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jaxjagman

Tn Valley Severe Weather 2018-19

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Thursday morning: Slight kink in surface wind trajectories is noted on the TN/KY border. Boundary occasionally shows on visible satellite. However both sides are pretty veered off. MCV is approaching so I expect the Slight verifies for mainly wind. Deep layer shear is meh. However low level shear is OK, esp on the boundary and straight east of the MCV. Probably not a big deal, but it's something to talk about in our Region.

Otherwise I think the seasonal progression toward the Plains is on-track. They had quite a week!

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This date back in 2002 there was an F3 tornado go through Rutherford and Cannon,TN(counties).This was one of two F3's that came through Middle Tn that said year.In Nov. another F3 went through Cumberland, county that claimed four lives with that storm 162527012_NWSNashvilleForecastAreaTornadoDatabase.png.3383f4cc9a7effc0277d7cdc015b81a5.png

 

 

Morgan Co got hit hard that November also. I think like 7 died in the Mossy Grove community.

 

 

.

 

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On 4/28/2019 at 1:52 PM, jaxjagman said:

CIPS shows some potential severe storms around the middle of next week,mainly hail and wind.LL/Shear looks weak with some sad looking hodos right now per GFS,

Believe there will be a better system as the models continue to show a trough going through S/Korea,so maybe we'll see some better storms around the 8th give or take like the GFS is showing,right now.

 

ehi03.conus.png

This period still looks good,still some timing differences along with some potential VBV and other junk as well.We'll probably need a short term severe thread upcoming, still some timing differences but all seems like right now we could be dealing with all severe modes upcoming,starting around mid week possibly into next weekend.

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Be interesting if the Euro is right into next weekend. Next Saturday the trough goes negative tilt with a potent shortwave coming through the Tn Valley,this would enhance an impressive LLJ if it were true

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Sure don't look as good today,glad i didn't start a thread.Best chance of severe storms would seem to be Thursday right now

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Slight goes up the Mississippi Alabama line almost to Tenn. 2% strong! Just kidding. The Plains beckons in a week.

Locally we do have outflow lifting through MS/AL. Thunderstorms are in progress from west Mississippi. Looks sloppy without any new development. However they are on or close to that boundary.

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23 hours ago, nrgjeff said:

Slight goes up the Mississippi Alabama line almost to Tenn. 2% strong! Just kidding. The Plains beckons in a week.

Locally we do have outflow lifting through MS/AL. Thunderstorms are in progress from west Mississippi. Looks sloppy without any new development. However they are on or close to that boundary.

Picked my son up from college Thursday morning.When i got close to the Tn/Al line i saw my first accident in Tn before the state line.As i went trough into N/ Al it was like a war zone.I saw cars flipped on their roofs,on their side,etc.etc,multiple accidents and some real bad looking ones.I wasn't going to stop and detour but there was some good storms that went through

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Though not our area, I feel it's still worth a brief mention here in case anyone focuses mostly just on our region. There is a high risk for a significant tornado outbreak in the southern Great Plains today. First SPC High Risk since 2017. A lot of troubling parameters in play for this to verify. If anyone has relatives out there, never hurts to give attention. There will be a main thread in the Central/Western Subforum to follow as the event unfolds.

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May 30: If that cell on the Upper Plateau does anything I'm going to slam my head through a computer monitor. We've all seen how inflow is better at elevation. However everything is sooo veered off today. Crazy cell has weak rotation at 12:45 Central Time. 

Deep breaths. I already saw amazing stuff in the Plains last week...

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Crap I missed it! Friday featured a notable LLJ over the area with modest WSW flow at 500 mb. I'm not surprised to see reports of a small tornado and landspout.

However I'm quickly losing interest in severe. I have fallen hard in love with the East trough on-deck, and associated 50s dewpoints. :wub:

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Maybe some decent storms for guys in the east

 

Day 2 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1136 PM CDT Mon Jun 10 2019

   Valid 121200Z - 131200Z

   ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS POCKETS
   OF THE COUNTRY FROM WEST TX TO NC...

   ...SUMMARY...
   A few strong storms are possible across pockets of the US from west
   Texas to coastal Carolinas. Wind and hail are the primary threats.

   ...Discussion...

   Latest short-range model guidance continues to suggest a notable
   mid-level speed max will dig southeast across the High Plains into
   the base of central US trough over northern MS by 13/00z. This
   feature will eject into the southern Appalachians during the
   overnight hours along with an attendant increase in large-scale
   forcing for ascent.

