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  • DAY48SVR: Nws Storm Prediction Center Norman Ok

    From COD Weather Processor @1:2320/107 to All on Thu Jul 9 09:02:22 2026
    ACUS48 KWNS 090902
    SWOD48
    SPC AC 090900

    Day 4-8 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0400 AM CDT Thu Jul 09 2026

    Valid 121200Z - 171200Z

    ...DISCUSSION...
    Medium-range models continue to indicate that the center of strong
    mid-level ridging building northeast of the Four Corners states will
    shift across the middle Missouri Valley early next week, where it
    may reach peak intensity by about Tuesday, before becoming
    suppressed. Even as this commences, mid-level ridging in the
    westerlies may be maintained near and north/northeast of the
    international border, from the Great Plains through the Great Lakes,
    while large-scale downstream troughing amplifies southeastward
    across the Northeast.

    Associated with this evolution, a plume of very warm elevated
    mixed-layer air still appears likely to advect on the southern
    fringe of a belt of strengthening flow around the northern through
    northeastern periphery of this ridging. As the nose of the warmer
    air overspreads the Great Lakes region early next week, forcing for
    ascent associated with warm advection could begin supporting
    organizing thunderstorm clusters potentially impacting portions of
    New England, and/or the lower Great Lakes through Mid Atlantic.

    As guidance suggests that the westerlies will initially remain split
    downstream of the ridge, and a potentially notable short wave trough
    (and associated cold front) migrating around its periphery and
    eventually suppressing it, it remains unclear how potential frontal
    and pre-frontal convection will pan out on any particular day. Due
    to both synoptic and sub-synoptic predictability issues, severe
    probabilities remain at less than 15 percent in the day 6-8 time
    frame. However, this probably will change in later outlooks closer
    to this time period, when the potential for introducing unduly large
    forecast false alarm decreases.

    ..Kerr.. 07/09/2026

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    --- scorpsmtpd
    * Origin: Capitol City Online (1:2320/107)
  • From COD Weather Processor @1:2320/107 to All on Fri Jul 10 09:01:20 2026
    ACUS48 KWNS 100901
    SWOD48
    SPC AC 100859

    Day 4-8 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0359 AM CDT Fri Jul 10 2026

    Valid 131200Z - 181200Z

    ...DISCUSSION...
    Ensemble guidance continues to indicate that the western US
    mid-level ridge will build into the north-central US during the
    first part of the forecast period. Toward the middle and end of the
    week, this ridge should retrograde westward as a series of mid-level
    troughs move across the apex of the ridge in central Canada. One
    particularly strong trough will impact New England on Tuesday into
    Wednesday.


    ... Tuesday/Day 5 ...

    GEFS and EPS ensemble guidance is in remarkably good agreement that
    a strong short-wave trough will approach New England during the day
    on Tuesday and move across the region Tuesday night. Ahead of this
    trough, both ensemble systems have mean surface temperatures in the
    70Fs and 80Fs with surface dewpoints in the mid-to-upper-60Fs across
    much of the area. The result will be MUCAPE values in the 1000-2000
    J/kg range amidst seasonably strong vertical shear. Supporting this
    are ensemble probabilities greater than 50 percent for the supercell
    composite index to be greater than 1.

    As the trough approaches New England, the expectation is for one or
    more clusters of storms to develop during the afternoon across
    portions of Quebec and move into and then across New England during
    the late afternoon into evening/overnight hours. Although there is
    some spread within the ensemble regarding the timing of the wave
    moving across the area, with solutions ranging from afternoon to
    overnight, the overall environment should remain favorable for
    damaging thunderstorm winds to occur, even into the early overnight
    hours.


    ... Friday/Day 8 ...

    Ensemble guidance is beginning to suggest some severe potential
    across portions of the Ohio Valley into the Mid-Atlantic region.
    This area is forecast to be on the eastern periphery of the strong
    western US ridge and near the basal region of a long-wave trough
    across eastern Canada and New England. Surface temperatures are
    expected to range from the upper-80Fs to mid-90Fs with surface
    dewpoint temperatures in the 60Fs. Parcel trajectories around the
    western ridge do not favor much in the way of an elevated mixed
    layer, so scattered thunderstorm development is likely. The
    magnitude of the severe potential will likely rest on the strength
    of the deep-layer shear and the number of storms.

