• DAY1SVR: Day 1 Convective Outlook Resent 1

    From COD Weather Processor@1:2320/105 to wx-storm@lists.illinois.edu on Tue Feb 21 19:28:57 2023
    ACUS01 KWNS 211928
    SWODY1
    SPC AC 211927

    Day 1 Convective Outlook RESENT 1
    NWS Storm Prediction Center Norman OK
    0127 PM CST Tue Feb 21 2023

    Valid 211630Z - 221200Z

    ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS THE
    MID-ATLANTIC AND SOUTHERN PLAINS...

    ...SUMMARY...
    Isolated thunderstorms capable of locally damaging winds will be
    possible across parts of the Mid-Atlantic from about Noon to 4 PM
    EST. Isolated severe wind and hail will be possible after 2 AM CST
    across a portion of western north Texas into central Oklahoma.

    ...Mid-Atlantic States...
    A low-amplitude shortwave trough over southern Ontario and the Lower
    Great Lakes will continue east-northeastward toward New England
    tonight. Boundary layer moisture will remain limited within the
    post-coastal frontal environment, but cloud breaks/moderate heating
    and 40s F surface dewpoints will lead to weak destabilization early
    this afternoon. This could allow for the development of some
    low-topped thunderstorms (less than 25k ft) across eastern
    Pennsylvania to New Jersey and the Delmarva vicinity. A few storms
    could produce small hail this afternoon along with
    strong/convectively enhanced wind gusts, particularly given the
    strength of the background west-southwesterly low/mid-tropospheric
    winds.

    ...Southern Great Plains...
    Influenced by a southern-stream low-latitude trough that will reach
    eastern New Mexico/far west Texas tonight, late-day lee cyclogenesis
    and a strengthening of southerly low-level winds will influence
    additional moistening across the region. Initially modest moisture
    and residual capping will likely preclude thunderstorm development
    until later tonight.

    A narrow corridor of meager boundary-layer destabilization with
    MLCAPE of 250-500 J/kg is anticipated to evolve late tonight and
    early Wednesday ahead of a sharpening cold front ejecting eastward
    from the High Plains. Strengthening forcing for ascent downstream of
    an elongated shortwave trough over the southern High Plains will
    support increasing convective development, especially in the 09-12Z
    time frame. A few instances of severe hail and/or wind may occur
    across southwest/central Oklahoma and western North Texas.

    ...East-central Illinois to southwest Ohio...
    Elevated convection is expected to develop late tonight/early
    Wednesday amid strengthening lower-level warm theta-e advection.
    Most of this activity should occur within scant elevated buoyancy,
    but strong speed shear through the cloud-bearing layer may support
    small hail in the more robust updrafts.

    ..Guyer/Supinie.. 02/21/2023

    $$

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  • From COD Weather Processor@1:2320/105 to wx-storm@lists.illinois.edu on Wed Apr 19 02:34:26 2023
    ACUS01 KWNS 190234
    SWODY1
    SPC AC 190232

    Day 1 Convective Outlook RESENT 1
    NWS Storm Prediction Center Norman OK
    0932 PM CDT Tue Apr 18 2023

    Valid 190100Z - 191200Z

    ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
    SOUTH DAKOTA...NEBRASKA...WESTERN/CENTRAL IOWA...AND SOUTHWEST
    MINNESOTA...

    ...SUMMARY...
    Isolated severe thunderstorms are possible the remainder of the
    evening into the overnight hours across parts of South Dakota,
    Nebraska, southwest Minnesota and western/central Iowa.

    ...01z Update...

    The Marginal risk (Level 1 of 5) has been removed along much of the
    dryline from KS into western OK/northwest TX. Isolated thunderstorms
    will continue near the NE/KS border, shifting east/northeast through
    the remainder of the evening, but additional thunderstorm
    development is unexpected further south. Thunderstorms over eastern
    WY into western SD/NE will percolate eastward, and some additional
    development is expected overnight with this activity, as well as an
    increase in coverage with the south-central NE cluster. As this
    convection shifts east/northeast overnight toward eastern SD,
    southwest MN and western/central IA, sporadic strong gusts and hail
    will be possible.

