• MESO: Mesoscale Discussion 0812

    From COD Weather Processor@1:2320/105 to wx-storm@lists.illinois.edu on Wednesday, May 18, 2022 18:39:22
    ACUS11 KWNS 181839
    SWOMCD
    SPC MCD 181838=20
    KYZ000-TNZ000-INZ000-182045-

    Mesoscale Discussion 0812
    NWS Storm Prediction Center Norman OK
    0138 PM CDT Wed May 18 2022

    Areas affected...Southern IN...Western/Central KS...Middle TN

    Concerning...Severe potential...Watch possible=20

    Valid 181838Z - 182045Z

    Probability of Watch Issuance...40 percent

    SUMMARY...A few severe thunderstorms capable of all severe hazards
    are possible this afternoon. Uncertainty regarding development
    limits overall forecast confidence, but convective trends are being
    monitored.

    DISCUSSION...A strong mesoscale convective vortex generated by last
    nights thunderstorms across the central Plains is currently centered
    near the southern IL/IN border (approximately 50 miles north of
    EVV). A cluster of showers and thunderstorms over southern IN
    immediately precedes this vortex. Areas farther south/southeast have
    yet to destabilize as the best low-level moisture (i.e. mid 60s
    dewpoints) currently remains south of western/middle TN.=20=20

    The greatest near-term severe thunderstorms potential appears to be
    with the ongoing cluster near the vorticity maximum, but the lack of
    stronger buoyancy should keep any hail or damaging wind gusts very
    isolated. Farther south, a conditional severe risk will be in place
    this afternoon. The main uncertainty is whether or not the favorable
    low-level moisture will advect far enough northward before the
    ascent attendant to the MCV passes through the region. If storms do
    develop, a few supercells capable of all severe hazards are
    possible. Convective trends will be monitored closely across this
    region this afternoon.

    ..Mosier/Grams.. 05/18/2022

    ...Please see https://urldefense.com/v3/__http://www.spc.noaa.gov__;!!DZ3fj= g!7jZzH9_ax7Z0IH3D-ze2y55-QS3XZBBvKGKXWETjTpfIDgzK56E_QbgB957hXdOfBIrG-BaKe= VrE3-_wPMkZK7vnUps$ for graphic product...

    ATTN...WFO...JKL...ILN...LMK...OHX...PAH...MEG...

    LAT...LON 37248815 38428716 38788528 38048430 35798533 35468707
    36128842 37248815=20


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  • From COD Weather Processor@1:2320/105 to wx-storm@lists.illinois.edu on Thursday, May 18, 2023 18:00:37
    ACUS11 KWNS 181800
    SWOMCD
    SPC MCD 181800=20
    TNZ000-ALZ000-MSZ000-182000-

    Mesoscale Discussion 0812
    NWS Storm Prediction Center Norman OK
    0100 PM CDT Thu May 18 2023

    Areas affected...Northeast Mississippi to northern Alabama and
    southern Middle Tennessee

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

    Valid 181800Z - 182000Z

    Probability of Watch Issuance...5 percent

    SUMMARY...Isolated strong downburst winds and occasional severe hail
    are possible this afternoon. This threat will remain too transient
    and localized to warrant watch issuance.

    DISCUSSION...Convective initiation is well underway across northern
    MS into northern AL in the vicinity of a weak surface low and
    attendant weak warm front/differential heating boundary draped to
    the east. Latest GOES imagery and lightning trends indicate that
    much of this convection is intensifying, likely owing to ample
    diurnal warming with temperatures warm through the upper 70s into
    the low 80s. Further warming, combined with cool temperatures aloft
    in the vicinity of a weak upper low, will support MLCAPE values
    upwards of 1500-2000 J/kg by mid-afternoon across northern AL to
    southern middle TN. Although deep-layer shear is fairly modest,
    favorable thermodynamics (aforementioned buoyancy combined with
    PWATs above 1.5 inches and low-level lapse rates near 8 C/km) will
    support the potential for damaging downburst winds as storms begin
    to cluster and propagate north/northeast. Additionally, sporadic
    hail approaching severe limits will be possible with the more
    intense updraft pulses, though storm longevity will likely remain
    too limited to support a substantial hail threat.=20

    Further south across south-central MS, stronger mid-level flow is
    likely supporting effective bulk shear values on the order of 25-30
    knots within a similar thermodynamic environment. While this region
    is conditionally more favorable for organized severe convection,
    confidence in storm coverage remains very limited owing to very
    weak/localized forcing for ascent.

    ..Moore/Grams.. 05/18/2023

    ...Please see https://urldefense.com/v3/__http://www.spc.noaa.gov__;!!DZ3fj= g!-ymgZDGo1c7kBCYknKF3VjH07oi99DqEJsYtN8WB7-T_0X-JiotPIIeyc52VKUj8B_LtFSVU7= mUhKdYjTkn8u3iko5k$ for graphic product...

    ATTN...WFO...MRX...OHX...BMX...HUN...MEG...JAN...

    LAT...LON 33708646 33798715 33848805 33628863 33428928 33258984
    33469011 34028983 34578923 35168803 35458737 35578695
    35598632 35428601 35268587 34778570 34298557 33898568
    33708601 33708646=20


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