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Tn Valley Severe Weather

jaxjagman

By jaxjagman,
in Tennessee Valley

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Matthew70

Matthew70

Posted
Posted

Tomorrow the winds alone will be quite crazy.  55+ gusts with some 75+ gusts some data is showing.  That will bring down some trees.  Especially as soft as the ground has become.  Glad the severe wx so far has not panned out.  Seems TN has a cap on severe wx lately. Kinda like the snow cap especially for east TN.  Weird wx these days. 

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jaxjagman
jaxjagman

After 4-years of the last one, time for another thread to get going 

nrgjeff
nrgjeff

Day 4-8 looks valid for Monday severe Mid-South. 12Z Wed. is slowing it down, into the flatter Delta region. Nice! Friday system tugs on Gulf Moisture; then, front does not clear the Coast over the

PowellVolz
PowellVolz

I’m not going to pretend I know half as much about severe weather as @jaxjagman but here’s my opinion based on what I have seen over the years and I’d like for Jax to chime in. ETn IMO is very speci

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jaxjagman

jaxjagman

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Posted 
National Weather Service Nashville TN
223 PM CST Thu Mar 2 2023

...New SHORT TERM, LONG TERM...

.SHORT TERM...
(This afternoon through Friday)
Issued at 201 PM CST Thu Mar 2 2023

Go outside. Enjoy this tranquil weather. Tomorrow is not going to be
like this. Partly to mostly cloudy skies and winds 10 mph or less is
quiet compared to what we`re expected tomorrow.

Let`s start with tonight. As I type this, an already intense closed
low system has dug into northern Mexico. This system will eject
northeastward over the next few hours and as it does, a severe
weather outbreak will begin over ArkLaTex. They`re going to be in
for a long night. At the same time, a warm front will be lifted
through Middle TN. Mostly showers, maybe a few thunderstorms are
expected here at home. Initially, we were concerned about the
potential for a few strong to severe storms with the warm front,
but it looks like we`re not going to destabilize near enough for
any intense storms. However, as the night goes on and the upper
low becomes negatively tilted over Arkansas and deep, strong
cyclogenesis occurs, the pressure gradient will tighten
tremendously over the region. This is going to do two things: 1.)
pull more moisture/instability into the area and B.) it will make
the wind blow as though a severe storm is over the whole area. The
combination of instability nearing 500 J/Kg and great forcing
along the front will open the door for severe storms. Mainly,
damaging straight line winds will be the threat with any storm,
but low-level helicities nearing 250 m2/s2 will also cause storms
to exhibit some rotation, so a tornado or two is also possible. Of
course, all of that is fine and dandy, and while we might issue a
few warnings, I really think the bigger story of tomorrow is
going to be the gradient winds. For the first time in my 16+ year
NWS career, I have preemptively issued a High Wind Warning. This
will replace the Wind Advisory completely and run from 6 am to 6
pm CST. Here`s why this is going to be significant: winds are
going to gust 45 to 60 mph probably before storms get to wherever
you are. This will open the door for trees to fall (especially
with grounds already wet) and power outages to occur. This means
you will need to have your smart phone charged to 100% TONIGHT and
make sure you have fresh batteries in your NOAA Weather Radio so
you can reliably get warnings if the power goes out. This is going
to be a unique situation and we need to treat it as such.
Gradient winds aside, models continue to show storms breaking
across the TN River around 7-8 am tomorrow morning and traversing
Middle TN through the mid-afternoon hours. Winds will start to
subside around sunset in the west and last a few more hours in the
east.

In regards to the flood threat, QPF value are not sky high. I do
believe we can see the light at the end of the tunnel as far as
that`s concerned. However, with several spots seeing 3 inches last
night, additional rainfall tonight and again tomorrow over the same
areas could cause at a minimum localized flooding. For this reason,
I will maintain the Flood Watch, though it could be cancelled early
if rain totals look even smaller than what I`m seeing now.
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matt9697

matt9697

Posted
Posted
1 hour ago, jaxjagman said: 
National Weather Service Nashville TN
223 PM CST Thu Mar 2 2023

...New SHORT TERM, LONG TERM...

.SHORT TERM...
(This afternoon through Friday)
Issued at 201 PM CST Thu Mar 2 2023

Go outside. Enjoy this tranquil weather. Tomorrow is not going to be
like this. Partly to mostly cloudy skies and winds 10 mph or less is
quiet compared to what we`re expected tomorrow.

