• Flood potential KA/MO/NE

    From Mike Powell@618:250/1 to All on Tue Sep 23 08:43:57 2025
    AWUS01 KWNH 231000
    FFGMPD
    MOZ000-KSZ000-NEZ000-231500-

    Mesoscale Precipitation Discussion 1123
    NWS Weather Prediction Center College Park MD
    600 AM EDT Tue Sep 23 2025

    Areas affected...Northeast Kansas...Northwest Missouri...Far
    Southeast Nebraska...

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

    Valid 231000Z - 231500Z

    SUMMARY...Broad scale over-turning of remaining unstable air will
    have short-term rates of up to 2"/hr and localized totals to 2-3"
    in 1-3 hours, resulting in possible localized flash flooding.

    DISCUSSION...GOES-E WV suite depicts broad diffluent region
    downstream of strengthening deep layer cyclone over the central
    Rockies. An embedded shortwave is sharpening and vertically
    stretching within the divergent pattern aloft, providing solid
    DPVA across northeast KS into far southeast NEB and northwest MO.
    This area has remained conditionally unstable and capped through
    the early overnight period with broad 2000 J/kg MUCAPE reservoir
    along and southwest of the Missouri River Valley.

    Outflow boundary and southward sinking cold front out of IA and
    east-central NEB initially provided sufficient convergence along
    the northeast edge of the instability core and rapid expansion has
    occurred over the last hour or so as southwesterly WAA has further
    impinged on the area. Strong ascent and ample deep layer moisture
    has supported localized rates of 1.5-2"/hr and with very
    slow/stationary cell motions, generally only moving due to
    outflow/propagation, an hour or so of intense rainfall may again
    result in widely scattered 2-3" totals in 1-3 hours.

    Additionally, as the southern stream shortwave melds with the
    northern stream feature, effectively elongating the mid-level
    trough toward a longer negative tilt orientation, but also
    strengthened southwesterly flow and deep layer convergence with
    the core of the southerly LLJ and effective moisture flux.
    Leading edge convergence is also building a west to east oriented
    arc of thunderstorms along the southwestern edge of the unstable
    air, slow northward migration and intersection with the convective
    outflow from the northwest will see a larger slab ascent with
    broad overturning of the remaining 1.5-1.75" total Pwats in the
    column and likely result in similar hourly rates up to 2"/hr but
    likely to diminish quickly thereafter, likely resulting in widely
    scattered pockets of 2-3" totals further southwest across
    northeast KS toward the KC Metro. The sheer rates may result in
    localized flash flooding conditions, especially near urban centers.

    Gallina

    ATTN...WFO...EAX...GID...OAX...TOP...

    ATTN...RFC...KRF...NWC...

    LAT...LON 40709689 40639608 40299516 39759444 39249384
    38599419 38469488 38769571 39159679 39429830
    40279804 40599744
    $$
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