• MESO: Mesoscale Discussion 1028

    From COD Weather Processor@1:2320/105 to wx-storm@lists.illinois.edu on Saturday, June 04, 2022 18:13:33
    ACUS11 KWNS 041813
    SWOMCD
    SPC MCD 041812=20
    MEZ000-NHZ000-VTZ000-042015-

    Mesoscale Discussion 1028
    NWS Storm Prediction Center Norman OK
    0112 PM CDT Sat Jun 04 2022

    Areas affected...Northern New Hampshire and northwestern Maine

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

    Valid 041812Z - 042015Z

    Probability of Watch Issuance...5 percent

    SUMMARY...Isolated to scattered thunderstorms will likely continue
    to develop through the remainder of the afternoon and may be capable
    of sporadic damaging winds and hail.

    DISCUSSION...Mid-afternoon water-vapor imagery reveals an
    upper-level low over southeastern Canada. Cool temperatures aloft
    (500 mb temps generally between -18 to -22 C) and broad difluence on
    the southeastern periphery of the low is providing sufficient MLCAPE
    (generally around 500 J/kg) and lift to support isolated to
    scattered thunderstorms. While the better instability and lift
    resides on the Canadian side of the border, portions of northern NH
    and northwestern ME are within the periphery of this environment.
    Morning soundings and recent RAP forecast soundings show 50-70 knot
    flow near and above 6 km, though much of the mixed-layer and most
    unstable layer CAPE profiles lie beneath this level. Forecast
    soundings and VWP observations suggest that winds within the
    CAPE-bearing layer are considerably weaker, generally 15-25 knots. Consequently, the propensity for organized convection may be limited
    to any storms that can achieve sufficiently deep updrafts to achieve upper-level venting provided by the stronger winds aloft. Given the
    somewhat weak forcing for ascent, this potential appears limited in
    the near term, though may increase as a cold front moves through the
    region later this afternoon and early evening. Steepening low-level
    lapse rates will support the potential for strong, possibly
    damaging, downburst winds, and some hail is possible given the cold temperatures aloft. However, this threat is expected to be limited,
    and a watch is not expected.

    ..Moore/Guyer.. 06/04/2022

    ...Please see https://urldefense.com/v3/__http://www.spc.noaa.gov__;!!DZ3fj= g!6C3JE1aioQCBykEIgQqzEO4cl15W9n9bU3GQtvMKDZKL_dVESGIOw83ltxh6NGj6V39zdGPcB= KGLLTTxSovLgCzhLjI$ for graphic product...

    ATTN...WFO...CAR...GYX...BTV...

    LAT...LON 44527051 44387121 44717172 45147178 45277157 45917059
    46617017 47136971 47146916 46786895 46256885 45776905
    45096955 44527051=20


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  • From COD Weather Processor@1:2320/105 to wx-storm@lists.illinois.edu on Wednesday, June 14, 2023 06:58:25
    ACUS11 KWNS 140658
    SWOMCD
    SPC MCD 140657=20
    MSZ000-ARZ000-LAZ000-TXZ000-140830-

    Mesoscale Discussion 1028
    NWS Storm Prediction Center Norman OK
    0157 AM CDT Wed Jun 14 2023

    Areas affected...ArkLaTex into the ArkLaMiss vicinity

    Concerning...Severe Thunderstorm Watch 287...

    Valid 140657Z - 140830Z

    The severe weather threat for Severe Thunderstorm Watch 287
    continues.

    SUMMARY...Some threat for hail and locally damaging gusts will
    spread east/southeast overnight. Downstream watch issuance will
    eventually need to be considered into west-central MS.

    DISCUSSION...A cluster of supercells is ongoing early this morning
    across the ArkLaTex region, with a notable left-moving supercell
    farther north approaching northwest MS. An environment favorable for
    organized storms is expected to persist overnight, with MUCAPE of
    1500-2500 J/kg, effective shear of 50-70 kt, and elongated
    hodographs supporting splitting supercells. In the short term, the
    most favorable environment is expected to persist near the AR/LA
    border, where very large hail will continue to be possible with
    slightly elevated supercells. Also, despite the presence of a
    near-surface inversion, some threat for damaging winds may also
    evolve with time, with the potential for an outflow-driven cluster
    to move east-southeastward. Some threat may eventually approach the
    MS River near west-central MS, where downstream watch issuance may
    need to be considered later this morning.=20

    To the northeast, some severe hail threat may move out of WW 287
    with the ongoing left-moving supercell and any additional
    left-movers that may develop with time. However, with somewhat
    weaker buoyancy in this region, the severe threat may remain rather
    isolated into northern MS and western TN, where watch issuance is
    currently considered unlikely in the short term.

    ..Dean/Guyer.. 06/14/2023

    ...Please see https://urldefense.com/v3/__http://www.spc.noaa.gov__;!!DZ3fj= g!-ia9YJVKgmcFt8oCGwMxqOUJ_fRTDOcWwIwUkD9IMD54b3IM-Hw7WJgxe38oDR0XhW-kR5DKI= MgOZiT4axwCzzwHmkY$ for graphic product...

    ATTN...WFO...MEG...JAN...LZK...SHV...

    LAT...LON 33109480 34789243 34879126 34549074 33899033 32699029
    31829080 31919177 32699425 33109480=20


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