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Decision Brief: Upgrade to HiResWindow

Decision Brief: Upgrade to HiResWindow. Mesoscale Modeling Branch Geoff DiMego Matt Pyle & Eric Rogers 4 September 2007. where the nation’s climate and weather services begin. Why Did SPC Start Looking at High Resolution WRF Models?.

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Decision Brief: Upgrade to HiResWindow

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  1. Decision Brief: Upgrade to HiResWindow Mesoscale Modeling Branch Geoff DiMego Matt Pyle & Eric Rogers 4 September 2007 where the nation’s climate and weather services begin

  2. Why Did SPC Start Looking at High Resolution WRF Models? • Severe weather types (tornadoes, hail, wind damage) can be closely related to convective mode • Tornadoes (discrete supercells) • Damaging wind (bow echoes and QLCSs) • SPC working to increase lead time of watches and provide probabilistic information about tornado, hail, and wind threats in Day 1 Severe Weather Outlooks • Accurate forecasts require knowledge about “where” and “when” storms will develop and how they will evolve • There is a need to better predict convective mode and character of storms(stormscale details) • Environmental clues (CAPE/shear, etc.) may not be sufficient • Operational mesoscale models often lack smaller scale details Courtesy of SPC: Weiss et. al.

  3. There were some striking successes from the very beginning. • Beginning in April 2004, Matt Pyle began running offline (on development/backup side of NCEP’s computer) and providing to SPC: • 00z run each day to 36 hours • High resolution WRF-NMM • Initially 4.5 km, ultimately 4.0 km resolution • Initially central CONUS, ultimately east-central CONUS • SPC so ‘pleased’ with the guidance, they would not let Matt turn the run off after initial Spring Program 2004 and he has been making the run every day since.

  4. Example of Explicit 4.5 km WRF-NMMcourtesy of Jack Kain WRF 24 hour 4.5 km forecast of 1 hour accumulated precipitation valid at 00Z April 21, 2004 (better than 12 hour forecasts by operational models) 4.5 km WRF-NMM Verifying 2 km radar reflectivity

  5. Over the Years, SPC Finds Value in HiRes Guidance • Primarily in Convective Mode • To lesser extent in location & evolution • Not surprising, then, they have requested • Higher resolution • Larger domain • More frequent runs

  6. HiResWindow Upgrade:12/19/2006 Request from SPC • Elevate Matt Pyle’s daily offline 00z run: • Twice per day runs at 00z & 12z • Expanded (East-Central) domain • Higher (4 km) resolution WRF-NMM • Will get 48 hr guidance instead of 36 hr • Will get both WRF-NMM and WRF-ARW • New requirements incorporated into plans for 2007 HiResWindow upgrade

  7. HiResWindow Upgrade 2007 • Model Upgrades • Upgrade WRF-NMM • From version 1.3 to 2.2 • IJK loop & storage ordering (5-10% faster) • Increase resolution from 5.2 km to 4.0 km • Upgrade WRF-ARW • From version 1.3 to 2.2 • Increase resolution from 5.8 km to 5.1 km • Expand large domains • Roughly double area covered • 3 CONUS nests reduced to 2 overlapping (West-Central & East Central) • Allows schedule adjustment to run SPC’s preferred domain (East-Central CONUS) at both 00z and 12z • Post-Processing and New Products • Add ability to output simulated reflectivity

  8. HIRES Window 2007 UpgradeDomain Size Changes New Large Domains 4.0 km for WRF-NMM 5.1 km for WRF-ARW Small domain size is unchanged Current Large & Small Domains 5.2 km for WRF-NMM 5.8 km for WRF-ARW

  9. Old vs New Schedule Retain FOUR routine runs made at the same time every day. Both cores run for one large domain and one small domain. Old Schedule • 00Z : Alaska & Hawaii • 06Z : Western 1/3 CONUS & Puerto Rico • 12Z : Central 1/3 CONUS & Hawaii • 18Z : Eastern 1/3 CONUS & Puerto Rico New Schedule • 00Z : Eastern 2/3 CONUS & Hawaii • 06Z : Western 2/3 CONUS & Puerto Rico • 12Z : Eastern 2/3 CONUS & Hawaii • 18Z : Alaska & Puerto Rico Everyone gets daily high resolution runs if & only if hurricane runs are not needed.