    ..Marsh.. 07/10/2026

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    * Origin: Capitol City Online (1:2320/107)
  • From COD Weather Processor @1:2320/107 to All on Sat Jul 11 09:02:36 2026
    ACUS48 KWNS 110902
    SWOD48
    SPC AC 110900

    Day 4-8 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0400 AM CDT Sat Jul 11 2026

    Valid 141200Z - 191200Z

    ...DISCUSSION...
    Ensemble guidance continues to indicate that the CONUS-wide
    mid-level ridge centered over the north-central United States will
    build westward during the upcoming week in response to a series of
    mid-level troughs moving through central Canada. These troughs will
    help to carve out a seasonably strong trough across eastern Canada.
    By the end of the week, the US ridge will be centered over the
    Rockies with the eastern Canada trough centered over Quebec. The
    result will be a strong mid-level height gradient (and strong
    mid-level flow) stretching from the Upper Great Lakes southeast into
    the Mid-Atlantic and encompassing New England.


    ... Tuesday/Day 4 -- New England ...

    Multiple ensemble systems continue to support a favorable severe
    weather environment being in place across New England on Tuesday.
    Strong diurnal heating and southwesterly surface flow should allow
    surface temperatures to warm into the mid-80Fs to perhaps low-90Fs
    by late afternoon ahead of a seasonably strong surface cold front.
    Ahead of the cold front, surface dewpoint temperatures should rise
    into the 60Fs to perhaps 70Fs, leading to MUCAPE between 1000-2000
    J/kg. Current thinking is that thunderstorms will develop along and
    ahead of the surface cold front during the afternoon across Quebec
    and move into New England during the late afternoon before
    dissipating overnight. Strong vertical shear in excess of 50 knots
    will combine with strong instability to support severe
    thunderstorms. The most probable scenario is for one or more broken
    lines of storms to move across the region, with perhaps a few
    embedded supercells. All severe hazards seem possible at this time.


    ... Friday/Day 7 and Beyond -- Upper Great Lakes into the
    Mid-Atlantic ...

    Strong northwest flow will be established between the previously
    described western US ridge and eastern Canadian trough. Rich
    boundary layer moisture is expected to be present to the south of a
    residual cold front that will be draped somewhere from the Great
    Lakes southeast into the Mid-Atlantic/Southern New England. Strong
    diurnal heating each afternoon will support scattered thunderstorm
    development capable of producing damaging outflows. Severe
    probabilities were introduced for Day 7 with this outlook given
    increasing confidence in thunderstorms developing within surface
    troughing east of the Appalachians. The exact location of these
    highlights will likely be refined with subsequent outlooks.

    Additionally, the overall large-scale pattern seems conducive for
    one or more shortwave troughs to move through the broader
    northwesterly flow across this region. Given the (seasonably)
    strongly unstable and sheared environment, one or more southeastward
    moving MCSs may be possible during the Day 7 - Day 10 period.
    Ensemble guidance varies significantly as to the timing and location
    of these potential short-wave troughs, but the overall pattern would
    suggest additional severe weather potential at the end of the
    forecast period and in the days that follow.

    ..Marsh.. 07/11/2026

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    --- scorpsmtpd
    * Origin: capitolcityonline.net * KY, USA (1:2320/107)
  • From COD Weather Processor @1:2320/107 to All on Sun Jul 12 09:02:54 2026
    ACUS48 KWNS 120902
    SWOD48
    SPC AC 120900

    Day 4-8 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0400 AM CDT Sun Jul 12 2026

    Valid 151200Z - 201200Z

    ...DISCUSSION...
    An expansive mid-level ridge centered over the north-central US will
    continue to retrograde during the early part of the forecast period,
    before becoming centered over the Rockies toward the end of the
    upcoming week. A seasonably strong mid-level trough will be
    positioned over northern Quebec, positioning strong northwesterly
    flow from the Upper Midwest southeast into the Mid-Atlantic and
    areas to the northeast. A combination of deterministic and ensemble
    forecast solutions, including AI emulators, show one or more
    short-wave troughs or jet streaks moving through this enhanced flow
    field.

    The position of these mid-level features will help drive a surface
    front southward across the eastern US that will stretch from
    somewhere in the central/north-central US into the Mid-Atlantic. To
    the north of this boundary, a seasonably cool, dry airmass should be
    found. Along and south of this surface boundary, a very warm, moist,
    and unstable airmass will be found.

    As the aforementioned short-wave troughs move through the enhanced
    mid-level flow, one or more rounds of thunderstorms/mesoscale
    convective systems are likely to develop and move east/southeast.
    Ensemble guidance continues to show a very unstable airmass (MUCAPE
    in excess of 2000-3000 J/kg) along and south of where the surface
    boundary resides, with strong vertical shear. The overall pattern
    would seem to suggest multiple rounds/days of severe potential, with
    prior days' convection likely modulating the where and intensity of
    subsequent days' convection.

