• MESO: Mesoscale Discussion 1338

    From COD Weather Processor@1:2320/105 to wx-storm@lists.illinois.edu on Sunday, July 03, 2022 18:09:44
    ACUS11 KWNS 031809
    SWOMCD
    SPC MCD 031809=20
    WYZ000-MTZ000-IDZ000-031915-

    Mesoscale Discussion 1338
    NWS Storm Prediction Center Norman OK
    0109 PM CDT Sun Jul 03 2022

    Areas affected...Southwest Montana

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

    Valid 031809Z - 031915Z

    Probability of Watch Issuance...80 percent

    SUMMARY...Thunderstorms are expected to intensify across southwest
    Montana this afternoon, with a risk of a few supercells capable of
    large hail and damaging winds. A severe thunderstorm watch is
    likely.

    DISCUSSION...Radar/satellite imagery show a small cluster of
    thunderstorms over southern Lemhi county ID, along with increasing
    towering cumulus clouds over the Sawtooth mountains of central ID.=20
    This activity is ahead of a shortwave trough over eastern WA/OR that
    will track northeastward across the region this afternoon and
    evening. Mid and high clouds are slowly clearing to the east of
    this activity, which should allow strong heating and destabilization
    to occur. Rather cool temperatures aloft (-13 to -14C at 500mb)
    coupled with dewpoints in the low-mid 50s will aid in MLCAPE values
    over 1000 J/kg in the mountains of southwest MT. Sufficient
    effective shear values suggest a risk of a rotating storms capable
    of large hail and damaging wind gusts. Trends are being monitored
    for watch issuance in parts of the discussion area.

    ..Hart/Grams.. 07/03/2022

    ...Please see https://urldefense.com/v3/__http://www.spc.noaa.gov__;!!DZ3fj= g!9AF3YicnxU4KEI7LEK7hmRWV4tOOdvb3ZYCYTpJykJrWli_09Oz1X3b986XjMjdnooRXWHSZ9= BvLmQsbvfQdgaY2MYc$ for graphic product...

    ATTN...WFO...BYZ...RIW...TFX...PIH...MSO...

    LAT...LON 44601356 45701425 46221340 46791181 47011035 46110973
    45171061 44241237 44601356=20


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  • From COD Weather Processor@1:2320/105 to wx-storm@lists.illinois.edu on Thursday, June 29, 2023 17:40:38
    ACUS11 KWNS 291740
    SWOMCD
    SPC MCD 291740=20
    SDZ000-NEZ000-COZ000-WYZ000-291945-

    Mesoscale Discussion 1338
    NWS Storm Prediction Center Norman OK
    1240 PM CDT Thu Jun 29 2023

    Areas affected...CO Front Range and adjacent high plains...southeast
    and eastern WY...western NE Panhandle

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

    Valid 291740Z - 291945Z

    Probability of Watch Issuance...80 percent

    SUMMARY...Convective initiation will occur over the Medicine
    Bow/Laramie Ranges by 12pm MDT, and the Front Range by 1-2pm MDT.=20
    Discrete supercells are forecast to develop later this afternoon
    once updrafts mature/intensify. A couple of tornadoes are possible,
    including very large hail (diameters 2-3 inches).

    DISCUSSION...Visible satellite imagery shows developing convection
    over the Medicine Bow Range with a building cumulus field located
    near the Continental Divide west of Denver. The airmass is very
    moist with mid 50s surface dewpoints prevalent from the Palmer
    Divide northward through Cheyenne and into northeast WY. Strong
    heating will continue to occur through mid-late afternoon as
    temperatures warm through the 70s. Forecast soundings indicate
    convective inhibition is minimal as temperatures warm into the
    mid-upper 70s. Very steep lapse rates are denoted on the forecast
    soundings (around 8 deg C/km in the surface to 300 mb layer).

    The moist low-level upslope flow coupled with orographic lift
    downstream of a mid-level trough pivoting eastward through the
    eastern Great Basin, will promote scattered thunderstorms developing
    by mid afternoon from near I-70 northward along I-25 into eastern
    WY. Moderate buoyancy (2000-2500 J/kg MLCAPE) and long hodographs
    will favor discrete supercells initially with the more intense
    storms. Large to very large hail is becoming increasingly probable
    this afternoon both in the general Denver vicinity and near/north of
    the Cheyenne Ridge per CAM model guidance. The moist low levels
    coupled with a supercellular mode lend the possibility for
    tornadoes. As storms move into the western NE Panhandle and far
    northeast CO during the early evening, expecting storm outflows to
    promote some clustering into a potential MCS.

    ..Smith/Guyer.. 06/29/2023

    ...Please see https://urldefense.com/v3/__http://www.spc.noaa.gov__;!!DZ3fj= g!_3rhTRbXaqHPXNRBI8kSDeomtZKRfZwsAeIZCVqHiFmlXuCQ_zcF3xuqhh-CGw1391GakHTNC= Qs7tvjLRGqBslTMDKw$ for graphic product...

    ATTN...WFO...UNR...BOU...CYS...

    LAT...LON 39510525 41030568 41500616 42670600 43240558 43400486
    42940385 41170365 39730377 39270433 39270494 39510525=20


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