  10. HiResWindow WRF Configurations (No Parameterized Convection)

  11. Online Sites • Matt Pyle’s online site:http://www.emc.ncep.noaa.gov/mmb/mmbpll/cent4km/v2/ • Online Display at NCEP’s Parallel Model Analysis and Forecast page established ~2 July 2007:http://www.nco.ncep.noaa.gov/pmb/nwpara/analysis/ • EMC’s verification 7-day time-series. However, with the lack of runs due to tropical cyclone activity, these are very sparse:http://www.emc.ncep.noaa.gov/mmb/mmbpll/mmbverif.hiresw_new2007/

  12. Pyle Webpage Now Displaying Simulated Reflectivityhttp://www.emc.ncep.noaa.gov/mmb/mmbpll/cent4km/v2/

  13. Mesoscale Detail – this 12 h forecast captures the reflectivity minimum in eastern NY in the lee of the Berkshires/Green Mountains, and some of the enhanced reflectivites in northern CT and extending into SE New York. Albany, NY Radar Image HRW Simulated Radar Reflectivity

  14. Spring Program 2007 NMM4 ARW4 Circles denote locations of rotating updrafts where updraft helicity is at least 50 m2s-2 Observed Composite Reflectivity Courtesy Kain, Weiss & Bright

  15. Forecast Fit-to-Sfc Temperature Obs Observed Operational Parallel ARW for 23-30 August NMM for 18-30 August

  16. Forecast Fit-to-Sfc Wind Obs Observed Operational Parallel ARW for 23-30 August NMM for 18-30 August

  17. Eastern & Western QPF scores Eastern (WRF-NMM), 8/18 to 8/28 Western (WRF-NMM), 8/18 to 8/28* * minimal precip to verify during this period

  18. Longer Duration QPF Verification12 Dec, 2006 – 29 Aug, 2007 (less Feb/Mar) • SPC 4km run serving as proxy for Para HRW because Opnl Central CONUS run is a 12Z run while the SPC run is a 00Z run and they didn’t cover exactly the same domain - so: • Each was independently verified against the NAM (these individual comparisons to the NAM are clean) • The ratio of (ops HRW / NAM) is applied to get a relative score for the ops HRW against the NAM verifying the SPC run. Not perfect, but it levels the playing field.

  19. QPF Verification Summary • Parallel HiResW precip (WRF-NMM core) has comparable to slightly better ETS and a higher bias for heavier precipitation than the current production version. • Improving the high warm season precip bias in the WRF-NMM will become an even more important priority between now and when there are 4 km Alaska & CONUS nests run within the NAM in 2010.

  20. 14 August 2007 Example Case • The HiresW runs (WRF-ARW and particularly the WRF-NMM) provide useful guidance of a convective line sagging south on the morning of 14 August 2007. • Both HiresW runs miss the timing by several hours (too slow), but highlight the possibility of heavy rain that is absent in the NAM forecast. • Ops HiresW WRF-NMM run appears to capture event as well, but without instantaneous precipitation intensity information a direct comparison is impossible.

  21. 09 Z

  22. 10 Z

  23. 11 Z

  24. 12 Z

  25. 13 Z

  26. 14 Z

  27. 14 Z 11 Z

  28. NAM forecast valid 12Z NAM forecast valid 15Z

  29. NMM para hiresw forecast valid 12Z NMM para hiresw forecast valid 15Z

  30. ARW para hiresw forecast valid 12Z ARW para hiresw forecast valid 15Z

  31. NMM ops hiresw forecast valid 12Z 3 h precip NMM ops hiresw forecast valid 15Z 3 h precip

  32. Eastern Region Interest • 21 June, Jeff Tongue wrote: Geoff - This is wonderful information! I'm still not clear on the timeline for the change to the 00 and 12 runs for the Eastern HiRes WIndow? We can wait for OB 8.3 [or] what ever to get the data in AWIPS, but we're wondering when they'll be available on the web? (P.S. I'll subscribe to the [ModelEval] list server - thanks). • EMC will attempt to add the hourly BUFR sounding data Jeff requested here in the near future when we add the hourly gridded output capability for SPC.

  33. SPC Feedback • List of NWS forecasters who participated in the 2007 Spring Experiment for one week each: • Central Region - Matt Bunkers (SOO Rapid City SD) • Western Region - Randy Graham (SOO Salt Lake City UT) • Southern Region - Eric Platt (Forecaster Midland TX) • Southern Region - Ken James (Forecaster Norman OK) • Eastern Region - Steve Zubrick (SOO Sterling VA) • Eastern Region - Paul Sisson (SOO Burlington VT) • Southern Region - Bernard Meisner (SSD SRH Fort Worth TX)

  34. SPC Evaluation: Steve Weisspart 1 • SPC had only limited opportunities to examine the parallel runs of the HRW WRFs during the summer 30 day evaluation period.  • More importantly, however, we have been utilizing the once daily experimental WRF-NMM4 in both the annual Hazardous Weather Testbed Spring Experiment activities and daily operational severe weather forecasting at SPC since April 2004.  • This convection-allowing model was first tested during the 2004 Spring Experiment, which focused on exploring the utility of high resolution versions of the WRF-NMM, as well as WRF-ARW models from NCAR and OU-CAPS, to provide useful guidance for severe weather forecasters.  • Spring Experiments examining WRF-NMM and WRF-ARW models were also conducted in 2005 and 2007, where intensive tests and evaluations were again conducted daily during severe weather episodes across the central and eastern U.S. 

