• HVYRAIN: Excessive Rainfall Discussion...corrected

    From COD Weather Processor@1:2320/105 to wx-storm@lists.illinois.edu on Wed Feb 18 19:44:52 2026
    FOUS30 KWBC 181944 CCA
    QPFERD

    Excessive Rainfall Discussion...CORRECTED
    NWS Weather Prediction Center College Park MD
    244 PM EST Wed Feb 18 2026

    Corrected for typo in last sentence of Day 2 text

    Day 1
    Valid 16Z Wed Feb 18 2026 - 12Z Thu Feb 19 2026

    The probability of rainfall exceeding flash flood guidance is less
    than 5 percent.

    Otto


    Day 2
    Valid 12Z Thu Feb 19 2026 - 12Z Fri Feb 20 2026

    A potent mid-level shortwave/closed low is forecast to bring
    another round of heavier precipitation to southern CA beginning
    Thursday morning, ahead of a progressive cold front. Peak model=20
    consensus of MUCAPE no greater than 250 J/kg and IVT values of=20
    300-400 kg/m/s appear to be slightly weaker than what was=20
    associated with the round of heavier rain which impacted the=20
    Transverse Ranges early Wednesday morning. However, locally high=20
    48-72 rainfall totals have impacted portions of southern CA along=20
    with a number of flooding reports since Monday.

    The next round to affect southern California's Transverse and=20
    Peninsular Ranges is expected to bring peak hourly rainfall values
    in the 0.5 to 1.0 inch range on Thursday (12Z HREF probs for=20
    greater than 0.5 inches in 1 hour were 30-40 percent), from roughly
    15Z/18 to 03Z/19, advancing southward along the coast with time.=20
    Given the progressive nature, peak total rainfall is forecast to=20
    fall in the 1 to 2 inch range for the Transverse and Peninsula=20
    Ranges but could be a bit higher for the Peninsular Ranges given a=20
    longer and more favorable fetch of low level moisture into the
    region. While the 12Z NAM_nest is likely overdone, it does show 3+
    inch potential for localized areas below snow levels which look to
    briefly rise in the 5000-6000 foot range. Any flood related=20
    impacts should remain isolated and minor in magnitude.

    Otto


    Day 3
    Valid 12Z Fri Feb 20 2026 - 12Z Sat Feb 21 2026

    The probability of rainfall exceeding flash flood guidance is less
    than 5 percent.

    Otto


    Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!5N6V9V2B7mOBPkkk83gviV1QOp-KPIThnoDtotJCDSMp= Oxs1D9J8KAZl4bq-GQtCL1HCHu6xjK6pCKGFmVnr3otuy5g$=20
    Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!5N6V9V2B7mOBPkkk83gviV1QOp-KPIThnoDtotJCDSMp= Oxs1D9J8KAZl4bq-GQtCL1HCHu6xjK6pCKGFmVnrzXQnRvQ$=20
    Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!5N6V9V2B7mOBPkkk83gviV1QOp-KPIThnoDtotJCDSMp= Oxs1D9J8KAZl4bq-GQtCL1HCHu6xjK6pCKGFmVnrxLulBk0$=20

    =3D =3D =3D
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