• DAY2 3/5 Risk Area Posted

    From Mike Powell@618:250/1 to All on Wed May 14 07:39:00 2025
    ACUS02 KWNS 140556
    SWODY2
    SPC AC 140555

    Day 2 Convective Outlook
    NWS Storm Prediction Center Norman OK
    1255 AM CDT Wed May 14 2025

    Valid 151200Z - 161200Z

    ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS PARTS OF THE
    UPPER MISSISSIPPI RIVER VALLEY AND WESTERN GREAT LAKES...

    ...SUMMARY...
    Scattered severe thunderstorms are expected across parts of the
    upper Mississippi River Valley and western Great Lakes region
    Thursday afternoon and evening. More isolated severe thunderstorms
    are expected through the lower Ohio River Valley, Ozarks Plateau,
    and parts of the Mid-Atlantic.

    ...Synopsis...
    The upper-level trough currently over the Intermountain
    West/northern Rockies is forecast to eject into the upper MS River
    Valley over the next 48 hours. As this occurs, a Pacific cold front
    will rapidly push east into the MS Valley and Midwest as an intense
    surface cyclone begins to occlude over the eastern Dakotas/western
    MN. Scattered thunderstorms are expected to develop along the front
    by early-afternoon with increasing coverage across the upper MS
    Valley through early evening. Increasingly sparse, but severe,
    thunderstorms are anticipated along the front across the Midwest
    into the lower OH Valley and Ozarks/Texarkana regions through the
    evening and overnight hours.

    ...Upper MS Valley and western Great Lakes...
    04 UTC surface observations show upper 50s to low 60s dewpoints
    already spreading northwest into the upper MS Valley as a surface
    low begins to organized across the northern Plains. Confidence
    remains high that dewpoints in the mid 60s should overspread much of
    the region by mid-day Thursday and will contribute to regional
    MLCAPE values upwards of 2000-2500 J/kg. Strong forcing for ascent
    along the approaching front and within the left-exit region of a
    50-60 knot mid-level jet will erode capping at the base of a stout
    EML and promote thunderstorm development by early afternoon across
    parts of central to southern MN. Elongated hodographs with
    cross-boundary mean winds will promote organized, initially discrete/semi-discrete cells with an attendant severe wind and hail (potentially as large as 2 inches) threat. Veering winds through the
    lowest 2 km will also support a tornado threat with early convection.

    With time, persistent strong forcing along the front should promote
    some degree of upscale growth/clustering, though supercells will
    remain likely on the southern fringe of the line where capping will
    remain stronger and favor more isolated convection. The potential
    for somewhat longer-lived supercells may be maximized across
    southeast WI into adjacent portions of IL, northern IN, and
    southwest lower MI. Forecast soundings depict ESRH values on the
    order of 200-300 m2/s2, suggesting a significant tornado threat
    could materialize. Confidence in the coverage of such cells remains
    limited, but trends will be monitored for the need for increased
    tornado risk probabilities.

    ...Midwest and Ohio Valley...
    Forecast guidance continues to show the best moisture return across
    parts of IL, IN, and northern KY by Thursday afternoon. Dewpoints in
    the upper 60s to low 70s under nearly 8 C/km mid-level lapse rates
    will support a very unstable air mass with MLCAPE values approaching
    4000 J/kg. Despite the very favorable buoyancy, capping at the base
    of the EML is expected to limit storm coverage across this region.
    Recent guidance has trended towards perhaps a slightly increased
    coverage of thunderstorms compared to previous runs, but the overall
    consensus among deterministic and CAM ensemble guidance is that
    storm coverage should be sparse. Nonetheless, effective bulk shear
    values on the order of 40-50 knots will promote supercells during
    the late afternoon/evening hours with all hazards possible,
    including the potential for significant hail/tornadoes.
    Consideration was given for an expansion of the Enhanced risk area,
    but limited confidence in convective coverage precluded such expansion.

    ...Texarkana to the Ozark Plateau...
    Weaker forcing along the front and strong capping will likely limit thunderstorm coverage from the Texarkana region into the Ozark
    Plateau during the afternoon/evening. Heading into the overnight
    hours, increasing low-level isentropic ascent over the frontal
    boundary will support thunderstorm development - especially across
    the Ozarks into the mid-MS Valley. Strong deep-layer shear will
    promote initial supercells, but storm propagation along the front
    will likely promote clustering with time. Nonetheless, a severe
    hail/wind threat will likely materialize within this corridor.

    ...Mid-Atlantic...
    A moist, weakly capped air mass is expected to remain in place
    across the Mid-Atlantic through Thursday afternoon. While lapse
    rates will be modest after several days of convective overturning,
    temperatures warming into the upper 70s/low 80s will promote
    sufficient buoyancy for thunderstorm development. Upper ridging
    moving into the region will likely limit thunderstorm coverage, but
    convection developing along the Blue Ridge Mountains will mature in
    an environment with increasing deep-layer shear. A few organized
    cells appear possible with an attendant severe hail/wind threat.

