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Evaluation of The NCEP WRF Nmm and Arw Models For Some Recent High-impact Weather Events


At the last Weather Analysis and Forecasting/Numerical Weather Prediction Conference in Washington, D.C. in the summer of 2005, a number of presentations were made (Session 7) on the Developmental Testbed Center (DTC) Winter Forecast Experiment (DWFE), conducted during the winter of 2005. The goal of that experiment was to run and evaluate two versions of the Weather Research and Forecasting (WRF) model at high resolution (~5-km horizontal grid resolution) on the CONUS scale, and distribute the output in real-time to National Weather Service (NWS) forecasters. Evaluation of the DWFE models by forecasters was generally quite positive, and the overall success of the effort prompted the National Centers for Environmental Prediction (NCEP) to announce, during the conference, that they would start running the two models again on a daily basis. This has been done now since late in 2005, with ~5-km horizontal grid resolution versions of the WRF Nonhydrostatic Mesoscale Model (NMM) and WRF version of the Eulerian Mass core model (ARW) run in four different sub-CONUS windows, each once per day. A set of graphics is distributed via the NCEP web page at and at another web site located at During the past winter we examined the performance of these two new models for a number of cases, comparing the forecasts to the operational North American Mesoscale (NAM) and Global Forecast System (GFS) models. In this paper we will show a couple of the cases, looking at the performance of these models for two highimpact weather events during the winter season. Our focus will be on precipitation forecasts from the operational and high-resolution models. One of the cases will be the first of two major storms that crippled Colorado and nearby states around the Christmas holiday in late 2006, resulting in major travel delays and other critical impacts. A companion paper (Wesley et al. 2007) will examine the guidance at longer ranges from the operational models for this and other Colorado events. We will try to determine whether the high-resolution models provided improved guidance for operational forecasters.

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January 01, 2007

This publication was presented at the following:

22nd Weather Analysis and Forecasting Conference
American Meteorolgical Society
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