This paper presents results from an ongoing investigation of boundary layer (BL) impacts on the microwave refractivity field and electromagnetic (EM) propagation during the period of a field study at Wallops Island, VA. High-resolution (3 km inner mesh) forecasts have been performed using the Navy’s Coupled Ocean/Atmosphere Mesoscale Prediction System (COAMPS) covering the period 1 Apr-15 May 2000 of this field program and hourly forecast fields archived. Measurements in Wallops-2000 were taken by groups from DOD laboratories, universities, and elsewhere including low-elevation radar frequency pathloss, meteorological conditions (e.g., from buoys, rocketsondes, helicopter profiles), and radar clutter returns (an extensive description of the field campaign appears in TR-01/132 of the Naval Surface Weapons Division, Dahlgren Division by Stapleton et al.). The “Delmarva” or Tidewater Peninsula along which Wallops Island lies (the Chesapeake Bay to the west and the Atlantic Ocean to the east) contains complex topographic and land surface characteristics, as well as pronounced spatial SST variability, all contributing to complex BL structures (e.g., internal BL’s; sea/land breezes; coastal jets). The COAMPS 1.5 month long numerical database is being used to conduct individual case studies of the impact of particular synoptic and mesoscale events upon refractivity and EM propagation. Studies relating to the passage of a synoptic cold front; internal BL development; and sea-land breeze impacts are been developed, and we are now planning a study of subrefractive conditions associated with the warm sector of a synoptic wave. Such subrefractive conditions can significantly reduce the effective propagation range of near surface transmissions.