Tn Valley Severe Weather

[jaxjagman]

Best thunderstorm in awhile here in Brentwood right now.Even dropping some pea sized hail

[Matthew70]

1 hour ago, jaxjagman said:

Best thunderstorm in awhile here in Brentwood right now.Even dropping some pea sized hail

Yes here in Boro was the same. Been awhile it seems with some good lighting.  The flash flooding is also impressive. 

[PowellVolz]

A lot more rain today than expected. Almost 2” in Knoxville. On the bright side this should end any fire threats left in the mountains


.

[PowellVolz]

...Mid-MS/lower OH river valleys...
Thunderstorms are expected to develop along the cold front by the mid morning hours across parts of southern MO/northern AR. Mean storm motions along the front will favor a quick transition from quasi-discrete cells to more linear storm modes. Convection will continue to grow upscale as it approaches the mid-MS river valley amid increasing low-level moisture and daytime heating. Increasing low-level flow (up to 50-60 knots between 925-850 mb) will likely support bowing segments and the potential for widespread damaging winds. The potential for multiple 65+ knot wind reports and/or significant wind damage support an upgrade to a wind-driven Moderate risk for portions of the mid-MS/lower-OH river valleys. Elongated 0-3 km hodographs ahead of the line will also support embedded circulations. The warm advection regime and broad scale ascent ahead of the line may support a few more discrete cells across the lower OH river valley by mid to late afternoon. This potential may be conditional on the degree of destabilization that can occur behind early-morning rain/weak thunderstorms that should exit the region by early afternoon. However, if discrete convection can become established, all hazards will be possible, including the potential for large hail and strong tornadoes.

...Lower MS river valley...
The surface cold front will likely lag to the west across the Texarkana/lower MS valley regions, but this will allow for several hours of daytime heating between cloud breaks and continued boundary-layer moistening amid low-level theta-e advection. With 7-8 C/km mid-level lapse rates atop a deep, moist boundary layer will likely support upwards of 1500-2500 J/kg MLCAPE by late afternoon. Glancing upper-level ascent from the synoptic wave to the north combined with isentropic ascent and lift along any confluence axes and/or lingering outflow boundaries from overnight convection, should be sufficient for isolated to scattered thunderstorms by mid to late afternoon. Adequate deep-layer shear and strong flow in the 0-3 km layer will be favorable for supercells with all severe hazards possible. Some solutions hint at forecast ESRH values between 300-400 m2/s2, which will support the potential for strong tornadoes. The signal for isolated convection is notable in recent CAM solutions and in ensemble guidance, warranting an upgrade to a Moderate risk where the tornado potential is highest


.

[nrgjeff]

Most of that Moderate is wind driven. However the southern quarter of the MDT is 15% tornado, which straddles the Arkansas and Mississippi border. 

Pre-frontal trough is quite likely along that AR/MS state line, and eventually moving into Mississippi. Outflow from morning rain and/or the usual Alabama boundary will intersect the prefrontal trough. That intersection is ahead of (southeast of) the synoptic triple point (TP). 

Synoptic cold front may have a line of storms as SPC says, and the TP a cluster near the warm front. However the pre-frontal trough and OFB intersection farther south could feature discrete supercells if enough local SRH storm relative helicity. 

Chart looks like a reasonable initiation of any tornadic cells. Could lumber farther east into Mississippi later. Alabama has lower forecast CAPE - but could get some straight winds Wed. night.

Wed. Apr. 13 TOR probs.

[Silas Lang]

Today we had the most rain in a while in Knoxville. Also, the best thunder and lightning of the season this far. Saw a few huge bolts this morning. Think one struck very close to work. 

Last few storm threats have been mostly wind here, so it was a nice change of pace. 

[Daniel Boone]

1 hour ago, Silas Lang said:

Today we had the most rain in a while in Knoxville. Also, the best thunder and lightning of the season this far. Saw a few huge bolts this morning. Think one struck very close to work. 

Last few storm threats have been mostly wind here, so it was a nice change of pace. 

Only managed 0.14" here as most of the rain went to our south. What was moving toward us disipated.

[John1122]

1 minute ago, Daniel Boone said:

Only managed 0.14" here as most of the rain went to our south. What was moving toward us disipated.

