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Severe Severe threat February 24th

Discussion in 'General Weather' started by tennessee storm, Feb 19, 2018.

  1. tennessee storm

    tennessee storm Member

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    Looks like decent threat late in week... euro more aggressive than gfs Arkansas west tenn . Wind fields look pretty
    Decent . If instability can increase may be decent threat. Updates later.
     
  2. NWMSGuy

    NWMSGuy Member

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    Here's the related 2/19 Outlook and Discussion from SPC.

    Weather.gif

    Day 4-8 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0358 AM CST Mon Feb 19 2018

    Valid 221200Z - 271200Z

    ...DISCUSSION...
    Better agreement/consistency is evident at this time with respect to
    various medium-range model runs through a majority of the day 4-8
    period, as compared to 24 hours prior. Models in general depict
    that a major short-wave trough -- digging across California and the
    Great Basin day 4 (Thursday) will eject east across the Desert
    Southwest/southern Rockies day 5, and then the central and southern
    Plains day 6 (Saturday). While this feature is progged to
    weaken/deamplify with time due to persistence of southeastern U.S.
    ridging, surface lee cyclogenesis is expected over the southern High
    Plains early in the day which will deepen/shift quickly
    east-northeast into the Ohio Valley/Midwest overnight. Ahead of
    this system, low-level moisture return from the Gulf of Mexico
    should prove sufficient for at least some warm-sector CAPE
    development which -- combined with what should be a favorable
    background lower- and middle-tropospheric wind field -- suggests
    that some severe weather risk may evolve Saturday. While degree of
    instability may limit risk to some degree, ample evidence exists to
    suggest initial introduction of 15% severe weather probability from
    the Arklatex vicinity east across parts of the lower Mississippi and
    into the Tennessee Valleys.

    As the weakening upper system shifts quickly east-northeast across
    the lower Great Lakes region day 7 (Sunday), expect the trailing
    surface front to weaken and become oriented increasingly
    west-to-east across the Gulf Coast region, suggestive of diminished
    severe potential. In addition, model differences increasing through
    the end of the period result in reduced confidence with respect to
    the convective forecast through early next week.
     
  3. Webberweather53

    Webberweather53 Meteorologist

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    Nice call on the thread, knew we weren't gonna stay quiet for long with deep moist southwesterly flow in mid-late Feb off the Gulf which is stupid warm atm.
     
  4. NWMSGuy

    NWMSGuy Member

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    2/20 Outlook and Discussion from SPC:

    Severe.gif


    Day 4-8 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0337 AM CST Tue Feb 20 2018

    Valid 231200Z - 281200Z

    ...DISCUSSION...
    Model consensus is that a significant shortwave trough will eject
    northeast through the central Plains and middle MS Valley region
    (Day 5) Saturday and Saturday night. Some deamplification of this
    feature is expected, but model differences persist. GFS maintains a
    more amplified trough with a deeper surface low suggesting the
    potential for a greater severe threat compared to ECMWF, UKMET and
    the Canadian. In either case a few severe storms might evolve in
    vicinity of frontal zone from east TX into the lower MS and TN
    Valley region as the low-level jet strengthens and shifts northeast
    in response to the approaching shortwave trough. Storms may be
    ongoing along baroclinic zone over a portion of this region, with
    potential to intensify within zone of modest destabilization and
    forcing associated with the migrating low-level jet. Limiting
    factors are likelihood of widespread clouds and tendency for the
    approaching shortwave trough to weaken with deeper forcing likely
    remaining northwest of warm sector.

    Some severe threat might linger into day 6, but overall potential
    should decrease later day 6 into day 7 as a cold front moves into
    the northern Gulf coast area.
     
  5. NWMSGuy

    NWMSGuy Member

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    Looks like a nice line on ICON model 00z Sun.

