Warm Season Convective Weather Systems over the Great Lakes and Vicinity

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The focus of this research is on continued studies of organized convective weather systems that occur primarily during the warm season in the vicinity of the Great Lakes. Specifically, the research is targeted at mesoscale convective systems (MCS) and embedded mesoscale convective vortices (MCV) as well as intense quasi-linear convective systems know as derechos. Derechos often appear as bowing line segments in operational Doppler radar imagery. Derechos and MCVs were the major focus of the Bow Echo and Mesoscale Convective Vortex Experiment (BAMEX). The research builds on opportunities from BAMEX. Specific research tasks include: 1) establish how the vorticity fields associated with the MCV and the triggering upper-level disturbance reorganize and scale upward after deep convection begins, 2) assess MCS/derecho life cycle sensitivity to the structure of the triggering upper-level forcing disturbances and the extent of surface boundary, pre-existing and convectively driven, interactions, 3) investigate MCV/MCS/derecho structure and life cycles through new diagnostic analyses that take advantage of available higher spatial and temporal resolution gridded datasets 4) employ the state-of-the-art Weather Research and Forecasting (WRF) model to simulate MCV life cycles and compare MCV development with incipient tropical cyclone development, 5) perform WRF model simulations of real and idealized MCS/derecho events to assess at what point larger scale forcing becomes unimportant and when storm-scale dynamics becomes dominant, and 6) expand an ongoing research effort targeted at developing a better understanding of the physical mechanisms that govern warm season severe weather (convection) events that occur over the Great Lakes. The research will be facilitated by the availability of high resolution, global, gridded analyses from operational forecast centers. Advantage will also be taken of the gridded 13 km analyses form the NOAA Regional Update Cycle (RUC) system. The availability of hourly surface and upper air RUC analyses over North America will permit an investigation of the life cycles of long-lived MCVs and derechos. These analyses when coupled with the special BAMEX datasets and simulations from the WRF model will permit more comprehensive research investigations of important convective weather events through multiscale case studies than has been previously possible. In terms of broader impacts, existing weather prediction models do a relatively poor job of simulating convective mode and life cycles properly. In this regard, the operational weather prediction models are limited in how well they can forecast severe weather. The results from the research will add to new knowledge of severe weather events. The graduate students trained and supported under this project will facilitate the transfer of research knowledge to operations as they pursue careers in the field after graduation. This project also presents the opportunity to work with various government agencies (e.g., the NOAA Storm Prediction Center) and other educational institutions to help facilitate the transfer of research knowledge to operations and students.