That's crazy. It rained 1.9 inches here. I hoped everyone to the East got soaked. 

[Daniel Boone]

1 hour ago, John1122 said:

That's crazy. It rained 1.9 inches here. I hoped everyone to the East got soaked. 

Yeah, really disappointing for sure. Water levels are getting low.

[nrgjeff]

Wednesday April 13: My target area has shifted, though I do not plan a real chase. Virtual target is north of my previous post last night. Dyersburg, esp the flatter area west of is my target. Lunch in Dyersburg would have been nice!

Mississippi dewpoints are under-achieving, not a shock given MCS. Also 800mb is warm on most soundings and fcst soundings (between standard constant press level charts). That means Miss has to work even harder to recover surface T/Td. Yes it'll hit 80 deg. However it might not be enough.

Meanwhile outflow boundary OFB lifts north into northwest Tenn. 800mb will cool sooner there. Temps and Dews will almost match Mississippi. In fact dews could recover better, circumnavigating the mixed air over Miss.

Dotted green is edge of the more pronounced lower T/Td. Yellow line is the chaser's OFB. It is forecast to lift into the red position by late afternoon. Prefrontal trough is not drawn, but I expect the red OFB to intersect it in northwest Tenn. Hence chase target. 

1KM SHR below satellite, numerical models NWP shows my conceptual model. However NWP could misplace the OFB. NWP has robust cells on its intersection with the pre-frontal trough. Chaser would follow the boundary, not the NWP. Just good to see the conceptual model confirmed. 

[yoda]

Tornado Watch coming shortly

Mesoscale Discussion 0476
   NWS Storm Prediction Center Norman OK
   1232 PM CDT Wed Apr 13 2022

   Areas affected...Portions of the Lower Ohio Valley and
   Mid-Mississippi Valley.

   Concerning...Severe potential...Tornado Watch likely 

   Valid 131732Z - 131930Z

   Probability of Watch Issuance...80 percent

   SUMMARY...Rapid destabilization is expected across portions of the
   Ohio and Mid-Mississippi Valley

   DISCUSSION...A stable airmass is currently in place across the lower
   Ohio Valley and mid-Mississippi Valley in the wake of a morning MCV.
   However, low-level moisture is expected to improve significantly
   over the next several hours. The leading edge of richer Gulf
   moisture can now be seen on visible satellite where the cu field is
   expanding north across Mississippi and western Alabama.
   Extrapolating northward movement of this better moisture and
   northeastward movement of ongoing thunderstorm activities, it
   appears better low-level moisture will arrive prior to the
   convective line east of the Mississippi River and possibly slightly
   west. Expect this better moisture to reach the Missouri bootheel
   around 19-20Z, southern Illinois 20-21Z and southern Indiana around
   22Z. MLCAPE is expected to increase to the 1000 to 2000 J/kg range
   ahead of these storms which should be sufficiently unstable to not
   only support a significant severe weather threat with the squall
   line, but also potentially allow for some more discrete convection
   to develop ahead of the line. In addition, surface winds are
   expected to back across the warm sector as the upper-level trough
   advances northeastward. Therefore, significant elongation of the
   low-level hodographs is anticipated. Therefore, all severe weather
   hazards are expected this afternoon/evening including the potential
   for 75+ mph wind gusts and a couple of strong (EF2+) tornadoes. A
   tornado watch will likely be issued in the next 1 to 2 hours.

   ..Bentley/Thompson.. 04/13/2022

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

   ATTN...WFO...LMK...OHX...IND...PAH...ILX...MEG...LZK...

[yoda]

 

[nrgjeff]

There is the MD for which I'm waiting. If the SPC and I draw the same boundary and forecast, is that a good sign or a bad sign?

At any rate instability and low level turning with height will increase markedly when it all comes together West Kentucky and northwest Tenn. Any discrete cell(s) will ingest it all.

However that whole MD may get whacked by wind too. MEM south is at risk for QLCS tornadoes.

[SmokeEater]

80/50, tor probs in the watch for TN and N MS just issued.

