Application of Forecast Verification Science to Operational River Forecasting in the National Weather Service. Julie Demargne, James Brown, Yuqiong Liu and D-J Seo. UCAR. NROW, November 4-5, 2009. Approach to river forecasting. Observations. Forecasters. Models. Input forecasts. Users.
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Julie Demargne, James Brown,
Yuqiong Liu and D-J Seo
NROW, November 4-5, 2009
Major river system
River basin with river forecast points
High resolution flash
Headwater basin with radar rainfall grid
Hydrologic forecasts must be verified consistently across all spatial scales and resolutions.
MinutesHydrologic forecasting: a multi-scale problem
Forecast Lead Time
Protection of Life & Property
Flood Mitigation & Navigation
Seamless probabilistic water forecasts are required for all lead times and all users; so is verification information.
http://www.nws.noaa.gov/oh/ rfcdev/docs/ Final_Verification_Report.pdf
River forecasting system
To be evaluated by forecasters and forecast users
Min.Diagnostic verification products
American River in California – 24-hr precipitation ensembles (lead day 1)
Zero error line
Forecast error (forecast - observed) [mm]
Observed daily total precipitation [mm]
Performance for different months
Performance under different conditions
“Hit rate” = 90%
60% of time, observation should fall in window covering middle 60% (i.e. median ±30%)
Live forecast was too high
Live forecast (L)
Analog forecasts (H):μH = μL ± 1.0˚C
“Day 1 forecast is probably too high”
Forecast lead day
Requires forecasters’ input!
collaboration on training
OHD-Deltares collaboration for CHPS enhancements
HEPEX Verification Test Bed
(CMC, Hydro-Quebec, ECMWF)