The NWS National QPF Verification Program

The U.S. Weather Research Program and the National Weather Service (NWS) have recently identified precipitation estimates and forecasts as a priority for improvement in the operational and research communities. Objective assessment and quantification of the skill of precipitation forecasts in the NWS end-to-end forecast process are necessary to identify the value added at each step of the process and to assist in improving the forecasts. However, no such program currently exists. Thus, the NWS has recently outlined a uniform national precipitation verification program and created the National Precipitation Verification Unit (NPVU) to fulfill these requirements. Verification statistics from the NPVU will serve to support NWS programmatic decisions and NWP model changes, provide feedback to individual forecasters and forecast offices, and ultimately improve precipitation forecasts and associated products for outside users. The success of the program is dependent upon the real-time availability of all precipitation estimates and forecasts.

The conceptual outline of the national precipitation verification program will be presented. Recent verification statistics from the HPC's 06-h, 24-h, and 5-day precipitation forecasts will be discussed. Also, the verification methodology and results from the NWS QPF Process Assessment Team report will be shown. It is believed that these results are the first known verification statistics computed for the complete end-to-end forecast process. Preliminary efforts at the NPVU indicate the need for format standardization of precipitation forecasts, higher quality precipitation estimates for verification, and more robust and informative verification measures.