• MESO: Mesoscale Discussion 2151

    From COD Weather Processor@1:2320/105 to wx-storm@lists.illinois.edu on Sat Oct 18 17:54:28 2025
    ACUS11 KWNS 181753
    SWOMCD
    SPC MCD 181753=20
    ARZ000-LAZ000-TXZ000-OKZ000-181900-

    Mesoscale Discussion 2151
    NWS Storm Prediction Center Norman OK
    1253 PM CDT Sat Oct 18 2025

    Areas affected...portions of eastern Texas...northwestern Louisiana...southwestern Arkansas...and southeastern Oklahoma

    Concerning...Severe potential...Watch likely=20

    Valid 181753Z - 181900Z

    Probability of Watch Issuance...80 percent

    SUMMARY...Initial storms may produce damaging gusts and large hail
    across portions of eastern Texas, northwestern Louisiana,
    southwestern Arkansas, and southeastern Oklahoma, and the threat for
    tornadoes may increase later this afternoon. A watch will likely be
    needed.

    DISCUSSION...A pacific front is impinging upon a moist and unstable
    air mass across eastern Texas, southern Arkansas, and western
    Louisiana. Additionally, a mid-level cloud deck across much of
    eastern Oklahoma and central Arkansas has resulted in the
    development of a weak differential heating boundary near the Red
    River and points just eastward. Convection has begun to develop east
    of the pacific front along a confluence line in the moist sector,
    and the differential heating boundary may provide a focus for
    additional development through the afternoon. While ample buoyancy
    exists for severe convection, shear is relatively modest, with ~11
    kts 0-1 km shear present on the KSHV VWP. Though the low-level and
    deep-layer shear should improve with time as a stronger mid-level
    jet moves in from the west later this afternoon, and short-term
    forecast profiles show improving low-level shear by later this
    afternoon.

    Given improving mid-level flow and deep-layer shear this afternoon,
    some threat for damaging gusts and large hail is expected with these
    storms. Additionally, given the relatively gentle forcing for storms
    in the short term and a favorable orientation of the shear vector,
    storms are expected to remain at least semi-discrete through the
    afternoon, and this may result in a greater tornado threat when the
    shear improves later in the day.

    ..Supinie/Thompson.. 10/18/2025

    ...Please see https://urldefense.com/v3/__http://www.spc.noaa.gov__;!!DZ3fj= g!6zFW9NwkhKR_ChcCSRREpZ6gccS44NXgIo4NVEq7_lyW-PqRYiiXeyfX0HL2RXw_riaY1e6hN= 4SUCx_ZFy6vBLcZICY$ for graphic product...

    ATTN...WFO...SHV...TSA...FWD...

    LAT...LON 32019405 31899447 31699537 31739620 32129664 32529667
    33229610 33859554 34059402 33729346 33099337 32019405=20

    MOST PROBABLE PEAK TORNADO INTENSITY...100-130 MPH
    MOST PROBABLE PEAK WIND GUST...55-70 MPH
    MOST PROBABLE PEAK HAIL SIZE...1.00-1.75 IN


    =3D =3D =3D
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