Allison Rains in Houston, TX: Were their magnitude predictable from NWP models?

  Tropical storm track

Abstract

This is the first of three cases examining numerical weather prediction (NWP) aspects of Tropical Storm Allison, which moved into Texas from the Gulf of Mexico on 5 June 2001. The Houston, TX area was inundated by up to three feet of rain between 5 and 8 June, most of which occurred on June 8th, three days after the storm made landfall. Twenty-two deaths resulted, many of which were the result of cars being swept away by flash flooding. Importantly, flash flood watches and warnings were made in a timely manner by the Houston/Galveston TX WFO, in spite of the Eta forecast problems.

This first case mainly considers whether the volume of rain that occurred over the Houston, TX area, particularly on 8 June, was predictable using the Eta-22 and Eta-10 (threats nest) models from the National Centers for Environmental Prediction (NCEP).

Learning objectives

  1. A good storm track does not necessarily produce a good precipitation forecast.
  2. A good storm track and better resolution does not necessarily produce a good precipitation forecast.
  3. Consideration of results from a study of frequency of occurrence of threshold precipitation amounts in NWP models may help in the prediction of extreme precipitation events.

Credits

Mike Eckert (HPC) for providing text and graphics discussions for HPC QPF
Stephen Jascourt (UCAR/COMET) for helpful discussions and developing the HTML format
Eric Rogers (NCEP) for assistance in obtaining Eta-22 and Eta-10 data


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