    ..Leitman.. 04/19/2023

    $$

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  • From COD Weather Processor@1:2320/105 to wx-storm@lists.illinois.edu on Mon May 29 21:14:46 2023
    ACUS01 KWNS 292114
    SWODY1
    SPC AC 292113

    Day 1 Convective Outlook RESENT 1
    NWS Storm Prediction Center Norman OK
    0413 PM CDT Mon May 29 2023

    Valid 292000Z - 301200Z

    ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF
    THE NEBRASKA VICINITY...

    ...SUMMARY...
    Isolated strong to severe thunderstorms capable of producing hail
    and damaging winds remain possible this afternoon and evening in
    parts of the central High Plains into Nebraska and South Dakota.

    ...Discussion...
    With current expectations in line with the ongoing outlook, no
    appreciable changes appear necessary with this update. For
    additional short-term information, please refer to MCD 893 and 894.

    ..Goss.. 05/29/2023

    .PREV DISCUSSION... /ISSUED 1117 AM CDT Mon May 29 2023/

    ...Northern and Central Plains...
    A weak upper trough remains in place over the northern and central
    Plains states today, providing relatively cool temperatures aloft
    and subtle large-scale forcing for ascent across the region. This
    will lead to scattered afternoon thunderstorm development, and at
    least some potential for hail and gusty winds. Forecast soundings
    throughout the region show moderately steep mid level lapse rates
    and just enough bulk shear for marginal organization. Therefore
    will maintain the MRGL risk for much of the region.

    One area that appears to have a slightly more favorable environment
    is along a weak surface confluence zone that extends from southwest
    to northeast NE. A consensus of CAM solutions suggest this narrow
    corridor will become convectively active by late afternoon. A 30-40
    knot westerly mid-level jet will track across WY and nose into this
    region this evening, enhancing the deep-layer shear and further
    promoting a few severe storms, with a risk of large hail and
    damaging winds for a few hours.

    ...South TX...
    A weak upper trough is also tracking across TX today, where a very
    moist and moderately unstable air mass will develop this afternoon
    (MLCAPE around 2000 J/kg). Winds aloft are sufficiently strong to
    aid in organization to any robust thunderstorms that can form.
    Given the 12z CAM solutions of widely scattered convection, will add
    a MRGL risk area for afternoon/evening hail and wind risk.

    $$

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  • From COD Weather Processor@1:2320/105 to wx-storm@lists.illinois.edu on Sun Jun 4 13:15:31 2023
    ACUS01 KWNS 041315
    SWODY1
    SPC AC 041313

    Day 1 Convective Outlook RESENT 1
    NWS Storm Prediction Center Norman OK
    0813 AM CDT Sun Jun 04 2023

    Valid 041300Z - 051200Z

    ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER THE
    SOUTHERN APPALACHIANS/TENNESSEE VALLEY REGION...AS WELL AS PARTS OF
    SOUTH TEXAS...

    ...SUMMARY...
    Damaging to isolated severe gusts, along with isolated severe hail,
    are possible over the southern Appalachians/Tennessee Valley region,
    as well as parts of south Texas.

    ...Synopsis...
    Blocking aloft, with slight retrogression, will continue through
    this period. In moisture-channel imagery, a mid/upper-level high
    was apparent near Winnipeg, with broad anticyclone extending across
    much of south-central Canada and the north-central CONUS. The high
    should drift westward to near the southern MB/SK border by 12Z
    tomorrow. As this occurs, a pronounced cyclone centered south of ME
    and east of MA will drift erratically for most of today before
    slowly turning southward to southeastward overnight. Farther
    southwest, a weak perturbation apparent over the western Carolinas
    and eastern TN should drift southwestward today.

    A quasistationary, negatively tilted, weak upper trough will persist
    from a small cyclone over northern UT southeastward across the
    southern Rockies/High Plains to the Red River and Sabine Valleys.
    Several embedded, slow-moving perturbations are likely to meander
    erratically within the associated broad height weakness, which
    extends a couple hundred miles either side of the axis. Meanwhile,
    a few additional vorticity lobes of varying sizes and strengths may
    be convectively generated today and tonight.

    At the surface, the synoptic pattern remains rather messy and
    nebulous over most of the CONUS east of the Rockies, save for a
    "back-door" cold front drawn at 11Z from southern NC across northern
    GA then northward over eastern TN/KY to near Lake Michigan. This
    boundary should drift westward to southwestward and become more
    diffuse through the period. A dryline was drawn from southeastern
    CO across eastern NM to the Pecos Valley area of west TX.

