• MESO: Mesoscale Discussion 0730

    From COD Weather Processor@1:2320/105 to wx-storm@lists.illinois.edu on Thursday, June 14, 2018 04:57:15
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    ACUS11 KWNS 140457
    SWOMCD
    SPC MCD 140456
    IAZ000-MNZ000-NEZ000-SDZ000-140730-

    Mesoscale Discussion 0730
    NWS Storm Prediction Center Norman OK
    1156 PM CDT Wed Jun 13 2018

    Areas affected...Parts of the mid Missouri Valley

    Concerning...Severe potential...Watch unlikely

    Valid 140456Z - 140730Z

    Probability of Watch Issuance...20 percent

    SUMMARY...Increasing thunderstorm development, which could be
    accompanied by a risk for severe hail, appears possible by 3-4 AM
    CDT. It is not anticipated that this will require a severe weather
    watch, but trends will be monitored.

    DISCUSSION...A fairly broad area of lower/mid tropospheric warm
    advection has evolved across much of the north central Plains/mid
    Missouri Valley region. This is generally focused beneath and on
    the northeastern periphery of a broad plume of warm elevated mixed
    layer air emanating from the Great Basin. Associated forcing for
    ascent near the edge of the stronger capping appears to be
    contributing to ongoing convective development near Sioux City IA.
    This is likely being supported by weak CAPE associated with elevated
    moisture return (perhaps near/above 700 mb), emanating from richer
    low-level moisture beneath the cap, generally across the higher
    plains to the west of the Missouri river.

    However, latest VWP data from Hastings and North Platte indicate
    that southerly low-level jet strengthening to 40-50 kt centered
    around 1 km AGL has taken place during the past few hours. Peak
    speeds will likely be reached within the next hour or two, with a
    subsequent weakening, but gradually veering of the jet to a
    southwesterly component through 07-09Z. As this takes place,
    advection of low-level moisture into the vicinity of the mid-level
    moisture gradient is expected to contribute to considerable
    destabilization near/northeast of the Missouri River. Most
    convection allowing guidance, including the NCEP HRRR indicate that
    this will coincide with increasing/intensifying thunderstorm
    development. In the presence of at least modest vertical shear,
    supported by considerable veering of winds with height, the
    development of moderately large CAPE may support a severe hail
    threat in stronger storm development.

    ..Kerr/Weiss.. 06/14/2018

    ...Please see www.spc.noaa.gov for graphic product...

    ATTN...WFO...DMX...FSD...OAX...

    LAT...LON 44059777 44059597 42219416 41549473 41759584 42709670
    43509781 44059777



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