The Consumer Option for an Alternative System to Allocate Losses (COASTAL) Act requires a time history of mean wind, wind gust, surface pressure and air-sea temperature difference (atmospheric stability, AS) over the area impacted by a land falling tropical cyclone in order to estimate the strength and timing of damaging winds and also to force wave and surge models. Near-surface (10 m) wind and surface pressure analyses are produced hourly at 2.5 km resolution by the operational NWS Un-Restricted Mesoscale Analysis (URMA) that uses the same software as the Real-Time Mesoscale Analysis (RTMA) but operates on a time delay to allow more data to be gathered. For near-shore oceanic environs, in the presence of tropical storms and hurricanes, the operational Hurricane Weather Research and Forecast (HWRF) system can be used in retrospective (historical) mode to generate the URMA background field. The HWRF executes operationally at 2 km resolution near the tropical cyclone’s center where the strongest winds are usually found. The URMA and HWRF systems can provide a consistent starting point for the NSEM wind analyses since they are of comparable resolution.

A two-year effort will generate wind and surface pressure analysis by running the HWRF system retrospectives for the selected storms. HWRF will provide the background fields while URMA will perform the mean wind, gust, and surface pressure and AS analyses (detailed under a separate SOW for COASTAL ACT).