    ..Moore.. 05/14/2025

    $$
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  • From Mike Powell@618:250/1 to All on Sat May 17 08:50:00 2025
    ACUS02 KWNS 170603
    SWODY2
    SPC AC 170602

    Day 2 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0102 AM CDT Sat May 17 2025

    Valid 181200Z - 191200Z

    ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS NORTHERN
    OKLAHOMA AND MUCH OF CENTRAL AND EASTERN KANSAS...

    ...SUMMARY...
    Severe thunderstorms capable of all severe hazards are expected on
    Sunday across portions of the central and southern Plains.

    ...Synopsis...
    A mid-level shortwave trough will move from the Southwest into the
    Central Plains on Sunday as the broader trough develops across the Intermountain West. By 00Z Monday, a ~992mb lee cyclone will develop
    along the KS/CO border. A warm front will extend from this surface
    low into northern Kansas/southern Nebraska by Sunday evening and
    will remain mostly stationary across the Southeast. A dryline will
    extend from central Kansas to the southern Plains.

    ...Kansas and northern Oklahoma...
    A very moist airmass will be in place east of the dryline on Sunday
    with low 70s dewpoints forecast across much of Texas, Oklahoma, and
    southern Kansas ahead of the surface boundary. As temperatures warm,
    strong to very strong instability is forecast to develop. As the
    mid-level shortwave trough emerges across the Plains, synoptic-scale
    ascent will combine with the increasing instability to decrease
    inhibition across much of the dryline. Forecast guidance shows
    limited convergence along the dryline in Oklahoma and Texas during
    the day Sunday with the better convergence focused across Kansas.
    Therefore, confidence is higher for storms across central and
    southern Kansas and perhaps into northern Oklahoma.

    Any storms which develop will be supercellular with a threat for
    very large hail and tornadoes, particularly by later in the evening
    as the low-level jet strengthens. While confidence is higher in
    storms across the Enhanced risk area, storm evolution remains
    unclear. 00Z CAM guidance has wide variations in the northeastward
    progression of the surface warm front which will significantly
    impact storm development on Sunday. A more discrete storm mode would
    likely pose a greater very large hail and tornado threat, while more
    widespread storm development would likely favor development into a
    MCS which could pose a greater severe wind threat across eastern
    Kansas and into Missouri.

    Despite the uncertainties, the Enhanced (Level 3 of 5) risk seems
    appropriately placed where severe storms are most likely. The 10%
    tornado probabilities do not extend to the northern extent of the
    Enhanced due to the aforementioned uncertainties in the warm frontal
    position. However, elevated hail will remain a threat north of the
    warm front.

    ...Oklahoma/Texas...
    A dryline will be in place across western Oklahoma and north Texas
    for much of the day Sunday. Convergence will be mostly weak along
    the Oklahoma dryline for much of the day with better convergence
    farther south in Texas, farther from the better upper-level forcing.
    However, by the evening, convergence will increase somewhat which
    could result in isolated supercell development as the low-level jet
    intensifies during the evening. The environment across Oklahoma and
    North Texas will be very volatile with a conditional threat for
    intense supercells capable of very large hail and strong tornadoes.

    ...Northeast CO/Southwest Nebraska Vicinity...
    By Sunday afternoon, low to mid 60s dewpoints will advect westward
    around the surface low into northwest Kansas, northeast Colorado,
    and southwest Nebraska. Moderate to strong instability is forecast
    ahead of the dryline which will aid in supercell development by the
    afternoon. A narrow corridor of instability will be the primary
    limiting factor to the tornado threat in an otherwise very favorable
    STP environment. It appears supercells will likely be north of the
    boundary before maturing which will support a primary threat for
    large hail. However, if a storm can rapidly mature as it develops
    off the dryline, it could pose a tornado threat given the favorable
    low-level shear across the region.

    ...Mid Mississippi Valley to the Southeast...
    Isolated thunderstorms are possible along a stalled frontal zone
    that will extend from the Mid-Mississippi Valley to the Southeast.
    Moderate to strong instability will be in place within a moderately
    sheared environment. Forcing will be weak along the front with
    neutral to perhaps slightly rising heights aloft. However, forecast
    soundings show minimal inhibition and therefore, isolated
    development is possible. A greater severe threat could materialize
    from a remnant MCV/MCS which will likely evolve from Day 1/Saturday
    convection across north Texas. If this maintains along the frontal
    zone into the late morning on Sunday, it could provide a focused
    region of greater severe weather threat Sunday afternoon across
    AL/GA.

    ..Bentley.. 05/17/2025

    $$
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  • From Mike Powell@618:250/1 to All on Sun May 18 08:13:00 2025
    ACUS02 KWNS 180602
    SWODY2
    SPC AC 180600

    Day 2 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0100 AM CDT Sun May 18 2025

    Valid 191200Z - 201200Z

    ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FOR PORTIONS OF
    THE CENTRAL/SOUTHERN PLAINS INTO THE OZARKS....

