• HVYRAIN: Excessive Rainfall Discussion...corrected

    From COD Weather Processor@1:2320/105 to wx-storm@lists.illinois.edu on Thu Feb 12 08:32:08 2026
    FOUS30 KWBC 120831 CCA
    QPFERD

    Excessive Rainfall Discussion...CORRECTED
    NWS Weather Prediction Center College Park MD
    331 AM EST Thu Feb 12 2026

    Day 1
    Valid 12Z Thu Feb 12 2026 - 12Z Fri Feb 13 2026

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

    Putnam


    Day 2
    Valid 12Z Fri Feb 13 2026 - 12Z Sat Feb 14 2026

    ...There is a Marginal Risk of Excessive Rainfall Across Portions
    of the Southern Plains on Friday...

    Moist southerly flow from the Gulf will begin to increase across=20
    the Southern Plains during the day Friday and especially into the=20 evening/overnight hours as a southern-stream upper-trough=20
    approaches the region from the Southwest. This will help to=20
    reinforce a frontal boundary left from prior shortwave(s) passage=20
    with a roughly west or west-southwesterly axis from the western=20
    Ozarks through Oklahoma and into northwest Texas. The late arrival=20
    of an appreciable combination of increasing low level winds along=20
    the boundary and height falls from the approaching upper-trough=20
    should limit any storm development until after 00Z. The lack of=20
    particularly notable moisture (surface dewpoints less than 60)=20
    given that this will be day one of return flow as well as the onset
    of night will lead to limited/elevated instability, with the=20
    chance that development could also be mostly north of the quasi-=20
    stationary boundary. Additionally, antecedent conditions are rather
    dry suggesting initial rainfall would be mostly beneficial.=20
    Nevertheless, model guidance has been consistent in depicting the=20
    potential of locally heavy bouts of rainfall in the 2-2.5" range=20
    which, if realized, could lead to some isolated flooding concerns=20 particularly for urban areas.=20

    Putnam


    Day 3=20
    Valid 12Z Sat Feb 14 2026 - 12Z Sun Feb 15 2026

    ...There is a Slight Risk of Excessive Rainfall from the ArkLaTex=20
    to Mid-South Saturday...

    The upper-trough will fully emerge over the Southern Plains on=20
    Saturday and progress eastward towards the Lower Mississippi Valley
    by Sunday morning. Consolidating/deepening surface low pressure=20
    will sweep eastward in tandem with an expected track based on the=20
    latest model guidance from the Red River Valley east-northeast=20
    through the Ozarks and into the Mid-South, with an eastward=20
    extending warm front and trailing cold front. A strengthening low=20
    level jet with an additional day of moist southerly return flow=20
    from the Gulf will help to better prime the warm sector with=20
    dewpoints into the 60s and some rather modest but relatively higher
    instability in the 500 J/KG range.=20

    Storms will likely be ongoing at the start of the period in=20
    vicinity of the low and eastward along the warm front, roughly in=20
    the western Ozarks vicinity, with the potential for some lingering=20
    isolated flooding concerns. More potent thunderstorms capable of=20
    locally heavy rainfall are expected to develop with daytime heating
    southwest along the trailing cold front through the ArkLaTex and=20
    into eastern Texas. Increasing wind fields aloft, deep-layer flow=20
    roughly parallel to the boundary, and eastward progression of the=20
    cold front will likely lead to a line of numerous, potentially=20
    organized thunderstorms with training potential, increasing the=20
    likelihood of some locally heavy totals. Additional storms may=20
    develop ahead of the surface low track in vicinity of the warm=20
    front helping to prime soils and increase totals. However, the=20
    front is expected to remain progressive, which will keep an upper=20
    limit on rainfall totals, particularly with southern extent. A=20
    Slight Risk has been maintained from the ArkLaTex northeast into=20
    the Mid-South roughly following the expected low track. While=20
    antecedent conditions are generally dry, a consensus of model=20
    guidance supports areal average rainfall in the 1.5-2" range, with=20
    locally heavier totals of 3-4", which could still lead to some=20
    scattered instances of flash flooding. The latest 00Z model=20
    guidance suggests the axis of heaviest rainfall is more likely on=20
    the southeastern side of the Slight Risk, but have avoided any=20
    significant adjustments for now, especially outside of the hi-res=20
    window.=20

    Putnam


    Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!46NEEr1pCetZo53fznzHj33-cEYhtRPJBx1aHQ4g1drR= 2VXVqQu_UV20qOx-FZSR3yGhAcEwpFWJkI-LgdJo9q9SLxM$=20
    Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!46NEEr1pCetZo53fznzHj33-cEYhtRPJBx1aHQ4g1drR= 2VXVqQu_UV20qOx-FZSR3yGhAcEwpFWJkI-LgdJofW1-6Ms$=20
    Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!46NEEr1pCetZo53fznzHj33-cEYhtRPJBx1aHQ4g1drR= 2VXVqQu_UV20qOx-FZSR3yGhAcEwpFWJkI-LgdJov5d0nc0$=20

    =3D =3D =3D
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  • 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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