   Early in the period, convection is expected to be ongoing along a
   cold front across the lower MO Valley into northeast OK. Strong
   heating ahead of the wind shift is expected to aid buoyancy through
   steepening lapse rates across the Ozarks, primarily north of
   aforementioned digging jet. Will maintain 5% severe probs across
   this region due to dryer than normal boundary layer. A few strong
   storms may also develop along the surging front across portions of
   west TX where strong heating should remove CINH.

   Downstream, a narrow corridor of low-level moisture will advance
   north across the eastern TN Valley around the western periphery of
   wedge front in the lee of the Appalachians. Latest guidance suggest
   surface heating should aid buoyancy along a corridor from northeast
   AL into southeast IN. As exit region of approaching jet affects this
   zone of instability, convection should readily develop by early
   evening. Given the strength of the sharpening trough, there is some
   concern severe probs may need to be raised to account for this
   increasingly dynamic system.

   As mid-level heights fall across the southern Appalachians during
   the latter half of the period, a surface wave should evolve along
   coastal front over southeast GA/southern SC. This feature should
   lift north-northeast and may allow more moist/buoyant air mass to
   return to eastern NC. Will introduce 5% severe probs to account for
   convection that should develop within an increasingly sheared
   environment during the overnight hours.

   ...MAXIMUM RISK BY HAZARD...
   Tornado:   2%     - Marginal
   Wind:      5%     - Marginal
   Hail:      5%     - Marginal
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Though they kept the graphic marginal, the wording is such that they definitively left the door open for a slight risk to be added tomorrow over the eastern Valley. Perhaps even a small area of enhanced if buoyancy and lapse rates are in line with the sharpening trough. We shall see...7c52363dbd9ac8aac784aa70ffe64aea.gif

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SPC sticking with marginal for Tennessee and Ohio Valleys.

 

Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0752 AM CDT Wed Jun 12 2019

   Valid 121300Z - 131200Z

   ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
   THE OHIO/TENNESSEE VALLEYS INTO THE SOUTHEAST AND COASTAL
   CAROLINAS...MISSOURI/ARKANSAS VICINITY...AND WEST TEXAS...

   ...SUMMARY...
   Isolated strong to severe thunderstorms will be possible today
   across parts of the Ohio/Tennessee Valleys into the Southeast and
   coastal Carolinas, Missouri/Arkansas vicinity, and west Texas.
   Marginally severe hail and strong/gusty winds should be the main
   threats.

   ...Synopsis...
   For convective purposes, the mid/upper-level pattern will be
   dominated by a high-amplitude, synoptic-scale trough now located
   from northwestern ON across the upper Mississippi Valley, to the
   KS/MO border area and deep south TX.  By 12Z, this trough should
   shift eastward to Lakes Superior and Michigan, IN, middle TN, AL,
   and the north-central Gulf.  Several embedded/minor shortwaves will
   traverse the associated cyclonic-flow field through the period,
   contributing to relatively maximized potential convective coverage
   on the mesoscale.  Farther west, a weak shortwave trough will move
   inland over parts of the Pacific Northwest and northern CA,
   contributing to locally gusty dry thunderstorms, as noted in the SPC
   fire-weather outlook.

   At the surface, 11Z analysis showed a wavy, quasistationary frontal
   zone from southern SC across central/southern GA, to near the LA
   coastline, and across deep south TX.  This boundary should move
   little through the day, while becoming more diffuse west of
   central/eastern GA.  Another cold front was drawn from Hudson Bay
   across northern ON, Lake Superior, to a low near CID, to another
   weak low near TUL, and finally, to yet another weak low near INK. 
   This front will move eastward/southeastward through the period,
   reaching lower MI, southern MO, the Arklatex region, and portions of
   central/southwest TX by 00Z.  By 12Z, the approach of the mid/upper
   trough will induce frontal-low formation over southeastern Lower MI.
   The cold front will extend from the MI low across eastern TN,
   southeastern MS, and south-central TX.

   ...Southeastern CONUS to Ohio Valley...
   Scattered thunderstorms should develop through this afternoon in an
   arc of favorable buoyancy and weak CINH, wrapping around the
   southern/western Appalachians, along and outside of the low-theta-e
   damming air mass.  Isolated severe hail and damaging to marginally
   severe gusts are possible.