Sent from my SM-S901U using Tapatalk

[yoda]

URGENT - IMMEDIATE BROADCAST REQUESTED
   Tornado Watch Number 122
   NWS Storm Prediction Center Norman OK
   135 PM CDT Wed Apr 13 2022

   The NWS Storm Prediction Center has issued a

   * Tornado Watch for portions of 
     Eastern Arkansas
     The Missouri Bootheel
     Northern Mississippi
     Western Tennessee

   * Effective this Wednesday afternoon and evening from 135 PM
     until 900 PM CDT.

   * Primary threats include...
     Several tornadoes likely with a couple intense tornadoes
       possible
     Widespread damaging winds and isolated significant gusts to 75
       mph likely
     Scattered large hail and isolated very large hail events to 2
       inches in diameter possible

   SUMMARY...A broken band of storms in Arkansas will continue to
   spread eastward toward northern Mississippi and western Tennessee
   through the afternoon/evening, with isolated supercell development
   possible ahead of the ongoing Arkansas storms.  A mix of
   clusters/line segments and supercells support all severe hazards,
   including the potential for a couple of strong tornadoes, corridors
   of damaging winds to 75 mph, and isolated large hail.

   The tornado watch area is approximately along and 85 statute miles
   east and west of a line from 35 miles north of Dyersburg TN to 50
   miles southwest of Oxford MS. For a complete depiction of the watch
   see the associated watch outline update (WOUS64 KWNS WOU2).

[yoda]

[SmokeEater]

Something better change fast for any of this to verify, looks grungy as heck right now.

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[mob1]

I thought we had the first two confirmed tornadoes till I remembered that Memphis words all their warnings as "tornado producing storm". Either way, looks like the current line has some decent embedded rotation, though nothing even remotely discrete for now. 

[yoda]

1 hour ago, SmokeEater said:

Something better change fast for any of this to verify, looks grungy as heck right now.

Sent from my SM-S901U using Tapatalk
 

The new MCD I think explains why -- at least down in MS and LA

https://www.spc.noaa.gov/products/md/md0482.html

 Mesoscale Discussion 0482
   NWS Storm Prediction Center Norman OK
   0336 PM CDT Wed Apr 13 2022

   Areas affected...portions of central/northern LA into
   southern/central MS

   Concerning...Tornado Watch 123...

   Valid 132036Z - 132200Z

   The severe weather threat for Tornado Watch 123 continues.

   SUMMARY...Convection is slowly increasing in coverage and intensity.
   Should semi-discrete cells ahead of the cold front become better
   organized, the tornado threat will increase over the next 1-3 hours.

   DISCUSSION...Convection continues to increase across
   northern/central LA this afternoon. An additional band of convection
   is also noted along a weak low-level confluence band from near HEZ
   in MS to BTR in LA. Moderate instability resides across the region
   where upper 60s to low 70s surface dewpoints are in place.
   Convection has still been struggling to organized, despite effective
   shear magnitudes greater than 40 kt and sufficient large-scale
   ascent. Of note in visible satellite loops is that while storm
   motion is toward the northeast, the anvils attached to stronger
   storms have been spreading east or even southeast. This is
   consistent with forecast hodographs showing backed midlevel winds,
   and as a result, some cooling within (from anvil shadow), and
   precipitation into storm inflow, may be occurring, ultimately
   causing issues for storm organization.

   With time, RAP forecast hodographs across parts of northern LA into
   central MS improve and would allow convection to become better
   organized and updrafts to remain sustained over a longer time period
   within the favorable thermodynamic environment. If this occurs, any
   discrete convection would see an increase in tornado potential, with
   perhaps a strong tornado or two occurring over the next 1-3 hours.
   Otherwise, convection further west should consolidate near the cold
   front into early evening with an attendant risk for damaging gusts
   and QLCS tornadoes.

   ..Leitman.. 04/13/2022

[SmokeEater]

TW Jackson, MS, rotating wall cloud over the city.

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[Witness Protection Program]

Man, Murfreesboro may be Nashville's biggest tornado magnet.

[John1122]

Hopefully, if that's on the ground, it misses Jax. 

