Variations in subtropical storm types and their contribution to rainfall in southeast Texas
Dianne K. Boothby, Texas A&M University, College Station, TX; and A. C. Ferrel, L. J. Hopper, Jr., and C. Schumacher
Rainfall in southeast Texas, a subtropical region affected by both mid-latitude and tropical influences, arises from a variety of storms caused by many different forcing mechanisms. A five-year (March 2002 – February 2007) NEXRAD storm climatology for southeast Texas based on dynamical forcing (i.e., weak forcing, drylines, cold fronts, warm fronts, stationary fronts, and upper-level disturbances) and precipitation structure (i.e., isolated, scattered, widespread, linear, unorganized, and leading-line/trailing stratiform) is compiled. A storm is defined as a region of radar echo that contains at least one pixel with a reflectivity value of 30 dBZ within Brazos County or that covers at least one-third of Brazos County with echo greater than or equal to 10 dBZ. A new storm is identified if there was no rain in Brazos County in the previous five hours. Dynamical forcing classifications are determined using upper air maps, surface maps, and soundings. When multiple forcing mechanisms appear to be present, the primary initial forcing is selected. All storms except drylines and upper-level disturbances are also subcategorized based on precipitation structure from NEXRAD radar images.
Once the storm climatology is firmly established, rain gauge data within and in the vicinity of Brazos County will be applied to quantify each storm type's contribution to total rainfall. Storms are also separated by season to determine if certain storm types are more prevalent during particular times of the year and how they contribute to the annual rainfall total. This research will provide a basis for driving future subtropical research by showing which storms are climatologically important in southeast Texas and provides a template that can be extended to other subtropical regions.
Poster Session 1, Student Conference General Poster Session
Sunday, 20 January 2008, 5:30 PM-7:00 PM, Exhibit Hall B
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