• DAY1SVR: Day 1 Convective

    From Dumas Walker@21:1/175 to All on Sat Dec 28 17:12:00 2024
    ACUS01 KWNS 281949
    SWODY1
    SPC AC 281947

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0147 PM CST Sat Dec 28 2024

    Valid 282000Z - 291200Z

    ...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON
    AND TONIGHT ACROSS PORTIONS OF EAST TEXAS...LOUISIANA...CENTRAL AND
    SOUTHERN MISSISSIPPI...AND SOUTHWESTERN ALABAMA...

    ...SUMMARY...
    Tornadoes (some strong with at least EF2 damage possible), severe
    gusts and hail are expected today into tonight. The threat area will
    continue to shift eastward across east Texas and the lower
    Mississippi Valley today, then over the Tennessee Valley, parts of
    Georgia, and the central Gulf Coast tonight.

    ...20Z Update...
    Severe probabilities have been adjusted in portions of central into
    East Texas as well as portions of Arkansas/western Tennessee. These
    areas have been impacted by earlier convection and further
    destabilization does not appear likely. The remainder of the
    outlook, the Moderate risk area in particular, is unchanged. The
    corridor of greatest concern appears to be from portions of central
    Louisiana into southwest Mississippi. Upper 60s to low 70s dewpoints
    are in place and the potential for discrete/semi-discrete storms
    should be maximized here later this afternoon/evening as the
    mid-level jet moves overhead and the low-level jet strengthens.

    ..Wendt.. 12/28/2024

    .PREV DISCUSSION... /ISSUED 1029 AM CST Sat Dec 28 2024/

    ...East TX to AL/GA...
    A powerful mid-level shortwave trough and associated 80-90 knot jet
    max will rotate quickly eastward across TX today and become
    negatively-tilted as it tracks into the lower MS Valley this
    evening. Ample low-level moisture (dewpoints in the mid 60s to
    lower 70s) is in place ahead of this system across east TX, much of
    LA, and central/southern MS. Morning convection is slowly weakening
    across the warm sector, and low-clouds will continue to erode. This
    will help to develop a corridor of moderate instability with MLCAPE
    values of 1500-2000 J/kg. This will set the stage for a significant
    severe weather event through the evening as supercells and bowing
    structures form over east TX and race eastward across LA into MS.

    The co-location of the mid-level jet, strengthening winds in the
    low-levels, surface cyclogenesis, and ample moisture provide a synoptically-evident setup for all severe hazards through the
    evening. The corridor of greatest concern will be late afternoon
    through the evening from central LA into central MS. Considered an
    upgrade to HIGH for this area, but will maintain the ongoing MDT
    after consultation with local WFOs. Strong and long-tracked
    tornadoes and widespread damaging winds are possible in this region,
    with the primary uncertainty regarding storm-mode and linear forcing mechanisms.

    Activity will spread across AL overnight, where slightly less
    low-level moisture will somewhat decrease the overall severe threat.
    Nevertheless, an active squall line with damaging wind potential
    and embedded rotating storms/tornado threat will likely persist.

    $$
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  • From Dumas Walker@21:1/175 to All on Sat Feb 8 09:05:00 2025
    ACUS01 KWNS 081245
    SWODY1
    SPC AC 081244

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0644 AM CST Sat Feb 08 2025

    Valid 081300Z - 091200Z

    ...NO SEVERE THUNDERSTORM AREAS FORECAST...

    ...SUMMARY...
    Isolated to scattered thunderstorm development is possible across
    parts of the Ohio Valley today.

    ...Ohio Valley...
    A low-amplitude shortwave trough currently extends from western ND southwestward through western/central WY. This shortwave is expected
    to progress quickly eastward throughout the day, moving across the
    Great Lakes and reaching the Northeast by early tomorrow. In
    response, the surface low currently over central OK is forecast to
    rapidly translate northeastward through the Mid MS and OH Valleys,
    moving along the leading edge of low-level moisture advection.
    Strengthening warm-air advection throughout the warm sector
    preceding this low will help moisten the low- to mid-levels enough
    to support limited buoyancy, particularly as mid-level temperatures
    cool. Ascent attendant to the approaching shortwave trough will be
    augmented by both persistent warm-air advection and more mesoscale
    lift near the surface low. The resulting combination of lift and
    buoyancy should support deeper convective structures capable of
    lightning production. Most likely time frame for these deeper storms
    is between 21Z to 04Z, with the highest coverage anticipated over
    the Middle and Upper OH Valley.