   The most favorable conditions at various levels for severe will be
   horizontally displaced from each other across this broad, arching
   area, but individual elements may contribute to at least marginal
   severe potential locally.  Moisture quality and theta-e will be
   greatest over the FL/GA/Carolinas swath, while mid/upper flow,
   cooling aloft, and deep shear will increase northward/northwestward
   through the western Appalachians/Ohio Valley lobe.  Warm and moist
   advection north of the frontal zone, across western GA and eastern
   portions of AL/KY, will contribute to destabilization through the
   afternoon, in tandem with diabatic heating, enabling a narrow
   corridor of 500-1500 J/kg MLCAPE to develop there.  Despite modest
   midlevel lapse rates, pockets of 1500-2500 J/kg MLCAPE should
   develop this afternoon in the Southeast.  Weak low-level flow is
   forecast area-wide, except for some hodograph enhancement possible
   above the surface late afternoon and evening near the Atlantic
   coastal areas of GA/Carolinas.  An assortment of boundaries will
   focus convection, including the frontal zone, outflow, differential-
   heating areas, confluence lines in the warm sector, and sea breezes.


   ...Ozarks and vicinity...
   Airmass recovery following the morning clouds/convection should
   become favorable for the next round of thunderstorms -- this time
   including surface-based cells -- by mid/late afternoon.  Seasonably
   cold, -16 to -18 deg C 500-mb temperatures will spread over this
   region this afternoon, near the mid/upper-level trough.  When
   juxtaposed with residual boundary-layer moisture, afternoon surface
   diabatic heating and related strengthening of low/middle-level lapse
   rates, forecast soundings reasonably suggest around 500-1000 J/kg
   MLCAPE with little or no MLCINH and a well-mixed subcloud layer.

   Organization will be tempered by lack of more robust moisture and
   shear, with little directional shear and effective-shear magnitudes
   generally less than 30 kt.  However, strong anvil-level flow will
   aid in ventilation aloft, and the most robust cells may offer
   marginally severe hail/gusts.  With convective potential extending
   northward into much of IA, the northern bound of the marginal risk
   area is, in reality, much fuzzier than the graphical line indicates,
   but already low-end severe potential still appears to diminish with
   northward extent into lesser magnitudes of cloud-layer shear and
   low-level theta-e.

   ...TX Big Bend/Trans Pecos...
   Isolated thunderstorms may develop this afternoon over this region
   south of the cold front, especially near higher terrain where
   diabatic heating will erode MLCINH preferentially.  Severe hail and
   strong to marginally severe gusts are possible from any sustained
   convection that can form, though convective coverage is in question.
   Low-level convergence will be maximized near the generally
   southward-moving surface low, and any associated convergence zone
   extending southward.

   The main uncertainty involves whether associated lift will be
   sufficient to form/maintain thunderstorms long enough to produce
   severe, in an environment characterized by steep low/middle-level
   lapse rates and adequate boundary-layer moisture.  Surface dew
   points in the mid 50s to low 60s F contribute to potential MLCAPE
   1500-2500 J/kg in modified model soundings.  In areas south to
   southeast of the low where an easterly surface wind component will
   enhance directional shear, 35-45 kt effective-shear magnitudes may
   be found.  Any severe threat in this region should be conditional
   and short-lived, decreasing markedly after dark.

   ..Edwards.. 06/12/2019

 

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Alex, I'll take outflow boundary for $400. Actually Knoxville does look at bit stable. Chattanooga might at least get a good Marginal thunderstorm later. 

Modest flow is aloft at SPC notes. LLJ may be a little veered off. 850 mb is forecast to veer off. 925 mb is trying but still SSW, and the surface will be from the SSE. Moisture might be the main question. Did I just write that in June?

Honestly, much as I like storms, I love low humidity in summer. Every day with low humidity is one less of (root canal without Novocaine) misery. 

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Marginal risk day 3.I'm starting to think the best chance of severe storms will come after this.Wed-Thursday. both the GFS and Euro are showing LP system going into the Mo Valley.This should in turn strenghten the LLJ.Both models though show this,right now anyways some sort of shortwave,trough, coming through the Valley during this time.Trying to pin point shortwaves though at his time would be kinda tough

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Yes a real short-wave is forecast midweek. Today (Monday) the Marginal held with modest flow aloft. Looks like little more flow is forecast Wednesday. NWP is mixed on how much turning. At least some bows and perhaps good shelfies should be on-deck for Wednesday. 

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Wed. June 19: Northern half of the MD has a watch out. Since the MD has more forecast information than the watch, and covers areas that could see storms later, I'll post the MD.