    Given these sensitivities to prior days' convection, there will
    likely be run-to-run variability within the deterministic guidance
    suite as we approach the latter half of next week. Thus, while
    confidence is high in severe potential during the Day 4-8 period
    (and perhaps beyond), highlighting specific locations and days of
    severe potential will prove challenging, with likely areas changing
    from model run-to-run.


    ... Friday/Day 6 -- Mid-Atlantic Region ...

    This evening's deterministic guidance suite (20260712 00 UTC), along
    with yesterday morning's deterministic guidance suite (20260711 12
    UTC), is faster moving the surface boundary south than last night's
    guidance suite (20260711 00 UTC). However, the overall ensemble
    guidance continues to suggest severe potential across the region,
    owing to differences in the position of the surface boundary and the
    timing of mid-level vorticity maxima. Severe probabilities (15%)
    have been retained with this forecast in a nod to the ensemble
    guidance suite, but if the current trend of pushing the surface
    boundary farther south on Thursday (Day 5) continues, severe weather probabilities may need to be removed as the surface boundary will
    push south of the better deep-layer shear.

    ..Marsh.. 07/12/2026

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    --- scorpsmtpd
    * Origin: capitolcityonline.net * KY, USA (1:2320/107)
  • From COD Weather Processor @1:2320/107 to All on Mon Jul 13 09:07:42 2026
    ACUS48 KWNS 130907
    SWOD48
    SPC AC 130905

    Day 4-8 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0405 AM CDT Mon Jul 13 2026

    Valid 161200Z - 211200Z

    ...DISCUSSION...
    All ensemble guidance suites are in broad agreement that the central
    US ridge will once again build westward in response to the
    development of a eastern North America long-wave trough during the
    forecast period. However, significant differences exist within and
    between ensembles regarding the timing and exact nature of this
    transition.

    At the start of the forecast period, a frontal boundary will be
    pushing south and west in the wake of a strong short-wave trough
    that moved across New England in the prior days. The trend over the
    past 48 hours is for this front to push farther south and west,
    bringing a continental dry airmass into New England and portions of
    the Mid-Atlantic. For example, several days ago ensemble guidance
    was in good agreement that the front would be draped across the
    Mid-Atlantic on Friday. Many, but not all, of the recent runs now
    push the front south into southern Virginia and northern North
    Carolina. This results in significant uncertainty regarding the
    potential severe weather environment on Friday (Day 5) across the
    Mid-Atlantic. For example, the GEFS mean temperature for Washington
    D.C. is 93F on Friday afternoon, while the EPS mean temperature is
    102F. However, both ensembles have dewpoint temperatures in the
    50Fs.

    Given the increasing uncertainty as to the location of the surface
    boundary on Friday and the overall quality of the severe weather
    environment, unconditional 15% severe probabilities for Friday are
    removed with this forecast. It is possible that severe probabilities
    may be reintroduced in later outlooks should it become apparent that
    the surface boundary washes out earlier than expected and quality
    low-level moisture is able to return sooner.

    That said, the front should begin to dissipate by Saturday in
    response to a mid-level trough digging southeast across the Great
    Lakes. This will allow rich boundary-layer moisture to advect
    northeastward into the Mid-Atlantic and southern New England. This
    increase in boundary-layer moisture and strong diurnal heating will
    allow for afternoon MUCAPE values between 1000-2000 J/kg, perhaps
    locally higher on Saturday and into Sunday.

    This unstable and vertically sheared environment will be ripe for thunderstorm/severe thunderstorm development ahead of any digging
    mid-level trough. However, as alluded to previously, the timing,
    magnitude, and number of these troughs is highly variable within the
    ensemble guidance, leading to too little confidence to pinpoint
    where and when unconditional severe probabilities should be added.
    As confidence in the timing, track, and strength of these embedded
    troughs becomes clear, severe probabilities will likely be needed
    somewhere across the region stretching from the Upper Midwest
    southeast into the Mid-Atlantic for one or more days.

    ..Marsh.. 07/13/2026

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    --- scorpsmtpd
    * Origin: capitolcityonline.net * KY, USA (1:2320/107)
  • From COD Weather Processor @1:2320/107 to All on Tue Jul 14 09:04:12 2026
    ACUS48 KWNS 140903
    SWOD48
    SPC AC 140901

    Day 4-8 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0401 AM CDT Tue Jul 14 2026

    Valid 171200Z - 221200Z

    ...DISCUSSION...
    Ensemble guidance remains in good agreement that the US mid-level
    pattern will transition from a CONUS-wide ridge centered over the
    north-central US to a western US ridge and eastern US trough.
    However the details of how this transition evolves are still
    uncertain.

