2002 Annual

Tuesday, 15 January 2002: 8:44 AM
Using ensembles of numerical weather forecasts for road weather prediction
Paul Schultz, NOAA/FSL, Boulder, CO
Poster PDF (120.5 kB)
The Federal Highways Administration is taking steps to improve the nation's surface transportation system by taking advantage of technological advances in the area of weather forecasting. One FHWA project is aimed at developing computer techniques to help winter road maintenance operators make good decisions about when to plow, when to apply road treatments, etc.

The goal of this project is to create the Maintenance Decision Support System (MDSS). FHWA has engaged six national laboratories to integrate their respective contributions in the areas of weather detection, forecast modeling, forecast information assimilation, road condition forecasting, decision support software, and a graphical user interface. This paper discusses the weather forecast modeling component of MDSS, developed by the NOAA Forecast Systems Laboratory.

The forecast modeling services are configurable. For a real-time demonstration this winter, three regional-scale models (RAMS, MM5, and WRF) will each be initialized and bounded by each of three national-scale models (Eta, AVN, and RUC) provided by the National Weather Service, for a total of nine ensemble members. The concept behind ensemble forecasting is that several equally-likely predictions of an imperfectly-described predictand (in this case, the atmospheric state) can be combined such that the resulting forecast is superior to any single ensemble member. This has been demonstrated on global and national-scale modeling domains, but not yet on regional and local scales. Indications of success and failure should be available for presentation at the Conference.

An ensemble of forecasts can also be used to provide probabilistic forecasts of key predictands such as temperature below freezing, wind in excess of 25 kt, precipitation amounts at several thresholds, the occurrence of snow, etc. This is essential information for the decision support component of MDSS, which gives the user recommendations about what weather-response actions should be taken based on what kinds of weather-related situations that must be considered as possible threats.

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