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Getting Beyond Cold Starts: Improving WRF Forecasts with Rapid Refresh Initializations. Cliff Mass and David Ovens University of Washington Seattle, Washington. Is there an easy way to get beyond cold starts?. For many WRF applications, users take either of two routes:

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Getting beyond cold starts improving wrf forecasts with rapid refresh initializations

Getting Beyond Cold Starts:Improving WRF Forecasts with Rapid Refresh Initializations

Cliff Mass and David Ovens

University of Washington

Seattle, Washington


Is there an easy way to get beyond cold starts
Is there an easy way to get beyond cold starts?

  • For many WRF applications, users take either of two routes:

    • Cold start using GFS, ECMWF, or other operational model grids

    • High-resolution data assimilation using local data assets using WRFDA, DART EnKF, or something else.

  • Today, there is potentially another possibility over much of North America: high-resolution initialization using NOAA Rapid Refresh grids.


Mesoscale data assimilation why not let someone else do the hard work
Mesoscale Data Assimilation: Why not let someone else do the hard work?

  • The NOAA/NWS runs the Rapid Refresh (RR) and High Resolution Rapid Refresh (HRRR) systems hourly, completing analyses and short-term forecasts.

    • RR: 13 km grid spacing, 18 hr forecast

    • HRRR, 3-km grid spacing, 15 hr forecast

  • Both make use a wide variety of mesoscale data sources, including radar, satellite, mesonets, soundings, aircraft data, and more.


Getting beyond cold starts improving wrf forecasts with rapid refresh initializations

Rapid the hard work?

Refresh


Getting beyond cold starts improving wrf forecasts with rapid refresh initializations

HRRR the hard work?


Rapid refresh for wrf initialization
Rapid Refresh for WRF Initialization the hard work?

  • My perception is that Rapid Refresh has become substantially more realistic and skillful during the last few years.

  • But one is hard pressed to prove this from stats on their web site!

  • The 3-D grids are available.

  • So why not try using RR grids for initialization of WRF?


June 3 2014 21 utc
June 3, 2014 21 UTC the hard work?

A test: Can mesoscale initialization from RR help with coastal stratus, major problem for the Northwest real-time WRF?


Three runs
Three Runs the hard work?

  • UW Real-time WRF initialized with GFS using YSU PBL, Thompson Microphysics, NOAA LSM, SAS Cumulus Param. ,RRTM radiation

  • UW Real-Time WRF with same physics, but initialized with Rapid Refresh grids

  • WRF with RUC physics and Rapid Refresh initialization (RUC LSM, MYNN PBL, Grell CU, Thompson Micro)


Gfs initialization
GFS Initialization the hard work?





Getting beyond cold starts improving wrf forecasts with rapid refresh initializations

900 6/4/13 at 12UTC


Getting beyond cold starts improving wrf forecasts with rapid refresh initializations

925 6/4/13 at 12UTC


May 20 th 18 utc
May 20 6/4/13 at 12UTCth, 18 UTC



Real time gfs forced
Real-Time GFS-forced 6/4/13 at 12UTC

925


Forced by rr
Forced by RR 6/4/13 at 12UTC

925


Rr init and rr physics
RR Init and RR Physics 6/4/13 at 12UTC

925


Long term tests april may
Long-Term Tests 6/4/13 at 12UTCApril-May


Temperature mae 12 hr forecast
Temperature MAE, 12 hr forecast 6/4/13 at 12UTC

GFS Init

RR Init

RR Init and RR Physics


Dew point mae
Dew Point MAE 6/4/13 at 12UTC


Wind direction mae
Wind Direction MAE 6/4/13 at 12UTC


Wsp mae
WSP MAE 6/4/13 at 12UTC


Conclusions
Conclusions 6/4/13 at 12UTC

  • Initialization with NOAA Rapid Refresh grids does help in initializing shallow low clouds and maintaining them early in the forecasts.

  • Rapid Refresh (RUC) physics package contributes to establishment and maintenance of shallow, stable features.

  • Overall verification for the entire domain (NW U.S. and adjacent waters) for an extended does not suggest much overall improvement.


Conclusions1
Conclusions 6/4/13 at 12UTC

  • The effects of initialization fades over the first day of the forecast, but physics effects remain substantial.

  • Will verify impacts on other seasons before deciding to go with this approach in the operational system.


The end
The End 6/4/13 at 12UTC