9403636 Ulrickson Many times weather of interest to the public are controlled by factors that are very local in nature. The researchers will study the climatology and dynamics of a low-level easterly flow in the Spokane, Washington vicinity that occurs beneath a regional westerly flow at least a few days each month and in all seasons of the year. Synoptic-scale analyses of weather observations indicate that the environmental flow should be westerly at all levels; therefore, the factors controlling this reverse flow must exist locally, or on the mesoscale. These winds are of more than academic interest. The significance lies in several effects: (1) the easterlies modify temperatures and dew points; (2) when mountain fogs form, the easterlies transport them into the Spokane area; (3) the area's frequent surfaced-based inversions, which strongly influence regional air quality and controls, are modified; (4) because of their diurnal occurrence, the easterlies affect air traffic control; (5) these winds influence the transport of suspended particles and airborne chemicals. The Principal Investigators will attack this problem using climatological and diagnostic studies as well as a mesoscale numerical model. They also will collaborate with forecasters at the local National Weather Service Office with the intent of formulating methods for improved prediction of these episodes. ***