    The general pattern through the forecast period will favor northwest
    flow from the Upper Midwest southeast into the Mid-Atlantic and
    areas north and east from there. Individual members of the ensemble
    suite, including the control members, show several small
    vorticity/speed maxima moving through the flow this weekend in quick succession, with significant variability in the strength of these
    waves. Ensemble guidance does have support for a more substantial
    shortwave trough moving through the area, but differ on when this
    will occur. For example, both the control runs of the ECMWF and GFS
    have a stronger wave moving across the Great Lakes, but the GFS does
    so on Saturday and Sunday, whereas the ECMWF does so on Monday and
    Tuesday.

    Thus, while the overall pattern will favor thunderstorm development,
    perhaps in relatively quick succession, uncertainty is too high to
    highlight any severe areas with confidence at current lead times.

    ..Marsh.. 07/14/2026

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    --- scorpsmtpd
    * Origin: capitolcityonline.net * KY, USA (1:2320/107)
  • From COD Weather Processor @1:2320/107 to All on Wed Jul 15 09:01:20 2026
    ACUS48 KWNS 150901
    SWOD48
    SPC AC 150859

    Day 4-8 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0359 AM CDT Wed Jul 15 2026

    Valid 181200Z - 231200Z

    ...DISCUSSION...
    The mid-level pattern will continue to transition toward a western
    US ridge and eastern Canada trough during this forecast period. The
    strongest mid-level flow across the US will be in the region between
    the ridge and trough, namely the Upper Midwest into the Northeast
    and Mid-Atlantic.

    Ensemble guidance suites continue to indicate several stronger
    mid-level short-wave troughs moving through the longwave trough
    across eastern North America. In particular, one such trough will
    move across the Great Lakes and Northeast on Saturday into Sunday,
    with a secondary wave moving across the same general area late
    Monday into early Wednesday. In between these main waves,
    smaller-scale vorticity/speed maxima are likely to traverse the
    region.

    Prior cyclones moving across the region will have left behind a
    surface boundary arcing from the Great Lakes into the Mid-Atlantic.
    As each of the previously mentioned waves approaches this boundary,
    the surface boundary will lift northward before being pushed farther
    southward in the wake of the departing wave. By the end of the
    forecast period, this boundary may push as far south as the
    Southeast US.

    Widespread showers and thunderstorms will be possible with each
    passing wave, with more isolated potential in between the main waves
    in association with any of the small/subtle vorticity/speed maxima
    moving through the flow. The best areas for thunderstorms look to be
    south of the better mid-level flow, which would tend to favor any
    severe potential being driven by the degree of low-level
    warming/steepening of the low-level lapse rates. At this time it
    appears that the timing of the midlevel waves may favor early day
    convection, especially across the Lower Great Lakes into the
    northern Mid-Atlantic area. This early day convection may temper
    afternoon heating and the overall organization/areal extent of any
    severe potential. Thus, confidence remains too low to introduce
    unconditional 15% severe weather probabilities at this time, despite
    the acknowledgment that some severe potential is likely during this
    time period.

    ..Marsh.. 07/15/2026

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    --- scorpsmtpd
    * Origin: capitolcityonline.net * KY, USA (1:2320/107)
  • From COD Weather Processor @1:2320/107 to All on Thu Jul 16 09:07:28 2026
    ACUS48 KWNS 160904
    SWOD48
    SPC AC 160902

    Day 4-8 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0402 AM CDT Thu Jul 16 2026

    Valid 191200Z - 241200Z

    ...DISCUSSION...
    The mid-level pattern across the US will continue to be
    characterized by a West Coast trough, Intermountain West ridge, and
    Great Lakes/East Coast trough through the extended period. The main
    belt of westerlies will be found along the northern periphery of the Intermountain West ridge.

    A couple of short-wave troughs will feature prominently during the
    forecast period. The first of these will be moving off the East
    Coast on Sunday (Day 4). The second will be the closed low located
    across the Pacific Northwest on Sunday. This low will open into a
    mid-level short-wave trough as it crests the Intermountain West
    ridge, before diving southeast across the Great Lakes early next
    week.