Mesoscale Discussion 1134
 
MD 1134 graphic
   Mesoscale Discussion 1134
   NWS Storm Prediction Center Norman OK
   1235 PM CDT Wed Jun 19 2019

   Areas affected...Parts of southeast Missouri...northeast
   Arkansas...western Tennessee and Kentucky...and adjacent portions of
   southern Indiana

   Concerning...Severe potential...Watch possible 

   Valid 191735Z - 191930Z

   Probability of Watch Issuance...60 percent

   SUMMARY...A further increase in thunderstorm intensity and
   organization appears possible through 3-5 PM CDT.  This may be
   accompanied by an increase in severe weather potential which could
   require a watch within the next couple of hours.

   DISCUSSION...An ongoing increase in thunderstorm development appears
   to be associated with a secondary band of large-scale ascent
   pivoting from the Ozark Plateau into the lower Ohio Valley, within
   the leading edge of larger-scale low-amplitude mid/upper troughing. 
   As this is occurring, inhibition for seasonably moist boundary layer
   parcels continues to weaken in response to insolation, with
   mixed-layer CAPE approaching 2000 J/kg.  At the same time, westerly
   deep-layer ambient mean fields and vertical shear are also beginning
   to increase, as a 40-50 kt 500 mb speed maximum gradually propagates
   eastward from the south central Plains.  

   Into mid to late afternoon, the environment across western into
   central (middle) Kentucky and Tennessee, and surrounding portions of
   the lower Ohio Valley, may become conducive to increasingly
   organized convection.  It is possible that this may include a few
   supercell structures, then perhaps one or two upscale growing
   clusters of storms accompanied primarily by a risk for potentially
   damaging wind gusts.

   ..Kerr/Guyer.. 06/19/2019
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That was the best storm we've seen here since the tornado a couple years ago.Some huge hail.I was picking my son up from gymnastics practice and my car was getting pounded,ran over a few lines,dodged some big branches.Few roads are blocked off i saw coming back home.Glad i left my radar on so i could capture the hail,but i have no clue how big it was,it wasn't over 3" for sure the radar estimated.We live right on the out-skirts of Nolensville,but basically it's still Brentwood,glad the power survived though.

kohx_20190620_0053_MEHS1.png

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Looks like a mature bow echo will be coming through overnight

URGENT - IMMEDIATE BROADCAST REQUESTED
   Severe Thunderstorm Watch Number 406
   NWS Storm Prediction Center Norman OK
   1020 PM CDT Wed Jun 19 2019

   The NWS Storm Prediction Center has issued a

   * Severe Thunderstorm Watch for portions of 
     Northern and central Alabama
     Northeastern Arkansas
     Central and northern Mississippi
     Southern middle and southwestern Tennessee

   * Effective this Wednesday night and Thursday morning from 1020
     PM until 600 AM CDT.

   * Primary threats include...
     Widespread damaging winds likely with isolated significant gusts
       to 80 mph possible
     Isolated large hail events to 1.5 inches in diameter possible
     A tornado or two possible

   SUMMARY...A well-organized cluster and separate bow echo initially
   over eastern Arkansas, each with a well-developed wind signature and
   history of severe gusts, will proceed into and across the watch
   area.  These systems could merge as well.  Severe thunderstorm wind
   will remain the main threat, though an embedded tornado or two also
   is possible.
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North Chattanooga and especially Hixson got it this morning (Thursday). Not bad for a sunrise special.

Friday and Saturday more MCSs may move through Tennessee and our Regional forum. Reservoir of impressive instability looks to camp out in the region along and south of outflow boundaries. WAA is forecast at 850/700 mb which would help maintain convection. Don't see any robust 500 mb waves so it should not get too crazy. In fact 500 mb heights are neutral or slightly rising both days. Still it is the season for southeast propagating MCSs.

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21 hours ago, jaxjagman said:

That was the best storm we've seen here since the tornado a couple years ago.Some huge hail.I was picking my son up from gymnastics practice and my car was getting pounded,ran over a few lines,dodged some big branches.Few roads are blocked off i saw coming back home.Glad i left my radar on so i could capture the hail,but i have no clue how big it was,it wasn't over 3" for sure the radar estimated.We live right on the out-skirts of Nolensville,but basically it's still Brentwood,glad the power survived though.

kohx_20190620_0053_MEHS1.png

Once the hail threat diminished some, that momentum really brought the wind to Smyrna, Walter Hill, and northern Murfreesboro. My folks took some tree damage and there were numerous snapped and uprooted trees near the Siegel schools and the VA Medical Center.

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