• Hydrologic Outlook for San Bernadino County-Upper Colorado River Valley County, California
  • Hydrologic Outlook issued September 28 at 11:33AM PDT by NWS
  • Effective: Monday, October 1, 2018 at 11 a.m.
  • Expires: Saturday, September 29, 2018 at 6 a.m.
  • ...Heavy Rain Possible Sunday night through Tuesday...
    * What: Heavy rain. Widespread amounts of 1 to 2 inches with
    localized amounts up to 4 inches are possible.
    * Impacts: Localized flooding causing some roads to be impassable.
    Local washes and waterways may exit their banks and impact
    nearby structures.
    * Confidence: High on potential for rain. Medium on timing,
    locations, and amounts.
    * Where: Across the Southwest US, including south-central and
    southwest Arizona and southeast California. This includes
    Phoenix, Yuma, Globe, and Casa Grande in Arizona, and the
    Imperial Valley in California.
    * When: Beginning Sunday night and continuing through Tuesday.
    * Summary: Abundant moisture associated with a tropical system
    will move northward into the Southwest US. Meanwhile, a low
    pressure system will move through California and the Four
    Corners states. This setup will cause widespread rain to
    develop. Rain rates may be quite high at times, in excess of 2
    to 4 inches per hour, which will have the potential to cause
    localized flooding. Due to the duration of the event, the
    potential exists for more widespread flooding to occur.
    Continue to monitor forecasts for updates as this situation
    unfolds. Follow NWS Phoenix on Facebook at and on Twitter at

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