Hydrometeorological Analysis of Tropical Storm Hermine and Central Texas Flash Flooding, September 2010

We examine the primary hydrometeorological controls leading to heavy rainfall across central Texas and flooding along Bull Creek

Chad Furl

2015

Scholarcy highlights

  • In central Texas, the unique combination of flood-prone physiography and susceptibility to extreme meteorological events has produced some of the largest rainfall events and flood magnitudes in the United States and the world
  • Weather Research and Forecasting Model simulations with and without the Balcones Escarpment terrain indicate that orographic enhancement affected rainfall
  • Texas consistently leads the nation in flash flood–related deaths, the majority of which occur across central Texas in an area dubbed Flash Flood Alley
  • An mesoscale convective system formed from the remnants of Tropical Storm Hermine, producing torrential rainfall along a narrow swath of central Texas bordering the Balcones Escarpment
  • The system was able to persist through nighttime hours, bringing nearly 300 mm of rainfall to the 58 km2 Bull Creek watershed in Austin, TX
  • For Hermine, the Areal reduction factors suggested by Asquith would need to be increased by 10% to produce a 24-h recurrence interval matching the maximum from individual radar bin estimates
  • Weather Research and Forecasting simulations with and without Balcones Escarpment terrain suggest geography aided in the increased rainfall pattern along FFA
  • The well-defined, narrow rainbands and their persistence were key features that led to flooding

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