    Strengthening mid-level flow is also expected, with a belt of 100+
    kt 500-mb winds spreading across the region after 21Z. This could
    result in rotation and potentially some hail production within any
    deeper, more persistent updrafts. However, the scant buoyancy is
    expected to limit the number and duration of any deeper updrafts,
    with the overall severe potential remaining low as a result.

    ..Mosier/Broyles.. 02/08/2025

    $$
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  • From Dumas Walker@21:1/175 to All on Sun Feb 9 08:59:00 2025
    ACUS01 KWNS 091250
    SWODY1
    SPC AC 091248

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0648 AM CST Sun Feb 09 2025

    Valid 091300Z - 101200Z

    ...NO SEVERE THUNDERSTORM AREAS FORECAST...

    ...SUMMARY...
    A low risk for a few thunderstorms exists early in the period across
    the Mid-South region.

    ...Synopsis...
    Broadly cyclonic flow aloft, with several embedded shortwave
    troughs, is expected across the northern CONUS today. Largely zonal
    flow is anticipated across the southern CONUS, with negligible
    height changes. Recent surface analysis shows an expansive area of
    high pressure associated with a dry, continental airmass covering
    much of the central and eastern CONUS. A weak frontal boundary is in
    place from the TX Coastal Plains northeastward across the Southeast
    States into NC, between the cooler and dry airmass to its north and
    the modified Gulf airmass to its south. A slow southward progression
    of this front is anticipated throughout the day, with this front
    likely extending from southern GA westward along the Gulf Coast into
    South TX by 12Z Monday.

    ...Arklatex into the Mid-South...
    Modest warm-air advection across the frontal zone mentioned in the
    synopsis is contributing to showers and isolated thunderstorms
    across Arkansas this morning. 12Z LZK sounding sampled the airmass
    supporting these showers and thunderstorms well, with a notable warm
    nose contributing to scant elevated buoyancy above about 850 mb. The
    warm-air advection is expected to persist over the region for at
    least the next several hours, while it gradually shifts eastward and
    weakens. This will support the potential for isolated thunderstorms
    this morning from the Arklatex eastward into the Mid-South, with the
    overall thunderstorm potential diminishing with eastern extent.

    ..Mosier/Broyles.. 02/09/2025

    $$
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  • From Dumas Walker@21:1/175 to All on Mon Feb 10 09:13:00 2025
    ACUS01 KWNS 101247
    SWODY1
    SPC AC 101245

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0645 AM CST Mon Feb 10 2025

    Valid 101300Z - 111200Z

    ...NO SEVERE THUNDERSTORM AREAS FORECAST...

    ...SUMMARY...
    Isolated thunderstorms are possible from central Texas across
    southeast Oklahoma into western Arkansas tonight.

    ...TX/OK/AR...
    Recent satellite imagery shows a well-defined shortwave trough off
    the southern CA/Baja CA coast. This feature is forecast to progress
    quickly east-northeastward throughout the day, traversing the Southwest/northern Mexico and reaching the southern Plains by
    tomorrow morning. Airmass ahead of this feature across the southern
    Plains is currently cool and dry, with the moist airmass still
    offshore. Mass response ahead of the approaching shortwave will lead
    to some modest airmass modification, with upper 50s/low 60s surface
    dewpoints potentially reaching the TX Hill Country/central TX by
    tomorrow morning. Even with these moistening low levels, warm
    mid-level temperatures will preclude buoyancy and deep convection
    across much of the TX Coastal Plain.

    Greater thunderstorm potential is anticipated farther north in
    corridor from the Edwards Plateau into southeast OK and western AR
    about 200 mi northwest of the primary synoptic boundary. Here,
    aforementioned mass response and associated strengthening of the
    low-level southwesterly flow will lead to moderate to strong
    low-level warm-air advection and the development of modest elevated
    buoyancy (generally above 800-750 mb). Isolated thunderstorms will
    be possible as early as this afternoon across southeastern OK and
    western AR. Persistent warm-air advection will likely contribute to
    a continued potential for isolated thunderstorms across this region
    throughout the evening. This persistent warm-air advection will also
    help support the development of modest buoyancy into TX as mid-level temperatures cool ahead of the approaching shortwave. Resulting
    buoyancy combined with increasing large-scale ascent should result
    in addition isolated thunderstorm development from north TX into the
    Edwards Plateau, largely after 06Z. Limited buoyancy should keep the
    severe potential low throughout the period.