    Severe.png
     
  6. accu35

    accu35 Member

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    Im ready for action
     
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  7. Webberweather53

    Webberweather53 Meteorologist

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    The overall setup looks worthy of an enhanced risk of severe weather in parts of Arkalatex and lower MS valley with marginal mid-level lapse rates amidst a fairly unstable and moist boundary layer and modest bulk shear of 45-60 KT (if it becomes too strong could potentially be a detriment to severe in this case), and SRH of >150-300 m2/s2 that favors multicellular clusters and/or isolated supercells capable of producing damaging winds, hail, and isolated tornadoes. Certainly worth watching in north-central Louisiana, eastern Texas, southeastern Oklahoma, Arkansas, north-central Mississippi and southwestern Tennessee. The one limiting factor will be the most favorable synoptic-scale mid-upper level forcing remaining far removed from the best instability further south (as indicated by the stronger Q-vector convergence (in red) over the mid-MS Valley)
    us_f108.png
    srh03.conus.png
    us_f108.png
    bs0500.conus.png
    us_f114.png
     
  8. NWMSGuy

    NWMSGuy Member

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    Webber, are you thinking this will be a late afternoon/evening setup if it does materialize?
     
  9. tennessee storm

    tennessee storm Member

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    Timing don’t change. Close to 18z around ms river
     
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  10. NWMSGuy

    NWMSGuy Member

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    Well that certainly is concerning. o_O
     
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  11. NWMSGuy

    NWMSGuy Member

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    How did 12Z EURO handle the system compared to previous runs?
     
  12. stormcentral

    stormcentral Storm Central Wx Member

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    FB_IMG_1519162429517.jpg
    WAFF 48 Brad Travis posted this.
     
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  13. tennessee storm

    tennessee storm Member

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    interestting system saturday.... not looking like a big tornado threat.... but its our first legit threat of severe wx of the new season...
     
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  14. NWMSGuy

    NWMSGuy Member

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    2/21 Outlook and Discussion from SPC

    day4prob.gif

    Day 4-8 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0356 AM CST Wed Feb 21 2018

    Valid 241200Z - 011200Z

    ...DISCUSSION...
    A significant shortwave trough will eject northeast through the
    central Plains and middle MS Valley region (Day 4) Saturday and
    Saturday night. Some deamplification is expected, but the trough
    will take on a more negative tilt as it approaches the middle MS
    Valley. GFS is still the stronger solution with deeper cyclogenesis
    and suggests potential for a slightly more robust severe threat. In
    either case a forced line of potentially strong to severe storms
    might evolve in vicinity of cold front initially over northeast TX,
    before spreading into the lower MS and TN Valley regions as the
    low-level jet strengthens and shifts northeast through moistening
    warm sector. While vertical shear and overall character of the wind
    profiles should be more than adequate for organized severe storms,
    primary limiting factor appears to be a marginal thermodynamic
    environment given likelihood of widespread clouds and weak lapse
    rates.

    Some severe threat might linger into Sunday (day 5) over a portion
    of the Middle Atlantic, but confidence is not high enough at this
    time to introduce a categorical area. Overall severe potential
    should remain low day 6 into day 7 as a cold front settles into the
    northern Gulf coastal area.
     
  15. Tarheel1

    Tarheel1 Member

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    Y’all severe :weenie:‘s let one slip by yesterday! The 2-3 tornadoes from S of Dallas!? :mad: Y’all aren’t ready for severe! :eek:
     
  16. tennessee storm

    tennessee storm Member

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    Ready for Saturday. In my area
     
  17. tennessee storm

    tennessee storm Member

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    12 z euro. Upped the Annie also. With instability n shear
     
  18. NWMSGuy

    NWMSGuy Member

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    2/22 Outlook and Discussion from SPC.
    Possible upgrades in later Outlooks.

    day3otlk_0830.gif

    Day 3 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0219 AM CST Thu Feb 22 2018

    Valid 241200Z - 251200Z

    ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM A PORTION OF
    EAST TEXAS INTO THE LOWER MISSISSIPPI...TENNESSEE AND OHIO
    VALLEYS...

    ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM A PORTION
    OF THE SOUTHERN PLAINS THROUGH THE OHIO VALLEY AND SOUTHEAST
    STATES...

    ...SUMMARY...
    Strong to severe storms will be possible Saturday from a portion of
    northeast Texas through the lower Mississippi, Tennessee and Ohio
    Valleys.

    ...Northeast TX into the lower Mississippi Tennessee and Ohio
    Valleys...

