• DAY2SVR: ENHANCED RISK SE

    From Mike Powell to All on Tue May 7 08:10:00 2024
    ACUS02 KWNS 070602
    SWODY2
    SPC AC 070600

    Day 2 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0100 AM CDT Tue May 07 2024

    Valid 081200Z - 091200Z

    ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FROM NORTHEAST
    TEXAS INTO THE MID-SOUTH/MID MISSISSIPPI VALLEY AND LOWER OHIO
    VALLEY...

    ...SUMMARY...
    Scattered to numerous severe thunderstorms appear likely Wednesday
    across from parts of the southern Plains into the mid Mississippi,
    Ohio, and Tennessee Valleys. All severe hazards, including
    tornadoes, very large hail, and severe/damaging winds should occur.
    Some of the tornadoes may be strong.

    ...Synopsis...
    An upper cyclone initially over the northern Plains on Wednesday
    should gradually move towards the Upper Midwest through the period.
    A separate shortwave trough over the Great Lakes is forecast to
    advance eastward across NY and New England. A broad 50-70 kt
    mid-level west-southwesterly jet should remain over the
    southern/central Plains into the mid MS Valley, OH Valley/Midwest,
    and Northeast. This jet will aid in rather strong deep-layer shear
    across much of these regions.

    At the surface, a weak low over OK should develop northeastward to
    the mid MS Valley by Wednesday afternoon in tandem with a lobe of
    mid-level vorticity/ascent also spreading northeastward over this
    region. An attendant cold front should move east-southeastward
    across the southern/central Plains, with a dryline extending
    southward from central into south TX. A warm front should attempt to
    lift northward through the day across MO and southern IL/IN/OH. But,
    how far north the warm front will be able to lift northward remains
    rather uncertain. All of these boundaries should provide a focus for
    potential severe thunderstorm development Wednesday afternoon and
    evening.

    ...ArkLaTex into the Mid Mississippi Valley and Ohio Valley...
    A large area of significant severe potential remains evident across
    these regions on Wednesday. Across the broad warm sector, upper 60s
    to mid 70s surface dewpoints should generally prevail. Even modest
    daytime heating of this very moist low-level air, acting in concert
    with steepened mid-level lapse rates spreading eastward from the southern/central Plains, will foster around 2500-3500 J/kg of MLCAPE
    by Wednesday afternoon. Some locally higher/more extreme instability
    values will be possible. With enhanced flow associated with the
    previously mentioned mid-level jet, effective bulk shear of 40-50+
    kt will easily support organized severe thunderstorms, including the
    potential for numerous supercells and intense bowing line segments.

    Based on latest guidance trends showing the warm front stalling/not
    making as much northward progress into the OH Valley, the northern
    extent of the higher severe probabilities has been trimmed some
    across this area. Otherwise, very large hail appears probable with
    initial development along the cold front and warm front, which may
    begin across MO as early as mid Wednesday morning. Additional
    supercell development may also occur along/near the warm front by
    early Wednesday afternoon across parts of the mid MS Valley into the
    lower OH Valley. In addition to the large/very large hail threat, a
    concern for tornadoes also exists with this warm-frontal activity
    given ample 0-1 km shear to support low-level updraft rotation. Some
    of these tornadoes could be strong given the forecast strength of
    the low-level shear. An increasing threat for severe/damaging winds
    is also apparent through the late afternoon, and likely continuing
    into at least the early evening, as convection should attempt to
    grow upscale into one or more intense bowing clusters. With that
    said, convective evolution is somewhat uncertain, and attempting to
    pinpoint areas of greater severe-wind potential remains difficult.

    ...Iowa and Vicinity...
    Isolated strong to severe thunderstorms appear possible in
    associated with a cold-core upper low across parts of IA and
    vicinity, mainly Wednesday afternoon. Although forecast instability
    and deep-layer shear appear fairly weak/marginal, a few instances of
    hail and strong/gusty winds appear possible. A brief tornado or two
    may also occur along/near the occluded front.

    ...Southern New England into NY and the Mid-Atlantic/Carolinas...
    Occasional hail and strong to locally damaging winds appear possible
    with isolated thunderstorms across parts of NY into southern New
    England as a surface low and attendant cold front move eastward
    through the day. Farther south into the Mid-Atlantic/Carolinas,
    greater instability is forecast. But, better forcing should
    generally remain displaced to the west. It remains unclear how many thunderstorms will form. Still, any that do could become strong to
    locally severe.

    ..Gleason.. 05/07/2024

    $$