    Sunday's East Coast departing mid-level wave will leave behind a
    surface boundary arced from Virginia west-northwest into the Upper
    Midwest. To the south of this boundary, a warm, moist airmass will
    support afternoon MUCAPE values in the 1500-2500 J/kg range, locally
    higher. This boundary will slowly push southward into the Carolinas
    during the afternoon.

    Modest height falls will overspread this boundary across the
    Carolinas during the afternoon as a the region remains on the
    southern fringes of the departing wave's basal region. Additionally,
    a weak mid-/upper-level level low across Florida/the eastern Gulf
    will lift northward as it rejoins the westerlies. The combination of
    modest height falls, strong instability, and the presence of a
    surface boundary will result in scattered thunderstorm development
    capable of producing strong thunderstorm outflows and wind damage. A
    15% area has been introduced across the Carolinas for Sunday/Day-4
    to account for this potential.

    The next time/area of potential concern will be across portions of
    the Upper Midwest/western Great Lakes on Monday/Day-5. Here, both
    the physics-based GEFS and EC ensemble guidance and the GFS and
    EC-based AI emulators are in good agreement that height falls will
    overspread the region ahead of the next short-wave trough. However,
    the GFS-based ensemble means are considerably weaker with the
    strength of the trough, partially owing to differences in timing of
    the main wave. The background environment will likely be favorable
    for severe thunderstorms, with MUCAPE values in the 2000-3000 J/kg
    range and strong vertical shear, the magnitude of which will be
    largely influenced by the strength of the mid-level wave. That said, west/southwesterly flow in the 925-700 millibar layer should support
    a strong EML given the antecedent hot and dry airmass upstream of
    this flow. This leads to concerns regarding convective initiation
    within the favorable severe background environment. These concerns
    are supported by the ensemble guidance with varying degrees of QPF
    shown within the ensemble members. Given this is still 5 days away,
    will hold off on introducing unconditional severe probabilities with
    this forecast.

    ..Marsh.. 07/16/2026

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    --- scorpsmtpd
    * Origin: capitolcityonline.net * KY, USA (1:2320/107)
  • From COD Weather Processor @1:2320/107 to All on Fri Jul 17 07:57:04 2026
    ACUS48 KWNS 170756
    SWOD48
    SPC AC 170755

    Day 4-8 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0255 AM CDT Fri Jul 17 2026

    Valid 201200Z - 251200Z

    ...DISCUSSION...
    ...Days 4-6/Mon-Wed -- Great Lakes/Midwest to the
    Mid-Atlantic/Northeast...

    A shortwave upper trough initially over the Canadian Prairies and
    northern Plains will develop east/southeast across the Upper
    Midwest/Great Lakes on Monday, then the Ohio Valley and Mid-Atlantic
    vicinity on Tuesday. Meanwhile, another upper shortwave trough will
    develop across the Great Lakes to the Northeast/Mid-Atlantic on
    Wednesday. These features will support enhancement of mid/upper
    level flow as a surface low tracks across Ontario/Quebec and New
    England during this time. A trailing cold front will likewise
    progress east/southeast over this three day period, with a very
    moist and unstable airmass present ahead of the front. This overall
    pattern will likely bring multiple days of severe storm potential
    from the Upper Midwest/Great Lakes to portions of the Ohio Valley,
    Northeast and Mid-Atlantic vicinity Monday through Wednesday,
    necessitating severe probabilities. While these areas may shift some
    over the coming day as the timing of mesoscale features and
    influence of prior days convection becomes more clear, these general
    regions are most likely to see at least isolated to widely scattered
    damaging wind potential as the upper trough and surface cold front
    sweep across the area.

    ...Days 7-8/Thu-Fri...

    Surface high pressure building behind the aforementioned surface
    cold front will become centered over the Midwest late in the
    forecast period. Upper troughing will persist across the East while
    an amplified upper ridge remains oriented from TX to MT. Overall,
    severe potential appears low late in the forecast period.

    ..Leitman.. 07/17/2026

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    --- scorpsmtpd
    * Origin: capitolcityonline.net * KY, USA (1:2320/107)
  • From COD Weather Processor @1:2320/107 to All on Sat Jul 18 07:59:14 2026
    ACUS48 KWNS 180759
    SWOD48
    SPC AC 180757

    Day 4-8 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0257 AM CDT Sat Jul 18 2026

    Valid 211200Z - 261200Z

    ...DISCUSSION...
    ...Day 4-5/Tue-Wed -- Ohio Valley to Mid-Atlantic Vicinity...