Let`s start with tonight. As I type this, an already intense closed
low system has dug into northern Mexico. This system will eject
northeastward over the next few hours and as it does, a severe
weather outbreak will begin over ArkLaTex. They`re going to be in
for a long night. At the same time, a warm front will be lifted
through Middle TN. Mostly showers, maybe a few thunderstorms are
expected here at home. Initially, we were concerned about the
potential for a few strong to severe storms with the warm front,
but it looks like we`re not going to destabilize near enough for
any intense storms. However, as the night goes on and the upper
low becomes negatively tilted over Arkansas and deep, strong
cyclogenesis occurs, the pressure gradient will tighten
tremendously over the region. This is going to do two things: 1.)
pull more moisture/instability into the area and B.) it will make
the wind blow as though a severe storm is over the whole area. The
combination of instability nearing 500 J/Kg and great forcing
along the front will open the door for severe storms. Mainly,
damaging straight line winds will be the threat with any storm,
but low-level helicities nearing 250 m2/s2 will also cause storms
to exhibit some rotation, so a tornado or two is also possible. Of
course, all of that is fine and dandy, and while we might issue a
few warnings, I really think the bigger story of tomorrow is
going to be the gradient winds. For the first time in my 16+ year
NWS career, I have preemptively issued a High Wind Warning. This
will replace the Wind Advisory completely and run from 6 am to 6
pm CST. Here`s why this is going to be significant: winds are
going to gust 45 to 60 mph probably before storms get to wherever
you are. This will open the door for trees to fall (especially
with grounds already wet) and power outages to occur. This means
you will need to have your smart phone charged to 100% TONIGHT and
make sure you have fresh batteries in your NOAA Weather Radio so
you can reliably get warnings if the power goes out. This is going
to be a unique situation and we need to treat it as such.
Gradient winds aside, models continue to show storms breaking
across the TN River around 7-8 am tomorrow morning and traversing
Middle TN through the mid-afternoon hours. Winds will start to
subside around sunset in the west and last a few more hours in the
east.

In regards to the flood threat, QPF value are not sky high. I do
believe we can see the light at the end of the tunnel as far as
that`s concerned. However, with several spots seeing 3 inches last
night, additional rainfall tonight and again tomorrow over the same
areas could cause at a minimum localized flooding. For this reason,
I will maintain the Flood Watch, though it could be cancelled early
if rain totals look even smaller than what I`m seeing now.

I can echo what the forecaster said, I do not recall another time in my life, I have lived in Middle TN my entire 51 years, where we have had a high wind warning issued 

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PowellVolz

PowellVolz

Posted
Posted
What does this mean?

It just shows the potential for tornadoes. Doesn’t mean there will be tornadoes but the potential is there. There’s some 11 of 12’s showing up there and I thought the “meter” only went up to 10. I believe a 3 or 4 is considered a heightened risk level.


.
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Runman292

Runman292

Posted
Posted

MRX AFD: 

For Friday, the upper level system and associated strong
cyclogenesis will lift northeast toward the Ohio valley.
Impressive 850-700mb jet with NAEFS showing anomaly high wind
field over the Tennessee valley. The 850mb jet of 75kts+ will move
across the region with strong momentum transfer of the low-level
jet to the surface. Even though the wind gusts of 50-60 mph in the
valley may be below warning criteria, saturated ground will make
conditions more susceptible to down trees and power lines. Power
outages Friday are likely.

Beside the gradient induced high winds, a severe threat also
exists. Damaging straight line will be the main concern. Isolated
tornadoes are also possible as 0-1km and effective shear are off
the charts. Limiting factors are the low-CAPE and possible high
LCL heights. Also, the strongest of the synoptic forcing lift
north of the area.

Will need to monitor the potential of tornadoes closely. Latest
HRRR model does show an increasing potential but HREF CAMS showed
the best 2-5km updraft helicity tracks over Kentucky.
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Windspeed

Windspeed

Posted
Posted

I think we should probably isolate a thread for this event. The ground is saturated. 55+ mph wind gusts alone are going to make for a very bad day for utility companies. But with potential strong storm modes plus strong LLJ, regardless of tornado potential, we're likely to see significant winds with this system mixing down to the surface. Widespread 65+ mph gusts seem quite possible, with numerous isolated 80+ mph winds. With such parameters in place, it wouldn't be much of a reach if the NPC upgrades to moderate for the Cumberland Plateau into Kentucky. Timing of cells and storm modes ironed out in the morning.

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