The National Precipitation Verification Unit (NPVU): Operational implementation

The U.S. Weather Research Program and the National Weather Service (NWS) have identified precipitation estimates and forecasts as a priority for improvement in the operational and research communities. Objective assessment and quantification of the skill of quantitative precipitation forecasts (QPFs) in the NWS QPF process are necessary to identify the value added at each step and to assist in improving the forecasts. As a result, the NWS has outlined a uniform national precipitation verification program and created the National Precipitation Verification Unit (NPVU) to fulfill these requirements. The NPVU will become operational by October 2000. 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 QPFs and associated products. The success of the program is dependent upon the real-time availability of all QPFs and high-quality precipitation estimates.

The (prototype) NPVU participated in the NWS QPF Process Assessment (1998-1999) and the Western Region Follow-On Assessment (1999-2000) by providing objective QPF verification. QPF verification methodologies and results from these assessments have already been presented. However, real-time application of these verification methodologies are being incorporated into the daily procedures of the NPVU via an Operational Test and Evaluation (OT&E). An overview of the QPF verification methodologies, including data acquistion and presentation of results, will be illustrated to indicate the scope and magnitude of the national QPF verification program. QPF verification results from July - December 2000 will be shown. Also, future plans for the NPVU will be provided.

It has previously been shown that QPF verification statistics at the Hydrometeorological Prediction Center (HPC) have helped to improve QPF forecasts in various weather regimes. These results are heavily scrutinized in precipitation extreme events, such as intense winter storms, land-falling tropical cyclones, and strong convective systems. The NPVU will thus be providing QPF verification for the entire NWS, from the NWP models to the HPC to River Forecast Centers to Weather Forecast Offices, and have the ability to provide real-time QPF verification statistics of precipitation extreme situations.