Tn Valley Severe Weather

[PowellVolz]

Man look at the SSTS off the JAPAN coast,Sea of JAPAN and even Sea of OKHOTSK.Then you factor in the warmer than normal SST'S in he Gulf.Seems prime for a fun severe season,if you like severe.Of course this is only a model in Nov and we are talking April,but still.This is the IMME

Even though severe is very rare in ETn, I’m about to build a house and it’s going to have a storm shelter in it. Like a 10x10 pored concert walls room. I can store dry goods and my guns in it also.


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[jaxjagman]

20 hours ago, PowellVolz said:

Even though severe is very rare in ETn, I’m about to build a house and it’s going to have a storm shelter in it. Like a 10x10 pored concert walls room. I can store dry goods and my guns in it also.


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Sounds like you are waiting on the apocalypse,sorry couldn't resist,just playing..lol

[Fred Gossage]

One of the hopes I had was that having so many tropical systems in the Caribbean would lead to the water temperatures getting worked over and that would introduce boundary layer moisture quality concerns like we saw in the 2005-2006 cool season into spring after the 2005 hurricane season that had systems target the same areas.  Our higher quality boundary layer moisture in Dixie Alley, until about May, comes from the Caribbean... not the Gulf of Mexico.  It appears any hopes of having that warmer near-surface water being worked over is not happening.  That was probably one of our better chances of finding a way to skirt around something serious happening as a result of the -PDO/+TNI combo that's building, and it looks like those hopes are dashed.  With the trade winds setting up in western regions to help drive cooling there and the coastal Gulf of Alaska and West Coast of the USA cooling, leading toward a more classic -PDO configuration going forward (even though the whole NPAC won't be cooler), pretty much all the large scale red flags are there... not just for an active time east of the Plains... but for the door to be open for something bad to happen in terms of a system with the potential for large scale violence.  All of this put together into one setup is the kind of background state you most often have when bad things happen.

My main questions going forward are overall amplitude of the large scale pattern this cool season and how that affects placement of the jet stream... and how that affects the timing of when Dixie Alley is most under the gun.  Seeing the subtropical ridge stay stout but centered at a lower latitude off the Southeast coast and from the Bahamas eastward, and allowing cold shots to still frequent the east so far this fall, is unsettling to me.  If the ridge during the cool season stays lower latitude in nature, that not only opens the door for systems to target the heart of Dixie well into April, but it provides a background pattern over the CONUS, in conjunction with the NPAC pattern that results from the -PDO and La Nina, for individual synoptic systems to be of a lower amplitude variety as well.  Low-amplitude troughs, regardless of their tilt, tend to be more dangerous... especially in Dixie Alley... because of more subtle forcing out over the warm sector, more westerly deep-layer shear vectors, less focused linear forcing near the cold front, etc.  Lower amplitude troughs are how we can get intense tornado events (4/7/2006, 5/18/1995, 4/8/1998 to name a few) here from even positive tilt troughs.  April 3, 1974's trough started out negative tilt, but by later in the day before any of the F4-F5 tornadoes happened in Alabama, its trough had evolved into a lower amplitude positive tilt.  We can only go by reanalysis data, but if it is correct, the troughs with both the 3/21/1932 and 1936 Tupelo event were probably both low-amplitude positive tilt.  Low amplitude upper-level patterns are not good, regardless of trough tilt.

Nothing is certain, but there are a lot of red flags there...

[nrgjeff]

I share some of Fred's thoughts and concerns above. However I'm hoping it's not wall-to-wall severe. While I love a good Pains chase, I really don't like this crap in Dixie - especially trying to shelter my family at 1am.

The pattern Fred describes is my secondary pattern for the winter and spring outlook. Trough comes through the Plains. Depending on the lingering SER severe weather would be favored in Hoosier Alley, Dixie Alley, or both. He covers the hemispheric situation. I'm talking the synoptic troughs. We saw this at times in October, but without much incident. Same deal in late winter or early spring would be impactful.

Fortunately my primary pattern is the current one, influenced by the stubborn +ABNA. Warm northeast China. Trough Aleutians, Bering Sea, sometimes GOA. AN heights and temps much of eastern Canada. AN stuff bleeds into Great Lakes USA. Leaves the Southeast near normal heights. Temps would be above, but no big systems or low-amp troughs with moisture. Could be low-amp cloudy drink more coffee days.

I'm one of the severe wx enthusiasts here, but I also got a family here and know we have some members who hate severe wx. While I do agree spring will be active, I have no reason to forecast anything historic. To quote Spann, severe wx is normal and we'll get through it.

