261 Sensitivity of High-Resolution WRF Forecasts to Radiosonde Observations over Central TX

Monday, 11 January 2016
Hall D/E ( New Orleans Ernest N. Morial Convention Center)
Mark David Benoit, University (Texas A&M), College Station, TX; and D. T. Conlee and C. J. Nowotarski

The contiguous USA has around 70 upper-air sites, where weather balloon launches are done twice every day. Often, the separation between radiosonde observations (RAOBs) can be several hundred kilometers, which presents a problem to forecasters, who rely not only on modeled fields, but on Skew-T Log-P diagrams from a model to accurately predict the weather, especially in high impact situations. At Texas A&M, the Student Operational Upper-air (SOUP) program launches balloons when the Houston, Dallas/Ft. Worth, Austin/San Antonio NWS, or even the Storm Prediction Center (SPC) requests a launch. These supplementary RAOBs have proven useful to forecasters, as the closest upper-air site is more than 250km away. Would they, however, provide forecast value to a model since they are one of the main sources of assimilated data? Upper-air observations, especially midlevel moisture, are not perfectly known, which presents uncertainty in forecasts. Assimilation of these single sounding located at Texas A&M may improve a high-resolution forecast. About thirty RAOBs from different dates will be assimilated, and high-resolution WRF simulations will be done using WRFDA. A simulated reflectivity comparison with real data is one way that differences in model fields are seen most readily, but other fields, such as mid-level humidity and winds will also be helpful in this assessment. If a single point in this upper-air hole proves beneficial, realtime assimilation of these infrequent data points into the Texas A&M WRF could be implemented for use to forecasters.
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