Tn Valley Severe Weather

[crossbowftw3]

Watching from afar here in New York. Day 5 broad-brush 15% into the Lower Ohio Valley. The overall look is beginning to look pretty dang ugly at this range. 

[McMinnWx]

How ugly are we talking regarding this Wednesday event?

[crossbowftw3]

24 minutes ago, McMinnWx said:

How ugly are we talking regarding this Wednesday event?

Pretty substantial potential verbatim as of this moment, but vbv exists in soundings so cautiously sending out the message as of now

[nrgjeff]

I was thinking Deep South MCS wash-out. Just heavy rain Tennessee. That's ugly to storm chasers, lol.

6 hours ago, McMinnWx said:

How ugly are we talking regarding this Wednesday event?

OK getting, serious, beyond hyper-cynical dripping-sarcasm Jeff, the wind fields are there. 700 mb Ts* are just right (not too warm cap, not necessary widespread rain) however the ECMWF is showing just that type of rain. Deep South goes slop-fest, which cuts off LLJ into Tenn. If you fear severe, all that is good stable news Tennessee.

I infer caution from MRX. Does not sound like they are sounding alarm bells even internal. Any media hype is total trash. Something interesting for severe wx enthusiasts to track. However it'll probably bust.

*I use 700 mb Ts to cross check instability this time of year. Five days out is awful early to use forecast temperature soundings. Winds like VBV can be used for the same reason we look at constant pressure charts (850/700/500 etc). 

ANSWER to BELOW: Chattanooga Easter 2020 tornado was within two miles, at Midnight. Even storm chasers don't like that crap!

[McMinnWx]

24 minutes ago, nrgjeff said:

I was thinking Deep South MCS wash-out. Just heavy rain Tennessee. That's ugly to storm chasers, lol.

OK getting, serious, beyond hyper-cynical dripping-sarcasm Jeff, the wind fields are there. 700 mb Ts* are just right (not too warm cap, not necessary widespread rain) however the ECMWF is showing just that type of rain. Deep South goes slop-fest, which cuts off LLJ into Tenn. If you fear severe, all that is good stable news Tennessee.

I infer caution from MRX. Does not sound like they are sounding alarm bells even internal. Any media hype is total trash. Something interesting for severe wx enthusiasts to track. However it'll probably bust.

*I use 700 mb Ts to cross check instability this time of year. Five days out is awful early to use forecast temperature soundings. Winds like VBV can be used for the same reason we look at constant pressure charts (850/700/500 etc). 

Thank you to you and @crossbowftw3!

I had the displeasure of experiencing the 2011 tornadoes. To see it was a bit traumatic is an understatement. 

[PowellVolz]

I’m shocked at MRX’s AFD for Wednesday. I’ve never seen this kind of wording this far out from them. I get being aware of the situation but dang.


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[jaxjagman]

Models keep showing a trough going through East Asia even into Korea next weekend,by far the best trough through that region it seems like in a couple months.PNA might be tilted more + but there also seems to be another EKW today getting into region 3 and a KW into NA into week 3 of March,seemingly around the 28th of March give or take might be our next shot of severe storms after this one upcoming right now

[PowellVolz]

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[McMinnWx]

Nah. Get that 2011 talk out of here. Nope. Let’s not do that again. 

[PowellVolz]

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[jaxjagman]

1 hour ago, PowellVolz said:

 

 

 

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GWO is in phase two today

[jaxjagman]

Meant the put the link up,here it is

 

https://journals.ametsoc.org/view/journals/mwre/144/2/mwr-d-15-0289.1.xml

[PowellVolz]

GWO is in phase two today

Oh wow


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[Matthew70]

17 minutes ago, jaxjagman said:

GWO is in phase two today

By looks that (reading correctly)?  Looks like severe stays south of TN.

[PowellVolz]

By looks that (reading correctly)?  Looks like severe stays south of TN.

Read the link he posted. It says phase 1 and 2 have a higher likelihood of having EF2 or greater tornadoes.


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[jaxjagman]

3 minutes ago, PowellVolz said:

Read the link he posted. It says phase 1 and 2 have a higher likelihood of having EF2 or greater tornadoes.


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Right,i just posted this to show the similarity to where the GWO is in phase 2 from this paper,it does not mean we can't get severe weather in Tn

[jaxjagman]

Interestingly, no (E)F5 tornadoes were recorded in phases 3, 4, or 5 during the study period. Cross-phase variability explained by the GWO is substantial, and has not been demonstrated to this magnitude by other known teleconnection indices [e.g., the North Atlantic Oscillation (NAO)]. A robust example is shown when analyzing (E)F1+ tornadoes during strong GWO events. During GWO phases 1 and 2, statistically significant positive tornado count and average tornado count per day anomalies are found. In contrast, phases 4 and 5 revealed negative counts and negative tornado count per day anomalies at the 95% confidence level (Fig. 2).

