1. Forum
  2. FidoNet
  3. WEATHER

  • MESO: Mesoscale Discussion 1674

    From COD Weather Processor @1:2320/107 to All on Mon Jul 20 18:53:36 2026
    ACUS11 KWNS 201853
    SWOMCD
    SPC MCD 201853
    MIZ000-WIZ000-IAZ000-MNZ000-202100-

    Mesoscale Discussion 1674
    NWS Storm Prediction Center Norman OK
    0153 PM CDT Mon Jul 20 2026

    Areas affected...Northeast Iowa into northwest/north-central
    Wisconsin

    Concerning...Severe potential...Tornado Watch likely

    Valid 201853Z - 202100Z

    Probability of Watch Issuance...95 percent

    SUMMARY...All severe hazards, including some significant, are
    possible as supercells develop by late afternoon. Timing and
    location of initiation are the main uncertainties. A tornado watch
    is likely.

    DISCUSSION...A very moist airmass is evident ahead of a cold front
    in the Upper Mississippi Valley. A capping inversion was present on
    the 12Z MPX observed sounding. Cumulus along the front have yet to
    become vertically developed as a result. Mid-level convection has
    been ongoing in southern Minnesota. This activity is now moving into
    modifying outflow from an earlier MCS in the La Crosse/Davenport
    vicinity. Lift from a shortwave trough in northern Minnesota will
    continue to overspread the area this afternoon. With time, continued
    heating and moistening ahead of the cold front and near the outflow
    front intersection should allow storms to develop, most likely by
    late afternoon. Given strong shear (50-60 kt effective) across the
    cold front, supercell structures will be favored. Steep mid-level
    lapse rates will support the threat for large to very-large hail. A
    tornado threat, some possibly strong, will also be present with
    supercells. Severe winds will also be possible. Wind gusts of 75+
    mph are possible, particularly where activity grows upscale. The
    exact timing/location of storm initiation is not clear though a
    tornado watch is likely.

    ..Wendt/Thompson.. 07/20/2026

    ...Please see https://urldefense.com/v3/__http://www.spc.noaa.gov__;!!DZ3fjg!5ExASKsIu-mhSCWas8flx3VOb25FJAWX0OpKbJ7KU6AeeIvisJLdbH8FyDnlR6pTPmA_ogtuTTsf9xtw38rs2WlDeo8$ for graphic product...

    ATTN...WFO...MQT...GRB...MKX...DLH...ARX...MPX...

    LAT...LON 43609277 44549244 46519079 46729022 46408897 45168894
    43798985 43379033 43099126 43079238 43609277

    MOST PROBABLE PEAK TORNADO INTENSITY...120-145 MPH
    MOST PROBABLE PEAK WIND GUST...65-80 MPH
    MOST PROBABLE PEAK HAIL SIZE...1.50-2.50 IN


    = = =
    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.
    --- scorpsmtpd
    * Origin: capitolcityonline.net * KY, USA (1:2320/107)