• MESO: Mesoscale Discussion 1449

    From COD Weather Processor@1:2320/105 to wx-storm@lists.illinois.edu on Mon Aug 9 04:58:54 2021
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    ACUS11 KWNS 090458
    SPC MCD 090458=20

    Mesoscale Discussion 1449
    NWS Storm Prediction Center Norman OK
    1158 PM CDT Sun Aug 08 2021

    Areas affected...Parts of central Iowa

    Concerning...Severe potential...Watch unlikely=20

    Valid 090458Z - 090700Z

    Probability of Watch Issuance...20 percent

    SUMMARY...Isolated supercell development may continue between Fort
    Dodge and Des Moines into the 1-2 AM CDT time frame. Beyond that it
    remains unclear. Until activity finally diminishes, it may continue
    to pose a risk for locally strong surface gusts, with perhaps some
    potential for a tornado.

    DISCUSSION...Models suggest that a digging jet in the 700-500 mb
    layer may have contributed to forcing for ascent along a persistent
    zone of lower/mid tropospheric warm to the southwest of a mid-level
    low centered near southeastern Minnesota. Guidance also suggests
    that this jet may begin to redevelop eastward around base of the low
    during the next few hours, and large-scale ascent supporting
    persistent isolated supercell development may begin to weaken by the
    05-07Z time frame.

    However, at least weak low/mid-level warm advection will persist in
    a rough northwest-southeast corridor across central Iowa, where it
    appears that a seasonably moist boundary-layer remains characterized
    by CAPE in excess of 2000 J/kg. So it remains unclear how soon
    vigorous convective development will diminish. While potential for
    substantive upscale convective growth appears low, deep-layer shear
    remains strong and supportive of the continuing evolution of
    supercell structures capable of producing localized strong surface
    gusts and perhaps some risk for a tornado. However, while
    thermodynamic profiles are supportive of tornadic potential,
    low-level hodographs are more uncertain, with a weakness evident
    around the 850 mb level.

    ..Kerr/Hart.. 08/09/2021

    ...Please see https://urldefense.com/v3/__http://www.spc.noaa.gov__;!!DZ3fj= g!pE_SEUjz93m_6R_dqPIcrsNehEOK6Qp5hr4jC2XEaJre-LBa_XGdAXkoBMeH81CQAGxUHNJq$=
    for graphic product...


    LAT...LON 42479346 41989297 41589342 41739402 42289449 42479346=20

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