• MESO: Mesoscale Discussion 1282

    From COD Weather Processor@1:2320/105 to wx-storm@lists.illinois.edu on Friday, June 24, 2022 22:37:00
    ACUS11 KWNS 242236
    SWOMCD
    SPC MCD 242236=20
    SDZ000-NEZ000-250000-

    Mesoscale Discussion 1282
    NWS Storm Prediction Center Norman OK
    0536 PM CDT Fri Jun 24 2022

    Areas affected...portions of central and eastern South Dakota into north-central Nebraska

    Concerning...Severe Thunderstorm Watch 408...

    Valid 242236Z - 250000Z

    The severe weather threat for Severe Thunderstorm Watch 408
    continues.

    SUMMARY...The severe threat continues across Severe Thunderstorm
    Watch 408. Very large hail and severe wind gusts are possible with
    the more mature, sustained supercell structures. Upscale growth into
    an intense squall line with significant severe winds is possible
    later this evening. A WW issuance may eventually be needed later
    across eastern South Dakota.

    DISCUSSION...MRMS mosaic radar data depicts multiple supercells
    underway across central SD into northern NE, with 50 dBZ echo tops
    approaching 45 kft and MESH swaths indicating hail up to 2 inches in
    diameter. Up to 6000/4500 J/kg SBCAPE/MLCAPE characterize the
    ambient thermodynamic environment ahead of the supercells. 22Z
    mesoanalysis and RAP forecast soundings indicate that this high
    buoyancy is driven by surface-500 mb 8.5 C/km mid-level lapse rates
    and rich low-level moisture. Given modest strengthening and veering
    of the vertical wind profile, 25-40 kts of effective bulk shear
    coincides with the extreme instability. As such, 2+ inch hail and
    severe gusts (perhaps 75+ mph) may accompany the most intense
    supercells through the evening hours.

    Storm/cold-pool mergers may support the development of a more
    organized, leading-line/trailing-precipitation MCS during the
    evening. The steep, deep-layered lapse rates overspreading a
    relatively mixed boundary layer would support a more organized,
    significant severe wind threat under the condition such an MCS
    develops. A separate MCD will be issued to address this threat
    should the development of a bow-echo MCS becomes apparent. Either
    way, organized severe storms are expected to approach the eastern
    bounds of Severe Thunderstorm Watch 408, and a new WW issuance may
    eventually be needed later this evening.

    ..Squitieri.. 06/24/2022

    ...Please see https://urldefense.com/v3/__http://www.spc.noaa.gov__;!!DZ3fj= g!6ls8IBLoEoZts63CMpqzPCCIZFYU6HFS4mSKhUUEE_BezINkmZBJGtrtAY0fy3ev82VzDgXMC= Y9WqhMMkL0GJGEIZDU$ for graphic product...

    ATTN...WFO...FSD...ABR...LBF...UNR...

    LAT...LON 42709998 42410073 42390133 45059985 45629883 45759795
    45459707 44939675 44399681 43739747 43139883 42709998=20


    =3D =3D =3D
    To unsubscribe from WX-STORM and you already have a login, go to https://lists.illinois.edu and use the "Unsubscribe" link. Otherwise email Chris Novy at cnovy@cox.net and ask to be removed from WX-STORM.

    --- SBBSecho 3.14-Linux
    * Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105)
  • From COD Weather Processor@1:2320/105 to wx-storm@lists.illinois.edu on Monday, June 26, 2023 16:36:53
    ACUS11 KWNS 261636
    SWOMCD
    SPC MCD 261636=20 NYZ000-NJZ000-PAZ000-MDZ000-DEZ000-VAZ000-NCZ000-DCZ000-WVZ000-SCZ000-26190=
    0-

    Mesoscale Discussion 1282
    NWS Storm Prediction Center Norman OK
    1136 AM CDT Mon Jun 26 2023

    Areas affected...Portions of SC...NC...VA...the eastern WV Panhandle...MD...DC...DE...central/eastern PA...NJ...and
    southern/western NY

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

    Valid 261636Z - 261900Z

    Probability of Watch Issuance...95 percent

    SUMMARY...Scattered to numerous damaging winds and large hail will
    become an increasing concern this afternoon. Multiple Severe
    Thunderstorm Watches will likely be needed to address this severe
    threat over the next couple of hours.