[Wintersnow888]

Leading edge just came through 

[Matthew70]

Here is Boro just some wind damage reports.  I believe Jax is in Williamson which had a lot of wind damage reports also.  The tornado warning went right over my house.  Fortunately just insane winds.  Most intense since moved here in 2005.  
The pic below has a video also. Still figuring out how to copy paste link.   That vehicle is totaled after that lightning strike.  Circuits & boards fried. 

https://twitter.com/RiskeChris/status/1514388956040867846?s=20&t=GsIQwKJ27GuN6t80O-EWgQ

[John1122]

Strong winds and heavy rain here. It lost its steam right as it got to the Plateau. 

[nrgjeff]

Thanks Yoda. Also I think the warm sector never fully recharged from the morning MCS despite many hours. Dews did not recover as well as temps.

A little veer-back could be overcome if the low-level CAPE was not so low (narrow on sounding). Dews below 65 made it harder for rising air parcels to overcome a warm layer about 800 mb. Said layer was also dry enough to promote the evaporative cooling SPC mentions. Rain falling through it exacerbated the situation (for the storm) but it was a blessing for the Public. Not a tornado day after all. Plenty of straight line wind though. As one would expect if evaporative cooling gets a cool pool going with a big squall line. Convective models got the QLCS.

Separately @Matthew70 that picture is incredible. Were they OK in the car? Faraday cage hopefully protected the people, even if all the electronics are shot. What to tell the insurance company? Struck by lightning NOT storm chasing - just going to the store in a non-severe thundershower, ha!

On 4/13/2022 at 4:48 PM, yoda said:

The new MCD I think explains why -- at least down in MS and LA

https://www.spc.noaa.gov/products/md/md0482.html

 Mesoscale Discussion 0482
   NWS Storm Prediction Center Norman OK
   0336 PM CDT Wed Apr 13 2022

   DISCUSSION...Convection continues to increase across
   northern/central LA this afternoon. An additional band of convection
   is also noted along a weak low-level confluence band from near HEZ
   in MS to BTR in LA. Moderate instability resides across the region
   where upper 60s to low 70s surface dewpoints are in place.
   Convection has still been struggling to organized, despite effective
   shear magnitudes greater than 40 kt and sufficient large-scale
   ascent. Of note in visible satellite loops is that while storm
   motion is toward the northeast, the anvils attached to stronger
   storms have been spreading east or even southeast. This is
   consistent with forecast hodographs showing backed midlevel winds,
   and as a result, some cooling within (from anvil shadow), and
   precipitation into storm inflow, may be occurring, ultimately
   causing issues for storm organization.

   ..Leitman.. 04/13/2022

 

[jaxjagman]

On 4/13/2022 at 10:51 PM, Matthew70 said:

Here is Boro just some wind damage reports.  I believe Jax is in Williamson which had a lot of wind damage reports also.  The tornado warning went right over my house.  Fortunately just insane winds.  Most intense since moved here in 2005.  
The pic below has a video also. Still figuring out how to copy paste link.   That vehicle is totaled after that lightning strike.  Circuits & boards fried. 

https://twitter.com/RiskeChris/status/1514388956040867846?s=20&t=GsIQwKJ27GuN6t80O-EWgQ

Make sure you are signed into twiiter then right click and hit the copy video URL

[Dsty2001]

Thor was very angry with that car

[nrgjeff]

Happy Easter forecast. SPC has a slight risk Deep South. Lean South is prudent since outflow boundaries tend to reinforce south with repeating waves of convection, as has happened and is forecast Friday night through Sunday. ARWs (NSSL) and HRRR are in line south.

NAM version opens the door a little farther north into central Mississippi on Sunday, with a little less morning rain and/or it departing sooner. FV3 also has less morning rain and some storms North Mississippi later, but that should be elevated given the boundary position.

12Z Sat. NAM low-level EHI (blend of SRH and CAPE) valid Sunday afternoon is below. Boundary tries to lift north (green central Miss.) however, best CAPE (orange) is south. NAM is struggling to juxtapose CAPE and shear, but it's close. 

Sunday will all depend on morning rain (shocker I know) but even more than usual. LLJ cranks in the afternoon; however, it does not line up with far south boundary (LLJ veered south). If the said boundary lifts north enough it'll line up (LLJ backed north). Mississippi and Alabama issue only. 

[dwagner88]

Lots of ill-timed thunder last night while I was supposed to be resting up for an important licensing exam this AM. That was really great.