• MESO: Mesoscale Discussion 0313

    From COD Weather Processor@1:2320/105 to wx-storm@lists.illinois.edu on Wednesday, May 02, 2018 16:37:05
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    ACUS11 KWNS 021636
    SWOMCD
    SPC MCD 021636
    KSZ000-OKZ000-TXZ000-021900-

    Mesoscale Discussion 0313
    NWS Storm Prediction Center Norman OK
    1136 AM CDT Wed May 02 2018

    Areas affected...Eastern TX/OK Panhandles western OK to parts of
    southwest and south-central KS

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

    Valid 021636Z - 021900Z

    Probability of Watch Issuance...95 percent

    SUMMARY...Development of additional thunderstorms is expected
    between 17-19Z across portions of the Texas Panhandle into the
    eastern Oklahoma Panhandle into southwest and south-central Kansas.
    Severe storms will be likely by early afternoon, with all severe
    hazards possible, including very large hail and a tornado threat.

    DISCUSSION...Trends in morning surface analyses and visible
    satellite imagery showed a quasistationary boundary extending from
    extreme southeast NE to southwest KS into the OK Panhandle (east of
    KGUY) to far northern TX Panhandle. In KS this boundary was
    analyzed at 15Z to the south of KCNK and south of KGBD. Although
    surface heating, given breaks in high-level clouds, is resulting in
    mixing, persistent southerly low-level winds are compensating to
    maintain surface dew points in the middle-upper 60s from the eastern
    TX Panhandle into western and central OK to southern and eastern KS.
    Moisture return has also spread farther westward this morning into
    more of the TX Panhandle. This moisture combined with diabatic
    heating will further weaken inhibition, resulting very strong
    instability (MUCAPE of 2500-3500 J/kg) this afternoon.

    Recent lightning data, satellite and radar imagery showed a storm
    had developed near the intersection of the quasistationary boundary
    and dry line in Hansford County TX (extreme northern TX Panhandle).

    A 70-75 kt southwesterly 500-mb jet accompanying a shortwave trough
    will move through the southern High Plains early this afternoon and
    proceed downstream into western OK to central KS by late afternoon.
    Forcing for ascent attendant to this trough and exit region of the
    500-mb jet are expected to reach western portions of the discussion
    area between 17-19Z supporting additional storm development into the
    afternoon. This scenario is suggested by the last several runs of
    the operational HRRR and the 12Z HREF. These initial storms will
    continue to form from the northern TX Panhandle to part of southwest
    and adjacent south-central KS where low-level convergence is the
    strongest, given strengthening low-level winds into the
    quasistationary boundary. Storms will also develop equatorward
    along and east of the dryline, as it mixes eastward this afternoon
    into the eastern TX/OK Panhandles, and into western OK. The
    available MUCAPE and increasing effective bulk shear will be
    favorable for supercells producing tornadoes, very large hail, and
    damaging winds. Storms that develop along the dryline and into
    western OK will have a greater likelihood to be discrete, given
    shear vectors crossing the initiation boundary. Shear vectors in
    vicinity of the boundary in KS may tend to be more parallel
    resulting in bows with embedded supercells.

    ..Peters/Grams.. 05/02/2018

    ...Please see www.spc.noaa.gov for graphic product...

    ATTN...WFO...TOP...ICT...OUN...DDC...LUB...AMA...

    LAT...LON 34580139 35800143 37050058 38399882 39269745 38879669
    38139647 37029768 35289889 34409920 34380083 34580139



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  • From COD Weather Processor@1:2320/105 to wx-storm@lists.illinois.edu on Saturday, April 13, 2019 06:52:19
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    ACUS11 KWNS 130652
    SWOMCD
    SPC MCD 130652
    LAZ000-ARZ000-TXZ000-130845-

    Mesoscale Discussion 0313
    NWS Storm Prediction Center Norman OK
    0152 AM CDT Sat Apr 13 2019

    Areas affected...Northern/northeastern Texas into northern/central
    Louisiana and far southern Arkansas

    Concerning...Severe potential...Watch unlikely

    Valid 130652Z - 130845Z

    Probability of Watch Issuance...20 percent

    SUMMARY...Occasional, marginally severe hail is possible with storms
    across the discussion area for the next several hours. A WW is not
    anticipated due to the isolated nature of the threat.

    DISCUSSION...Elevated convection - including isolated supercells -
    continue within a warm-advection regime across the discussion area.
    These storms are in an environment characterized by steep mid-level
    lapse rates (7.5-8.5 deg C/km) as observed in RAP point forecast
    soundings and 06Z upper air soundings from FWD and SHV, and strong
    vertical shear in the cloud-bearing layer. This regime should
    persist for the next several hours as warm-advection continues well
    ahead of an approaching mid-level wave and surface low located over
    New Mexico and Texas respectively. 1" to 1.5" hailstones are
    possible with stronger storms - especially those that exhibit
    mid-level rotation. Given the isolated and marginal nature of the
    threat, a WW issuance is not anticipated, although convective trends
    will continue to be monitored.

    ..Cook.. 04/13/2019

    ...Please see www.spc.noaa.gov for graphic product...

    ATTN...WFO...JAN...LCH...SHV...HGX...FWD...

    LAT...LON 31749643 32239671 32819669 33229617 33309543 33249429
    33189342 33049233 32889143 32429118 31709143 31309187
    31269203 31019268 30849343 30909481 31149580 31749643



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