83rd Annual

Thursday, 13 February 2003: 2:45 PM
An Analysis of Verification Statistics Used at NWS River Forecast Centers
Neftali (Lee) Cajina, NOAA/NWS, Silver Spring, MD; and E. Welles
The National Weather Service (NWS) has started verifying river forecasts issued at River Forecast Centers (RFCs) across the country. To help the RFCs in the verification process, the Office of Hydrologic Development (OHD) developed the Interactive Verification Program (IVP), which provides tools for completing the verification process in a single environment. IVP uses a variety of statistics to measure accuracy and discrimination of forecasts. One of the first steps for computing most of the verification statistics in IVP is to define intervals for partitioning the data into categories based on stage. Determining these intervals is often a subjective decision that may affect the verification results. OHD recently initiated an analysis to evaluate the sensitivity of how the data are partitioned. This initial analysis focuses on three statistics that measure accuracy in IVP (probability of detection, under forecast rate, and over forecast rate) and the discrimination score (Brown et. al 1989) that measures discrimination between forecasts. The results of the analysis will provide insight into the strengths and weaknesses of these statistics, and give forecasters a better idea of which ones are useful for verification.

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