JP4.3 Use of High-Resolution Ensemble Analyses and Forecasts Products for Guidance in Predicting Microburst Events in a Mountain Desert Environment

Thursday, 4 June 2009
Grand Ballroom Center (DoubleTree Hotel & EMC - Downtown, Omaha)
Elford G. Astling, West Desert Test Center, Salt Lake City, UT; and S. Krippner

Microburst winds represent high-impact weather events that require continued investigation in order to improve efforts to analyze and predict them. In this study, microburst events were defined as wind gusts equal to or exceeding 16 m/s (35 mph) and were selected from archival wind measurement files that extended over a 4-year period from 2004 to 2008. Microburst phenomena were examined in measurements taken from a network of 26 Surface Atmospheric Measurement System (SAMS) stations at Dugway Proving Ground (DPG) compared with recent mesoscale analysis and forecast products from a 30-member ensemble Four-Dimensional Weather (4DWX) system operating on a high performance computer (HPC). The ensemble 4DWX provides operational mesoscale weather analysis and forecast products. Output from the ensemble 4DWX system used for guidance in forecasting microburst events includes standard deviations, histograms, and exceedance values for wind and temperature. Two examples of operational products are presented to illustrate the system applications and types of ensemble 4DWX numerical prediction products of mesoscale analyses and probabilistic forecasts. One example represents an afternoon microburst event that extended over a portion of the mesoscale network and was characterized by non-uniform flow directions. A second example is a line of convective elements that extended across the mesoscale network and was characterized by uniform flow directions. Analyses of seasonal and diurnal occurrence of microbursts over the mesoscale network at DPG provide background information for comparisons with the ensemble 4DWX products. The work was carried out in collaboration with the National Center for Atmospheric Research (NCAR) Research Applications Laboratory, Boulder, Colorado. Operational ensemble forecasting experience gained from this study could aid forecasting of microburst events in other geographic locations.
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