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Tn Valley Severe Weather


jaxjagman
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Ended up with around 2” but the big hailer that moved through Roan Co to W Knoxville fell apart around interstate 75 just 5 miles to my west or I would have been pushing 3-4”. One of my wife’s FB friends from Kingston area showed a picture of hail bigger than golf ball.


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Late spring La Nina things...

On 5/7/2022 at 1:10 AM, dwagner88 said:

Incredible. It hasn’t rained in nearly a month here. I had enough wind to knock out my power and strip some siding off my neighbors house, but zero rainfall. 

KCHA airport reported wind gusts to the 50s but I forgot the exact reading. Twas a good storm. Chattanooga had established an inverted V sounding, as dews mixed out, which promoted the strong straight line winds.

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  • 2 weeks later...
Hazardous Weather Outlook
National Weather Service Morristown TN
302 AM EDT Thu May 19 2022

NCZ060-061-TNZ012>018-035>047-067>074-081>087-098>102-VAZ001-002-
005-006-008-200715-
Cherokee-Clay-Scott TN-Campbell-Claiborne-Hancock-Hawkins-
Sullivan-Johnson-Morgan-Anderson-Union-Grainger-Hamblen-
Northwest Cocke-Cocke Smoky Mountains-Northwest Greene-
Southeast Greene-Washington TN-Unicoi-Northwest Carter-
Southeast Carter-Roane-Loudon-Knox-Jefferson-Northwest Blount-
Blount Smoky Mountains-North Sevier-Sevier Smoky Mountains-
Sequatchie-Bledsoe-Rhea-Meigs-McMinn-Northwest Monroe-
Southeast Monroe-Marion-Hamilton-Bradley-West Polk-East Polk-Lee-
Wise-Scott VA-Russell-Washington VA-
302 AM EDT Thu May 19 2022 /202 AM CDT Thu May 19 2022/

This Hazardous Weather Outlook is for portions of southwest North
Carolina...east Tennessee and southwest Virginia.

.DAY ONE...Today and Tonight

A round of showers and thunderstorms is expected this afternoon
into tonight. The primary threat will be strong straight line
winds and large hail. If multiple storms move over the same area
it could lead to isolated flooding of low lying areas.

.DAYS TWO THROUGH SEVEN...Friday through Wednesday

No hazardous weather is expected at this time.

.SPOTTER INFORMATION STATEMENT...

Spotter activation may be needed this afternoon and evening.
Please relay any information about severe weather to the NWS while
following local, state, and CDC guidelines.

$$
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Attention then turns towards this afternoon and evening as
additional convection is expected to redevelop within the warm and
humid atmosphere. Temperatures are expected to climb into the 80`s
across the area, and dew points will peak in the upper 60`s. This
means there will be plenty of moisture for storms to feed off of in
the afternoon if convection can get started. Today is a bit
different than yesterday`s convection as there isn`t really a
significant source of synoptic level forcing to initiate storm
development, so determining location and timing of storms is a bit
more difficult. Water vapor imagery shows a bit of a moisture
boundary from southern Illinois down to northeast TN/southwest VA.
This could axis could be one of the forcing mechanisms for storm
initiation, especially south of this boundary...In addition to any
outflow boundaries left over from the overnight convection moving
out of eastern Kentucky. At this point the expect storms to
redevelop in the afternoon hours with the strongest solar heating
taking place. Forecast soundings and mesoanalysis continue to show
ample surface based CAPE of up to 4,000 J/kg in the most aggressive
models, and steep mid level lapse rates of over 7-8.5 C/km. Luckily
the deep layer shear looks fairly weak, and is mostly uni-
directional across our area, which will hopefully limit (but not
totally eliminate) tornadic development. An additional surge of
storms could move into the area after sunset from stronger storm
development over western Kentucky, but still some uncertainty if
this will move more into WV or VA.

The main threats with storms this afternoon and evening will be
Large hail possibly up the size of ping pong balls, and strong
straight line winds in excess of 70 mph. In addition storms training
over the same location could cause isolated flooding of low lying
and poor drainage areas, and an isolated tornado cannot be ruled out
at this point.

Storms will eventually come to an end after sunset and loss of solar
energy. Fog will be possible overnight as skies slowly clear out,
mainly in areas that receive rainfall from the afternoon storms.
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Boundary is sharpening up on the TN/KY border and drifting north into KY. ARWs were a disaster with the false washout in East Tenn. HRRR and NAM sniffed out the north bias. FV3 was in between - but still wrong!

At any rate, action might start from MO to IL before rolling into Kentucky (our Region). Could get going as a nice QLCS. Any sups ahead would offer more rotation risk - esp riding the boundary.

Purple dots is MCV aloft. Red line is surface WF / wind shift boundary. Higher dews south are marked by deeper Cu field. However I expect the severe weather mainly Kentucky. Maybe drop into TRI later, but weaker by evening.

image.png.57dfeb3092ecbf432be411e3ade92f6f.png

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Large hail recorded throughout central and western Lee County last night and this afternoon. Dime size at my home east of Jonesville. Ping pong/ golf ball size Jonesville proper south and west. Trees were downed last night just west of Jonesville. 

 1-3 inches of rain was recorded within the area as well .

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Global models point to a late season Mid South setup Tuesday 5/24 and perhaps Tenn. Valley Wednesday 5/25; however, I doubt the latter as low level winds will tend to veer off.

Tuesday we have a system with vort max dug into Texas coming out into the Mid South. While it feels late in the season, long-term climo May is still severe weather season. Recent years the South shut down by mid-May. It has not always been that way.

