Author(s): Bryce Finnerty; Dennis Johnson

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Keywords: No Keywords

Abstract: Historically, hydrologic forecasts and calibration of the National Weather Service (NWS) hydrologic models are typically prepared using inputs of 6-hour mean areal precipitation (MAP) estimates derived from rain gage networks. However, operational hydrologic forecasts can now be prepared using 1-or 6-hour MAPs derived from high resolution gridded precipitation estimates from the NWS Next Generation Radar system, NEXRAD. An initial analysis of 7 months (May 1993-December 1993) of 1-and 6-hour operational MAP time series for nine basins revealed differences between the gage and radar MAPs in the long term accumulations, individual storm totals, and timing of events. The 7-month radar MAP accumulations were 10-25 percent less than the gage MAP accumulations. The 6-hour radar and gage MAPs had similar estimates of the timing of events, but the 1-hour radar and gage MAPs showed more discrepancies in the timing of events. The radar MAPs captured more of the variability in the precipitation fields than the gage MAPS at the 1-hour time step. However, the variability of the radar and gage MAPs was nearly equal at the 6-hour time step.

DOI:

Year: 1997