Medium-Range Ensemble Forecast Tools at the Weather Prediction Center
Bill Lamberson, WPC/IMSG, College Park, MD
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Abstract
The Weather Prediction Center (WPC) currently provides national forecasts of heavy rainfall, snowfall, and hazardous weather out to 7 days. Currently, WPC is experimenting with extending daily forecasts farther out in time (perhaps as far as 10 days). These 8 – 10 day forecasts will rely heavily on ensemble forecasts as they can capture the range of possible forecast scenarios and also give an indication of each scenario’s likelihood. In preparation for potentially extending WPC forecasts farther out in time, WPC has taken the initiative to create a public-facing website that contains ensemble tools that help forecasters visualize and process ensemble forecasts. These tools place particular emphasis on the early recognition of potentially hazardous weather events. These tools are currently used in operations at WPC and in the preparation of experimental 8 – 10 day forecasts.

Past experience has shown that comparing an ensemble forecast to a climatology from a reanalysis dataset (e.g., Climate Forecast System Reanalysis), or the model’s own internal climatology is an effective and efficient way to recognize the potential for hazardous weather events at longer lead times. Consequently, most of the tools on the website involve comparing the ensemble forecast to a reanalysis climatology or the model’s own internal climatology. The development of these tools has been a collaborative effort between meteorologists at WPC and the research community. This presentation will provide an overview of the products currently available on the website and how they can be used in operational forecasting.