• Flooding Likely TX Hills

    From Mike Powell@618:250/1 to All on Mon Jul 7 10:48:00 2025
    AWUS01 KWNH 071355
    FFGMPD
    TXZ000-071955-

    Mesoscale Precipitation Discussion 0611
    NWS Weather Prediction Center College Park MD
    955 AM EDT Mon Jul 07 2025

    Areas affected...Parts of the Texas Hill Country

    Concerning...Heavy rainfall...Flash flooding likely

    Valid 071355Z - 071955Z

    SUMMARY...Slow-moving thunderstorms producing local rainfall rates
    over 3"/hr are ongoing and expected to continue through early this
    afternoon. Some significant instances of flash flooding are
    possible, especially given the sensitive flood-prone terrain of
    central TX.

    DISCUSSION...Radar and satellite imagery highlight strengthening
    thunderstorms oriented along a strung-out 700 mb trough in a
    west-southwest to east-northeast direction. MRMS estimates hourly
    rainfall rates just west of Killeen over 3"/hr, with a HADS
    observation (supprted by surrounding obs) recording 4.2" in 3
    hours by 1330Z.

    The same highly moist and unstable environment remains over
    central TX, with mean layer flow generally less than 5 kts.
    However, upwind propagation vectors remain out of the
    north-northeast which supports back-building through this
    afternoon. MLCAPE remains elevated in the 1000-1500 J/kg range and
    will increase throughout the day due to the combination of
    southerly flow out of the western Gulf and diurnal heating. This
    setup supports the continuing threat of slow-moving thunderstorms
    producing 2-3"+ hourly rates, with scattered flash flooding
    likely. Significant flash flooding is also possible where any
    mesoscale circulations develop within thunderstorms and can stall
    these extreme rainfall rates over a region for a few hours (like
    what was seen west of Killeen). Locally, rainfall totals may
    exceed 5" within these intense thunderstorms.

    1-hr FFG across the sensitive soils of central TX are generally
    below 2" and as low as 1" locally. The 12z HRRR depicts convection
    eventually migrating westward, probably under the influence of the
    700 mb trough tilting west-east and lifting north. So, while the
    ongoing activity will likely move within a few hours it can be
    expected that scattered intense rainfall rates develop elsewhere
    and lead to flash flooding.

    Snell

    ATTN...WFO...EWX...FWD...SJT...

    ATTN...RFC...FWR...NWC...

    LAT...LON 31739862 31509790 31039776 30649827 30309938
    30190046 30460087 31100046 31619958

    $$
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