    ...Southern Appalachians/Tennessee Valley...
    Widely scattered to scattered thunderstorms with isolated, marginal
    severe potential should develop this afternoon near the frontal zone
    and move southwestward across the area. Subtle large-scale ascent
    near the mid/upper perturbation will contribute to destabilization
    aloft today. This will occur atop a boundary layer characterized by
    weak CINH, diurnal heating/destabilization, and surface dewpoints
    generally in the mid 50s to low 60s F after some mixing. 500-1200
    J/kg MLCAPE should develop atop inverted-v thermodynamic profiles in
    low levels, supporting downdraft acceleration to surface. Though
    deep layer winds and vertical shear will be weak, strong to perhaps
    isolated severe downbursts may cause some wind damage -- especially
    with any localized, cold-pool-aided thunderstorm clusters that may
    develop. Hailstones up to near severe limits also are possible.

    ...South TX...
    Thunderstorms are possible this afternoon into evening over a large
    part of the corridor near the upper trough, from the Great Basin to
    the western Gulf Coastal Plain -- and isolated severe gusts or hail
    cannot be ruled out almost anywhere over that vast swath. However,
    within an expansive favorable-moisture/weak-shear regime, relative concentrations of multicellular convection may focus severe
    potential somewhat better on the mesoscale. The most probable area
    for that to happen currently appears to be across parts of south TX
    near the outflow boundary, and over the higher terrain of
    northeastern MX, each of which may focus development and
    southeastward propagation of strong thunderstorms southwest of the
    trough aloft (in modest, west to northwest flow aloft). Strong
    heating of a favorably moist, weakly capped boundary layer is
    expected throughout the midday into afternoon, with surface
    dewpoints generally in the 60s F, leading to areas of 2000-3000 J/kg
    MLCAPE. Weak shear will temper organization somewhat, though one or
    two bands/clusters of convection may aggregate upscale and offer
    damaging to severe gusts after an initial, isolated hail threat in more-discrete stages.

    ..Edwards/Smith.. 06/04/2023

    $$

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  • From COD Weather Processor@1:2320/105 to wx-storm@lists.illinois.edu on Sat Jun 24 14:26:35 2023
    ACUS01 KWNS 241426
    SWODY1
    SPC AC 241424

    Day 1 Convective Outlook RESENT 1
    NWS Storm Prediction Center Norman OK
    0924 AM CDT Sat Jun 24 2023

    Valid 241300Z - 251200Z

    ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM PARTS OF IOWA
    AND MINNESOTA INTO THE MID MISSISSIPPI VALLEY...

    ...SUMMARY...
    Severe thunderstorms, associated with wind damage, large hail and
    perhaps a couple of tornadoes, will be possible from parts of Iowa
    and Minnesota into the mid Mississippi Valley this afternoon and
    evening.

    ...Synopsis...
    Although the mean/large-scale ridge position aloft still extends
    from the northern MX high across the central Plains to ON, it will
    be penetrated today by a compact cyclone now evident in moisture-
    channel imagery over the northern High Plains. The 500-mb low is
    forecast to move erratically eastward to near the MN Twin Cities
    region by the end of the period, with shortwave trough to
    northeastern KS. Today, strongly difluent mid/upper flow will
    spread across the mid/upper Mississippi Valley to its east and
    southeast. A longstanding, gradually weakening upper trough over
    the eastern CONUS will shift slowly eastward toward the East Coast.

    At the surface, 11Z analysis showed a low over east-central SD near
    HON, with cold front across south-central NE to northwestern KS and southeastern CO. The low will closely follow the mid/upper vortex
    center track, while occluding. The cold front should reach western
    IA, northeastern KS and southeastern CO by 00Z. By 12Z tomorrow,
    the cold/occluded front will reach eastern parts of IA/MO as well as southwestern MO, southwestern OK and eastern NM. A warm front was
    drawn over the lower Missouri Valley, and should move/redevelop
    northeastward across the mid/upper Mississippi Valley through the
    period ahead of the low.

