• MESO: Mesoscale Discussion 1366

    From COD Weather Processor@1:2320/105 to wx-storm@lists.illinois.edu on Tuesday, July 05, 2022 02:48:31
    ACUS11 KWNS 050248
    SWOMCD
    SPC MCD 050247=20
    MIZ000-INZ000-ILZ000-WIZ000-IAZ000-050415-

    Mesoscale Discussion 1366
    NWS Storm Prediction Center Norman OK
    0947 PM CDT Mon Jul 04 2022

    Areas affected...portions of far eastern Iowa into far southern
    Wisconsin...far northern Illinois and southwestern Lower Michigan

    Concerning...Severe Thunderstorm Watch 432...

    Valid 050247Z - 050415Z

    The severe weather threat for Severe Thunderstorm Watch 432
    continues.

    SUMMARY...The severe threat continues across Severe Thunderstorm
    Watch 432. Damaging gusts are the main threat, especially with
    merging storms. Large is also possible and a tornado cannot be ruled
    out.

    DISCUSSION...Warm-air advection and the northward passage of a 500
    mb vort max (in northeastern WI) has allowed for the initiation and
    sustenance of multiple supercells along an east-west line from far
    eastern IA, spanning eastward along the WI/IL border. Given the lack
    of strong deep-layer ascent, low-level lift in the form of warm-air
    advection and the intensification of a low-level jet should sustain
    storms into the evening hours. The ongoing storms are advancing
    south-southeast along an MLCAPE gradient (ranging from 1000-3000
    J/kg) amid 40+ kts of effective bulk shear, suggesting that updrafts
    should remain robust and organized, with a damaging gust/large hail
    threat.=20

    Despite the presence of widespread 300+ m2/s2 of effective SRH,
    regional VWPs show modestly curved hodographs in the surface-3 km
    layer, with velocity and shear magnitudes rapidly dropping off
    around 700 mb. In addition, the 850-700 mb layer appears slightly
    neutral in instability on the 00Z observed DVN sounding. As such,
    the vertical shear/MLCINH introduced in this layer may be the main
    limiting factor for a more robust tornado threat. Finally, a locally
    greater damaging gust threat could materialize with any supercells
    that congeal and grow upscale into an MCS. This especially may be
    the case later this evening, when the LLJ veers to more
    west-southwesterly, aligning more parallel with the line of storms.
    As such, the severe threat may spread into southwestern Lower
    Michigan, where a WW issuance may eventually be needed.

    ..Squitieri.. 07/05/2022

    ...Please see https://urldefense.com/v3/__http://www.spc.noaa.gov__;!!DZ3fj= g!4Sm3VRktuwz3YaGBTwExuGNRQPPromxLk0vMoJK8v4L7PS5bcSYNOv6O70ZRPb8BeuMgt_wji= oSBW-2kQIRATkbCwMw$ for graphic product...

    ATTN...WFO...IWX...GRR...LOT...MKX...DVN...ARX...

    LAT...LON 42209121 42469141 42819147 43209034 43358699 43348592
    42978538 42418517 42158538 41878595 41698652 41658745
    41848902 42079035 42209121=20


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  • From COD Weather Processor@1:2320/105 to wx-storm@lists.illinois.edu on Saturday, July 01, 2023 01:57:22
    ACUS11 KWNS 010157
    SWOMCD
    SPC MCD 010156=20
    TNZ000-GAZ000-ALZ000-010330-

    Mesoscale Discussion 1366
    NWS Storm Prediction Center Norman OK
    0856 PM CDT Fri Jun 30 2023

    Areas affected...Southern Middle TN...Northern AL...Far Northwest GA

    Concerning...Severe potential...Watch possible=20

    Valid 010156Z - 010330Z

    Probability of Watch Issuance...40 percent

    SUMMARY...Strong/severe thunderstorms across Middle Tennessee will
    continue to spread southward toward northern Alabama. Convective
    trends are being monitored for a possible downstream Severe
    Thunderstorm Watch.

    DISCUSSION...Clusters of storms are currently ongoing across
    northern Middle Tennessee including near Nashville and the I-40
    corridor as of 145z/845pm CDT. These storms, particularly on the
    western flank, have access to robust instability, with the 00z
    observed Nashville sounding sampling 4400 J/kg MLCAPE. However, a
    slowly cooling boundary layer should lead to a gradual diminishing
    intensity trend over the next couple of hours. The easternmost
    storms/updrafts, in particular, are now showing a trend of warming
    cloud tops and diminished updraft intensity. While the need for a
    Severe Thunderstorm Watch southward across far southern Middle
    Tennessee, northern Alabama, and possibly far northwest Georgia are
    uncertain, short-term trends will continue to be monitored for that possibility.

    ..Guyer/Hart.. 07/01/2023

    ...Please see https://urldefense.com/v3/__http://www.spc.noaa.gov__;!!DZ3fj= g!9RM4bT1zofcqY_JIZ-5Ij_2Ut-DKTOnOJKzHhRgg62nYRpZ54ZxwL1-zCHC10x9VDslqY_rd_= dfF52jyt7HhpF6LB7Y$ for graphic product...

    ATTN...WFO...MRX...FFC...OHX...HUN...

    LAT...LON 35158747 35418557 34868545 34288631 34588759 35158747=20


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