• DAY1SVR: Day 1 Convective Outlook Corr 1

    From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Fri Apr 3 08:10:24 2026
    ACUS01 KWNS 030810
    SWODY1
    SPC AC 030808

    Day 1 Convective Outlook CORR 1
    NWS Storm Prediction Center Norman OK
    0308 AM CDT Fri Apr 03 2026

    Valid 031200Z - 041200Z

    ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS NORTHERN
    MISSOURI AND SOUTHERN IOWA...

    CORRECTED FOR CORRECTED CATEGORICAL GRAPHIC

    ...SUMMARY...
    Storms are expected to evolve into an extensive line by Friday
    evening from Iowa to Oklahoma and northwest Texas, with the primary
    threats of large hail and damaging winds. A few tornadoes and
    isolated very large hail will be possible from northern Missouri
    into southern Iowa with any sustained supercells.

    A midlevel trough, emanating from a previous TPV, will move across
    the northern US today and tonight. This feature will maintain a
    modest surface cyclone that will progress northeastward from central
    Kansas to southern Wisconsin by Saturday morning. As the surface low
    lifts northeast, a west-east orientate warm front will push
    northward toward Lower Michigan.

    ... Northern Missouri and Southern Iowa ...

    As the surface cyclone lifts northeast in response to increasing
    pressure falls in advance of the midlevel trough, southerly winds
    will draw low-level moisture northward, with low-to-mid 60Fs
    dewpoints possible along and south of the aforementioned warm front.
    Residual steep mid-level lapse rates and modest insolation will
    contribute to MLCAPE values up to 2000 J/kg (and MUCAPE values
    approach 3000 J/kg). Despite the low-level jet weakening through the
    day, deep-layer shear will be sufficient for supercells along and
    south of the warm front and east of the Pacific cold front/dryline.
    However, given persistent warm-air advection/isentropic ascent
    associated with the advancing warm front, concerns abound regarding
    the number of storms, storm interactions, and an overall messy storm
    mode evolution.

    If a more discrete mode emerges, the overall kinematic wind field
    would support sustained supercells and an increased tornado threat
    along both the Pacific Front/dryline and the northward moving warm
    front. Very large hail would also be possible. If a more linear mode
    emerges, the primary severe hazard would focus more on strong winds
    and a QLCS tornado threat. Of note, even with a more linear mode,
    uncertainty in the coverage of potential strong convective winds is
    low owing to a weakening low-level jet and storm interactions. The
    Level 3/Enhanced was kept at this time, but the need for a
    wind-driven Level 3/Enhanced will be revisited in subsequent
    forecasts.

    ... Central Illinois east into Ohio and north into Lower Michigan
    ...

    Thunderstorms will be possible along the northward moving warm front
    during the afternoon on Friday. Although there is uncertainty
    regarding the number/coverage of storms, the overall thermodynamic
    and kinematic fields would support the potential for hail and wind
    along and north of the warm front. Across the western portions of
    this area, a brief tornado threat would exist as any discrete
    supercells traverse through the warm frontal zone.

    ... Southeast Kansas/Southwest Missouri southwest toward Northwest
    Texas...

    Thunderstorms will develop southward from northern Missouri into
    Oklahoma during the afternoon as the Pacific cold front/dryline
    pushes east into an increasingly unstable airmass. At the same time,
    additional thunderstorms are likely to develop across Northwest
    Texas and southwest Oklahoma in association with a subtle
    perturbation within the subtropical jet. Forecast wind fields
    indicate low-level flow will be weaker here than areas farther north
    and east, and have pronounced weakness in the 3-6 km AGL range. The
    combination of this wind field and the widespread nature of the
    convection would lend itself to large hail and damaging winds as the
    main severe hazards, although a tornado cannot be ruled out with any
    discrete storm or along the leading edge of any organized linear
    segments.

    ... Southwest Texas ...

    Isolated thunderstorms will be possible during the afternoon/evening
    along the higher terrain and a surface dryline. Wind fields will
    support supercells capable of producing large hail and damaging
    winds. However uncertainty regarding overall storm coverage
    precludes a categorical upgrade to Level 2/Slight Risk.

    ..Marsh/Chalmers.. 04/03/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Sun Apr 5 05:56:40 2026
    ACUS01 KWNS 050556
    SWODY1
    SPC AC 050554

    Day 1 Convective Outlook CORR 1
    NWS Storm Prediction Center Norman OK
    1254 AM CDT Sun Apr 05 2026

    Valid 051200Z - 061200Z

    ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FOR THE
    CAROLINAS TO THE MID-ATLANTIC REGION...

    CORRECTED FOR WORDING

    ...SUMMARY...
    Thunderstorms with isolated damaging wind gusts will be possible
    this afternoon from the eastern Carolinas to the Mid-Atlantic
    region.

    ...Synopsis...
    A mid-level trough will impinge on the East Coast as upper ridging
    builds over the Interior West today. This upper air pattern will
    support a surface trough and accompanying cold front moving offshore
    over the East Coast as surface high pressure becomes established to
    the west of the Appalachians, over much of the CONUS. Low-level
    moisture along the East Coast will promote thunderstorm potential
    ahead of the cold front given associated deep-layer lifting. A few
    strong thunderstorms are possible across the Carolinas into the
    Mid-Atlantic, where deep-layer ascent and vertical wind shear will
    be strongest.

    ...Carolinas into the Mid-Atlantic...
    By late morning into early afternoon, breaks in the clouds from
    central NC to the NJ shoreline will contribute to boundary layer
    mixing, along with destabilization (given the presence of 60+ F
    surface dewpoints). 6 C/km mid-level lapse rates overspreading this
    boundary layer will result in tall, thin CAPE profiles. A few
    hundred J/kg MLCAPE may develop along the Mid-Atlantic shoreline,
    with up to 1000 J/kg MLCAPE possible over the eastern Carolinas. As
    the surface cold front approaches by early afternoon, a line of
    storms should develop along the cold front. Modestly curved
    low-level hodographs should support some organization of the squall
    line, with a few damaging gusts possible during the afternoon.

    ..Squitieri/Chalmers.. 04/05/2026

    $$

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