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Tn Valley Severe Weather


jaxjagman
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Obviously everyone knows Ryan Hall but I’ve paid good attention to his experimental tornado forecasts on twitter. Typically his forecasts are more aggressive than the SPC but I feel like he verifies well. Yesterday his forecast was much more aggressive than SPC and his outlook called a 15% props in ETn north of 40 into SE Kentucky while the SPC went 2%. Here’s his Twitter link if anyone is interested.




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I think I follow Nadocast. It can get carried away, but it also gets things like Plateau magic. Can I say magic? Nobody got hurt. I did not know Ryan runs it though, haha! Just another tool either way.

Thanks @John1122 for the reports Sunday. Glad you and yours are well. Nice pics @PowellVolz and @Holston_River_Rambler showing up the Mid-South with action in scenic East Tenn.

I'm fairly confident the Cumberland Plateau over-achieves with tornadoes because it's elevated, which gets it greater low-level inflow. Wind typically increases with height. With the exception of a few areas of (scenic) bonus relief the Plateau is relatively flat compared to say the Mountains. I believe Alabama's Sand Mountain (more a plateau) gets the same effect. Areas of upslope likely play a role too. Any of the above increases local storm relative helicity SRH / low level shear LLS.

Main reason chasers pick boundaries is due to greater SRH and LLS. Terrain does the same thing. High Plains chasers love terrain plays like the Palmer Divide and Raton Mesa, which also increase SRH/LLS. Palmer is also associated with the Denver Cyclone DCVZ. I'm not sure the Cumberland Plateau has anything like the DCVZ, but I believe the Plateau gets greater SRH/LLS. Combine boundary with terrain, and odds increase. If a boundary is over the Plateau, it may go!

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I think I follow Nadocast. It can get carried away, but it also gets things like Plateau magic. Can I say magic? Nobody got hurt. I did not know Ryan runs it though, haha! Just another tool either way.
Thanks [mention=499]John1122[/mention] for the reports Sunday. Glad you and yours are well. Nice pics [mention=14393]PowellVolz[/mention] and [mention=16126]Holston_River_Rambler[/mention] showing up the Mid-South with action in scenic East Tenn.
I'm fairly confident the Cumberland Plateau over-achieves with tornadoes because it's elevated, which gets it greater low-level inflow. Wind typically increases with height. With the exception of a few areas of (scenic) bonus relief the Plateau is relatively flat compared to say the Mountains. I believe Alabama's Sand Mountain (more a plateau) gets the same effect. Areas of upslope likely play a role too. Any of the above increases local storm relative helicity SRH / low level shear LLS.

Main reason chasers pick boundaries is due to greater SRH and LLS. Terrain does the same thing. High Plains chasers love terrain plays like the Palmer Divide and Raton Mesa, which also increase SRH/LLS. Palmer is also associated with the Denver Cyclone DCVZ. I'm not sure the Cumberland Plateau has anything like the DCVZ, but I believe the Plateau gets greater SRH/LLS. Combine boundary with terrain, and odds increase. If a boundary is over the Plateau, it may go!

Just to clarify… I can’t say 100% it’s “tornado forecast” but he promotes it like it’s his.


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WBIR has video of two...one near Crossville and another in Fentress.  Just looking at those, we were very fortunate not to see worse outcomes. 
 
https://www.wbir.com/article/weather/severe-weather/severe-storms-damage-tornado-tennessee/51-f6c76c20-cfa9-4a47-9f86-32fcae2e9108

I’m kinda surprised the Fentress Co tornado was just a EF1 considering how the CC drop looked. Obviously that area isn’t the greatest for radar coverage but I thought we might have a significant tornado on the ground at one point. Even after the tornado lifted, you could see the debris fan out to the NE in the cell.



f896644f9868bac8a8e40c32c6e44d3d.jpg


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MD #1035 for central Alabama Storm Prediction Center Mesoscale Discussion 1035 (noaa.gov) kind of leaves the door open for a couple rotating storms. I would say the southern outflow boundary (green) has the most locally enhanced SRH. Northern OFB (yellow) has less direct access to the LLJ. Southern OFB also has better wind barb kinks. I used surface chart wind barbs and dewpoints along with visible satellite to place those outflow boundaries. 

image.png.04cfc4df972f59c14053e2c62e15a373.png

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Monday the cells had slight rotation due lingering winds turning with height. Fortunately the turning was not enough, and the speed shear was weaker than on Sunday. I was doing time-lapse towering Cu just for fun near Chattanooga, and discerned some turn but only with the speed-up. It was weak, but still fun to time-lapse.

This picture is actually on Tuesday. If you know the area, I was at the I-75 interchange with East Brainerd Rd. Bargain Hut parking lot offers a little perch for viewing, if one does not mind the power lines. The view is not nearly as far and wide as from US Express, but BH was on my way already.

I was not chasing, but yeah I stopped for the tail-cloud like feature. No rotation was observed, at least not in real-time. Due to time constraints, I could not do a suitable time-lapse. Too cool for severe and the heavy shower didn't have lightning either.