    ...Mid/upper Mississippi Valley region...
    Scattered thunderstorms may develop this afternoon between the
    northern Red River Valley near the deep-layer low, and the mid
    Mississippi Valley region. The greatest severe threat still appears
    to be over parts of IA, MO and IL, though a good deal of it remains conditional. Tornadoes, along with large to very large hail and
    locally severe gusts, are possible.

    An ongoing, slowly weakening, mostly non-severe thunderstorm complex
    across southwestern MN to northern/western IA will exert substantial
    influence on later severe-weather potential across the same region
    and nearby mesoscale areas. The northern part is expected to
    continue moving into a lower-theta-e environment over MN, WI and
    northern IA. Meanwhile, the southern part should shift eastward/
    southeastward across IA, with some afternoon rejuvenation possible
    along the associated pressure perturbation and UVV plume. The more
    probable scenario is for a new round of severe thunderstorms to form
    in its wake as warm/moist advection occur from the south and
    southwest, and diurnal heating destabilizes the boundary layer
    following departure of substantial associated cloud cover. Surface
    dewpoints in the 60s and perhaps near 70 F, and a few hours of
    heating, should support peak, prefrontal/preconvective MLCAPE in the
    2000-3000 J/kg range.

    This area also will reside in a regime of deep large-scale ascent --
    overlying the warm advection with midlevel DCVA and lift beneath the
    left-exit region of 250-300-mb jet. Sufficient flow aloft will
    exist for 35-45-kt effective-shear magnitudes, with a pocket of
    large low-level hodographs and SRH potentially developing over
    central/northern IA or southern MN. With the bulk of the morning
    MCS still over or west of the possible area of interest, there still
    is considerable uncertainty on where the optimal mesoscale pseudo-
    warm-frontal transition zone may set up in the wake of the complex.
    A focused area of enhanced supercell/tornado and large-hail
    potential may develop on any such boundary, with lower buoyancy,
    backed flow and high SRH to its northeast, and greater heating/CAPE
    but still adequate low-level shear to its southwest. If a dominant
    supercell or two can occur in this environment prior to upscale
    growth (not yet a given), greater tornado probabilities and perhaps significant-tornado area may be needed.

    Farther north across portions of central/northern MN, boundary-layer instability will be weaker this afternoon. However, a narrow plume
    of favorable, effectively surface-based parcels may develop east and
    southeast of the deep-layer low, supporting an arc of convection
    that may include low-topped supercells. Given uncertainties
    regarding airmass recovery, with considerable cloud cover likely
    over the area for most of the day, unconditional tornado potential
    remains marginal, but the most-aggressive destabilization scenarios
    support the potential for a few in that area.

    ...Southwest to north TX...
    Isolated to widely scattered, high-based thunderstorms are expected
    to develop along/ahead of a dryline drawn this morning over eastern
    NM and far west TX, but expected to mix rapidly eastward across west
    TX today, amidst seasonally intense diurnal heating. Activity will
    originate atop a very deep/well-mixed boundary layer with dry-
    adiabatic lapse rates (superadiabatic very near surface), with
    moisture content increasing and surface temperatures decreasing
    northeastward. Strong/isolated severe downbursts will be possible
    over the entire outlook area, and enough inflow-layer moisture to
    support isolated large hail is possible over northwest TX and
    perhaps parts of the Big Country.

    ..Edwards/Mosier.. 06/24/2023

    $$

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  • From COD Weather Processor@1:2320/105 to wx-storm@lists.illinois.edu on Thu Jun 29 14:50:16 2023
    ACUS01 KWNS 291450
    SWODY1
    SPC AC 291448

    Day 1 Convective Outlook RESENT 1
    NWS Storm Prediction Center Norman OK
    0948 AM CDT Thu Jun 29 2023

    Valid 291300Z - 301200Z

    ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS THROUGH THIS
    EVENING FROM NORTHERN MO TO IL...SOUTHWEST IN AND WESTERN KY...

    ...SUMMARY...
    Swaths of damaging winds of 60-80 mph, large hail up to 2.5 inches
    in diameter, and a couple of tornadoes will all be possible today
    from northern Missouri into Illinois and adjacent areas of southwest
    Indiana and western Kentucky. Other severe storms with large hail
    and damaging gusts will also be possible farther west into the
    central High Plains.

