• DAY1SVR: ENHANCED RISK GC

    From Mike Powell@618:250/1 to All on Mon May 13 08:31:00 2024
    ACUS01 KWNS 131251
    SWODY1
    SPC AC 131249

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0749 AM CDT Mon May 13 2024

    Valid 131300Z - 141200Z

    ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS SOUTH-CENTRAL/SOUTHEAST TEXAS AND THE GULF COAST...

    ...SUMMARY...
    Severe thunderstorms are expected today from central and east Texas
    across the Gulf Coast states. The potential exists for multiple
    corridors of significant wind gusts, very large hail, and a few
    tornadoes.

    ...Central/eastern Texas...
    The region will be influenced by moderately strong cyclonically
    curved westerlies within the base of the central Plains/Lower
    Missouri Valley-centered upper-level trough. Some northward spread
    of a very moist near-coastal air mass will occur today ahead of an
    upstream southeastward-moving cold front and weak surface wave.
    Beneath steep mid-level lapse rates (reference 12z observed
    soundings from DFW/CRP), strong destabilization is expected into the
    afternoon as multi-layer cloud cover becomes more scattered, with
    upwards of 2000-4000 J/kg MLCAPE across much of south-central and east/southeast Texas.

    A belt of stronger mid-level flow will overspread the region, with
    elongated, straight hodographs supporting splitting supercells as an
    initial storm mode. Large hail will be the main threat with these
    storms, with some of the largest stones potentially reaching 2-4
    inches in diameter where sustained supercell structure can develop
    and persist. With time, storms should grow upscale into an east/southeastward-moving MCS later in the afternoon and evening as
    they move toward the coastal plain and interact more favorably with
    the baroclinic boundary. By this point, severe gusts become the
    primary threat, with a couple of QLCS tornadoes also possible.

    ...Gulf Coast/Southeast...
    A quasi-linear storm cluster persists this morning across far
    southern Alabama and the Florida Panhandle, on the immediate cool
    side of a near-coastal warm front that will continue to develop north-northeastward through the day. This cluster may grow further
    upscale with a continued severe risk through the morning,
    particularly with 75-100 miles of the Gulf of Mexico. This includes
    the potential for all severe hazards including damaging winds, large
    hail and some tornado risk. Additional storm development and
    intensification is possible today along the outflow reinforced
    effective front that extends westward across far southern
    Mississippi and southern Louisiana.

    Additionally, linearly organized storms moving out of Texas could
    approach some of these same areas again late tonight. Any such secondary/tertiary rounds of severe risk will depend upon how far
    south the effective baroclinic zone has been shunted southward by
    convection through the afternoon/early evening, likely confining any
    such severe potential late tonight to more immediate coastal areas.

    ...Portions of the southern Plains into the Ozarks...
    Showers and thunderstorms should linger across much of the southern
    Plains into the Ozarks this morning to at least mid-afternoon. Weak
    surface low development is anticipated across Missouri/Arkansas
    later in the day, which will encourage modest low-level moisture
    advection beneath gradually steepening mid-level lapse rates. SBCAPE
    should rise into the 1000-1500 J/kg range later in the afternoon.
    Deep-layer shear is not expected to be overly strong with northward
    extent, though some elongation of straight hodographs suggests that
    multicells or brief, transient supercells may develop and produce
    isolated severe hail and/or wind.

    ...Florida Peninsula...
    To the south of potential MCS influences across northern Florida,
    surface temperatures are expected to rise into the 80s F amid
    dewpoints around 70 F. Though mid-level lapse rates will be
    relatively poor, the strong surface heating of the moist air mass
    will boost SBCAPE into the 1000-2000 J/kg range amid 30-40 kt of
    effective bulk shear. Multicells and transient supercells are
    expected to initiate during the afternoon, especially along
    sea-breeze boundaries, with isolated instances of hail and damaging
    winds gusts possible.

    ...Northern Montana...
    A few strong storms could occur from mid-afternoon through early
    evening, influenced by a low-amplitude mid-level disturbance and a
    modestly moist/unstable boundary layer. Some stronger wind
    gusts/hail could occur, but modest-strength low/mid-tropospheric
    winds should keep organized severe potential low.

    ..Guyer/Broyles.. 05/13/2024

    $$
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