• MESO: Mesoscale Discussion 1048

    From COD Weather Processor@1:2320/105 to wx-storm@lists.illinois.edu on Mon Jun 21 17:52:17 2021
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    ACUS11 KWNS 211752
    SWOMCD
    SPC MCD 211751=20 NJZ000-NYZ000-PAZ000-DEZ000-MDZ000-DCZ000-VAZ000-WVZ000-211945-

    Mesoscale Discussion 1048
    NWS Storm Prediction Center Norman OK
    1251 PM CDT Mon Jun 21 2021

    Areas affected...northern VA...much of MD...northern
    DE...central-eastern PA...western NJ

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

    Valid 211751Z - 211945Z

    Probability of Watch Issuance...80 percent

    SUMMARY...Clusters of strong to severe thunderstorms capable
    primarily of isolated to widely scattered damaging gusts, are
    possible this afternoon into the early evening. A severe
    thunderstorm watch will likely be needed over most of the discussion
    area by mid afternoon.

    DISCUSSION...Visible-satellite imagery shows a cluster of strong to
    locally severe thunderstorms over WV moving eastward. This
    thunderstorm cluster will approach the eastern panhandle of WV and
    far western MD (to the east of severe thunderstorm watch #299)
    during the next few hours. A cumulus field has developed over the
    remainder of the discussion area from VA north to the NY/PA border.=20
    It seems possible convective initiation occurs over central PA near
    State College over the next hour.

    Surface analysis indicates the airmass has destabilized early this
    afternoon with temperatures generally in the upper 80s deg F with
    upper 60s to lower 70s dewpoints. Modifying the the Pittsburgh, PA
    8am raob for current conditions over central PA yields around 2000
    J/kg MLCAPE. The Dulles, VA 8am raob was noticeably less unstable
    this morning compared to the Pittsburgh, PA raob. However, strong
    heating and moistening of the boundary layer east of the higher
    terrain has resulted in moderate buoyancy over this area too.=20=20

    The strong heating across this broad region has steepened low-level
    lapse rates. As storms move into the region from the west, the
    lapse rate profiles will support the potential for strong downdrafts
    with the heavier water-loaded cores or small bow-shaped segments
    that may evolve. Peak gusts ranging from 50-70 mph are possible
    with the strongest storms.=20=20

    It is uncertain whether isolated storms will develop over eastern PA
    during the afternoon or whether the thunderstorm risk will be
    delayed until storms arrive from the west. This uncertainty is due
    in part to large-scale subsidence likely suppressing activity on the
    northwest periphery of Tropical Storm Claudette.

    ..Smith/Hart.. 06/21/2021

    ...Please see https://urldefense.com/v3/__http://www.spc.noaa.gov__;!!DZ3fj= g!o67YD6iVSbU3nTufgRp5DfIbrIlAarBbUnknDd3Sd8Gh3i0ucmCY6jE-q_8L89QK3hGWnnAU$=
    for graphic product...

    ATTN...WFO...PHI...BGM...AKQ...CTP...LWX...RNK...PBZ...RLX...

    LAT...LON 41967569 41977758 39627938 38167972 37727908 37857820
    39317564 40657447 41497491 41967569=20



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