• MESO: Mesoscale Discussion 2007

    From COD Weather Processor@1:2320/105 to wx-storm@lists.illinois.edu on Thu Aug 17 01:24:38 2023
    ACUS11 KWNS 170124
    SWOMCD
    SPC MCD 170123=20
    MNZ000-WIZ000-IAZ000-170300-

    Mesoscale Discussion 2007
    NWS Storm Prediction Center Norman OK
    0823 PM CDT Wed Aug 16 2023

    Areas affected...portions of southern Minnesota into far northern
    Iowa

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

    Valid 170123Z - 170300Z

    Probability of Watch Issuance...20 percent

    SUMMARY...Thunderstorms may pose an isolated severe risk for hail
    and or a few strong wind gusts this evening. A WW is not
    anticipated.

    DISCUSSION...As of 0115 UTC, regional radar analysis showed isolated thunderstorm developing ahead of a southeastward moving cold front
    over parts of southern/southwestern MN. Ahead of the front, surface temperatures in the low 80s were supporting moderate buoyancy around
    2000 J/kg of MLCAPE from the 00z MPX sounding. While unstable,
    low-level capping was also observed, suggesting storms may be
    elevated above the surface, or only realizing part of the
    thermodynamic profile. Regardless, shear profiles are quite strong,
    with 50-60 kt of effective shear sufficient for organized storms,
    including supercells. The strongest storms may be capable of
    isolated hail and a few strong/damaging outflow gusts for a couple
    of hours this evening.

    Confidence in the evolution of the severe risk is low, and related
    mainly to uncertainties about the thermodynamic environment. Thus
    far, storms have remained closely tied to the cold front, likely
    aided by frontal circulations in forcing ascent through the
    low-level stable layer. This trend appears likely to continue, with
    updrafts located along the advancing front. This would tend to favor undercutting and a transition to elevated convection with time.
    Farther east, cooler temperatures and higher inhibition are also
    less favorable for near-surface based convection. Thus, a small
    window (next 1-2 hours) may exist for isolated hail and perhaps a
    few damaging gusts if the more organized storms can remain along the
    front this evening. However, given the uncertainties and the
    relatively confined severe risk, a new watch appears unlikely.

    ..Lyons/Guyer.. 08/17/2023

    ...Please see https://urldefense.com/v3/__http://www.spc.noaa.gov__;!!DZ3fj= g!9Ip5jV8L8rqyiqTJlKrfIk2Nry2pDRK-IIy7ZPVLPrS8E1-VcETvTehwFbZyvoqbmC_PuwIhj= jXbf4T9YxOApf914r4$ for graphic product...

    ATTN...WFO...ARX...MPX...DMX...FSD...

    LAT...LON 44699241 44359224 43859242 43569270 43389325 43299374
    43269419 43299462 43359497 43469522 43609543 43839552
    44009519 44249452 44629396 45039338 44899282 44699241=20


    =3D =3D =3D
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