    ...SUMMARY...
    Severe storms with all severe weather hazards are expected from the central/southern Plains into the Ozarks on Monday.

    ...Synopsis...
    A mid-level trough will shift from the Intermountain West into the
    central Plains on Monday. A moderate to strong mid-level jet streak
    will emerge along the southern periphery of this trough from the
    Southwest into the central/southern Plains. A surface low in
    Nebraska will gradually consolidate southward and deepen as the
    mid-level jet emerges across the southern Plains. A sharp dryline
    will be present from central Kansas to central Oklahoma and
    north-central Texas. A warm front will extend from near Omaha to the
    lower Ohio Valley and remain mostly stationary during the day.

    ...Central/Southern Plains into the Ozarks...
    Thunderstorms will likely be ongoing along the warm front in the
    northern Missouri border vicinity on Monday morning. Otherwise, a
    mostly convection-free warm sector is expected to the south. Very
    strong instability will develop along and east of the dryline with
    convective temperatures likely reached by early afternoon. As large
    scale ascent ahead of the approaching trough overspreads the
    dryline, expect scattered supercells to develop along the dryline in
    Kansas and Oklahoma. Very large to potentially giant hail will be
    possible with these supercells initially. In addition, hodographs
    will support tornadoes. The tornado threat will increase through the
    afternoon and peak during the evening as the low-level jet
    strengthens and low-level shear increases. However, by this time,
    storm mode could be messy which is one factor precluding higher
    probabilities at this time.

    00Z CAM guidance shows a range of solutions including:

    1. Earlier storms as the primary threat.

    2. Delayed dryline initiation with a potential tornado outbreak type
    solution across central/eastern Kansas and central/eastern Oklahoma.

    3. A combination of both solutions.

    The uncertainty in guidance at this time precludes a moderate risk,
    but higher probabilities may be needed when a more favored solution
    becomes more clear, especially if one of the higher-end scenarios
    appears likely.

    ..Bentley.. 05/18/2025

    $$
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  • From Mike Powell@618:250/1 to All on Mon May 19 08:18:00 2025
    ACUS02 KWNS 190557
    SWODY2
    SPC AC 190556

    Day 2 Convective Outlook
    NWS Storm Prediction Center Norman OK
    1256 AM CDT Mon May 19 2025

    Valid 201200Z - 211200Z

    ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FOR PORTIONS OF
    THE MID-MISSISSIPPI VALLEY...OHIO VALLEY...AND TENNESSEE VALLEY...

    ...SUMMARY...
    Severe thunderstorms are likely across portions of the Ohio Valley, Mid-Mississippi Valley, and Tennessee Valley on Tuesday.

    ...Synopsis...
    A mid-level trough will advance east to the TN/OH Valley by Tuesday afternoon/evening. At the surface, a surface low will move from
    northern MO/southern Iowa to the eastern Great Lakes by 12Z
    Wednesday. A cold front will extend south from this surface low and
    move east from the central/southern Plains at the beginning of the
    period to the eastern Great Lakes to Louisiana Coast by 12Z Wednesday.

    ...Mid-Mississippi Valley into the Ohio/Tennessee Valleys...
    Remnant Day 1 convection will likely be ongoing at the beginning of
    the period from the Midwest into the Ohio Valley with the potential
    for some ongoing strong to severe storms. One or more outflow
    boundaries will likely be located across the Ohio River region at
    the beginning of the period. 00Z guidance has come into better
    agreement that a mid-level dry slot associated with the mid-level
    jet streak will move quickly across the warm sector during the
    morning. This will allow heating and recovery across most of the
    warm sector, particularly south of the Ohio River. This was the
    primary factor which supported expansion of the Enhanced Risk into
    southern Kentucky.

    Moderate to potentially strong instability is forecast to develop
    across the warm sector by the early afternoon. Thunderstorm
    development will likely occur rather early in the afternoon as
    inhibition will be quickly eroded and upper-level forcing should
    overspread the warm sector during the afternoon. A 60 to 70 knot
    mid-level jet will overspread the warm sector and provide a very
    favorable supercell wind profile across most of the region. Initial
    supercells will pose a threat for all severe weather hazards
    including the potential or strong tornadoes. The uncapped warm
    sector and strong forcing suggest that eventual upscale growth is
    likely into several squall lines/clusters. Severe wind and
    line-embedded tornadoes (particularly where the line orientation
    becomes more favorable to the low-level shear vector) will become
    more likely by the evening as this more linear mode evolves.

    ...Carolinas into southern Virginia...
    A warm front is forecast to lift northward across the region during
    the day, allowing for a corridor of rich boundary-layer moisture to
    spread across parts of SC/NC/western VA. Vertically veering,
    supercell wind profiles along this boundary, and MLCAPE to 1500 J/kg
    MLCAPE is evident in forecast soundings. This could support a few
    strong to severe storms during the late afternoon or evening as
    modest height falls overspread the region.

    ..Bentley.. 05/19/2025

    $$
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