WRF Ensemble Model Performance during Atmospheric River Events in

California

Edward Tollerud1,5, Tara Jensen2,5, Huiling Yuan1,3, John Halley Gotway2,5, Paul Oldenburg2,5, Isidora Jankov1, Wally Clark4, Ellen Sukovich4, Gary Wick4, and Randy Bullock2,5

1 ESRL/GSD, Boulder, CO 2 NCAR/RAL, Boulder, CO3 CIRES, Boulder, CO 4 ESRL/PSD, Boulder, CO

5Developmental Testbed Center

Acknowledgments to the USWRP for funding

AGU 2010

Research Objectives: HMT and DTC

AGU 2010

DTC – Evaluate present and future and EMC operational models

HMT – Evaluate forecast values of regional ensemble forecast system

Principal focus on QPF

Investigate impact of verification data choices

DTC - Build demonstration realtime web display and examine standard and state-of-the-art verification methods

Precipitation during 1200 UTC 20 January – 21 January 2010

(Note poor observing network in Nevada)

Four days of heavy rainfall: 1/17-1/21

Cumulative Rainfall at ATA, 1200 UTC 17 Jan – 21 Jan

WRF ensemble member forecasts

The Forecast Prospect: Dealing with uncertainty

AGU 2010

WRF ensemble mean

GFS

Obs at ATA – 240 mm

The Forecast Prospect: Selecting NWP Guidance

AGU 2010

FY 2010 HMT-West: Demonstration Website

Basin-specific and RFC-specific verification domains installed

Assessment of ensemble member QPF possible in near real time; verification dataset options available

30-day boxplots provide statistical summary of model QPF performance

AGU 2010

ETS for January

Large day-to-day variability related to rainfall amount; extensive rain means better scores

RMSE for January

Large rainfall means larger errors

AGU 2010

AGU 2010Full-season statistics – Gilbert Skill Score – All events

30-day summary scoring for January, ETS

GFS degradation at higher thresholds

‘Quirky’ scores for verification using Stage IV analysis: Nevada impact

AGU 2010Score Idiosyncracies and Data Impacts

GSS for QPF Threshold > 0 inches Aggregated for January

for lead times 6-114 h

FAR for QPF Threshold >0.1 inches Aggregated for January

for lead times 6-114 h

AGU 2010

MODE/MET objects: Spatial Verification for ensemble QPF fields

In the pipeline: timeseries plots of quantitative attributes scoresSee Clark poster in afternoon session of more MODE applications

AGU 2010

Profiler Winds at Bodega Bay

Diurnal cycling of winds, from southerly to westerly (upslope); how well to models perform?

January 18

January 19

Full explanation and diagnosis could use wind field verification as well as QPF verification

Summary and Future DRTC /HMT Plans

• General Assessment from one field season: WRF ensemble mean at higher resolution than GFS performs better with most scoring metrics (not statistically scrutinized yet…..)

•This season’s real-time web display will include probabilistic scoring and other operational models (NMMB, RRR, SREF,…)

•HMT hypotheses for DTC testing: Best model for guidance, value of ‘hotstart’ analyses, value of ensemble forecast methods

• New direction for 2011: Assess operational and research model microphysical forecasts with HMT-West research observations

Final Thought: UNCERTAINTY, UNCERTAINTY, UNCERTAINTY (forecasts) (observations) (verification)

AGU 2010