A Comparison Between the LFM and NGM Models for Forecasting Trapped Cold Air East of the Appalachian Mountains

The National Meteorological Center's (NMC's) new Regional Analysis and Forecast System (RAFS) (National Weather Service, 1985a) has been subjected to intensive pre- implementation testing at NMC (National Weather Service, 1985b). The results indicate that RAFS was generally better than the currently operational Limited-area Fine Mesh (LFM) system, especially for precipitation amount forecasting. The Washington, D.C. National Weather Service Forecast Office (WBC) is cooperating with NMC in evaluating from a field perspective the Nested Grid Model (NGM), which is the forecast model in RAFS. WBC's evaluation, which began in December 1984, is based on forecasters' daily, subjective scrutiny of the NGM and is concerned with NGM performance mainly in the vicinity of WBC's area of forecast responsibility.