[nrgjeff]

Interesting evolution after Christmas from the ECMWF weekly charts just out. Trough lumbers from the Plains into the Southeast. Will that be heavy rain, severe, or both?
If severe probably Deep South or Gulf Coast. End of December isn't really our severe climo.

FREE for all Friday update: GFS keeps jawboning severe Christmas week, including proper dewpoints Deep South. Jawboning is my other way of conceding it's still fantasyland. We'll see. 

[jaxjagman]

On 12/10/2020 at 3:02 PM, nrgjeff said:

Interesting evolution after Christmas from the ECMWF weekly charts just out. Trough lumbers from the Plains into the Southeast. Will that be heavy rain, severe, or both?
If severe probably Deep South or Gulf Coast. End of December isn't really our severe climo.

FREE for all Friday update: GFS keeps jawboning severe Christmas week, including proper dewpoints Deep South. Jawboning is my other way of conceding it's still fantasyland. We'll see. 

Control has a +ve tilted trough with a ridge in the east and a ridge to the west around Christmas,potential big rain maker if it were to be anywhere right for the Valley

[nrgjeff]

Yeah looks like rain now. Too cool for severe. Too warm for snow at lower elevations. And clooouuudyyy, yuck!

Do Belize or Aruba take American tourists right now? 

[jaxjagman]

Went positive tilt yesterday to more neutral tilt today,looks like that ridge it was showing yesterday is getting broke down sooner in the east,least that what it shows this afternoon

 

[PowellVolz]

So glad we have a severe weather thread on here. Jax and Jeff do a fantastic job


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[Save the itchy algae!]

I’ve experienced one severe thunderstorm in my six years living in the valley.  It was a drive to get there and it was marginal. This is not the place to be a severe wx nerd—worse than snow.

[nrgjeff]

It was quiet between 2015 and 2019. Easter Sunday night was enough for me in town. 

East Tennessee is really not the bullseye. Chattanooga very much reminds me of Kansas City that way. It's close, but the real action is to the southwest. Chattanooga:Huntsville :: KC:Wichita. Then BHM/JAN = OKC/OUN. Knoxville is even less active than Chatty.

Heart of Dixie Alley is a fairly easy drive from here; so, my interest is sustained.

[PowellVolz]

It was quiet between 2015 and 2019. Easter Sunday night was enough for me in town. 
East Tennessee is really not the bullseye. Chattanooga very much reminds me of Kansas City that way. It's close, but the real action is to the southwest. Chattanooga:Huntsville :: KC:Wichita. Then BHM/JAN = OKC/OUN. Knoxville is even less active than Chatty.
Heart of Dixie Alley is a fairly easy drive from here; so, my interest is sustained.

Cullman Alabama


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[PowellVolz]

A little off topic but my 6 year old son asked me yesterday afternoon to put on some YouTube tornado videos on our big TV. Jeff might have a navigator in a few years.


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[nrgjeff]

When the winter wx forecast goes to the dogs, there's only one question to ask. Though I acknowledge winter hope on Sunday in places.. When's the next chance of severe weather?

Thursday night looks interesting, especially in the Deep South. The slower more amped, and perhaps cutting solutions, from the EC and NAM could get southeast Tennessee in play overnight. What a way to ring in the New Year! From the bathroom or closet?

Regrettably it does not look like a chase scenario attm. First of all it's the shortest daylight of the year. Second, it looks to get going after dark. The just right 700 mb temp may check early junk; however, it also delays the main show. That'd be much more interesting in March or April. Third, it's relying on a developing LLJ a bit east of the best upper dynamics. Finally, the usual, it's Dixie Alley.

All that said the wind fields are impressive. At first glance the 500-200 mb charts look a little meridional. However 850/925 is properly backed relative to those. 700 mb is just right temps for this time of year, and correct vectors. Surface temps/dews look to be there, again because 700 mb Ts hold off an early rain-out. The heavy rain advertised comes with the main system later.

Bottom line: Chattanooga, North Alabama and North Georgia could ring in the New Year with overnight fireworks. Why not? 

[Holston_River_Rambler]

We have to have the lightning and thunder for the Sunday system to work out, lol. On a more serious note, hopefully we can keep the .qpf in the ~3" or so range. Feels like it has the potential to bust high on rainfall somewhere in the TN Valley depending on where the preliminary boundary sets up as the storm develops. Let Arkansas have the monsoons this time. 

