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Tn Valley Severe Weather


jaxjagman
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MRX rightly is/has been more concerned about flooding. SPC has caved, lol. OK seriously, they did not cave. Shorter Term data not available or reliable at Day 4 shows the problems with the set-up now as we move in to Day 2.

It's too damn warm at the mid-levels. Oh this wind field would be amazing with April or even March surface temps. Winds with height turn almost 45 deg. Usually Dixie has about 30 deg. Rooted supercells would spin up in a hurry, but...

CAPE is hard to come by. They talk about low-CAPE high shear events. This is almost NO CAPE. Looks like skinny cape above 700 mb and questionable if any below. Lack of low-level CAPE juxtaposed (vertically) with low-level turning is a deal breaker. 

So, I have zero interest in chasing. I'm not really even worried about severe at home. I will be peacefully relaxing and watching Kansas at West Virginia. Uh, actually I'll probably be barking at my TV, lol!  Actually the ESPN crooks put it on + which I boycott. OK, hope for severe!

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Seemingly,untill the NWS inspects it.Lawrence Co got its 2nd tornado in a week.The first one was a EF-1 that hit downtown Lawrenceburg,luckily that was during the evening or that could have been much worse.Last night one hit towards 5-points.Nashvilles radar seemingly went down as the line got close to us.More than likely as the squall line got to the office on Old Hickory Rd the radar went down for a short time,so there was no alert from this.Luckily no injuries that i'm aware of.

https://www.wkrn.com/news/local-news/ema-lawrence-county-hit-again-with-straight-line-winds-possible-tornado/

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13 hours ago, Holston_River_Rambler said:

You severe folks can correct me, but this looks to me like it has severe potential written all over it:

giphy.gif

Yeah i mentioned this last night in the winter thread with the through going through Korea,this is the time frame you are showing but we'll have to see how the synoptics work out upcoming

f68ab015-253d-4566-88e2-f28cdf0f7e6d.gif

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Not a great looking pattern upcoming,its still winter right now tho.Control looks about about like what the GFS looks like in the long range today

On 2/15/2020 at 4:54 AM, Holston_River_Rambler said:

You severe folks can correct me, but this looks to me like it has severe potential written all over it:

giphy.gif

You almost hit it,poor theta with some K-Index and some weak showalter could get some elevated thunder,still looks like a clippper like system behind it that will spit some flakes at us Wednesday,but it dont look as strong today

AccuWeather com® Professional - Forecast Models (6).png

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1 hour ago, Holston_River_Rambler said:

Overnight Euro OP looks pretty good for y'all in terms of its pattern. As is my custom, here is some random map that I don't quite understand, but since I'm still paying these people for access to their stuff, might as well use it for something. 

giphy.gif

Yeah i was just looking,convection down south would choke off the capesLow cape/high shear.Sure we'll see changes upcoming

AccuWeather com® Professional - Forecast Models (11).png

AccuWeather com® Professional - Forecast Models (12).png

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Its about the same date  the EF4 hit Alabama last year

 Day 4-8 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0155 AM CST Thu Feb 27 2020

   Valid 011200Z - 061200Z

   ...DISCUSSION...
   Medium-range guidance continues to come into better agreement
   regarding the eastward ejection of an upper trough/low from the
   Southwest and northern Mexico across the southern/central Plains
   from Day 4/Sunday through Day 6/Tuesday. Low-level moisture will
   continue to advect northward across the southern Plains and lower MS
   Valley in this time frame. The past several runs of the
   deterministic ECMWF have been relatively consistent in the timing
   and amplitude of the eastward ejection of the upper trough/low.

   The potential for substantial low-level moisture return across parts
   of east TX into the ArkLaMiss by Day 6/Tuesday has increased. Low
   and mid-level flow are also forecast to markedly strengthen across
   these areas, particularly Tuesday evening into early Wednesday
   morning. With strong forcing for ascent preceding the upper
   trough/low, a surface low should deepen as it develops northeastward
   from portions of east TX into the vicinity of the Mid-South. A
   trailing cold front should also shift eastward across TX into parts
   of the lower MS Valley by the end of the Day 6/Tuesday period (early
   Wednesday morning).

   A thermodynamic and kinematic parameter space favorable for the
   formation and maintenance of organized severe thunderstorms will
   probably exist over these areas from Tuesday evening though early
   Wednesday morning. Storms could form both along and ahead of the
   eastward-moving cold front, with all severe hazards possible.
   Therefore, a 15% severe delineation has been introduced for Day
   6/Tuesday. There is some uncertainty with how far east the threat
   will extend into MS late Tuesday night, and adjustments to this 15%
   area are likely.