    DISCUSSION...16Z surface analysis shows a surface low centered over
    Lower MI with a cold front extending southward from this low across
    the OH Valley. A weak pre-frontal trough is present along/near the
    Blue Ridge Mountains into western/central NC. Much of the
    Mid-Atlantic still has considerable cloudiness early this afternoon,
    which will hamper diurnal heating to some extent. The clouds across central/eastern VA into MD is associated with a remnant
    MCV/mid-level vorticity maximum, with weak subsidence noted behind
    it. Better heating will continue across southwest VA into western NC
    and much of SC, where less cloud cover exists. Still, a moist
    low-level airmass is present across the Mid-Atlantic/Carolinas, with
    generally mid 60s to low 70s surface dewpoints in place. Continued
    heating of this airmass will likely promote around 1000-2500 J/kg of
    MLCAPE by mid afternoon, with greater instability expected in the
    Carolinas where mid-level lapse rates are steepened.

    Current expectations are for thunderstorms to continue developing
    across the higher terrain of the Appalachians, and perhaps the
    surface lee trough, as weak ascent associated with an upper
    trough/low centered over the Great Lakes overspreads the
    Mid-Atlantic. Convection is already ongoing across parts of PA and western/southern NY, with a measured severe gust recently recorded
    at KDKK in far western NY. Weaker forcing across the Carolinas casts
    some uncertainty regarding overall thunderstorm coverage with
    southward extent. Better mid-level flow around the base of the upper
    trough/low should tend to remain over the Carolinas through the day.
    30-40 kt of deep-layer shear across NC/SC will support some threat
    for supercells and large hail with initial development.

    Across the Mid-Atlantic, effective bulk shear should be somewhat
    weaker, generally in the 20-30 kt range. Mainly multicells/clusters
    should be the dominant mode across this region, with perhaps
    isolated/marginal supercells possible. Wherever enough clearing can
    occur to promote steep low-level lapse rates, a threat for damaging
    downdraft winds will exist. Multiple corridors of potentially
    greater coverage of scattered to numerous damaging gusts are evident
    based on observational and short-term guidance trends. One such
    possible corridor is across eastern PA into NJ. Multiple Severe
    Thunderstorm Watches will likely be needed this afternoon across the Mid-Atlantic and Carolinas to address the increasing threat for
    damaging winds and severe hail.

    ..Gleason/Grams.. 06/26/2023

    ...Please see https://urldefense.com/v3/__http://www.spc.noaa.gov__;!!DZ3fj= g!7nBtWcBEU9QohHM3JtimkBy03hpd4XInCwmlZnxQrxeu-giGd9SGbklISGJn1C7cQ8kIrMveK= Erm6xgEDb0a05lfkfc$ for graphic product...

    ATTN...WFO...OKX...ALY...PHI...BGM...AKQ...BUF...CTP...LWX... RAH...ILM...RNK...CAE...GSP...

    LAT...LON 33798208 34798225 36388125 38547930 40737817 42097914
    42857863 43337753 43447664 42867540 42117436 41567404
    40877377 39577418 38957477 38297507 37287569 36357710
    34787913 33498090 33338151 33798208=20


    =3D =3D =3D
    To unsubscribe from WX-STORM and you already have a login, go to https://lists.illinois.edu and use the "Unsubscribe" link. Otherwise email Chris Novy at cnovy@cox.net and ask to be removed from WX-STORM.

    --- SBBSecho 3.14-Linux
    * Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105)