  35. SPC Evaluation: Steve WeissPart 2 • Since 2004, the model has been periodically upgraded, including in early 2007 when NMM physics were standardized, grid length was decreased to 4 km, the domain was expanded, and model run time was optimized.  Most importantly, the early success of the WRF-NMM4 in spring 2004 resulted in the model output being distributed to SPC operational forecasters in real-time, and over the last three years they have evaluated its performance and utility for a wide variety of geographic, seasonal, and synoptic regimes over the central and eastern states.  Most of our attention has focused on the ability of the WRF-NMM4 to resolve smaller scale features such as convective storms through the use of simulated reflectivity fields.  Compared to operational mesoscale models that incorporate convective parameterization, the WRF-NMM4 has been found to provide unique information about details of convective initiation, intensity, evolution, and mode (or morphology), which are critical aspects to severe weather forecasting.  The accurate prediction of convective mode (such as discrete cells, lines, or multicell complexes) is directly related to the occurrence of  tornadoes, large hail, and damaging winds, which tend to occur preferentially with specific convective modes.  In this area alone, SPC forecasters have found that the near-stormscale resolution of the WRF-NMM4 has substantially contributedto more confident and skillful forecasts of specific severe weather threats.  This has been aided by the extraction of gridded information concerning the dynamic structure of model-generated supercell thunderstorms, which are convective storms with persistent rotating updrafts.  The value of the WRF-NMM4 has been especially evident during strongly forced situations that are associated with severe weather outbreaks. (See attached powerpoint file entitled “NWA 2006 WRF-NMM4 Outbreaks” that contains a presentation given at the NWA Meeting in fall 2006.) 

  36. SPC Evaluation: Steve WeissPart 3 • Since late 2006, SPC has had access to a real-time 4 km version of the ARW that is run once daily at NSSL.  SPC forecasters have been using both models in their severe forecasting mission, and have identified various strengths and weaknesses with both models but have learned how to use these performance characteristics to their advantage.  For example, the NMM appears to display a high convective storm/precipitation bias whereas the most recent ARW versions have a slight low bias.  Of course, the convection-allowing WRF models are relatively early in their development and considerable work remains, such as improving physics and development of cutting-edge data assimilation systems that are specifically designed for high resolution models with grid lengths < 4 km.  But we have also seen considerable evidence during the last three years that operational severe weather forecasters at SPC have benefited from the daily availability of the WRF-NMM4 output, and more recently WRF-ARW4 output, and these benefits are reflected in improved SPC forecast products on important severe weather days.  [See the attached powerpoint file entitled “WRF-NMM and WRF-ARW Use at SPC”, which was part of a presentation given at the 2007 AMS WAF/NWP Conference in June]. Furthermore, the increasing number of WFOs running local experimental limited-area WRF models and viewing the WRF-NMM4 online web page strongly suggests that local forecasters believe there are advantages to having routine access to operational high resolution model output. 

  37. SPC Evaluation: Steve WeissPart 4 • After using the WRF-NMM4 in operational severe weather forecasting for more than three years, the SPC strongly supports upgrading the High Res Window slot with the latest versions of the WRF-NMM4 and WRF-ARW5, and running them twice daily at 00z and 12z over an expanded central/east region, and once daily at 06z over an expanded west/central region. • Recommendation: Implement as proposed XXX* * The need for hourly grids “slipped through the cracks” for the HRW upgrade, as we had assumed that the hourly output frequency of Matt Pyle’s experimental run would automatically transfer to the HRW.  We agree with the advice of NCO to implement the proposed version in September and then provide hourly grids early in FY08.  We are concerned, however, that with the approach of the secondary fall severe weather season over the southeast/Ohio Valley region from late October into December, there may be a need to continue Matt’s experimental run until the hourly grids can be implemented in the HRW.  This has been discussed in several email exchanges earlier today with Brent Gordon. • EMC has agreed to continue running Matt Pyle’s experimental run with hourly output until this capability can be added to the Production run.

  38. OSIP / SREC Progress at Silver Spring • OSIP Project 07-012 • Cleared Gate 2 • Directed to SREC • Worked with regions to pare SBN output by 23 May to just over 900mb per cycle • Made list for AWIPS Build OB8.3, then dropped due to ‘resource limitations’ • Accepted as part of OB9

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