   Uncertainty in the placement of both the upper trough/low and
   related surface low increases into Day 7/Wednesday. At least some
   severe threat may continue across parts of the Southeast (mainly
   AL/GA vicinity), but low-level moisture should gradually decrease
   with eastward extent. 15% severe probabilities may be needed in a
   later outlook issuance over parts of the Southeast on Day
   7/Wednesday once the synoptic-scale evolution becomes a bit clearer.

   ..Gleason.. 02/27/2020

CIPS Extended Analog Guidance (4).png

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Euro retains at least 30 degrees of turning from 850 to 500 mb, and some runs it's close to 45 degrees. Speed shear is pretty much a given. If that directional shear verifies (tendency to get more uni-directional toward the day) and holds it could be a significant severe weather episode. Probably mostly Deep South though, not really our region. At least south of I-40. 

I was supposed to give up storm chasing for Lent, to keep me out of early season junk. Hmm, what else?

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Euro retains at least 30 degrees of turning from 850 to 500 mb, and some runs it's close to 45 degrees. Speed shear is pretty much a given. If that directional shear verifies (tendency to get more uni-directional toward the day) and holds it could be a significant severe weather episode. Probably mostly Deep South though, not really our region. At least south of I-40. 
I was supposed to give up storm chasing for Lent, to keep me out of early season junk. Hmm, what else?

It’s really nice you follow severe this close so far out. Appreciate the updates.


.
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Super Tuesday severe setup is now hampered by sharp divergence between the progressive GFS and slower Euro. Truth may end up in between, but mostly toward the Euro.

As for north/south tracking, EC Op surface low is buried in the Deep South. However the vast majority of its EPS (Ensemble) members have surface lows farther north including the Midwest. That's more severe and more heavy rain here. 

No wind fields analysis since the whole thing is a cluster now. One can imagine the north members have better wind fields. South members are cool rain. 

Heck now we can't even pick out the day or the place. Tuesday Wednesday or Thursday anywhere from the Delta to the Carolinas; but, probably only one day where everything comes together for severe in just a couple states.

Flooding rain is a different story in a different thread.

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Long range has some interesting looks.The MJO seemingly is fixing to have destructive interference from Rossby and Kelvin waves but the MJO signal should still be moving eastward into the IOD tho it looks like it might be into the Maritime.Also you if you look into East Asia there could be a robust through coming through that part  or troughs later into March1890896589_TropicalMonitoringNorthCarolinaInstituteforClimateStudies(2).png.bc64eaf520ed08ff3ffaba480cb64c84.png

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Day 3 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0223 AM CST Sat Feb 29 2020

   Valid 021200Z - 031200Z

   ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS
   OF THE MID-SOUTH REGION...

   ...SUMMARY...
   Isolated severe thunderstorms are possible across portions of the
   Mid-South from Monday afternoon to early Tuesday morning.

   ...Synopsis...
   Strong upper low expected to be centered over southern CA early
   Monday morning is forecast to gradually shift southeastward
   throughout the day, eventually becoming centered over northwest
   Mexico by early Tuesday morning. Downstream of this low,
   southwesterly flow aloft is expected to expand eastward through the
   Mid MS Valley and Southeast, increasing in speed as the upper
   pattern becomes more confluent. 

   At the surface, a cold front will likely extend from a low near the
   central MO/IL border southwestward to another low over central OK on
   Monday morning. Overall frontal position will slowly sag
   southeastward, impeded by the persistent moist southerly flow south
   of the front. Continued moisture advection is forecast to bring low
   60s dewpoints through much of the Mid-South by Monday evening.
   Thunderstorms are anticipated along front from Monday evening into
   early Tuesday morning, with the highest coverage expected across
   northeast AR, northern MS, western/middle TN, and southwest KY.

   ...Mid-South...
   Moist return flow is expected to bring low 60s dewpoints into
   northeast AR/western TN ahead of the approaching cold front. This
   low-level moisture coupled with steep mid-level lapse rates will
   result in modest instability amidst low convective inhibition.
   Strong westerly flow aloft will also be in place, contributing to
   strong vertical shear (i.e. 0-6 km bulk shear around 50-60 kt). The
   result will be an environment supportive of rotating thunderstorms
   if storms can develop and persist. 