20230620_Bargain-Hut.thumb.jpg.2327725cb4c4321afb8aab6fb415a49b.jpg

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Should have a chance for some strong storms Sunday into the evening,Lower levels look crappish  right now with the LP heading towards the lakes,but still a good chance for a good light show,wind and possibly hail here somewhere..Probably best to see what the models show tomorrow

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@PowellVolz, you are getting credit for this (VQ post).  Jax you mentioned this yesterday.  Decently strong signal for severe wx tomorrow into Monday(looks like night time).  This just came out this afternoon.  Jax and Jeff, feel free to add content.  I am just posting the graphic.  I hate hail - especially very large hail.  After 25K in damage several years ago(new roof, two cars mashed up), I want no part of that.  May look at putting some cars in the parking garage if this is legit.

Screen_Shot_2023-06-24_at_5.39.02_PM.png

 

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I had a new roof out on not to long ago. Would hate for hail to damage the roof, vehicles & plants.  The freeze in December was bad enough in doing damage to nature.  Expensive fall already coming for me to replace many shrubs & trees.  I would rather not add roof or vehicles to that list. 

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Cams keep showing a potential MCS later on around Ark/Mid South.Earlier models showed more rain here  but that never happened or is going to seemingly.Best chance for strong stroms here seems like early evening but there is a cap at the start seemingly but the 3capes are on the rise, dunno.This  system is more in Jeffs league,looks complex to me.Might be best to wait and see the afternoon model runs.

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Looking at SPC's latest guidance, it appears middle TN is going to be spared the worst of the action. Straight-line winds may be an issue but the large hail/tornado risk will stay to our north apparently. At this time yesterday, northern middle looked like it was more under the gun.

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467
ACUS11 KWNS 251531
SWOMCD
SPC MCD 251530
TNZ000-NCZ000-VAZ000-KYZ000-251730-

Mesoscale Discussion 1251
NWS Storm Prediction Center Norman OK
1030 AM CDT Sun Jun 25 2023

Areas affected...Portions of far southern KY...middle/eastern
TN...western NC...and extreme southwestern VA

Concerning...Severe potential...Watch possible

Valid 251530Z - 251730Z

Probability of Watch Issuance...40 percent

SUMMARY...The threat for scattered damaging winds may gradually
increase over the next couple of hours. Watch issuance is possible.

DISCUSSION...A small cluster of convection is ongoing late this
morning across parts of south-central KY into middle TN. This
activity is loosely tied to thunderstorms that occurred overnight
and early this morning across the Upper Midwest. Well-below-severe
wind gusts have been observed at various ASOS and KY Mesonet sites
over the past hour or so, suggesting that the stronger velocities
noted on area radars are not yet reaching the surface. The 12Z
observed sounding from BNA shows a rich low-level airmass already in
place across middle TN, with mid 60s surface dewpoints and 14 g/kg
mean mixing ratio. A similar boundary-layer moisture profile will
also exist across eastern TN and vicinity, downstream of the ongoing
thunderstorms.

As daytime heating warms surface temperatures into the 80s across
this area over the next couple of hours, destabilization and erosion
of lingering MLCIN should quickly occur. MLCAPE exceeding 1000-1500
J/kg seems increasingly likely by 17Z, and convection may become
surface based by early afternoon. Although details regarding
convective evolution remain uncertain, there appears to be some
potential for ongoing thunderstorms to consolidate into a loosely
organized cluster while spreading east-southeastward across eastern
TN and vicinity this afternoon. A veering boundary-layer wind
profile observed on recent KOHX VWPs, and westerly winds
strengthening with height through mid levels, will foster around
25-35 kt of deep-layer shear, aiding in some convective
organization. Steepening low-level lapse rates ahead of the possible
cluster should allow for a more efficient transfer of strong/gusty
winds with downdrafts to the surface with time. Scattered damaging
winds may become an increasing concern through the early afternoon,
and isolated severe hail may occur with any supercell that can
form/persist on the southwest flank of the cluster. While not
immediately likely, observational trends will be monitored for
possible watch issuance by early afternoon.

..Gleason/Grams.. 06/25/2023

...Please see www.spc.noaa.gov for graphic product...

ATTN...WFO...GSP...MRX...JKL...LMK...OHX...

LAT...LON 35038500 35188572 35738629 36348604 36858546 36968483
36888375 36718292 36468239 36178215 35778226 35458252
35168292 34998370 35038500

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3 hours ago, *Flash* said:

Looking at SPC's latest guidance, it appears middle TN is going to be spared the worst of the action. Straight-line winds may be an issue but the large hail/tornado risk will stay to our north apparently. At this time yesterday, northern middle looked like it was more under the gun.

Yeah SPC FINALLY put a 10 % tornado into Kentucky,i might have went more south into KY,i'm not sure what is still going to happen here,still seems like a cap will be in place into the early evening,same as into Ky but they still have much better 3capes that should over ride that cap into the evening

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14 minutes ago, Matthew70 said:

Looking like I24 East will get todays rain & storms. 

17z HRRR is a hair west of 16z with the precip shield. We'll see if the primary axis is I-24 east or along I-24 and east. At this point, I'll gladly take some wattery severe storm or no severe storm. 

https://www.pivotalweather.com/model.php?m=hrrr&p=ref1km_ptype&rh=2023062517&fh=13&r=us_ov&dpdt=&mc=

Screenshot 2023-06-25 at 1.46.07 PM.png

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