Gravity Waves, Lee Cyclones and Precipitation Bands

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9708170 Rauber The proposed research relates to the organization and evolution of phenomena associated with mid-latitude cyclones and their influence on clouds, precipitation and other meteorological elements. Specifically, research will focus on three phenomena: mesoscale gravity waves, lee cyclones, and mesoscale precipitation bands. The high spatial and temporal resolution data sets obtained during the Stormscale Operations and Research Meteorology-Fronts Experiment, Systems Test (STORM-FEST) provides the Principal Investigators with a unique opportunity to further understanding of mesoscale gravity waves. It is suspected that these gravity waves are sometime associated with locally heavy snowfalls. Analyses of observations and ongoing numerical modeling studies will enable the investigation of the mechanisms that generated and maintained a well-defined mesoscale gravity wave that occurred on 14-15 February 1992, as well as the interaction between the wave and the convection. Analyses by the Principal Investigators of observations for four STORM-FEST cyclone cases have raised important questions concerning the variability in the pre-storm low level environment and its influence on the structure and evolution of fronts, embedded precipitation and associated mesoscale phenomena within lee cyclones. Understanding the influence of pre-storm environmental conditions on the formation and subsequent structure and evolution of lee cyclones is critical toward developing a comprehensive model of mid-latitude cyclones. The focus of the proposed research is to investigate the mechanisms behind the variability of the structure and evolution of upper-level precursor disturbances, surface and upper level fronts, lee cyclones, and mesoscale precipitation bands. Research on heavy snowbands will be conducted in association with the Lake-Induced Convection Experiment (Lake-ICE) scheduled in the Great Lakes region in the winter of 1997-98. The Lake-ICE is a large, multi-investigator project that is designed to further understanding of the impact of the Great Lakes on different weather phenomenon. The research activities of the Principal Investigators within Lake-ICE will consist of detailed observational and modeling studies of the evolution of winter cyclones and embedded mesoscale processes as the cyclones interact with the Lakes. Successful completion of this research will lead to better conceptual models of wintertime weather and could eventually lead to better forecasts. ***