   Large-scale forcing for ascent will be largely negligible but the
   surface low initial over central OK is expected to move
   northeastward along the front, likely providing the mesoscale ascent
   needed for convective initiation. Primary threat with these storms
   will be damaging wind gusts and hail but there will likely be enough
   low-level shear for a low probability threat of tornadoes.

   ..Mosier.. 02/29/2020
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Least there is a chance of some strong storms.The heavy rains the models were advertising has shifted even further south today thanks to the cut-off H5 out west which today basically don't get kicked out until Tuesday per Euro.Should be at least of a chance for the west,this is where the best instability is showing right now

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Seems like the next few days Kelvin waves will go through East Asia.Could see a coupe troughs going through this area in the long range.MJO signal looks weak into the long range,if the CFS is right there might even be a Kelvin or Equatorial Kelvin wave that should excite the subtropical jet.ERTAF has started up again and shows the same thing into week 2 of March

Tropical Monitoring    North Carolina Institute for Climate Studies (3).png

Tropical Monitoring    North Carolina Institute for Climate Studies (4).png

_1

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If we can get anything to pop during this time,could see some big baseballs tossed at above.PW's look mehish until any cap breaks like said above,looks more into the evening to  early morning  in our parts after the cap breaks,any strong updraft you might want to make sure your vehicle is covered up ..:thumbsdown: Of course this can change,plus a tornado and wind risk with any severe

 

Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1202 AM CST Mon Mar 02 2020

   Valid 021200Z - 031200Z

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM NORTHEAST
   ARKANSAS EASTWARD ACROSS THE TENNESSEE VALLEY AREA...

   ...SUMMARY...
   Isolated severe thunderstorms are possible from portions of the
   Mid-South region southwestward across parts of northeastern Texas 
   Monday afternoon through early Tuesday morning.

   ...Synopsis...
   As northern-stream upper troughing expands/shifts gradually eastward
   across central and eastern Canada and the north-central U.S., an
   upper low initially off the southern California coast is progged to
   turn eastward with time, reaching northwestern Mexico later in the
   period.  Meanwhile, fast/low-amplitude westerly to
   west-southwesterly flow will prevail over the south-central and
   southeastern portions of the country.

   At the surface, a cold front initially stretching from the Upper
   Great Lakes region southwestward to western Texas will advance
   eastward with time, reaching a position from New England to
   southeast Texas by the end of the period.  This front will focus a
   zone of convection from parts of the Ohio and Tennessee valleys into
   northeastern Texas from this afternoon into the overnight hours.

   ...Mid South region southwestward across northeastern Texas...
   As the cold front advances gradually southeastward across
   Kentucky/Tennessee/Arkansas/northeastern Texas through the day, an
   initial area of warm-advection-induced storms will spread eastward
   through the Mid South region.  In its wake, weak destabilization is
   expected ahead of the front, though capping will hinder new storm
   development into the afternoon hours.

   Substantial model differences exist with respect to the degree of
   cap erosion, with HRRR and NAM forecasts the most aggressive models
   with elimination of capping by late afternoon, resulting in an
   uncapped/amply unstable environment.  Given favorable shear across
   the region, this thermodynamic evolution would support at least
   isolated supercell storms, and attendant severe risk -- particularly
   in the form of hail.  Other/isolated storms are more consistently
   forecast by the models southwestward across Arkansas and northern
   Louisiana and portions of northeastern Texas.

   Based on the consistently more bullish output from NAM/HRRR runs, an
   upgrade to slight risk appears reasonable.  Primary risk appears to
   be hail, but locally damaging winds and even a couple of tornadoes
   would be possible should capping erode to the degree depicted in
   some guidance.  Primary risk appears to exist across the western
   Tennessee vicinity in roughly the 23 to 04Z time frame.  Marginal
   risk is also being extended as far southwestward as northeast Texas,
   where a few stronger storms appear likely to initiate during the
   afternoon.

   ..Goss/Nauslar.. 03/02/2020

 

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ERTAF has begun! Cue up, It's the Most Wonderful Time of Year! Agree with them though, it looks benign for a while. Just as well until after the Final Four.

Japan satellite shows the two Kelvin waves (MJO pulses) well. Also got a trough trying to dig into central China. Probably get a ton of MJO interference though.

Though both sets of weekly forecasts appear on fire with the West trough, devil is in the details. Soft underbelly Deep South hints split flow chaos. 

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