Tuesday, 11 February 2003: 9:00 AM
Short-term radar nowcasting for hydrologic applications over the Arkansas-Red River basin
The accuracy of hydrologic modeling results relies heavily on the
quality of the precipitation estimates or forecasts used to drive
a rainfall-runoff model. For short lead-times (0-3 hours), short-term
extrapolation is considered to have higher forecast skill as compared
to other available methods. To provide forecasts with high
spatial and temporal resolution, this paper presents the use of an
algorithm for short-term quantitative precipitation forecasts (QPFs)
of two NEXRAD-based data products (Stage III and WSI). The chosen
extrapolation model is the MIT Lincoln Laboratory Growth and Decay
Stormtracker (GDST). This model utilizes a scale separation filtering
process to accurately track the large scale, envelope motion of the
storm. Several different storm cases varying in spatio-temporal
organization have been selected from archived radar data for the
Arkansas-Red River Basin over the 1998-2001 period. Results from
radar extrapolation using the GDST are evaluated using
the Critical Success Index (CSI) as a base statistic. The CSI concept
is expanded to use larger verification areas, as well as thresholds to more accurately demonstrate forecast performance.
Analysis results show that the short-term forecasts are useful for
hydrologic forecasting, with neighborhood CSI scores greater than 50%
for a 2 hour forecast and greater than 65% for a 1 hour forecast.
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