Hydrometeorological Analysis of the July 2025 Texas Hill Country Flash Flood Disaster

Details

• Journal Title:
  Bulletin of the American Meteorological Society
• Personal Author:
  Galarneau, Thomas J. ; Carlin, Jacob T. ; Clark, Robert A. ; Gourley, Jonathan J. ; Zhang, Jian
• NOAA Program & Office:
  OAR (Oceanic and Atmospheric Research) ; NSSL (National Severe Storms Laboratory) ; OAR (Oceanic and Atmospheric Research)
• Description:
  On 4 July 2025, multiple factors combined to produce a catastrophic flash flood in the Texas Hill Country. The event caused 137 fatalities across South Texas, with the greatest impacts in Kerr County (119 fatalities with two additional missing persons) near the Camp Mystic for Girls summer camp. Widespread convection occurred across the Texas Hill Country, including a focused ten-county area that received >150 mm of rainfall between 0300 and 1800 UTC, while a quasi-stationary supercell generated localized totals >250 mm largely within a 3-h period from 0600 to 0900 UTC over the Guadalupe River basin headwaters. This study synthesizes observations, reanalyses, convection-allowing model analyses, and hydrologic simulations to diagnose the event. Results show that the supercell formed as a northwestward-moving surface boundary intersected strengthening midlevel westerly flow on the southern flank of a mesoscale convective vortex that tracked from northern Mexico into south-central Texas. Increasing southwesterly flow aloft and a strengthening southeasterly low-level jet enhanced vertical shear, supporting supercell organization and limited storm motion. Deep tropical moisture from the southeast, modulated by Tropical Cyclone Barry, together with mid- and upper-level moisture from the tropical eastern North Pacific associated with Tropical Cyclone Flossie, promoted high precipitation efficiency and extreme rain rates. Hydrologic simulations indicate that storm placement over the basin promoted near-synchronous flood-wave superposition from the South Fork of the Guadalupe River and Cypress Creek at Camp Mystic, exacerbating inundation. A companion study examines short-term predictability using convection-allowing ensemble forecasts coupled with hydrologic prediction tools.
• Source:
  Bulletin of the American Meteorological Society (2026)
• DOI:
  https://doi.org/10.1175/bams-d-25-0227.1
• ISSN:
  0003-0007 ; 1520-0477
• Format:
  pdf
• Publisher:
  American Meteorological Society
• Document Type:
  Journal Article
• Rights Information:
  Other
• Compliance:
  Library
• Download URL:
  https://repository.library.noaa.gov/view/noaa/76031/noaa_76031_DS1.pdf
• File Type:
  [PDF - 5.51 MB]
• Collection(s):
  Office of Oceanic and Atmospheric Research (OAR)
• Main Document Checksum:
  urn:sha-512:7b08617b6c47addf1c9a4280148532d879f5fef0df7e34bbb55fcb33ca7f593d227995245afe445b526c86ac4a5d9dfbbf5d51fb67099e32668093ac0791764b