPA 17 UTC 08 July 2011 4 hr forecast valid 21 UTC Observation Valid 21 UTC 08 July 2011 Blend with CIWS

11. Blending Radar Nowcasts and HRRR Forecasts for Aviation CoSPA: Collaborative effort: ESRL/GSD, NCAR/RAL, MIT/LL Provide 0-8 hr thunderstorm intensity and echo top guidance to aviation community HRRR 15 UTC 08 July 2011 6 hr forecast valid 21 UTC CoSPA 17 UTC 08 July 2011 4 hr forecast valid 21 UTC Verification Valid 21 UTC 08 July 2011 Blend with CIWS CSI 0.20 Bias 1.30 Eastern US 30 dBZ threshold 40 km grid

12. Verification of RUC/RR (parent) vs HRRR Cold Season (1 Jan 2011 – 14 April 2011) RUC vs HRRR Lead Time Clouds Precip (13 km) Reflectivity (40 km) Upper-AirSurface Ceiling < 500 ft Vis < 0.5 mile > 0.1 inch > 1.0 inch 25 dBZ35 dBZTempRHWindTempDewptWind 1-hrHRRR N/A EqualHRRR EqualHRRR RUCHRRR 3-hrHRRR EqualHRRR RUCEqualN/A 6-hrHRRR RUCEqualHRRRRUCHRRR Warm Season (15 April 2011 – 25 October 2011) RR vs HRRR Lead Time Clouds Precip (13 km) Reflectivity (40 km) Upper-AirSurface Ceiling < 500 ft Vis < 0.5 mile > 0.1 inch > 1.0 inch 25 dBZ35 dBZTempRHWindTempDewptWind 1-hrHRRRRR HRRREqual HRRR RR HRRR 3-hrHRRR RREqualRREqual 6-hrHRRR RRHRRREqual

13. HRRR Verification < 500 ft ceiling, 6-hr forecasts TSS (3 day averages) HRRR consistently beats the RUC (cold season) HRRR RUC HRRR-RUC HRRR RR HRRR-RR HRRR consistently beats the RR (warm season) HRRR better RUC/RR better

14. HRRR Verification < 0.5 mi visibility, 6-hr forecasts TSS (7 day averages) HRRR consistently beats the RUC (cold season) HRRR RUC HRRR-RUC HRRR RR HRRR-RR HRRR consistently beats the RR (warm season) HRRR better RUC/RR better

15. HRRR Verification 10 m wind, 6-hr forecasts RMS (3 day averages) HRRR consistently beats the RUC (cold season) HRRR RUC HRRR-RUC HRRR RR HRRR-RR HRRR nearly equal to RR (warm season) RUC/RR better HRRR better

16. HRRR Verification Upper-Air Wind, 6-hr forecasts RMS HRRR and RUC nearly equal (cold season) HRRR RUC HRRR-RUC HRRR RR HRRR-RR RR consistently beats the HRRR (warm season) HRRR better RUC better HRRR better RR better

17. HRRR Verification Precipitation, 24-hr (2x12) forecasts 15 April – 25 October 2011 HRRR RR RUC HRRR consistently beats the RR/RUC (warm season) | | | | | | | | 0.01 0.10 0.25 0.50 1.00 1.50 2.00 3.00 in Threshold CSI 13 km BIAS 13 km Optimal Threshold | | | | | | | | 0.01 0.10 0.25 0.50 1.00 1.50 2.00 3.00 in

18. HRRR Verification Reflectivity, All Forecasts 25 dBZ CSI 40 km HRRR consistently beats the RUC At 4+ hrs (cold season) HRRR RUC HRRR-RUC HRRR RR HRRR-RR HRRR consistently beats the RR (warm season) HRRR better RUC/RR better

19. HRRR Verification Reflectivity, All Forecasts 35 dBZ CSI HRRR consistently beats the RUC (cold season) HRRR RUC HRRR-RUC HRRR RR HRRR-RR HRRR consistently beats the RR (warm season) HRRR better RUC/RR better

20. HRRR – wintertime forecast applications IFRLIFRMVFR Excellent skill for low ceiling / visibility |--------VFR-------------

21. HRRR – wintertime forecast applications IFRLIFRMVFR Excellent skill for low ceiling / visibility |--------VFR------------- LIFR IFR VFR MVFR

22. Very good skill for small-scale details in strongly forced convection and precipitation HRRR – wintertime forecast applications NSSL reflectivity 08z Jan. 17, 2010 HRRR 8h fcst.

23. Surface obs 08z Jan. 17, 2010 HRRR – wintertime forecast applications Good skill for small-scale terrain-related details 60 F

24. HRRR Reflectivity Verification Eastern US, Reflectivity > 25 dBZ 11-20 August 2011 Reflectivity DA in RR/RUC increases HRRR forecast skill HRRR bias depends strongly on parent model CSI 40 km RUC->HRRR Radar RR->HRRR Radar RR->HRRR No Radar RUC->HRRR No Radar RR->HRRR Radar RR->HRRR No Radar RUC->HRRR Radar RUC->HRRR No Radar BIAS 03 km Optimal

25. 00 hr HRRR forecasts RR – No radar data RR – Radar data Obs00z 12 August 2011

26. 01 hr HRRR forecasts Obs RR – No radar data RR – Radar data 01z 12 August 2011