    ...MO/IL/IN/KY/TN through this evening...
    Severe storm clusters, with embedded supercells, have been moving
    eastward early this morning near KS/NE border and are expected to
    continue eastward through late morning across northern MO and
    extreme southern IA, near a stalled front. A moist/unstable air
    mass is present along and south of the front, with MLCAPE of
    3000-4000 J/kg across northern MO, driven by boundary-layer
    dewpoints in the low-mid 70s beneath midlevel lapse rates of 9 C/km.
    These favorable thermodynamic profiles will favor continued strong
    updraft formation within the clusters as they move along the front
    and the north edge of the warmest elevated mixed layer, coincident
    with the southern fringe of the stronger midlevel westerlies.
    Isolated very large hail to 2.5 inches in diameter will be possible
    through the morning with the supercells, while large DCAPE favors a continuation of severe outflow gusts (60-80 mph). Though the
    details are still a bit uncertain, there is the potential for some
    upscale growth into a bowing MCS with swaths of significant wind
    damage from northern MO into IL and southwest IN.

    Once the expected MCS reaches central IL, the tendency should be for
    more southeastward motion with time, around the periphery of the
    midlevel ridge. The ongoing storms from eastern IL into southwest
    IN have shown some tendency to cluster this morning, and may persist
    for a few more hours while moving southeastward toward KY.
    Rain-cooled air from these morning storms could also provide a
    corridor for the upstream convection to move along this afternoon.
    The main threat with the morning storms will be large hail,
    primarily with elevated supercells, though some wind damage will
    also be possible. Damaging winds will be the main threat with the
    expected MCS this afternoon, and a couple of tornadoes may also
    occur with embedded circulations.

    ...Central High Plains this afternoon/evening...
    Post-frontal, upslope flow is established across eastern CO, and
    low-level moisture has spread west to the Front Range (aided by
    outflow from overnight storms). Modification of the rain-cooled air
    and breaks in the low clouds will support moderate buoyancy by mid
    afternoon (MLCAPE of 1000-2000 J/kg), when thunderstorm development
    will become more probable immediately east of the higher terrain
    from CO into southeast WY. The moderate buoyancy and relatively long
    hodographs with effective bulk shear in excess of 40 kt will support
    supercells capable of producing large hail of 1-2 inches in
    diameter. Some upscale growth into a few clusters will be possible
    this evening, with an attendant threat for isolated damaging winds.
    Though the details are fairly uncertain, some of the evening
    convection may persist into the overnight hours across southern
    NE/northern KS with some threat for isolated large hail/wind damage.

    ..Thompson/Gleason.. 06/29/2023

    $$

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  • From COD Weather Processor@1:2320/105 to wx-storm@lists.illinois.edu on Fri Nov 10 14:42:38 2023
    ACUS01 KWNS 101442
    SWODY1
    SPC AC 101441

    Day 1 Convective Outlook RESENT 1
    NWS Storm Prediction Center Norman OK
    0841 AM CST Fri Nov 10 2023

    Valid 101300Z - 111200Z

    ...NO SEVERE THUNDERSTORM AREAS FORECAST...

    ...SUMMARY...
    Isolated lightning flashes will be possible along parts of the Gulf
    coast, far west Texas/southwest New Mexico, and the Olympic
    Peninsula of Washington.

    ...Synopsis...
    A slow-moving front along the northwest/north central Gulf coast may
    focus isolated thunderstorm development through the period. Any
    convection will be generally along and to the cool side of the
    surface front, where weak buoyancy aloft may be sufficient for
    charge separation and isolated lightning flashes. Farther west,
    isolated thunderstorms have been observed early this morning across
    southwest NM and far west TX. Weak elevated CAPE and ascent
    downstream from a southern stream shortwave trough could support a
    few additional thunderstorms the first half of the day, before the
    threat ends during the afternoon.

    Otherwise, isolated low-topped thunderstorms will be possible the
    last few hours of the forecast period across the Olympic Peninsula
    as a pronounced shortwave trough approaches coastal WA and Vancouver
    by 08-12z. Isolated lightning flashes earlier this morning near the
    WV/VA border have ended and no additional thunderstorm development
    is expected today.

    ..Thompson/Gleason.. 11/10/2023

    $$

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