    ..Mosier/Broyles.. 02/10/2025

    $$
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  • From Dumas Walker@21:1/175 to All on Tue Feb 11 09:54:00 2025
    ACUS01 KWNS 111248
    SWODY1
    SPC AC 111247

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0647 AM CST Tue Feb 11 2025

    Valid 111300Z - 121200Z

    ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM SOUTHEAST
    TEXAS AND THE LOWER MISSISSIPPI VALLEY INTO SOUTHERN MISSISSIPPI AND
    CENTRAL ALABAMA....

    ...SUMMARY...
    Isolated to scattered thunderstorms are possible from the southern
    Plains into the lower Mississippi Valley. Some strong to severe
    thunderstorms are possible from southeast Texas and the Lower
    Mississippi Valley into southern Mississippi and central Alabama.

    ...Synopsis...
    A pair of shortwave troughs are expected to progress through the
    southern Plains today as the cyclonic flow aloft across the western
    CONUS deepens. The first of these shortwaves is currently moving
    through the southern High Plains while the second remains off the
    coast of the northern Baja Peninsula. Both of those shortwaves are
    expected to progress quickly eastward, with the lead wave reaching
    the Mid-Atlantic by early Wednesday and the second shortwave
    reaching central TX.

    ...Lower MS Valley into southern/central MS and AL...
    As mentioned in the synopsis, the lead shortwave trough is currently
    moving through the southern High Plains, with preceding warm-air
    advection contributing to an expansive area of precipitation from
    the TX Hill Country into the Mid-South. General expectation is that
    this area of precipitation will gradually shift northeastward
    throughout the day, remaining just ahead of the eastward-progressing
    shortwave. Low-level moisture return ahead of the first wave will be
    modest, particularly across TX where the modified Gulf moisture will
    likely remain confined to the coastal plain. Farther east, greater
    inland moisture advection is anticipated, with mid 60s dewpoints
    advection through much of the Lower MS Valley by the early
    afternoon. Lower 60s dewpoints are likely in the central portions of
    MS and AL by the late afternoon/early evening.

    Even with this low-level moisture advection, mid-level temperatures
    will remain warm, keeping the overall buoyancy modest (i.e. MUCAPE
    less than 1000 J/kg) across the region. In contrast to the modest
    buoyancy, vertical shear will be quite strong, with effective bulk
    shear over 50 kt from the Lower MS Valley into AL and MS during the
    afternoon and evening. This strong vertical shear may be able to
    compensate for the lower buoyancy, and there could be a window for a
    few strong to severe storms this afternoon/evening along and ahead
    of the cold front from southern MS into southern and central AL.
    Primary risk would be damaging wind gusts, but enough low-level
    shear exists for a low-probability tornado threat as well.

    ...Southern Plains late tonight...
    Strong large-scale forcing for ascent will spread across the
    southern High Plains and into west TX late tonight ahead of the
    second shortwave trough mentioned in the synopsis. Notable
    moistening between 850 and 700 mb combined with mid-level cooling
    will help support modest elevated buoyancy. Thunderstorms are
    expected to develop across West TX tonight before then spreading eastward/northeastward into more of OK and north/central TX. Much of
    this activity will be displaced well north/northwest of front and
    greater low-level moisture. Some hail is possible, but updraft depth
    and duration will be limited by weak buoyancy, and the current
    expectation is for any hail to remain very isolated.

    As these storms move east/southeast with time, some interaction
    could occur with a warm front gradually moving northward into more
    of southeast TX early Wednesday morning. Increased buoyancy as well
    as enhanced mesoscale ascent in the vicinity of the front is
    expected to result in greater thunderstorm depth and duration.
    Vertical shear will remain strong as well, with all of these factors
    supporting a greater severe potential across southeast TX and
    adjacent far southwestern LA early Wednesday morning. Damaging gusts
    and/or a brief tornado are the primary threats.

    ..Mosier/Broyles.. 02/11/2025

    $$
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  • From Dumas Walker@21:1/175 to All on Thu Feb 13 08:45:00 2025
    ACUS01 KWNS 131245
    SWODY1
    SPC AC 131243

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0643 AM CST Thu Feb 13 2025

    Valid 131300Z - 141200Z

    ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM THE FLORIDA
    PANHANDLE INTO SOUTHERN GEORGIA...AND OVER PARTS OF THE CENTRAL
    VALLEY OF CALIFORNIA...

