Title: Potential Benefit of NOHRSC SNODAS Snow Water Equivalent to RFC Forecasts
1Potential Benefit of NOHRSC SNODAS Snow Water
Equivalent to RFC Forecasts
Tom Carroll
2NOHRSC National Snow Analysis (NSA) Used
Operationally By OHRFC Little Kanawha River
Forecast Group West Virginia 2003 February
Forecast Improvement
NSA Snow Estimate
OHRFC Snow Est.
Statistic
1.5 ft
6.3 ft
RMSE
-1.3 ft
-6.1 ft
Avg Bias
3.7
17.8
Avg Abs Bias
79.2
1.3 ft
6.1 ft
Avg Abs Bias
3Benefits of NSA Products
Use of NSA Information Products at NCRFC
NWS River Forecast System N. Raccoon River, Des
Moines River Basin February 12 - March 11,
2004
NWSRFS without NOHRSC NSA Data
NWSRFS Updated with NOHRSC NSA Data
Original Snow-17 SWE
Increased Snow-17 SWE
Observed Stage
Corrected Forecast Stage
Underestimated Forecast Stage
- Example Two river discharge peaks were observed
but underestimated by NWSRFS - Updating the NWSRFS snow model states with NSA
SWE information corrected the problem.
42004 snow model experiment using operational
forecasts from NERFC, MARFC, OHRFC, and CBRFC.
Objective Assess the potential benefit of SNODAS
snow water equivalent information to operational
RFC forecasts.
5OPS MODEL The traditional RFC run that uses all
available snow information from all available
sources and all SNOW-17 MODS. It is the best
forecast that the RFC can generate using all
available resources.
6MODEL WITHOUT SNODAS The traditional RFC run
using all available snow information to estimate
mean areal snow water equivalent except SNODAS
information.
7MODEL WITH SNODAS Run making a full replacement
of the SNOW-17 water equivalent state variable
with the daily SNODAS estimates of basin mean
areal snow water equivalent.
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9Time Series Plots
- Snow Model Analysis Comparison
- Snow Model 24 Hour Forecast Comparison
- Snow Model 48 Hour Forecast Comparison
- Snow Model 72 Hour Forecast Comparison
- Snow Water Equivalent Analysis Comparison
- Snow Depth Analysis Comparison
- Snow Cover Analysis Comparison
10NERFC
11NERFC
12NERFC
13NERFC
14NERFC
Ice jams can contribute to observed and
forecast differences
15NERFC
16NERFC
17NERFC
18Snow factors affecting a snowmelt hydrograph
simulated by SNODAS
- Snow water equivalent
- Areal extent of snow cover
- Snowmelt
- Air temperature
- Forecasted air temperatures
- Wind speed
- Dew point
- Mean snowpack temperature
- Rain on snow
- Rain on ground
- Sublimation/condensation
19Snow Energy and Mass Balance
Snow-17 Update
Soil Moisture Accounting Model
20Thank you