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Evaluating High-Resolution Convection Allowing Models for Warm Season QPF Forecasting

This study evaluates the effectiveness of high-resolution convection allowing models in improving warm season Quantitative Precipitation Forecast (QPF) accuracy. The experiment's impact at HPC is discussed, along with future plans for expanding and improving the forecast.

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Evaluating High-Resolution Convection Allowing Models for Warm Season QPF Forecasting

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  1. The Quantitative Precipitation Forecasting Component of the 2010 NOAA Hazardous Weather Testbed Spring Experiment Faye E. Barthold1,2, Michael J. Bodner1, David R. Novak1, Richard Bann1, Robert Oravec1, Bruce Sullivan1, Andrew R. Dean3, Israel L. Jirak3, Christopher J. Melick3, Ryan A. Sobash4, Adam J. Clark5, Fanyou Kong4,6, Steven J. Weiss3, and Ming Xue4,6 1NOAA/NWS/Hydrometeorological Prediction Center 2I.M. Systems Group, Inc. 3NOAA/NWS/Storm Prediction Center 4University of Oklahoma 5NOAA/National Severe Storms Laboratory 6Center for Analysis and Prediction of Storms

  2. Motivation • Flash flooding is a leading cause of weather related deaths in the U.S. • Typically occurs in the warm season • Current operational models don’t handle convection well • HPC threat score lowest in the warm season

  3. QPF Component • GOAL: Determine whether high resolution convection allowing guidance provides added value over the current operational models • Forecasting Activities • Probabilistic 6 hr QPF forecasts • valid at 00Z and 06Z • 0.50” and 1.0” thresholds • Indicate highest possible amount within any 1.0” area • Forecast discussion • Evaluation of experimental forecasts and model performance

  4. High Resolution Model Data

  5. Experimental Ensemble Products • Probability matched mean—combines the spatial pattern of the ensemble mean QPF with the frequency distribution of the rainfall rates to provide a more realistic ensemble rainfall intensity forecast (Ebert 2001) • Ensemble maximum precipitation—maximum QPF from any ensemble member • Neighborhood probabilities—probability of an event within ~80 km of a point

  6. Forecast Valid 00Z 21 May 2010 6hr NSSLQ2 QPE valid 00Z 21 May 2010 NAM12 6 hr QPF (24 hr forecast)

  7. Forecast Valid 00Z 21 May 2010 6hr NSSLQ2 QPE valid 00Z 21 May 2010 WRF-NSSL4 6 hr QPF (24 hr forecast)

  8. Forecast Valid 00Z 21 May 2010 6hr NSSLQ2 QPE valid 00Z 21 May 2010 WRF-NMM4 6 hr QPF (24 hr forecast)

  9. Forecast Valid 00Z 21 May 2010 6hr NSSLQ2 QPE valid 00Z 21 May 2010 HRWE-ARW4 6 hr QPF (24 hr forecast)

  10. Forecast Valid 00Z 21 May 2010 6hr NSSLQ2 QPE valid 00Z 21 May 2010 SREF mean 6 hr QPF (27 hr forecast)

  11. Forecast Valid 00Z 21 May 2010 6hr NSSLQ2 QPE valid 00Z 21 May 2010 SSEF mean 6 hr QPF (24 hr forecast)

  12. Forecast Valid 00Z 2 June 2010 6hr NSSLQ2 QPE valid 00Z 2 June 2010 NAM12 6 hr QPF (24 hr forecast)

  13. Forecast Valid 00Z 2 June 2010 6hr NSSLQ2 QPE valid 00Z 2 June 2010 WRF-NSSL4 6 hr QPF (24 hr forecast)

  14. Forecast Valid 00Z 2 June 2010 6hr NSSLQ2 QPE valid 00Z 2 June 2010 WRF-NMM4 6 hr QPF (24 hr forecast)

  15. Forecast Valid 00Z 2 June 2010 6hr NSSLQ2 QPE valid 00Z 2 June 2010 HRWE-ARW4 6 hr QPF (24 hr forecast)

  16. Results Subjective Verification

  17. Results Objective Verification Courtesy Adam Clark, NSSL

  18. Results Ensemble Products • Ensemble mean—useful, provided a realistic depiction of precip amounts and coverage • Probability matched mean—question about validity of using this technique on a national scale • Future work: recalculate using a regional scheme • Neighborhood probabilities—probabilities often too high and coverage too broad • Future work: recalculate using different smoothing parameters • Ensemble maximum precipitation—not useful, values unrealistically high

  19. Convection-Allowing Guidance at HPC Up to five runs available per cycle • NCEP High Res Window ARW (east & west) • NCEP High Res Window NMM (east & west) • NCEP NMMB (new NAM) • NCEP NMM • NSSL WRF (ARW core) 547 AM EDT TUE JUL 20 2010 VERY FRUSTRATING QPF PATTERN…PIECES OF SHRTWV ENERGY FIRING CNVCTN WHICH THEN…BEGINS TO TAKE ON A LIFE OF ITS OWN…THE BULK OF MODEL GUIDANCE HAS WOUND UP BEING TOO FAR NORTH WITH THE AXIS OF HEAVIEST PCPN. THE HI RES ARW HAS DONE A MUCH BETTER JOB THAN NCEP AND NON-NCEP MODEL SUITES IN SHOWING THIS SRN DISPLACEMENT...

  20. Conclusions • While not perfect, high resolution convection allowing models are useful and can improve warm season QPF forecasts • SSEF represents a transformational improvement in warm season QPF • Experiment impact at HPC • Forecasters interested and using high-res guidance • New data available (WRF-NSSL4 and NMMB nest) • Renewed emphasis on verification of excessive rainfall events

  21. Future Plans • Add the 06-12Z forecast period to capture the nocturnal precip max • Add afternoon forecasting activities • Update the 00-06Z forecast period • Forecast for the 06-12Z forecast period • Expand the available post-processed guidance • e.g., development and evaluation of bias-corrected QPF • Expand hydromet participation • 2010 data available for post-analysis

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