 

Odd how there has never been a violent EF5 with this study,while in 3,4 and 5.The Wayne and Lawrence County EF5 happened in a LaNina year and the GWO was in phase 6

[Fred Gossage]

The Wayne/Lawrence County F5 happened coming out of the 1997-1998 Super Nino.  The 1998-2000 La Nina had not developed yet.

[jaxjagman]

1 hour ago, Fred Gossage said:

The Wayne/Lawrence County F5 happened coming out of the 1997-1998 Super Nino.  The 1998-2000 La Nina had not developed yet.

correct,i was looking at 1999,thanks

[nrgjeff]

ECMWF continues to insist a Deep South warm front rainout. Still nasty Mississippi and Alabama (excluding northeast Bama) but not so bad here. No promises either way!

16 hours ago, Matthew70 said:

By looks that (reading correctly)?  Looks like severe stays south of TN.

Little tricky using the GWO for mesoscale, but it'd be interesting if they line up.

[PowellVolz]

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[VOLtage]

From the MRX AFD:

https://forecast.weather.gov/product.php?site=MRX&issuedby=MRX&product=AFD&format=CI&version=1&glossary=1

Better environment for strong to severe thunderstorms will come
overnight Wednesday night as the low moves through the Ohio River
Valley forcing through a line of thunderstorms along the front.
Forecast soundings across southeast Tennessee (mostly near
Chattanooga) indicate that CAPE increases to 1000-1500 J/kg. At the
same time as the low gets nearer to the area the low level jet
really begins to ramp up and a strong southerly jet streak of over
50 knots intensifies over the area. This is reflected in forecast
soundings indicating low level shear of over 25 knots and deep layer
shear over 50 knots. During the day/evening on Wednesday expect the
strongest storms to form over MS/AL and we`ll need to keep an eye on
them as they move northeastward towards the forecast area as these
are the storms that will have the opportunity to tap into the
favorable environment. One of the biggest determining factors will
be the location of the warm front as storms move northeastward as
this will likely have the best chance to focus thunderstorms and
produce the most damaging severe storms, including the possibility of
some tornadoes. Storms that form away from front will still have the
threat to produce severe weather with straight line winds and
possibly hail being the biggest threat. In the eastern Tennessee
Valley it`s likely going to be a night time event and with this
being the first possibility of severe weather this season a good time
to prepare your severe weather safety plan for the rest of the
season.

Storms will continue to move northeastward through the remainder of
the evening, but as they do they`ll be fighting against night time
stability and a generally unfavorable environment, especially north
of Interstate 40. Expect strong storms to redevelop with this system
on Thursday, but by that time the low will have moved far enough
east that the threat for severe storms should be east of the
Appalachian Mountains. On Thursday expect the upper level portion of
the low to move right over the area a bring continued chances for
showers (and maybe a few rumbles of thunder) to the area with the
best chances for rain occurring in northeast Tennessee and southwest
Virginia closer to the better mid-level support. At the same time
surface flow begins to turn more northerly and surface temperatures
will drop as the systems exit the area. Daytime highs on Friday will
drop about 10-15 degrees compared to Thursday and this spat of
cooler weather will continue thorugh the weekend. Some of the
deterministic models continue to try and spit out light QPF at the
end of the work week and on Saturday, but still think they may be a
bit overdone, but will continue with low end chances as they`re
picking up on some weak lift over the area. Ridging will begin
building at the end of the weekend into next week and dry weather
with warm temperatures will be the trend to end the 7-day forecast.

[nrgjeff]

ECMWF now goes with the warm sector consensus of American guidance for Wednesday. Moderate risk is quite justified. Ongoing rain is still forecast on the front(s) so it won't get volatile enough to justify high risk. However Wednesday looks like the real deal. Moderate Risk is of course the real deal anyway.

In classic Dixie Alley fashion, not one, but two troughs are forecast between the cold front CF and warm front WF. Of course the CF will be in western Arkansas. A quasi-dry-line like feature DL will move from central to eastern Arkansas, a likely focus for some severe storms and possible supercells. Then a pre-frontal trough will likely develop and move from eastern Arkansas into Tennessee and Mississippi late Wednesday afternoon. With moist dewpoints either side of this pre-frontal trough, I believe it will be the focus for the most intense supercells. So yes, two lines going at once is possible in true Dixie fashion, quasi-DL feature and pre-frontal trough. WF is also highlighted by SPC. WF is quite conditional as usual. Two troughs is enough already.