    An upper trough will pivot across the region on Tuesday and
    Wednesday, bringing enhanced southerly flow aloft as a surface cold
    front sweeps east/southeast through Wednesday night. Ahead of the
    surface front, rich boundary layer moisture will be in place, and at
    least moderate destabilization should occur. Convection could be
    ongoing Tuesday morning across parts of IL/IN/Lower MI/western OH.
    The extent of this activity is unclear and will depend on the
    evolution of any potential MCS in the Day 3 period. Nevertheless,
    the downstream airmass across parts of the Ohio Valley will become
    favorable for scattered severe thunderstorms Tuesday afternoon and
    evening, likely in the form of one or more line segments organizing
    ahead of the advancing cold front. An additional area of severe
    storms will be possible on Tuesday across the Mid-Atlantic within a
    warm advection regime ahead of the approaching system over the Ohio
    Valley. Some areas could see more than one round of severe
    thunderstorms on Tuesday/Tuesday night.

    By Wednesday, the severe risk should spread east from the
    Mid-Atlantic into the Carolinas as the upper trough and surface cold
    front continue to shift east. It is uncertain how far north the
    severe risk may extend and probabilities may eventually need to be
    included across parts of the Northeast/New England. Where storms do
    form, damaging winds will be possible until the cold front moves
    offshore Wednesday evening/night.

    ...Days 6-8/Thu-Sat...

    Upper troughing will persist across the eastern U.S. through the end
    of the forecast period, but deep-layer flow will weaken. High
    pressure in the wake of the cold frontal passage will preclude
    severe potential across the Ohio Valley into the Mid-Atlantic and
    Northeast Thursday through Saturday.

    Across the Plains and western U.S., a strong upper anticyclone will
    park over the southern Plains, with an amplified upper ridge
    building into the northern Rockies. Some thunderstorm potential
    could develop across parts of the Plains as low-level moisture
    increases beneath the ridge. However, severe potential is uncertain
    as any potential would be driven by mesoscale features not well
    defined at this time frame, and as the upper ridge suppresses any
    large-scale support for organized severe thunderstorms.

    ..Leitman.. 07/18/2026

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    --- scorpsmtpd
    * Origin: capitolcityonline.net * KY, USA (1:2320/107)
  • From COD Weather Processor @1:2320/107 to All on Sun Jul 19 07:48:06 2026
    ACUS48 KWNS 190747
    SWOD48
    SPC AC 190746

    Day 4-8 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0246 AM CDT Sun Jul 19 2026

    Valid 221200Z - 271200Z

    ...DISCUSSION...
    ...Day 4/Wed - Mid-Atlantic/Carolinas...

    An upper trough will lift northeast across the region on Wednesday.
    At the surface, a cold front will be oriented from roughly the
    Hudson Valley to the central Appalachians at the beginning of the
    period. Within a zone of strong warm advection ahead of the surface
    front, widespread showers and thunderstorm may be ongoing across
    parts of the Mid-Atlantic and Northeast, resulting in uncertainty
    regarding northward extent of severe potential. For now, the 15
    percent severe probability has been confined to portions of the
    southern Mid-Atlantic and Carolinas ahead of the surface trough/cold
    front. A very moist airmass will be in place across the region, and
    25-35 kt effective shear magnitudes are forecast. Thunderstorm
    clusters or linear bands are expected to move across the region
    through evening, posing mainly a risk for damaging winds.

    ...Days 5-8/Thu-Sun...

    Severe potential is expected to be lower late in the week into the
    weekend. An upper trough will persist over the eastern U.S., but
    deep-layer flow will be weak. Further west, the subtropical high
    will intensify over the Plains and into the Four Corners vicinity
    while the associated amplified upper ridge persists northward into
    the Canadian Prairies. As boundary layer moisture spreads northward
    beneath the upper ridge, some severe potential could develop each
    day across parts of the High Plains. However, this will largely be
    driven by mesoscale processes not well resolved at longer lead
    times. Overall, the intense upper ridge should largely suppress
    greater severe potential.

    ..Leitman.. 07/19/2026

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  • From COD Weather Processor @1:2320/107 to All on Mon Jul 20 08:05:02 2026
    ACUS48 KWNS 200804
    SWOD48
    SPC AC 200802

    Day 4-8 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0302 AM CDT Mon Jul 20 2026

    Valid 231200Z - 281200Z

    ...DISCUSSION...
    Upper troughing will persist across the eastern U.S. through early
    next week. Meanwhile, a strong, amplified upper ridge will envelop
    the western half of the CONUS. This should largely limit greater
    severe potential beneath the upper ridge, though some daily
    mesoscale-driven strong thunderstorm risk could develop over parts
    of the Plains as moist southerly low-level flow maintains moisture
    across the central portions of the country. While any stronger flow
    aloft will mostly remain north of the international border, some
    model guidance trends over the last 24 hours indicate strengthening northwesterly flow aloft is possible as a shortwave impulse or two
    migrates atop the upper ridge and over parts of the northern Plains
    and Great Lakes. This could support an increasing severe risk across
    these areas over the weekend, though confidence is too low for any
    15 percent probability areas at this time.