27. RR – No radar data RR – Radar data Reflectivity 00z 12 August 2011 00 hr forecasts Convergence Cross-Section

28. RR – No radar data RR – Radar data Convergence Cross-Section Reflectivity 01z 12 August 2011 01 hr forecasts

29. 80-km valid (GMT) valid (EDT) 00 02 04 06 08 10 12 14 16 18 20 22 8p 10p 12 2a 4a 6a 8a 10a 12 2p 4p 6p “neighborhood” verification of 6-h forecasts from 3-km HRRR verification:10 June – 26 Sept 2010 40-km 20-km 25 dBZ 6-h fcst 3-km Many case All init times

30. 80-km valid (GMT) valid (EDT) 00 02 04 06 08 10 12 14 16 18 20 22 8p 10p 12 2a 4a 6a 8a 10a 12 2p 4p 6p “neighborhood” verification of 6-h forecasts from 3-km HRRR verification:10 June – 26 Sept 2010 Convective Initiation period 40-km 20-km 25 dBZ 6-h fcst 3-km

31. 80-km valid (GMT) valid (EDT) 00 02 04 06 08 10 12 14 16 18 20 22 8p 10p 12 2a 4a 6a 8a 10a 12 2p 4p 6p “neighborhood” verification of 6-h forecasts from 3-km HRRR verification:10 June – 26 Sept 2010 Convective Initiation period 40-km 20-km 25 dBZ 6-h fcst 3-km Convective Decay period

32. 80-km valid (GMT) valid (EDT) 00 02 04 06 08 10 12 14 16 18 20 22 8p 10p 12 2a 4a 6a 8a 10a 12 2p 4p 6p “neighborhood” verification of 6-h forecasts from 3-km HRRR verification:10 June – 26 Sept 2010 Convective Initiation period 40-km 20-km 25 dBZ 6-h fcst 3-km Convective Decay period

33. Time-lagged ensemble Model Init Time Example: 15z + 2, 4, 6 hour HCPF Forecast Valid Time (UTC) 11z 12z 13z 14z 15z 16z 17z 18z 19z 20z 21z 22z 23z 13z+4 12z+5 11z+6 13z+6 12z+7 11z+8 13z+8 12z+9 11z+10 HCPF 2 4 6 18z 17z 16z 15z 14z 13z 12z 11z Model runs used model has 2h latency 33

34. Spatio-temporal scale of probabilities? Probability of convection at fixed point in space/time is very small even during summer afternoons in the southeastern US Horizontal ScaleTime WindowProbability > 40 dBZ O(1 km)O(1 min)O(<< 1%) O(10 km)O(10 min)O(1 %) O(100 km)O(100 min)O(30%)

35. Spatio-temporal scale of probabilities? Observed convection near Atlanta, GA 22 UTC 26 October 2010 3 hr forecast valid 21 UTC 26 October4 hr forecast valid 22 UTC 26 October Same model run at different valid times

36. Spatio-temporal scale of probabilities? Observed convection near Atlanta, GA 22 UTC 26 October 2010 3-4 hr forecast valid 21-22 UTC 4-5 hr forecast valid 22-23 UTC Use a 2 hr time window

37. Spatio-temporal scale of probabilities? Observed convection near Atlanta, GA 22 UTC 26 October 2010 3-4 hr forecast valid 21-22 UTC 4-5 hr forecast valid 22-23 UTC Then apply spatial filter: 90 km radius shown here

38. Reliability vs Resolution/Sharpness Logistic regression using various observation time windows for calibration Parameter choices: 3 members (2 hr lag youngest member) Fixed 2 hr time window Fixed 60 km spatial filter 1.0 m/s updraft velocity detection threshold P(convection) = [1 + exp(-z)] -1 z = B 0 + B 1 x 1 + B 2 x 2 + B 3 x 3 where B i are the regressed weights and x i are the predictors (HRRR member forecasts) Obtain reliability while preserving resolution Probabilities constrained between 0 and 1

39. The HRRR and HCPF Confidence Probabilities and Deterministic Valid 23z 16 July 2010

40. The HRRR and HCPF Confidence Probabilities and Deterministic Valid 23z 16 July 2010

41. Updraft helicity from four consecutive HRRR runs 13-16 UTC (color coded by run) Tornado Reports Up to valid time (red dots) HRRR Severe Weather Forecasts Tornado Outbreak KS/OK 10 May 2010

42. Updraft helicity probability Four consecutive HRRR runs (13-16 UTC) Time-bracket of 2-hrs 45 km search radius HRRR Severe Weather Forecasts Tornado Outbreak KS/OK 10 May 2010

43. Summary HRRR now initialized by the RR as of 14 April 2011 Parallel (shadow) HRRR-dev will demo 2012 candidate changes in real-time and/or retrospective runs: - WRF v3.3.1 - MYNN PBL scheme - Shallow convective param - Satcast product - Soil moisture nudging - 3-km radar radial velocity assimilation - 3-km radar reflectivity assimilation - Refined 13-km Radar-DFI HCPF development Research Regular HRRR at NESSC as duplicate source 43 Targeting improved convective initiation forecasts Targeting improved convective maintenance forecasts Targeting confidence of convective forecasts Targeting improved reliability of HRRR } } } }

44. HRRR Precipitation Forecast TONIGHT 13UTC 25 October 2011 Run 14 hr Fcst Valid 03 UTC (9 p.m.)15 hr Fcst Valid 04 UTC (10 p.m.) Rain in Boulder Snow in Boulder How much? See Steve Weygandt’s Talk @ 3:30 p.m.