COAMPS^TM is the Navy's mesoscale prediction system. It was developed by the Marine Meteorology Division of the Naval Research Lab (NRL-MRY) and is implemented at the Fleet Numerical Meteorological and Oceanographic Center (FNMOC) to provide analyses and forecasts of mesoscale phenomena such as coastal winds, fronts, squalls, and other organized convection. One of the operational COAMPS^TM instances is a doubly nested (81/27 km) area covering the eastern North Pacific Ocean and U.S. 48 hour forecasts are made twice daily, using a 6-h update cycle for data assimilation.

This paper will investigate the ability of COAMPS^TM to resolve frontal passages across the west coast of the United States. Specifically, the timing and pre and postfrontal low-level wind flows will be evaluated against available observational data and/or model analyses. The emphasis will be on fronts associated with winter storms since frontal structure, including temperature gradient and directional and/or speed shear are generally most clearly defined during these events. The other area of investigation will include COAMPS^TM performance in forecasting the timing, areal coverage, and intensity of pre and postfrontal precipitation. The wealth of observational data collected through CALJET and/or PACJET experiments will aid the evaluation of COAMPS^TM performance.