• MESO: Mesoscale Discussion 1975

    From COD Weather Processor@1:2320/105 to wx-storm@lists.illinois.edu on Sun Nov 27 19:53:28 2022
    ACUS11 KWNS 271953
    SWOMCD
    SPC MCD 271952=20
    VAZ000-NCZ000-272215-

    Mesoscale Discussion 1975
    NWS Storm Prediction Center Norman OK
    0152 PM CST Sun Nov 27 2022

    Areas affected...Portions of northeastern NC and southeastern VA

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

    Valid 271952Z - 272215Z

    Probability of Watch Issuance...20 percent

    SUMMARY...Isolated strong/gusty winds and perhaps a brief tornado
    may occur as thunderstorms race northeastward this afternoon. Watch
    issuance appears unlikely at this time.

    DISCUSSION...A band of shallow convection has recently developed
    along the NC/VA border to the northeast of Raleigh NC. Very strong
    low-level wind fields, with 55-60+ kt of southerly flow at 850 mb
    per recent mesoanalysis and KAKQ VWP estimates, are present ahead of
    this band across northeastern NC and southeastern VA. Plentiful
    low-level and deep-layer shear will support updraft organization
    with any thunderstorm that can strengthen. Farther west, the VWP
    from KRAX shows the low-level flow has veered to southwesterly,
    which is limiting low-level shear across central NC.

    The main limiting factor continues to be poor low/mid-level lapse
    rates and related weak instability. While low-level moisture is
    streaming northward ahead of the band of thunderstorms, it remains
    uncertain if sufficient boundary-layer instability will be in place
    this afternoon ahead of it to support truly surface-based
    thunderstorms. Still, given the strength of the low-level flow,
    isolated strong to damaging downdraft winds may occur as this
    convection develops quickly northeastward across southeastern VA and northeastern NC over the next few hours. If a thunderstorm can
    become surface based, then a brief tornado may also occur, as
    effective SRH is forecast to remain enhanced for a couple more hours
    this afternoon, before gradually diminishing as the low-level flow
    slowly veers to southwesterly and weakens. Overall, it still appears
    the severe threat will remain rather isolated, and watch issuance is
    unlikely at this time.

    ..Gleason/Hart.. 11/27/2022

    ...Please see https://urldefense.com/v3/__http://www.spc.noaa.gov__;!!DZ3fj= g!67N4qgduoom9jQkGwVEiY4fiDphnB-reYiMWc1FlccwQPqHVk4H1TGoM02WluvZ4-bOg-XoD7= 1M4yc2a55-i-vz9Cf8$ for graphic product...

    ATTN...WFO...AKQ...MHX...RAH...

    LAT...LON 36127825 36567781 36927741 37707644 37817582 37667553
    37297571 36937591 36657580 36347609 36037678 35927729
    35877791 35947827 36127825=20


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  • From COD Weather Processor@1:2320/105 to wx-storm@lists.illinois.edu on Sat Aug 12 23:32:15 2023
    ACUS11 KWNS 122332
    SWOMCD
    SPC MCD 122331=20
    MDZ000-PAZ000-WVZ000-OHZ000-130100-

    Mesoscale Discussion 1975
    NWS Storm Prediction Center Norman OK
    0631 PM CDT Sat Aug 12 2023

    Areas affected...portions of southeastern OH...northern
    WV...southwestern PA and western MD.

    Concerning...Tornado Watch 634...

    Valid 122331Z - 130100Z

    The severe weather threat for Tornado Watch 634 continues.

    SUMMARY...Ongoing severe storms in the southern half of WW634 will
    likely persist beyond the 01z expiration. A new watch will likely be
    needed.

    DISCUSSION...As of 2330 UTC, several supercells were ongoing across
    parts of far eastern OH, and western PA. These storms have
    maintained intensity and should continue to do so after the 01z
    expiration of WW634. 40-50 kt of effective shear and 1500 J/kg of
    MLCAPE will favor organized storms including supercells and short
    line segments. Damaging wind gusts and hail appear likely with the
    strongest storms into this evening. Veered low-level flow in the
    wake of the earlier rounds of storms suggests the tornado threat is
    not overly high. However, a brief tornado will remain possible given
    the supercell mode and 15-20 kt of 0-1km shear. The severe threat
    will likely extend beyond the 01z expiration of WW634. A new watch
    will likely replace southern parts of the watch to cover the severe
    risk into early tonight.

    ..Lyons/Thompson.. 08/12/2023

    ...Please see https://urldefense.com/v3/__http://www.spc.noaa.gov__;!!DZ3fj= g!_fVf1nes3wCTojWKmp-4wjSipnn5A7VKDW9w_FrOVZrPI0T0YCFp9fbcuuXypDinm04lBlL0g= 20Qf3BneEZQbQy7F2U$ for graphic product...

    ATTN...WFO...CTP...LWX...PBZ...RLX...

    LAT...LON 40337922 40347848 40297819 40107810 39757825 39547854
    39377965 39288033 39128131 39228193 39508194 39678183
    39998149 40108090 40287989 40337922=20


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