# Presentation: 734895

## Ensemble Usage in the NWS Central RegionA WFO Snapshot

- Daniel Nietfeld
- Science and Operations Officer
**NOAA/NWS WFO Omaha/Valley Nebraska (OAX)**

## 150 Hour Dew Point GridValid at Noon next Tuesday, Nov. 7th

## NDFD Regional Dew point Valid at Noon next Tuesday, Nov. 7th

***Seamless ***

## Deterministic Snowfall

## 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***

## Directive NWSI 10-506

## TAFsTerminal Aerodrome Forecasts

- Can’t PROB30 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

## 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***

## 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

## 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

## Quick Poll of CR WFOs 

- SREF Web Site Products
- Ensemble products on NCEP web site
- Ensemble MOS
- REMOP

## 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)

## SREF Aviation Products

## SREF PSU Pages

**2 M temperature for one site**

## 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

## Ensemble MOS

## Ensemble MOS

- Roughly 1⁄2 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.

## 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)

## 144 Hr. Fcst Valid 00Z 10/28/2006

## 168 Hr. Fcst Valid 00Z 10/28/2006

## 144 Hr. Fcst Verification

## 168 Hr. Fcst Verification

## 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

## 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

## 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

## 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.

## Convective Forecasts

- 2 KM or 4 KM NCAR WRF-ARW core
- Convective Initiation
- Timing
- Convective Mode
- MCS Motion
- Improve that one model (?)

## Convective Forecast Problems

- 4 KM WRF-ARW

- Observed

## Convective Forecast Problems

- What use is:
- 20 runs
- 1⁄2 initiate convective cluster and 1⁄2 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+

## WFO Experimental Products

- Probability of Exceedence Graphics
- Snowfall amounts
- Freezing Temperatures
- Confidence Graphics
- “Range of Possibility” Graphics
- All experimental, grass roots dabbling