9612485 Bosart The U.S. Weather Research Program (USWRP) is an interagency activity designed to perform and implement the research necessary to improve the delivery of weather services to the nation. Under this Program, the National Science Foundation and the National Oceanic and Atmospheric Administration are jointly evaluating and supporting research of high priority to the USWRP. The objectives of this research are to understand the mechanisms controlling two difficult forecasting problems: intensity changes in hurricanes prior to landfall, and the precipitation they produce after landfall. These two problems often have a conceptual connection, in that interactions of the hurricane with middle latitude phenomena (fronts and/or synoptic scale mobile troughs) can produce sudden intensification of a hurricane prior to landfall, or heavy precipitation after landfall. It is these middle latitude interactions that will be the focus of this research. Of particular interest are (i) the processes by which upper tropospheric troughs interact with hurricanes, with the goal of describing what determines whether an interaction will intensify or weaken the hurricane; and (ii) the dynamic and thermodynamic characteristics that control the amount and distribution of precipitation after landfall. In addition to increased fundamental understanding of the nature of landfalling hurricanes, a potential outcome of the work will be an identification of common signatures of the potential for sudden deepening or localized flooding by tropical cyclones in time to give adequate warnings. ***
