• DAY2SVR: Updated

    From Mike Powell@618:250/6 to All on Thu Apr 23 13:40:08 2026
    ACUS02 KWNS 231752
    SWODY2
    SPC AC 231715

    Day 2 Convective Outlook
    NWS Storm Prediction Center Norman OK
    Issued by 15th OWS Scott Air Force Base IL
    1215 PM CDT Thu Apr 23 2026

    Valid 241200Z - 251200Z

    ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS PARTS OF THE
    SOUTHERN PLAINS INTO THE LOWER MISSISSIPPI VALLEY...

    ...SUMMARY...
    Scattered severe thunderstorms are possible Friday from the Southern
    Plains into the Lower Mississippi Valley. Large hail and damaging
    winds will be the main hazards, with a brief tornado also possible.
    Isolated strong wind gusts may occur across portions of the lower
    Ohio Valley as well.

    ... Synopsis ...

    Broad cyclonic flow will persist across much of the central and
    western US as a longwave trough remains anchored over the northern
    states. In the absences of stronger large-scale ascent across the
    southern US, convective evolution will be driven primarily by
    remnant boundaries and subtle perturbations within the broader
    cyclonic flow.

    ... Southern Plains into the Lower Mississippi Valley ...

    Convection is expected to be ongoing from portions of Oklahoma into
    Arkansas and Missouri at the start of the forecast period, largely
    tied to a convectively augmented cold front. This activity may still
    be capable of producing isolated strong wind gusts early in the
    period, but should gradually weaken through the morning as the
    low-level jet dissipates and the parent shortwave trough moves away
    from the region.

    The primary severe threat is expected to develop from the afternoon
    into the evening along the effective frontal zone and any residual
    outflow or differential heating boundaries. Current guidance
    suggests the boundary will settle near or south of the I-40
    corridor, though some uncertainty in the exact location remains.
    Notably, the HRRR is an outlier in maintaining a farther north and
    west boundary as compared to other members of the 20260423/Z HREF.

    By afternoon, strong heating south of the boundary will support a
    moderately to strongly unstable airmass (SBCAPE values in the
    2000-3000 J/kg range) from central/east Texas northward toward the
    boundary, with instability gradually decreasing with eastward extent
    into Mississippi and Alabama. Deep-layer shear will remain modest
    across the region (generally 30-35 knots), supporting organized
    multicells and occasional transient supercells.

    Thunderstorms should develop/intensify from eastern Oklahoma into
    Arkansas along one or more of boundaries across the region. Initial
    storms may pose a threat for large hail and localized damaging wind
    gusts as low-level shear will generally remain weak. However,
    localized enhancements along boundaries or any MCV could support a
    brief tornado risk.

    With time, storm interactions and consolidating outflows should
    support upscale growth into one or more clusters or linear MCS
    structures. These systems should move east-southeast into northern
    Louisiana and central Mississippi through the afternoon and evening
    hours. While the modest deep-layer shear may temper the overall wind
    threat somewhat, sufficient organization should still support a
    corridor of damaging wind gusts.

    Farther west into central and eastern Texas, isolated convection may
    occur along a dryline as diurnal heating weakens inhibition to the
    east. Storm coverage is expected to remain sparse given weak ascent,
    but any sustained updrafts in this strongly unstable environment
    could produce large hail.

    ... Portions of the Ohio Valley ...

    A separate corridor of thunderstorms may develop during the
    afternoon across portions of the eastern Indiana and western Ohio
    in the wake of earlier convection. Modest destabilization should
    occur with perhaps up to 1000 J/kg of SBCAPE. Although the low-level
    jet will be weakening through the day, residual flow and modest
    deep-layer shear may support loosely organized convection capable of
    producing damaging wind gusts.

    ..Afwa.. 04/23/2026

    $$
    --- MultiMail/DOS
    * Origin: Project Scorpio TEST (618:250/6)