Interesting things may get started in the flat Delta region of the Mid South. Usually that's not climo favored, compared to Mississippi and Alabama, but the timing lines up for the Delta and the Memphis metro. Mississippi may go into evening, but hopefully wrap up before bedtime. 

Biggest concern is Alabama going late Wednesday night, including tornadoes. LLJ strengthens and stays oriented to maximize low level shear.

[jaxjagman]

Sure looks like a active period is coming up.CFS shows a KW coming into play into wk3 and this Sunday a decent trough is going to go through East Asia.Models will more than likely struggle once again showing all kinds of solutions.

Just a note and certainly no forecast but the day before the storms hit into dixie alley CIPS showed the best analog as 4-15-11 and then 12 days later was the super outbreak,during that time frame

[PowellVolz]

Sure looks like a active period is coming up.CFS shows a KW coming into play into wk3 and this Sunday a decent trough is going to go through East Asia.Models will more than likely struggle once again showing all kinds of solutions. Just a note and certainly no forecast but the day before the storms hit into dixie alley CIPS showed the best analog as 4-15-11 and then 12 days later was the super outbreak,during that time frame

 

Saw a couple of tweets talking about later on this week. I feel like Knoxville is over due for a tornado. It’s been several years since we have had a good one. I was in Powell at my home in February of 93’ when a F3 hit about 3/4 of a mile from me. It started in Oak Ridge and ended up in Halls. Leveled about 20-30 houses in the subdivision next to mine. Same night Lenoir City to Ft Loudon dam got hit.

 

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[jaxjagman]

2 hours ago, PowellVolz said:

Saw a couple of tweets talking about later on this week. I feel like Knoxville is over due for a tornado. It’s been several years since we have had a good one. I was in Powell at my home in February of 93’ when a F3 hit about 3/4 of a mile from me. It started in Oak Ridge and ended up in Halls. Leveled about 20-30 houses in the subdivision next to mine. Same night Lenoir City to Ft Loudon dam got hit.

 

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It's actually been a quiet time in Tn,we have only had one tornado so far this year

[VOLtage]

I know it's impossible to predict this far in advance, but the European model is showing a pretty decent northward extent of the warm sector

[jaxjagman]

Cips shows this as the top analog today ( "ducking from Jeff :)"

[jaxjagman]

3 hours ago, VOLtage said:

I know it's impossible to predict this far in advance, but the European model is showing a pretty decent northward extent of the warm sector

The Euro wants to bomb the system out once it reaches into the O/V.This would start to strenghten the LLJ to around55-65 kts once it starts to get into the MO/V in Tn,it even shows the LLJ getting to around 70 kts into Ky afterwards

[jaxjagman]

National Weather Service Memphis TN
251 PM CDT Sun Mar 21 2021

.DISCUSSION...

Beautiful conditions are occurring across the Mid-South this
afternoon as upper ridging is occurring aloft. Temperatures have
climbed into the mid 60s.

Tranquil weather will come to an end as a large scale upper trough
will set up over the Rockies on Monday and will remain in place through
next week. As a result, a series of upper level low pressure
systems move within the flow.

The first will begin to dig into the Texas Panhandle on Monday.
Clouds will begin developing across portions of the Mid-South ahead
of the system late tonight into Monday morning. A few warm air
advection showers will also be possible, but at this time not
enough to mention 20 POPS. The upper level low will then lift
northeastward into Northwest Missouri by Tuesday afternoon. The
SFC low will be nearly stacked with the upper low tracking in a
similar path. The system will also become occluded as it lifts
northeastward pinching off instability limiting severe weather
potential. That being said, there could still be some gusty winds
from a decaying line of convection that moves into Eastern
Arkansas late Monday Night into early Tuesday morning.

The associated cold front will never clear the Mid-South and will
become stalled over the area Tuesday Night and Wednesday. Showers
and thunderstorms will be possible along and east of the front
through Wednesday.

Chances for showers and thunderstorms will continue Wednesday Night
through Thursday evening as the next upper level low pressure
system dives into the Southern Plains. The low will open up to a
potent upper trof becoming negatively tilted as it lifts into the
Lower Mississippi River Valley. The latest GFS has come more in
line with ECMWF and Canadian with the track of the SFC low in the
vicinity of the Mississippi Delta. However, differences remain
with timing of the system. A warm and unstable airmass will be in
place ahead of the system. Looking at the SLU CIPS Analog data,
the number one analog shows this could be a potentially dangerous
severe weather day across the portions of the Mid-South if the
system evolves as models indicate. Tornadoes, damaging winds, and
hail will be possible from storms that develop out ahead of the
system. Locally heavy rainfall will also be possible. Stay tuned.

The final system will move out of the Rockies next weekend
bringing another round of showers and thunderstorms to the Mid-
South.

Temperatures will remain mild through the period.

KRM