TWCA 2017 Annual Conference

1. The National Water Model and the
NWS West Gulf River Forecast
Center
Gregory Waller
Service Coordination Hydrologist
NWS – West Gulf River Forecast Center

2. NWS Mission
To provide weather, water, and climate data, forecasts and
warnings for the protection of life and property and enhancement
of the national economy.
NWS accomplishes this mission in close collaboration and cooperation
with State, Local, and Other Federal Agencies

3. The WGRFC Area
Diverse Water Issues
402,000 mi2 total area
87,000 mi2 in MX (Rio Grande headwaters)
320 forecast points, 15 major river systems
Over 65,336 miles of rivers (U.S. only)Snowpack
Water supply
• Hill Country Hydrology
• Flash flood threats
• Rapid river responses
• Cycles of Flood/Drought

4. Now…The Hydrologic Cycle
Courtesy of the USGS Water Science School

5. The Meteorology
• Past rainfall
– Hourly
– 4km grid
• Future rainfall
– 6 hourly
– Blend of model and human
– At West Gulf RFC, we routinely use 12 hours of
future rainfall in our hydrologic forecasts (can
extend on rare occasions)

6. Precipitation Best Estimate
• 4km x 4km spatial resolution
• 1 hour temporal resolution
• Human quality control of
data inputs
Gauge
Radar
Satellite
Best Estimate (Multi-
sensor Field)
Satellite

7. Precipitation Forecast/QPF
• 4 km x 4 km spatial resolution
• 6 hour temporal resolution
• 72 hours (12 periods) processed
– RFCs ingest 6-24 hours (1-4 periods)
operationally in hydrologic models
– Additional periods ingested based on
confidence in forecast
Guidance forecast issued by
National Center
Forecaster at RFC makes
adjustments based on local
expertise

8. The Hydro Model
• Community Hydrologic Prediction System
• Hydrologic Model
– Think “more math, less physics”
– Has capability of “plugging in” other models

9. Hydrologic Forecast Process
• A lot of estimates…
– Estimate how much rain gets into the river
• Rainfall to Runoff
– Estimate timing (how fast) of runoff to the river gage
• Unit Hydrograph
– Estimate how fast any upstream water arrives at the
gage
• Routing
– Estimate water flow (we use) into water height (the
public uses)
• Rating
• We can modify any/all of the above

10. Soil Accounting Model
Output
5cm
10cm
20cm
50cm
100cm
Fractional Water Content
at Depth
RDHM SacHT
Output

11. The Result – Our Model

12. Precipitation estimates and
forecasts merged into
continuous dataset
Precipitation dataset ingested
into hydrologic model.
Forecasters adjust model
parameters in real time
River forecast issued to
public
Rainfall
Analysis
Hydrologic
Modeling
Forecast
West Gulf River Forecast Center

13. Operational Evolution
• The National Water Center
• University of Alabama
• Bring federal water partners together…

14. The Change in Texas
102,000 NHDPlus reach catchments for Texas
Average area 7.1 km2
Average reach length 3 km
The Future…
NHDPlus reach catchment
Uniquely labeled across nation
• 15 Forecast Groups
– 320 Forecast Locations
– Almost 600 Modeled Watersheds
Now…

16. Timelines and Stuff
• Short Term
– Uses HRRR (High Resolution Rapid Refresh) QPF
– Out 15 hours (soon to be 18 hours in April)
– Ran hourly
• Medium Term
– Uses GEFS (Global Ensemble Forecast System) QPF
– Out 10 days
– Ran once per day (soon to be run 4 times daily in April)
• Long Term
– Uses bias corrected CFS (Climate Forecast System) QPF
– Out 30 days
– Ran once per day

17. Meteorology Inputs

18. WRF-Hydro Forecasting
Model
Runoff
Streamflow
RAPID flow routing (for continental US)
Probabilistic flood forecastsWeather model and forecasts (HRRR)
Land-Atmosphere Model (NOAH-MP)
PrecipitationWeather
Catchment-level
forecasts

19. National Water Model

20. The NWM

21. Drill Down…

22. Anomalies

23. Output from the NWM
• Output from model is here
– http://nomads.ncep.noaa.gov/pub/data/nccf/com/nwm
or
– ftp://ftpprd.ncep.noaa.gov/pub/data/nccf/com/nwm
• Geospatial data is here
– ftp://ftp.nohrsc.noaa.gov/pub/staff/keicher/WRFH_ppd/w
eb/NWM_nc_tools.tar.gz

24. How We Stay S.A.

25. Another Tool in the Toolbox
• Will be able to provide streamflow information at
“intermediate” points
• Higher resolution grids
• Expansion of flood inundation maps
• Requires verification and validation – ongoing at RFCs
• Operational August 2016
• http://water.noaa.gov/map
• IMO, expect full capability with 5 to 10 years

26. Questions/Comments?
Gregory Waller
Service Coordination Hydrologist
NWS West Gulf River Forecast Center
greg.waller@noaa.gov