CW3E Analysis – Tropical Storm Hilary: 16 August 2023

August 16, 2023

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Tropical Storm Hilary Potentially Impacting Southern California Beginning Sunday 20 August

  • The disturbance that was located off the coast of Southern Mexico in the Pacific was upgraded to Tropical Storm Hilary today, 16 Aug 2023
  • Tropical Storm Hillary is forecast to become a hurricane tomorrow, 17 Aug 2023, and continue strengthening
  • The storm is expected to impact the Baja Peninsula and Southern California, with Tropical Storm force winds likely to reach the Baja sometime late Friday to early Saturday and reach Southern California mid to late Sunday per the most recent NHC forecast
  • There is potential for heavy precipitation accompanying the high winds across much of Southern California as a result of the elevated moisture levels forecasted to be brought into the region by Hilary
  • A predecessor rain event (PRE) is forecast to occur north of Hilary on Saturday into Sunday, bringing heavy rainfall to the southwestern US, fed by of tropical moisture from Hilary
  • Stay alert to official NWS forecasts, watches, and warnings from the National Hurricane Center at, information from local NWS weather forecast offices at, and follow guidance from local emergency management officials

Click images to see loops of GFS Precipitation and IWV forecasts

Valid 1200 UTC 19 August – 1200 UTC 22 August 2023











Analysis provided by M. Steen, C. Castellano, S. Bartlett, S. Roj, and J. Cordeira; 8 August 2023

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