• MESO: Mesoscale Discussion 1643

    From COD Weather Processor@1:2320/105 to wx-storm@lists.illinois.edu on Wednesday, August 03, 2022 20:19:17
    ACUS11 KWNS 032019
    SWOMCD
    SPC MCD 032018=20
    MIZ000-OHZ000-INZ000-ILZ000-032215-

    Mesoscale Discussion 1643
    NWS Storm Prediction Center Norman OK
    0318 PM CDT Wed Aug 03 2022

    Areas affected...northern IN...southern Lower MI

    Concerning...Severe Thunderstorm Watch 514...

    Valid 032018Z - 032215Z

    The severe weather threat for Severe Thunderstorm Watch 514
    continues.

    SUMMARY...Strong to severe gusts (50-70 mph) capable of wind damage
    will be the primary hazard with the stronger storms. This activity
    will move west to east along the I-80/90 corridor in the Michiana
    region over the next couple of hours.

    DISCUSSION...Radar mosaic at 20 UTC shows an almost fully connected
    band of storms from the thumb of Michigan southwestward to southern
    Lake Michigan and southwest into central IL. The airmass ahead of
    the squall line has been primed with surface temperatures in the
    lower 90s and dewpoints in the mid 70s over northern IN into
    southwest Lower MI. The 18 UTC Detroit raob showed 2300 J/kg MLCAPE
    with a surface temperature-dewpoint of 85/72. Greater buoyancy now
    is present across southeast Lower MI with temperatures in the lower
    90s and dewpoints in the lower 70s.

    Reports of power outages have been noted with storms near the
    Kankakee, IL and Michigan City, IN areas during the 19-20 UTC
    timeframe. A couple of surface observation sites have sampled
    near-severe gusts [e.g., 47 kt (KIGQ at the IL/northwest IN border
    and KBEH--Benton Harbor, MI)]. KIWX and KGRR both show
    southwesterly tropospheric flow and the orientation of the squall
    line will likely be more conducive for stronger gusts with the line
    more orthogonal to the mean wind. In other words, the portion of
    the squall line from northwest IN into southwest Lower MI will
    probably favor the strongest gusts as it moves east over the
    Michiana region during the next several hours.

    ..Smith.. 08/03/2022

    ...Please see https://urldefense.com/v3/__http://www.spc.noaa.gov__;!!DZ3fj= g!_pdzJc73-1QwYspYQCux899uSsivks1uQEwb430KgFVBh_Ulyk0AS4xlqI2oT6PFk_jNF9Oy9= n6p2g9sqETs9vRSGAM$ for graphic product...

    ATTN...WFO...DTX...IWX...GRR...IND...LOT...ILX...

    LAT...LON 40528784 41308675 42188633 42448480 43548248 43028231
    42068374 40728669 40418748 40528784=20


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  • From COD Weather Processor@1:2320/105 to wx-storm@lists.illinois.edu on Thursday, July 20, 2023 18:15:40
    ACUS11 KWNS 201815
    SWOMCD
    SPC MCD 201815=20
    NYZ000-PAZ000-OHZ000-MIZ000-INZ000-ILZ000-201945-

    Mesoscale Discussion 1643
    NWS Storm Prediction Center Norman OK
    0115 PM CDT Thu Jul 20 2023

    Areas affected...Extreme east-central IL into central/northern
    IN/OH...far southern MI...northwest PA...western NY

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

    Valid 201815Z - 201945Z

    Probability of Watch Issuance...95 percent

    SUMMARY...The threat for severe thunderstorms will increase with
    time this afternoon. One or more additional watches will likely be
    needed soon.

    DISCUSSION...At 18 UTC, cumulus is increasing along a cold front
    from southwest lower MI into northwest IN, and also along a
    prefrontal trough from extreme east-central IL into western IN. As a well-defined midlevel shortwave trough moves across MI, confidence
    is high in additional storm development along the cold front this
    afternoon, with more scattered development possible near the
    prefrontal trough. Diurnal heating of an increasingly moist
    environment has resulted in MLCAPE increasing above 2000 J/kg across
    much of the prefrontal environment, with moderate midlevel flow
    supporting 40+ of effective shear, sufficient for organized clusters
    and a few supercells.=20

    Favorable buoyancy and relatively steep midlevel lapse rates will
    support a hail threat with the initial more discrete development. A
    tornado or two also cannot be ruled out with any sustained
    supercell. With time, one or more upscale growing clusters may
    evolve, with an increasing threat of damaging gusts.=20

    Farther east, an isolated storm that produced 1-inch hail around
    Erie, PA, near the lake breeze and along the leading edge of
    returning low-level moisture. In the short term, an additional
    strong storm or two may develop within this regime, with threat of
    isolated hail and strong/damaging gusts. Storms associated with the
    cold front (described above) will eventually move into this area by
    late afternoon or evening.=20

    Given the threats described above, one or more watches will likely
    be needed soon.

    ..Dean/Hart.. 07/20/2023

    ...Please see https://urldefense.com/v3/__http://www.spc.noaa.gov__;!!DZ3fj= g!4POs5uo7MfbD2tVmiJsewADpzy18JUcRsGZarGgP-ALyTboxQjvoNoLApmu6fXGrYIkvMWeHw= -iqEeFfFW0k_JUZBQk$ for graphic product...

    ATTN...WFO...BUF...CTP...PBZ...CLE...ILN...IWX...IND...LOT...
    ILX...

    LAT...LON 41678691 42018608 41988492 41688438 41728332 41988296
    42997859 42357827 41467944 40458152 39938399 39678681
    39838794 40218797 40468779 40988731 41678691=20


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