    A significant shortwave trough will eject northeast through the
    central Plains and middle to upper MS Valley region Saturday and
    Saturday night while taking on a negative tilt. In response to
    forcing accompanying this feature, a surface low initially over the
    southern Plains will deepen as it develops northeast through the
    middle MS Valley, eventually reaching the Great Lakes toward the end
    of the period. Warm front extending east from the surface low will
    move northward, reaching the OH Valley Saturday night. A cold front
    initially across west TX will advance through the Southern Plains
    and middle to lower MS Valley during the day reaching the OH and TN
    Valleys Saturday night. A strengthening low-level jet resulting from
    the deepening cyclone will transport richer gulf moisture northward
    with low 60s F dewpoints as far as the OH Valley and mid to upper
    60s from east TX to the lower MS Valley. However, instability will
    probably remain marginal due to widespread clouds and modest lapse
    rates with MLCAPE likely to remain below 1000 J/kg over most of the
    warm sector.

    A forced line of potentially strong to severe storms should evolve
    in vicinity of cold front initially over north central or northeast
    TX into southeast OK during the day. Activity will subsequently move
    into the lower MS, TN and OH Valley regions as the low-level jet
    strengthens to 60+ kt and shifts northeast through moistening warm
    sector. Vertical shear and overall character of wind profiles will
    be more than adequate for organized severe storms, with potential
    for LEWP, bowing segments and a few embedded supercells capable of
    damaging wind and a few tornadoes. An upgrade to higher
    probabilities might be needed in later outlooks once uncertainties
    regarding the thermodynamic environment have been mitigated.
     
  19. NWMSGuy

    NWMSGuy Member

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    From Memphis' AM AFD on Saturday:

    With regards to a severe threat...models are showing a prefrontal
    trough signal forming in eastern Arkansas by 00z Sunday as the
    surface wave crosses Missouri. Another feather in the cap for the
    potential for surface-based convection. A 70kt LLJ from the
    southwest will form just out ahead of the trough leading to an
    evening period of potentially backed surface winds and few low
    level mesos and/or bowing segments. Limiting factors will be
    lapse rates and instability amounts after sunset. Have placed
    wording in this morning`s HWO about this severe threat.
     
  20. tennessee storm

    tennessee storm Member

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    Surface winds are backed pretty good on 0z euro looking more likely some super cell development ahead of line which should produce tornadoes with surface base instability models been showing lately Getting concerning
     
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  21. Tarheel1

    Tarheel1 Member

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    Annie are you ok? Are you ok Annie
     
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  22. Webberweather53

    Webberweather53 Meteorologist

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    An upgrade to an enhanced risk of severe weather will likely occur here if more instability is realized in the warm sector. Could even see some residual marginal threat for wind in the Carolinas at day 4. Should be fun to monitor.
     
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  23. Tarheel1

    Tarheel1 Member

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    BE61B3DD-FAD3-4E24-B58E-F6F6C5354653.png If Jimbo is all in, I’m all in!
     
  24. NWTNWX

    NWTNWX Member

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  25. Webberweather53

    Webberweather53 Meteorologist

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    Lol a Broyles ENH risk. I love how he used the 0-3 km shear as justification for instituting the ENH.
     
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  26. MichaelJ

    MichaelJ Member

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    You guys in Tenn can keep this crap over there in your backyards, we don't want it (well at least most of us don't)
     
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  27. Frogge

    Frogge Member

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    Greg Forbes has the TORCON for East Arkansas and West Tennessee at a 5. There is plenty of potential not that much if any crapvection, and hints on the NAM that we might get some cloud breaks in the delta.
     
  28. tennessee storm

    tennessee storm Member

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    well good luck then.........
     
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  29. Webberweather53

    Webberweather53 Meteorologist

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    The shear looks fairly unidirectional and storm mode won't be discrete too long as is often the case in Feb. It's honestly just nice to get a couple legit severe weather threats under our belt before things get interesting and/or hairy later on in the latter parts of spring and summer when this Kelvin Wave reaches the EP and tries to flip the ENSO base state and this low frequency pattern away from a western us trough.
     
  30. Taylor C

    Taylor C Member

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    This doesn’t look too bad. Worth chasing I think. I’m leaving at 5 in the morning for eastern AR.
     
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