Ensemble Usage in the NWS Central Region A

Ensemble Usage in the NWS Central Region A WFO Snapshot Daniel Nietfeld Science and Operations Officer NOAA/NWS WFO Omaha/Valley Nebraska (OAX) NOAA/NWS WFO Omaha Nebraska

150 Hour Dew Point Grid Valid at Noon next Tuesday, Nov. 7 th NOAA/NWS WFO Omaha Nebraska

NDFD Regional Dew point Valid at Noon next Tuesday, Nov. 7 th NOAA/NWS WFO Omaha Nebraska

Deterministic Snowfall NOAA/NWS WFO Omaha Nebraska

That’s how we spend our 8 hour shift • ~ 950 to 1000 gridded forecasts – Individual forecasts – Deterministic forecasts • All collaborated to be in “agreement” with our 6 surrounding sites NOAA/NWS WFO Omaha Nebraska

Directive NWSI 10 -506 NOAA/NWS WFO Omaha Nebraska

TAFs Terminal Aerodrome Forecasts • Can’t PROB 30 within first 9 hours • Users want deterministic – Don’t forecast thunder unless you’re very confident – Don’t forecast LIFR unless we’re very confident – Don’t want high false alarm ratios – Desire short, quick products NOAA/NWS WFO Omaha Nebraska

Standard Phone Call • “How much snow we gonna git? ” - caller • “Did you check the forecast on the web? ” - fcstr • “Yep – somethin about 70% chance for snow, with 2 to 4 inches possible. I gotta plow if there’s 4, but I don’t if there’s 2. How much snow we gonna git? ” - caller • “You’ll get 3. ” - fcstr • “Thanks for the information. ” - caller Note: I can’t train the caller NOAA/NWS WFO Omaha Nebraska

We See a Need for BOTH • Still some need to provide simple, deterministic forecasts • We clearly see the need for more probabilistic forecasts • We WANT to provide more probabilistic forecasts NOAA/NWS WFO Omaha Nebraska

WFOs Use of Ensembles • We are directed to produce LOTS of deterministic forecasts • That directive shapes and drives the WFO’s use of ensembles • Officially, we use ensembles to come up with the best deterministic number NOAA/NWS WFO Omaha Nebraska

Quick Poll of CR WFOs • • SREF Web Site Products Ensemble products on NCEP web site Ensemble MOS REMOP NOAA/NWS WFO Omaha Nebraska

SREF Products • Most survey respondents utilize daily – Some WFOs consider SREFs “essential” • Aviation products used most • Web based only • Winter AWOC Course will result in more SREF usage (Plume maps) NOAA/NWS WFO Omaha Nebraska

SREF Aviation Products NOAA/NWS WFO Omaha Nebraska

NOAA/NWS WFO Omaha Nebraska

SREF PSU Pages 2 M temperature for one site NOAA/NWS WFO Omaha Nebraska

Ensembles on the Web (in general – all sources) • Most survey respondents use daily – Many WFOs consider some products “essential” – Mean/Spread, spaghetti, etc. . • Penn State “Eyewall” site preferred • Screaming for more on AWIPS • Canadian ensemble web site used frequently and like the individual solution maps NOAA/NWS WFO Omaha Nebraska

Ensemble MOS NOAA/NWS WFO Omaha Nebraska

NOAA/NWS WFO Omaha Nebraska

Ensemble MOS • Roughly ½ respondents utilize Ens. MOS • Ensemble MOS Mean Mx/Mn – be careful! Poor performance during those high impact events. Focus on the top/bottom ends for “near record” patterns. • Ensemble MOS from SREFs? Some would like to see this. NOAA/NWS WFO Omaha Nebraska

Relative Measure of Predictability REMOP • Those who are aware of it seem to use it regularly • Many are NOT aware of it • “Simple” yet very informative (operationally good) NOAA/NWS WFO Omaha Nebraska

144 Hr. Fcst Valid 00 Z 10/28/2006 NOAA/NWS WFO Omaha Nebraska

168 Hr. Fcst Valid 00 Z 10/28/2006 NOAA/NWS WFO Omaha Nebraska

144 Hr. Fcst Verification NOAA/NWS WFO Omaha Nebraska

168 Hr. Fcst Verification NOAA/NWS WFO Omaha Nebraska

Ensemble Usage • High Amplitude Patterns – Don’t like to see HPC lean towards ensemble mean because it supports a low amplitude solution – Ensemble Mean – Dampened amplitude pattern • Intelligent use of ensembles – needs to be part of the training NOAA/NWS WFO Omaha Nebraska

What’s Wrong with Web ? • Slow connections, thus slow graphics loading • Can’t import into GFE • Can’t interact with the graphics – Like to diagnose why the surface low bombs through overlaying PV, or overlaying Q-vectors, or cutting a cross section of frontogenesis, etc… • • Can’t zoom Ensembles MUST be incorporated into AWIPS ! We currently only get 84 hrs of GFS ensembles NO SREFS, NO GFS > 84 hrs, nothing else NOAA/NWS WFO Omaha Nebraska

WFO Perspective • What’s the goal? We use ensemble spread to give us confidence in our deterministic forecast, and to come up with the best deterministic forecast • Especially to deviate from climatology several days out (ie. Day 7), low spread provides more confidence to deviate more • We love the AFD NOAA/NWS WFO Omaha Nebraska

Forecaster Workload • At Omaha (and other WFOs), we dedicate a Forecaster to the Days 4 -7 period, to sort through the enormous amount of forecast information. NOAA/NWS WFO Omaha Nebraska

Convective Forecasts • 2 KM or 4 KM NCAR WRF-ARW core – Convective Initiation – Timing – Convective Mode – MCS Motion • Improve that one model (? ) NOAA/NWS WFO Omaha Nebraska

Convective Forecast Problems 4 KM WRF-ARW NOAA/NWS WFO Omaha Nebraska Observed

Convective Forecast Problems • What use is: – – 20 runs ½ initiate convective cluster and ½ don’t Timing between noon and 6 pm Movement from NW to SW • We probably already know all of the possibilities • Need solid agreement and low “spread” • Like the SPC usage for Days 2+ NOAA/NWS WFO Omaha Nebraska

WFO Experimental Products • Probability of Exceedence Graphics – Snowfall amounts – Freezing Temperatures • Confidence Graphics • “Range of Possibility” Graphics • All experimental, grass roots dabbling NOAA/NWS WFO Omaha Nebraska