• MESO: Mesoscale Discussion 1720

    From COD Weather Processor@1:2320/105 to wx-storm@lists.illinois.edu on Sat Jul 19 17:09:33 2025
    ACUS11 KWNS 191708
    SWOMCD
    SPC MCD 191708=20
    NCZ000-VAZ000-MDZ000-191915-

    Mesoscale Discussion 1720
    NWS Storm Prediction Center Norman OK
    1208 PM CDT Sat Jul 19 2025

    Areas affected...Virginia and northern North Carolina

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

    Valid 191708Z - 191915Z

    Probability of Watch Issuance...60 percent

    SUMMARY...Thunderstorms developing off the southern Appalachians
    will gradually intensify as they spread east through late afternoon.
    The potential for damaging winds will increase in tandem with
    thunderstorm intensity and coverage. Watch issuance is possible this
    afternoon to address this concern.

    DISCUSSION...The early stages of thunderstorm development is
    underway per recent GOES IR imagery and lightning trends within the
    southern Appalachians/Blue Ridge Mountains and in proximity to a
    diffuse thermal low across central/northern NC. Thunderstorm
    coverage should increase through mid-afternoon as daytime heating
    continues to erode lingering MLCIN and near-surface parcels begin to
    reach their convective temperatures. Regional 12z soundings sampled
    slightly weaker mid-level flow compared to yesterday (15-25 knots),
    so slower eastward propagation is anticipated. However, this will
    allow downstream temperatures to warm well into the 90s with MLCAPE
    increasing to 2000-3000 J/kg.=20

    Convection should undergo steady intensification as a mix of
    discrete cells and clusters migrate into, or develop within, the
    CAPE reservoir across northern NC and much of VA. 7 to 8 C/km lapse
    rates within the 0-2 km layer, coupled with theta-e deficits on the
    order of 25 K and PWAT values near 2 inches, will promote strong to
    severe downburst winds associated with deeper convective cores.
    Sporadic damaging/severe wind gusts are anticipated, and a few more
    focused swaths of damaging winds are possible if/when
    loosely-organized, cold pool-driven clusters emerge. Recent high-res
    guidance suggests this appears most probable across central to
    eastern VA later this afternoon around peak heating. Convective
    trends will continue to be monitored, and watch issuance is possible
    as the severe threat becomes more widespread.

    ..Moore/Smith.. 07/19/2025

    ...Please see https://urldefense.com/v3/__http://www.spc.noaa.gov__;!!DZ3fj= g!4595BOVjBgOXTZcUazhnlIj8zVl1J--cC4N9m3Hl7IsAmfaS3vmncST3LhuhZK0WzhjuBObgu= zuGxOqkV14bq7kbmSU$ for graphic product...

    ATTN...WFO...AKQ...MHX...LWX...RAH...RNK...GSP...

    LAT...LON 37377619 37027616 36787625 36497650 36207684 35967729
    35707783 35567825 35507902 35527968 35558009 35698040
    35938074 36138089 36388095 36598089 38767844 38877797
    38897739 38737703 38447663 37917634 37377619=20

    MOST PROBABLE PEAK WIND GUST...55-70 MPH
    MOST PROBABLE PEAK HAIL SIZE...UP TO 1.25 IN


    =3D =3D =3D
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