• DAY2SVR: Nws Storm Prediction Center Norman Ok

    From Mike Powell@618:250/10 to All on Thu Jul 16 09:26:44 2026
    ACUS02 KWNS 160607
    SWODY2
    SPC AC 160605

    Day 2 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0105 AM CDT Thu Jul 16 2026

    Valid 171200Z - 181200Z

    ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS
    OF NORTHERN IDAHO AND WESTERN MONTANA AS WELL AS PORTIONS OF THE
    UPPER MIDWEST AND NORTHERN GREAT LAKES...

    ...SUMMARY...
    Strong to potentially severe storms are possible on Friday across
    parts of western Montana and northern Idaho, and also across parts
    of the Upper Great Lakes region.

    ... Parts of the Upper Midwest and Great Lakes ...

    A subtle mid-level vorticity maximum evident in the 16/00 UTC
    guidance is expected to move southeastward across northern Minnesota
    and the Upper Great Lakes on Friday morning, supporting ongoing
    thunderstorms across the Arrowhead of Minnesota. This activity
    should spread southeastward through the morning with at least a
    marginal severe hail/wind threat.

    During the day, a surface frontal zone draped from northern
    Illinois/Indiana should begin to lift northward, ahead of a surface
    cold front moving through the northern Plains. To the south of the
    warm front and ahead of the cold front, diurnal heating may be
    somewhat muted by smoke and residual cloud cover from morning
    convection. However, increasing low-level moisture should still
    support moderate destabilization by the afternoon, especially where
    stronger diurnal heating occurs. Moderate mid-level northwesterly
    flow will provide enough vertical shear to support organized storms.

    As the stronger mid-level wave approaches the region during the late
    afternoon and evening, some potential exists for surface-based
    thunderstorm redevelopment -- especially near the intersection of
    the cold front and effective warm front. Large hail and strong
    thunderstorm winds will be possible with these storms, and the
    low-level wind field would support at least some potential for a
    tornado with any sustained surface-based storm during the evening.
    With time this activity should evolve into one or more clusters of thunderstorms moving southeast overnight across the northern Great Lakes.


    ... Western Montana and Northern Idaho ...

    A relatively favorable thermodynamic environment will once again be
    in place across parts of western Montana and northern Idaho by
    Friday afternoon. Relatively steep low- and mid-level lapse rates,
    sufficient moisture, and diurnal heating should support afternoon
    SBCAPE values in the 1000-1500 J/kg range, as suggested by the
    20260716 00UTC HREF. Mid-/upper-level flow will be less than in
    previous days as the region becomes increasingly displaced from a mid-/upper-level trough/low moving northward into southwest Canada.
    That said, effective-layer shear on the order of 25-35 knots will be
    possible, especially where east/southeasterly surface winds are maintained.

    Scattered thunderstorms are expected to develop during the afternoon
    and evening hours. The strongest thunderstorm clusters will be
    capable of large hail. Strong to severe thunderstorm gusts will be
    possible as well, especially where convective outflows can
    consolidate amid the steep low-/mid-level lapse rates. Most 16/00
    UTC HREF members show explicit convective outflow gusts approaching
    60 mph, supporting a localized severe threat.

    If convective coverage appears greater than currently forecast,
    severe probabilities may need to be increased in subsequent outlooks.


    ... Ohio Valley ...

    Scattered to numerous thunderstorms are expected to develop during
    the afternoon within a moist, moderately unstable, and weakly capped environment. Localized downburst winds could occur within this
    environment, though deep-layer flow/shear appears too weak to
    support an organized severe threat. Additionally, 16/00 UTC guidance
    suggests early initiation across the region, which would limit the
    development of widespread steep low-level lapse rates, which may
    provide some limit on a more widespread, storm-scale driven wind
    threat. This region will continue to be evaluated in subsequent outlooks.

    ..Marsh.. 07/16/2026

    $$
    --- MultiMail/DOS
    * Origin: capitolcityonline.net * KY, USA (618:250/10)
  • From Mike Powell@618:250/10 to All on Wed Jul 22 08:47:08 2026
    ACUS02 KWNS 220522
    SWODY2
    SPC AC 220520

    Day 2 Convective Outlook
    NWS Storm Prediction Center Norman OK
    1220 AM CDT Wed Jul 22 2026

    Valid 231200Z - 241200Z

    ...NO SEVERE THUNDERSTORM AREAS FORECAST...

    ...SUMMARY...
    Severe thunderstorm potential appears low on Thursday. However,
    locally gusty winds could occur with thunderstorms across the
    central High Plains.

    ...Discussion...

    In the mean, an amplified upper ridge will persist across he West,
    with the subtropical high over TX shifting west toward the Four
    Corners vicinity through the period. An upper shortwave trough
    embedded within the eastern periphery of the upper ridge will
    migrate southeast from the central Rockies to the Mid/Lower MO
    Valley through early Friday morning.

    Southerly low-level flow across the Plains will result in a belt of
    modest boundary-layer moisture across the central High Plains. Steep
    midlevel lapse rates will foster weak instability across parts of
    WY/CO into western KS. Scattered thunderstorms will develop during
    the afternoon and spread east/southeast across the central High
    Plains. A deeply mixed boundary layer will support isolated strong
    outflow gusts. However, weak vertical shear and limited instability
    will preclude severe probabilities at this time.

    ..Leitman.. 07/22/2026

    $$
    --- MultiMail/DOS
    * Origin: capitolcityonline.net * KY, USA (618:250/10)