Forecast Failures: Investigating the Texas Floods

Strategic Insights -

Investigations into the devastating floods in Central Texas have highlighted discrepancies between weather models and the National Weather Service's forecasts. Weather models suggested the possibility of 10-20 inches of rain, but the Weather Service's forecasts indicated only about half that amount. The consequences of these forecast failures were severe, with at least 100 people killed and over 170 still missing.

Key Takeaways:

  • The National Weather Service's (NWS) forecasts on the Fourth of July downplayed the risk of catastrophic flooding, despite weather models suggesting 10-20 inches of rain in some areas.
  • The NWS's San Antonio/Austin forecast office worked to warn the region of flood potential on Thursday and issue flood warnings as disaster struck on Friday, according to Weather Service officials and the National Weather Service Employees Organization.
  • The NWS meteorologists considered the outputs of dozens of weather models, including the High-Resolution Rapid Refresh (HRRR) and High Resolution Ensemble Forecast (HREF), which indicated more than 10 inches of rain could fall in isolated areas of Central or South Texas.
  • A Houston-based meteorologist, Matt Lanza, noted that while weather models can be inconsistent and occasionally exaggerate extreme weather potential, theirs showed extreme rainfall forecasts, and it was up to the meteorologists to discern the significance of the models.
  • The NWS's forecast was influenced by the desire to maintain public trust and avoid unnecessary alarm, potentially contributing to the underestimation of the flood risk.
  • The National Oceanic and Atmospheric Administration (NOAA) has been facing budget cuts and potential office closures, which may have affected the NWS's forecasting capabilities.
  • The investigation into the forecast failures is ongoing, with some suggesting that key vacancies at the NWS office covering Central Texas may have contributed to the tragedy.

Statistics:

  • At least 100 people were killed in the flash floods.
  • Over 170 people are still missing.
  • The Houston-based meteorologist, Matt Lanza, estimated that only a handful of times in his experience has a model predicted extreme weather that did not come to pass.
  • The NWS's flood watch briefing materials stated that 1-3 inches of rain was possible, with isolated areas seeing 5-7 inches.
  • The NWS issued flood warnings after 1 a.m. local time on Friday.
  • The Weather Prediction Center's technical analysis showed concerning trends that could lead to rainfall rates of more than 3 inches per hour.
  • The HRRR model predicted as much as 20 inches of rain could fall in the region by late Thursday.

Sources:

  • The Washington Post article by Scott Dance, July [blank]
  • National Weather Service
  • National Oceanic and Atmospheric Administration (NOAA)
  • Weather Service Employees Organization
  • Matt Lanza, Space City Weather