    ...SUMMARY...
    Isolated, marginally severe storms are possible from the Florida
    Panhandle into southern Georgia and parts of the Central Valley of
    California. Damaging winds and a brief tornado are the primary threats.

    ...Southeast...
    Lead shortwave trough continues to progress through the OH Valley
    this morning, and is expected to continue northeastward through the
    Northeast today. Primary surface low associated with this system is
    over the Lower Great Lakes, but a secondary triple point low exists
    farther south over west-central GA. A cold front extends
    southwestward from this secondary low off the AL coast while a warm
    front extends eastward into the SC Lowcountry before arcing
    northeastward along the SC and NC coasts. Warm sector between these
    two features is characterized by temperatures in the upper 60s/low
    70s and dewpoints in the 60s. A convective line is currently
    traversing this warm sector, extending from the MMT vicinity in
    central SC southwestward to off the FL Panhandle Coast east of ECP.
    Modest buoyancy precedes this line across the central FL Panhandle
    and southwest/south-central GA, but weakens with northern extent,
    with MLCAPE dropping to less than 250 J/kg over southeast GA. In
    contrast to this modest buoyancy, strong deep-layer shear extends
    across the warm sector, which is contributing to modest updraft
    organization within the line and occasional bowing segments. Shear
    is expected to weaken throughout the day as the parent shortwave
    trough becomes increasingly displaced north and the mid/low level
    flow weakens. As a result, the severe potential over this region
    today will likely be maximized from now through the next 4 to 6
    hours while some overlap between the modest buoyancy and strong
    shear exists. A few strong to severe storms are possible,
    particularly where the line interacts with the warm front. Damaging
    gusts will be the primary risk, but a brief line-embedded tornado is
    possible as well.

    ...Central Valley of California...
    Recent satellite imagery depicts an intense cyclone off the West
    Coast, with a strong shortwave trough moving through its southern
    periphery towards central CA. This shortwave is forecast to reach
    the coast later this afternoon, with the ongoing warm-air advection
    shower activity moving to the east/south as it does. As these
    showers clear out, temperatures should warm into the upper 50s/low
    60s while mid-level cold-air advection results in 500-mb
    temperatures in the -22 to -25 deg C range. This will support weak
    airmass destabilization, with modest buoyancy anticipated during the
    afternoon. This could result in some deeper, more sustained
    convection. Vertical shear will be strong enough to support
    transient rotation within any deeper updrafts, yielding a localized
    wind/brief tornado risk during the late afternoon.

    ..Mosier/Broyles.. 02/13/2025

    $$
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  • From Dumas Walker@21:1/175 to All on Thu Feb 13 18:02:00 2025
    ACUS01 KWNS 132053
    SWODY1
    SPC AC 131947

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    Issued by 15th OWS Scott Air Force Base IL
    0147 PM CST Thu Feb 13 2025

    Valid 132000Z - 141200Z

    ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER PARTS OF
    THE CENTRAL VALLEY OF CALIFORNIA...

    ...SUMMARY...
    Isolated, marginally severe storms are possible in parts of the
    Central Valley of California. Damaging winds and a brief tornado are
    the primary threats.

    ...Central Valley of California...
    Satellite imagery depicts an intense cyclone off the West Coast,
    with a strong shortwave trough moving through its southern periphery
    towards central CA. Clearing behind morning showers associated with
    WAA has allowed surface temperatures to rise into the upper 50s,
    with dew points reaching the low 50s. Upper level cold-air advection
    will result in 500-mb temperatures in the -22 to -25 deg C range,
    supporting weak airmass destabilization through this afternoon. With
    favorable shear profiles, current expectations is for a few stronger
    updrafts to take on transient supercell structures within the
    Central Valley, with the threat for marginally damaging winds and
    perhaps a brief tornado or two.

