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  • DAY48SVR: Day 4-8 Convective Outlook

    From COD Weather Processor @1:2320/107 to All on Sat Oct 10 08:22:58 2026
    ACUS48 KWNS 100822
    SWOD48
    SPC AC 100820

    Day 4-8 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0320 AM CDT Sat Oct 10 2026

    Valid 131200Z - 181200Z

    ...DISCUSSION...
    The 00Z models have slowed the progression of an upper low and
    associated trough from the Great Basin into the central Rockies on
    Days 4 and 5/Tuesday and Wednesday. By Day 6/Thursday and beyond,
    model spread increases in the handling of that midlevel system,
    leading to greater uncertainty in the evolution of the large-scale
    pattern.

    ...Day 4/Tuesday...

    There is some model signal that a subtle disturbance embedded within
    a belt of enhanced mid/upper-level flow will progress from the
    southern Rockies into the central High Plains, aiding in the
    deepening of a lee cyclone over southeast CO. Elsewhere, a
    low-amplitude disturbance is forecast to advance from the Great
    Lakes into the Northeast, in tandem with another surface low. A
    frontal system will connect the two lows, stretching from the lower
    Great Lakes through the OH Valley into the central Plains. A dryline
    will extend south from the lee cyclone to along the TX-NM border. A
    moist and unstable air mass will reside south of the front,
    especially over the central and southern Plains, where richer
    boundary-layer moisture is expected to reside.

    Isolated severe storms appear possible along the front Tuesday
    afternoon and evening, especially in the Northeast, and from the
    lower-MO Valley into the central and southern Plains. The most
    probable location for organized severe storm potential is over the
    southern High Plains in the vicinity of the lee cyclone and
    strengthening low-level jet where stronger forcing for ascent and
    vertical shear will coincide with a moderately unstable air mass.


    ...Day 5/Wednesday...

    The slowing of the upper-air system and the potential for
    thunderstorms Tuesday night into Wednesday morning lead to greater
    uncertainty in where the strongest instability will develop by
    afternoon. Isolated severe storms appear possible along and south of
    a surface front from the southern Mid-Atlantic into the central and
    southern Plains. However, confidence in delineating an area of more concentrated severe weather potential has diminished. And as such,
    the previously included 15% contour will be removed for this
    forecast update.


    ...Days 6 through 8/Thursday through Saturday...

    As alluded to above, spread increases across the models (especially
    the deterministic solutions) in the handling of the central Rockies
    low/trough. However, the general signal is for a trend toward a
    less-favorable synoptic pattern for severe storms by next weekend.

    ..Mead.. 10/10/2026
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    --- scorpsmtpd
    * Origin: capitolcityonline.net * KY, USA (1:2320/107)
  • From COD Weather Processor @1:2320/107 to All on Sun Oct 11 08:18:34 2026
    ACUS48 KWNS 110818
    SWOD48
    SPC AC 110816

    Day 4-8 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0316 AM CDT Sun Oct 11 2026

    Valid 141200Z - 191200Z

    ...DISCUSSION...
    A mid/upper-level low is forecast to progress from the eastern Great
    Basin into the central Rockies on Day 4/Wednesday. By Day
    5/Thursday, there is good model consensus in the break-up of the
    low, with much of it being enveloped by an amplifying polar-branch
    trough over the north-central CONUS. By Days 6 and 7/ Friday and
    Saturday, there is general model agreement that a broader-scale
    trough will spread from the MS Valley toward the Atlantic Coast.


    ...Day 4/Wednesday...

    At least isolated severe storms appear most probable over the
    southern Plains during the afternoon and evening, along and ahead of
    a surface front extending from the southern High Plains through the
    mid-MS Valley. The presence of a moist air mass will support
    moderate instability by afternoon in areas that experience greater
    daytime heating. Thunderstorms are expected to be ongoing Wednesday
    morning within the warm sector, leading to uncertainty in where the
    effective surface front will be located by afternoon to focus more
    robust storm development. While no 15% contour will be included in
    this forecast, at least level-1/Marginal Risk probabilities will
    likely be required in the subsequent Day 3 forecast for this time
    period.

    Elsewhere, a few strong to severe storms appear possible along the
    remaining length of the front from the mid-MS Valley into the
    Mid-Atlantic.


    ...Day 5/Thursday...

    Some severe weather threat may materialize from the Ozark Plateau
    into the OH Valley in the vicinity of a surface low and attending
    frontal system. However, the potential for early-day storms and
    model variability in the particular details of the upper-air pattern
    evolution result in considerable uncertainty in the magnitude of the
    threat.


    ...Days 6 to 8/Friday to Sunday...

    A cold front on the leading edge of a prominent surface high will
    push through most locations east of the Rockies by Saturday morning.
    A strong storm or two appears possible along the front in the
    Mid-Atlantic on Friday. Otherwise, the influx of a drier,
    continental-polar air mass is expected to limit the threat for
    severe storms.

    ..Mead.. 10/11/2026
    = = =
    To unsubscribe from WX-STORM and you already have a login, go to https://lists.illinois.edu and use the "Unsubscribe" link. Otherwise email Chris Novy at cnovy@cox.net and ask to be removed from WX-STORM.
    --- scorpsmtpd
    * Origin: capitolcityonline.net * KY, USA (1:2320/107)