Performance of operational HWRF for 2009 season and upgrades for 2010 implementation

1. Performance of operational HWRF for 2009 season and upgrades for 2010 implementation 64th Interdepartmental Hurricane Conference 3rd March 2010, Savannah, GA Vijay Tallapragada and the HWRF team Bill Lapenta, Steve Lord, Naomi Surgi, Qingfu Liu, Young Kwon, Zhan Zhang, Robert Tuleya, Janna O’Connor, and Sam Trahan Environmental Modeling Center National Centers for Environmental Prediction 5200 Auth Road, Camp Springs, MD 20746. 1

2. Outline • 2009 HWRF end-of-the-season performance • Atlantic 2009 • East-Pac 2009 • Testing & Evaluation for 2010 HWRF Implementation • New baseline configuration (H050) • Changes to initialization (H051) • Surface Physics changes (H052) • Gravity Wave Drag parameterization (H053) • Combination of individual components (H054) • GFS Phase2 upgrades (H056) • Extensive and systematic testing • 610 cases from 2008/2009 Atlantic and East-Pac (tested individually for each configuration) • Close collaboration with NHC 2

3. Average Track Error Statistics for 2009 Atlantic N-S Track Bias GFDL 50nm Better than HWRF at 96h E-W Track Bias 3

4. Intensity Error Statistics for 2009 Atlantic HWRF and GFDL intensity errors grow rapidly Intensity Bias 4

5. Hurricane Bill HWRF Tracks and Intensity Tracks are clustered tight, intensity has some fluctuations 5

6. TS Erika HWRF Tracks and Intensity sheared storm with northward track bias and +ve intensity bias 6

7. Operational HWRF GFS Analysis 7 HWRF fails to simulate increased shear in the environment

8. Track Error Statistics for 2009 East-Pac N-S Track Bias GFDL better than HWRF E-W Track Bias 8

9. Average Intensity Error Statistics for 2009 East-Pac HWRF and GFDL intensity errors grow rapidly (similar to Atlantic) Bias 9

10. Hurricane Carlos northward track bias and trouble predicting intensity fluctuations. Hurricane Felicia negative intensity bias. 10

11. Preparation for 2010 implementation • Define new baseline configuration for HWRF (H050: bug fixes + GFS Phase-1) • Proposed upgrades include: • H051: Changes to initialization (Additional data in GSI near the storm environment) • H052: Surface Physics Changes (Cd/Ch coefficients calculated based on observations) • H053: Gravity Wave Drag Parameterization • H054: Combination of all three above • H056: H054 with GFS Phase 2 data • Test cases include: • 2008 Atlantic – Cristobal, Dolly, Fay, Gustav, Hanna, Ike and Omar • 2008 East Pac – Elida, Fausto, Genevieve, Marie, Norbert • 2009 Atlantic – Bill, Claudette, Danny, Erika, Fred, Henri and Ida • 2009 East Pac – Felicia, Guillermo, Hilda, Ignacio, Jimena, Linda, Olaf and Rick • Total about 610 cases 11

12. FY2010 HWRF Testing Schedule 12

13. Improvement in track errors from changes to initialization H054 retained the skill improvement seen in H051 13

14. Improvement in intensity errors from changes to surface physics Retained skill improvement seen in H052 (except at 120hrs, mainly due to Gustav) 14 14

15. H054 retained the skill improvement seen in H051 and H053 15

16. H054 retained the skill improvement seen in H052 16

17. Skill improvement beyond 96hrs Frequency of superior performance is another indicator of the positive impact of proposed upgrades on HWRF forecast skill 17

18. Summary • 2009 Atlantic Hurricane season exposed some serious issues with HWRF forecast skill. • Failed to respond to large-scale shear • While Atlantic track errors suffered from southward and eastward bias (along track), intensity forecasts exhibited huge positive bias • East-Pac track errors also had similar increased southward and eastward bias, intensity errors showed mixed response to different storms • Improved track and intensity forecast skill from proposed upgrades for 2010 implementation • Fixing known bugs in HWRF model (mostly related to radiation) led to redefining baseline configuration of HWRF (scientifically correct) • Suggested upgrades based on improved initialization, surface physics, parameterization of gravity wave drag and mountain blocking showed promising results. • Extensive and systematic testing and evaluation of individual upgrades and their combination in close collaboration and guidance from NHC • Combining individual upgrades generally resulted in retaining improved track forecast skill from initialization changes and improved intensity forecast skill from surface physics changes 18

19. Moving forward…. • HWRF model Diagnostics • Evolution of large-scale flow in HWRF model • Sensitivity of model storm to environmental shear • Interactions of convection-clouds-radiation-microphysics • Scientific advancements • Increased resolution, with the possibility of including 3rd nest • Coupling to HYCOM and Wave-WatchIII • Improvements to PBL, radiation and microphysics • Improvements to vortex initialization • Partnerships and collaborations • Move to more advanced (current) WRF infrastructure (V3.2) - DTC supported R2O – O2R mechanism • Take advantage of HFIP funded research in improving operational HWRF system • Active collaborations with DTC, HRD, ESRL, URI, CIRA, UMD and others 19

20. Thanks for your attention. • Questions? 20