S92 Model verification and analysis of intense mesoscale convective vortices at the surface: simulation of Tropical Storm Erin 2007

Sunday, 23 January 2011
Dereka Carroll, UCAR, Jackson, MS; and C. Evans

While much is known about the evolution of mesoscale convective vortices (MCVs) found in the middle troposphere, less is known about the evolution of MCVs with strong surface reflections. In recent years, several such MCVs have impacted the central and eastern portions of the United States. While such MCV events are less frequent than their upper-level counterparts, they are commonly associated with large areas of severe surface winds. This makes understanding the evolution of these high-impact weather phenomena critical to improving watch/warning forecast lead times.

Before this can be done, an accurate, high-resolution meteorological data set must be obtained for each case to be studied. With a lack of direct observations from most MCV cases, such a data set must be obtained via numerical simulation. The focus of this work is to verify the ability of a numerical model to accurately represent the evolution of an intense MCV event, specifically the overland reintensification of Tropical Storm Erin (2007). Version 3.2 of the Advanced Research Weather Research and Forecasting model (WRF-ARW) is used to conduct a high-resolution simulation of Erin. The model exhibits a slight slow and weak bias with respect to track and intensity. Simulated reflectivity structures modestly resemble radar-based observations. Simulated thermodynamic quantities closely resemble those synthesized from observations. Simulations of additional cases are needed, however, to verify the model's ability to accurately represent multiple MCV events and to begin to draw insight into how these features develop, intensify, and decay.

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