    ...Southeast...
    The lead shortwave trough continues to progress through the OH
    Valley this afternoon, and is expected to continue northeastward
    through the Northeast into tonight. The surface low associated with
    this system continues to progress northeastward into far northern
    New England/southern Quebec. A cold front extends southwestward from
    this low through the eastern seaboard and off the Florida Coast.
    Although MUCAPE has approached 1500-2000 j/kg ahead of the front,
    deep layer shear has continued to decrease as the strongest dynamics
    continue to depart as the trough progresses further northeast, and
    boundary parallel flow will likely suppress any significant updraft organization. In turn, midday convection has continued to weaken,
    with additional weakening expected through the rest of the
    afternoon. Have opted to drop the marginal risk across the Florida
    panhandle. A few brief gusts of winds are still possible with any
    stronger updrafts, but any severe threat remaining appears to be minute.

    ..15_ows.. 02/13/2025

    $$
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  • From Dumas Walker@21:1/175 to All on Mon Feb 24 08:44:00 2025
    ACUS01 KWNS 241231
    SWODY1
    SPC AC 241230

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0630 AM CST Mon Feb 24 2025

    Valid 241300Z - 251200Z

    ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER FAR
    SOUTHERN FL INCLUDING THE KEYS...AND OVER PARTS OF EASTERN OR AND WA...

    ...SUMMARY...
    Scattered strong storms will be possible across the Florida Keys and
    into far southern Florida from late afternoon through evening.
    Localized damaging gusts or a brief tornado may occur. Isolated
    strong winds are also expected from the Oregon Cascades into
    southeast Washington.

    ...Far Southern FL and the FL Keys...
    Shortwave trough currently progressing off the TX Coast is expected
    to continue eastward across the Gulf today, reaching the FL
    Peninsula by early tomorrow morning. Cold mid-level temperatures and strengthening mid-level flow that accompany this shortwave are
    expected to spread over central/southern FL and the FL Keys after
    03Z. An attendant surface low attendant will progress quickly
    eastward just ahead of the parent shortwave. The general consensus
    among the guidance is for this low to be just off the west-central
    FL Coast around 00Z before continuing across the central FL
    Peninsula and into the western Atlantic by 12Z Tuesday.

    Moistening of the low-level airmass is expected ahead of the
    shortwave trough and attendant surface low, particularly after 18Z.
    Widespread showers throughout the day will likely mitigate buoyancy
    somewhat, but little to no surface-based inhibition is expected
    south of the warm front (which will extend eastward from the surface
    low across the central FL Peninsula) from the late afternoon onward. Thunderstorm coverage should increase along and ahead of the front
    as it gradually pushes eastward.

    Dewpoints near 70s across south FL and the FL Keys will result in
    stronger buoyancy and the potential for deeper, more long-lived
    updrafts. Strong vertical shear over the region supports the
    potential for a few supercells with an attendant risk for damaging
    wind gusts and a brief tornado or two. The development of a
    low-level convergence zone is possible, which could result in a
    favored corridor for strong to severe storms. Currently, this zone
    is expected to remain just off south FL Coast, but a few storms in
    this area could impact the Keys.

    ...Interior Pacific Northwest...
    Recent satellite imagery shows an intense shortwave trough off the
    Pacific Northwest coast, moving quickly northeastward. This
    shortwave is forecast to continue northeastward throughout the day,
    reaching the coastal Pacific Northwest this afternoon and the
    interior Pacific Northwest tonight. A frontal band, with occasional
    lightning, is expected to develop along the leading edge of the
    strong forcing for ascent associated with this system. Temperatures
    could reach the upper 50s/low 60s ahead of this line in northeast
    OR/southwest WA amid steep low-level lapse rates and modest
    buoyancy. As such, the overall environment supports the potential
    for strong downbursts within the line as it moves across the region.

    ...Eastern Dakotas into the Mid MS Valley...
    The low-amplitude shortwave trough currently moving through MT is
    expected to continue southeastward today, moving across the northern
    Plains and IA before ending the period over IL. A compact but strong
    jet streak will accompany this shortwave, with 500-mb winds within
    this streak from 90 to 100 kt. The downstream airmass will be dry,
    and strong heating/mixing will help push afternoon temperatures into
    the upper 50s and low 60s. Despite dry low levels, some modest
    buoyancy is possible amid the deep mixing and cold mid-level
    temperatures. Consequently, a few shallow thunderstorms are possible
    as the strong forcing for ascent attendant to the shortwave
    interacts with this limited buoyancy. Small hail and strong outflow
    is possible with these storms, but overall coverage is currently
    expected to remain too isolated to introduce any probabilities.

    ..Mosier/Grams.. 02/24/2025

    $$
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