    ..Leitman.. 07/20/2026

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    * Origin: capitolcityonline.net * KY, USA (1:2320/107)
  • From COD Weather Processor @1:2320/107 to All on Tue Jul 21 07:20:44 2026
    ACUS48 KWNS 210720
    SWOD48
    SPC AC 210718

    Day 4-8 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0218 AM CDT Tue Jul 21 2026

    Valid 241200Z - 291200Z

    ...DISCUSSION...
    ...Great Lakes/Midwest...

    An amplified upper ridge will persist across the Plains and Rockies
    through early next week. Periods of strengthening northwesterly
    mid/upper flow are expected on the eastern periphery of the upper
    ridge as a series of upper shortwave troughs move across the
    Canadian Prairies and glance the Great Lakes vicinity, mainly Day
    5-7/Sat-Mon. This could support areas of severe thunderstorm
    potential across parts of the Upper Midwest to the Ohio Valley
    vicinity during this time as stronger northwesterly flow overspreads
    a seasonally moist and unstable airmass. However, both traditional physics-based NWP and ML/AI NWP are inconsistent and/or show
    relatively low/broad probability areas -- increasing uncertainty in
    timing and spatial delineation of severe potential. Given the
    proximity to the upper ridge, capping may be a concern. Trends will
    be monitored and severe probabilities may become necessary is
    confidence increases in subsequent outlooks.

    ..Leitman.. 07/21/2026

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    * Origin: capitolcityonline.net * KY, USA (1:2320/107)
  • From COD Weather Processor @1:2320/107 to All on Wed Jul 22 07:28:16 2026
    ACUS48 KWNS 220728
    SWOD48
    SPC AC 220726

    Day 4-8 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0226 AM CDT Wed Jul 22 2026

    Valid 251200Z - 301200Z

    ...DISCUSSION...
    ...Upper Midwest to Ohio Valley and Mid-Atlantic...

    An upper ridge centered over the High Plains will persist through
    the middle of next week. Meanwhile, upper troughing will be
    maintained over the eastern U.S. Periods of enhanced northwesterly
    flow aloft are expected across parts of the Upper Midwest/Great
    Lakes into parts of the Ohio Valley and Mid-Atlantic on the eastern
    periphery of the Plains upper ridge. Several shortwave impulses are
    forecast to develop southeast from Canada within this northwest flow
    regime. This could support daily severe thunderstorm chances from
    the Upper Midwest into the Ohio Valley, and possibly the
    Mid-Atlantic. However, the timing of these features is uncertain,
    and midlevel capping could limit the spatial extent of severe
    potential. It is likely that portions of the Upper Midwest into the
    Ohio Valley will need severe probabilities in later outlooks,
    particularly for Day 4-6/Sat-Mon, and possibly the mid-Atlantic by
    Day 7/Tue. However, confidence in where this risk will develop each
    day is too low for 15 percent delineation at this time.

    ..Leitman.. 07/22/2026

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    --- scorpsmtpd
    * Origin: capitolcityonline.net * KY, USA (1:2320/107)
  • From COD Weather Processor @1:2320/107 to All on Thu Jul 23 07:29:00 2026
    ACUS48 KWNS 230728
    SWOD48
    SPC AC 230726

    Day 4-8 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0226 AM CDT Thu Jul 23 2026

    Valid 261200Z - 311200Z

    ...DISCUSSION...
    ...Days 4-5/Sun-Mon -- Upper Midwest toward the Ohio Valley...

    Enhanced northwesterly flow aloft will overspread the Upper Midwest
    to the Ohio Valley on Sunday and Monday as several shortwave
    impulses migrate through the area on the eastern periphery of a
    strong upper ridge over the Plains. A seasonally very moist airmass
    will reside across much of these areas, supporting strong
    destabilization each day. On Sunday, a corridor of severe
    thunderstorm potential appears possible across parts of MN/WI toward
    northern IA/IL as a weak shortwave impulse initially over the
    Dakotas spreads east. While details regarding storm coverage remain
    uncertain, sufficient deep layer shear and strong instability will
    be in place, and at least isolated storm clusters could pose a risk
    for damaging winds.

