• Heavy Rain/Flooding LA

    From Dumas Walker@21:1/175 to All on Fri Sep 6 08:12:00 2024
    AWUS01 KWNH 061154
    FFGMPD
    LAZ000-061501-

    Mesoscale Precipitation Discussion 0981
    NWS Weather Prediction Center College Park MD
    753 AM EDT Fri Sep 06 2024

    Areas affected...Central LA coastline

    Concerning...Heavy rainfall...Flash flooding possible

    Valid 061153Z - 061501Z

    Summary...Periods of 3-3.5"/hr rainfall rates along the eastern
    flank of a meso-low will drive a risk of additional flash flooding
    along the Central LA coastline through 15z.

    Discussion...Recent radar mosaic depicts an emerging mesoscale
    circulation near Vermilion Bay with a slow northeastward track,
    attached to a stationary front analyzed along the Gulf Coast. East
    of this low, periods of 3-3.5"/hr rainfall rates are noted within
    the warm sector of the front along the coastline.

    RAP forecasts suggest this boundary will slowly lift inland over
    the next several hours, ushering in 1000-2000 J/kg MUCAPE to
    maintain periods of very heavy rainfall close to the coastline in
    the presence of 1) 2.5-2.6" PWATS and 2) enhanced deep moisture
    convergence east of the low. The last 3-4 runs of the HRRR appear
    to have initialized the location of the and strength of the
    circulation better, and suggest very localized rainfall totals
    upwards of 4-6" are possible through 15z. Given 1-3 hour FFGs
    generally in the 2-3" range, additional flash flooding may result
    along the immediate coastline.

    Asherman

    ATTN...WFO...LCH...LIX...

    ATTN...RFC...LMRFC...NWC...

    LAT...LON 29999151 29799048 29378997 29079019 29039093
    29359144 29529181 29849188
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