• MESO: Heavy Rain SoCal

    From Dumas Walker@21:1/175 to All on Saturday, March 30, 2024 08:44:00
    AWUS01 KWNH 300854

    Mesoscale Precipitation Discussion 0117
    NWS Weather Prediction Center College Park MD
    453 AM EDT Sat Mar 30 2024

    Areas affected...portions of southern California

    Concerning...Heavy rainfall

    Valid 300851Z - 302051Z

    Summary...A landfalling atmospheric river will gradually shift
    southeastward across southern California through 21Z. Areas of
    hourly rain rates approaching 1 inch will continue to pose a
    flood/flash flood risk during that time.

    Discussion...A landfalling atmospheric river continues across
    southern California currently. The greatest integrated water
    vapor transport was focused into the Transverse Ranges as of
    0830Z, with several areas of 0.25-0.6 inch/hr rain rates observed
    and estimated per MRMS from Santa Barbara through Los Angeles
    Counties. Local rain rates approaching 1 inch/hr were also
    observed. The atmospheric river was located on the southeastern
    periphery of an anomalously deep and slow moving upper low
    centered about 150 mi west of San Francisco.

    This low and attendant atmospheric river will make slow
    southeastward progress today, with heavy rainfall eventually
    focusing along the eastern Transverse Ranges, Peninsular Ranges,
    and lower-elevation areas near Los Angeles and San Diego. The
    heaviest rainfall (including hourly rates of 0.25-0.9 inches) and
    peak IVT will continue to focus along the Transverse Ranges
    through the next 4-6 hours, before focusing across the Peninsular
    Ranges (and San Diego metro area) between 12-21Z today. With the
    atmospheric river expected to maintain its intensity today,
    multiple hours of moderate to heavy rainfall are expected
    (especially in terrain-favored areas). 0.25-0.9 inch/hr rain
    rates will remain likely where IVT is maximized. Storm totals of
    1.5-2.5 inches (locally higher) are possible through 21Z, which
    should continue to foster at least an isolated flood/flash flood
    risk especially in low-lying, sensitive areas.




    LAT...LON 35261923 34991773 34621690 33891616 33121613
    32611627 32521701 32801740 33481812 34161938
    34482032 35052000

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