    By Monday, an upper shortwave trough will emanating from an upper
    low near Hudson Bay will dig southward across the Great Lakes. This
    will result in increasing northwesterly flow aloft. Meanwhile, a
    surface low may move eastward across the Great Lakes near the
    international border while a stronger nocturnal low-level jet
    develops over parts of the Great Lakes and Ohio Valley. This
    stronger flow will overspread a moist and unstable airmass, and
    potential for thunderstorm clusters developing into an MCS appears
    possible.

    While details remain uncertain regarding convective evolution and
    coverage on Sunday and Monday, through broader synoptic pattern
    appears favorable for at least isolated severe thunderstorms. The 15
    percent severe areas may shift some in the coming days as details
    become more clear.

    ...Days 6-8/Tue-Thu...

    It is possible some severe potential could shift east/southeast on
    Tuesday toward the central Appalachians and the Mid-Atlantic.
    Deep-layer northwesterly flow will not be as strong as prior days,
    but could still be sufficient for some organized severe risk.
    Confidence in where greater risk corridors may develop is low, and
    will largely be influenced by convective evolution in the Days 4-5/Sunday-Monday periods.

    A strong upper ridge will shift west across the western U.S. late in
    the period, bringing a broad area of generally weak deep-layer
    northwesterly flow to the eastern half of the CONUS. Some
    thunderstorm potential is likely within this typical summertime
    pattern across the Plain into the East, but severe potential is
    uncertain.

    ..Leitman.. 07/23/2026

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    * Origin: capitolcityonline.net * KY, USA (1:2320/107)
  • From COD Weather Processor @1:2320/107 to All on Fri Jul 24 08:40:02 2026
    ACUS48 KWNS 240839
    SWOD48
    SPC AC 240837

    Day 4-8 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0337 AM CDT Fri Jul 24 2026

    Valid 271200Z - 011200Z

    ...DISCUSSION...
    ...Day 4/Monday...
    A prominent upper high will remain centered over the central and
    southern Plains with a belt of enhanced mid-level flow forecast
    along the periphery of that feature from the northern Plains into
    the Great Lakes. Within that flow regime, a short-wave trough is
    forecast to translate through the Great Lakes in tandem with a
    surface low and trailing cold front. A hot and moist boundary layer
    is expected ahead of the front, yielding moderate to strong
    instability by afternoon. Despite veered low-level winds,
    strengthening mid/upper-level winds in the exit region of a jet
    streak will contribute to sufficient vertical shear for organized
    severe storms across portions of the Great Lakes into the OH Valley
    Monday afternoon into night.


    ...Day 5/Tuesday...
    The Day 4/Monday short-wave trough is forecast to evolve into an
    upper low across southwest ON and the lower Great Lakes with an
    associated belt of stronger cyclonic flow developing from the OH
    Valley into the southern Mid-Atlantic and NC. At the surface, an
    area of low pressure will develop from the lower Great Lakes into
    central NY with a trailing cold front advancing through the upper OH
    Valley, central Appalachians, and Mid-Atlantic.

    Thunderstorms may be ongoing Tuesday morning along and ahead of the
    front from the lower Great Lakes and upper OH Valley into the
    Mid-Atlantic. Stronger heating is anticipated to the south of the
    early-day storms from the southern Mid-Atlantic into NC, where
    moderate to potentially strong instability is forecast. The
    strongest instability will coincide with modestly strong deep-layer
    shear to support some severe weather threat in those areas Tuesday
    afternoon and evening.


    ...Days 6-8/Wednesday-Friday...
    The 00Z ensemble means depict a slight westward regression of the
    dominant mid/upper-level high with persistent troughing along the
    East Coast. On the periphery of the high, a notable short-wave
    trough is forecast to progress from the Canadian Rockies on
    Wednesday through the Prairie Provinces on Thursday with modest
    height falls along the international border. By Friday, there is
    some model signal for another short-wave trough to move into the
    upper MS Valley and Great Lakes regions. At the surface, a more
    substantial cold front is projected to move into the northern Plains
    on Thursday, and the upper Midwest and Great Lakes by Friday.

    A few severe storms appear possible in the Southeast and northern
    Plains on Wednesday, the northern Plains on Thursday, and the upper
    Midwest into the Great Lakes on Friday. Confidence in the magnitude
    and areal extent of the threat is currently too low to delineate
    additional areas.

    ..Mead.. 07/24/2026

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    --- scorpsmtpd
    * Origin: capitolcityonline.net * KY, USA (1:2320/107)