Keep in mind Hoosier Alley (not far) gets slammed in mid-May even recent years. Pattern recognition is a little shaky vs recent years with a bowling ball vs open wave; however again, this used to happen. LLJ responds Tuesday, and not veered off trash. We'll see.

Late May we don't even have to worry about instability or dewpoints. Anyone step outside? If low level winds respond next week, it's game on!

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Sat. May 21: Boundary intersection forecast WSW of MEM this afternoon in the flat Ark. Delta. Technically not our Region, but I'm thinking about chasing it.

Boundary intersection is outflow / quasi-cold front, not preferred. Rather have a pre-frontal trough away from the CF. However instability is robust. Also modest LLJ flow is forecast. Upper levels are modest too. In late May that is great with high CAPE. Just the boundary pair is not my preferred combo.

CF and WF drawn IL/IN. Yellow is outflow. Magenta is possible boundary intersection forecasts. Idea is just get toward MEM. Normally I go through HSV (few trucks) but probably BNA to offer flexibility if Kentucky pops. Still the best shear looks Ark/Tenn/Miss.

General Public notes: This is a low probability event. Bored on a Saturday. Awaiting Gam 4s in NHL and NBA and USFL Sunday.

image.png.c5b07b86f723fc1f77180cba6da01d64.png

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5 hours ago, nrgjeff said:

Sat. May 21: Boundary intersection forecast WSW of MEM this afternoon in the flat Ark. Delta. Technically not our Region, but I'm thinking about chasing it.

Boundary intersection is outflow / quasi-cold front, not preferred. Rather have a pre-frontal trough away from the CF. However instability is robust. Also modest LLJ flow is forecast. Upper levels are modest too. In late May that is great with high CAPE. Just the boundary pair is not my preferred combo.

CF and WF drawn IL/IN. Yellow is outflow. Magenta is possible boundary intersection forecasts. Idea is just get toward MEM. Normally I go through HSV (few trucks) but probably BNA to offer flexibility if Kentucky pops. Still the best shear looks Ark/Tenn/Miss.

General Public notes: This is a low probability event. Bored on a Saturday. Awaiting Gam 4s in NHL and NBA and USFL Sunday.

image.png.c5b07b86f723fc1f77180cba6da01d64.png

Got some nice cells about to roll through hardeman county.  Thunder has been rumbling for about 10 minutes now.  

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MRX AFD for Thursday:

Discussion:

The main concern of the period is the severe weather potential on
Thursday. Agreement on timing looks to be a little better with the
NAM now coming in slightly faster, which puts it in better
agreement with the other models. If the trends hold, this would
put our best chances for seeing strong to severe storms from late
Thursday morning through Thursday evening. Due to the mean flow
being parallel to the cold front, there will be several clusters of
storms move through the area throughout the day. Because of this,
it`s hard to narrow down the timing of the severe threat.

Setup:

A quasi-cutoff upper low will make it`s way out of the Great Plains
on Thursday and into Western TN by Thursday evening. A strong upper
jet associated with the low and will move into our area through the
day. Due to the strong upper jet, combined with high pressure
anchored off the coastal Carolinas, a moderate to strongly sheared
environment will be in place across our area. Soundings show shear
values increasing through the day as the upper jet moves further
into the area. The NAM is still the most aggressive with shear
values, with 0-1km shear of near 40 kts and 0-1km SRH values around
350 m2/s2 which is concerning. The GFS isn`t as excited however.
Looking through the CAMs on SPC`s page, all of the members show a
few to several 2-5km helicity tracks across our area. This is
further indication of the severe/tornadic potential. Again, the main
threats with these storms will be damaging winds and few isolated
tornadoes. This will likely be a messy event due to several
rounds/clusters of storms moving in through the day.

In addition to the wind and tornado threat, isolated flooding will
also be of concern due to the moderate to heavy rainfall expected
with the stronger storms. The atmosphere will be very moist with PW
values averaging 1.6 inches, which is at the 90th percentile for BNA
sounding climatology. Also, still anticipating 30 to 40 mph wind
gusts across the higher terrain of the east TN mountains through the
the day Thursday due to the 40kt 850mb jet in place. The severe
threat will wind down Thursday night.
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Even before seeing MRX severe discussion, MRX mention of mountain wave means the LLJ will be there. Unless Gulf MCS cuts it off, but looks OK. Dews will be there. It's late May not March; so, MCS does is much less a deal killer here. 

If Mississippi is 5% Wednesday, Alabama is certainly 5% Thursday. That's some easy pickings. Day 2 update would not surprise me; but, they might wait until Day 1.

Thursday the 700 and 500 mb winds are not as straight south as Wed. More SSW. 200 mb is south, so some VBV; but again late season, those minor problems are not deal killers like in March.

CAPE looks skinny, esp low levels, so heating will have to over achieve. LI is definitely there; so, just low level CAPE has to come in. Look for pre-frontal trough Bama to East Tenn. Perhaps outflow intersection with it. Today and tonight rain will provide plenty of boundaries. 

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Boundary intersection in Kentucky. Goodie that terrain!

Sarcastic. 

Second chance if Gulf front can lift north enough to intersect pre-frontal trough in Alabama or Georgia. Doubtful.

Hoosier Alley is probably the preferred location, but I'm not interested enough to go into their Regional forum, lol.

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Boundary intersection in Kentucky. Goodie that terrain!
Sarcastic. 
Second chance if Gulf front can lift north enough to intersect pre-frontal trough in Alabama or Georgia. Doubtful.
Hoosier Alley is probably the preferred location, but I'm not interested enough to go into their Regional forum, lol.

Some of those storms that moved north of Knoxville into SE Kentucky had a pretty solid spin to them. Storm this morning in Western Virginia is pretty tight but the radar is probably having issues with the terrain.


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