[AMZ8990]

 

Pretty interesting stats, Middle Tn was In the bullseye this past year by the looks of it.  Wonder if that’s a standard occurrence 

 

[jaxjagman]

9 hours ago, AMZ8990 said:

 

Pretty interesting stats, Middle Tn was In the bullseye this past year by the looks of it.  Wonder if that’s a standard occurrence 

 

We've done really well with tornadoes recently.Since the NWS started collecting data in the 1800s, Middle Tennessee has been hit with 65 EF-3 tornadoes, 20 EF-4 tornadoes and one EF-5 tornado.

[AMZ8990]

5 hours ago, jaxjagman said:

We've done really well with tornadoes recently.Since the NWS started collecting data in the 1800s, Middle Tennessee has been hit with 65 EF-3 tornadoes, 20 EF-4 tornadoes and one EF-5 tornado.

Does it seem like more tornados hit in middle Tn based off the correlating data tO east and West Tennessee?

[jaxjagman]

https://www.weather.gov/ohx/tntornadostats

3 hours ago, AMZ8990 said:

Does it seem like more tornados hit in middle Tn based off the correlating data tO east and West Tennessee?

 

[Fred Gossage]

It's just south of the overall Tennessee Valley area but close by and within Dixie, but we've already had our first tornado injury of the year.  And despite the ENH Risk from the day before not materializing, this is at minimum the fourth system in a row over the past few weeks to produce tornado damage in one of the Dixie Alley states.  It's going to be a long 5-6 months ahead...

[jaxjagman]

14 hours ago, Fred Gossage said:

It's just south of the overall Tennessee Valley area but close by and within Dixie, but we've already had our first tornado injury of the year.  And despite the ENH Risk from the day before not materializing, this is at minimum the fourth system in a row over the past few weeks to produce tornado damage in one of the Dixie Alley states.  It's going to be a long 5-6 months ahead...

There seems to be some hints at the MJO could possibly strenghten into the Eastern IO and into the Maritime towards the end of the month into Feb

[nrgjeff]

Middle Tennessee is ever so slightly more active than West Tenn. East Tennessee was historically less active than the other two; however, that may change (is changing) with recent trends and shifts.

My conclusion on Mid vs West is based on historical tornado tracks, not really a map of the Alley. Those tracks have been floating around Twitter and other sites. North Alabama max bleeds north into Middle Tenn.

[jaxjagman]

 

Getting close to the positive range,we should be there next month.

 

2002   -1.780  -1.343  -1.287  -1.326  -1.663  -2.335  -2.871  -3.001  -2.878  -2.546  -2.413  -2.311
 2003   -2.523  -2.644  -2.910  -2.995  -3.040  -2.895  -2.723  -2.412  -2.082  -1.738  -1.596  -1.522
 2004   -1.600  -1.571  -1.913  -2.272  -2.637  -2.999  -3.376  -3.253  -2.993  -2.731  -2.505  -2.393
 2005   -2.598  -2.605  -2.408  -2.383  -2.284  -1.897  -1.885  -2.124  -1.999  -1.668  -1.264  -0.475
 2006    0.151   0.067  -0.099  -0.601  -1.170  -1.501  -1.289  -1.087  -0.991  -1.131  -1.184  -1.204
 2007   -1.594  -1.834  -2.022  -2.341  -2.655  -2.697  -2.565  -2.305  -1.865  -1.291  -0.302   0.850
 2008    1.836   2.404   2.671   2.493   2.015   1.613   1.429   1.173   0.955   0.839   0.787   0.779
 2009    0.793   0.753   0.514   0.107  -0.284  -0.476  -0.848  -1.309  -1.687  -2.025  -2.418  -2.571
 2010   -2.649  -2.398  -2.127  -1.750  -1.548  -0.957  -0.564  -0.218   0.113   0.681   1.167   1.530
 2011    1.523   1.577   1.546   1.271   0.844   0.675   0.387   0.168  -0.029   0.070   0.363   0.844
 2012    1.082   1.479   1.613   1.596   1.191   0.601  -0.046  -0.718  -1.412  -1.740  -1.626  -1.515
 2013   -1.149  -0.999  -1.167  -1.528  -1.929  -2.379  -2.398  -2.185  -1.936  -1.583  -1.043  -1.077
 2014   -1.358  -1.503  -1.408  -1.483  -1.122  -0.636  -0.406  -0.499  -0.813  -1.238  -1.715  -2.117
 2015   -2.476  -2.435  -1.984  -1.434  -0.702  -0.198   0.100   0.112  -0.139  -0.404  -0.676  -1.188
 2016   -1.630  -1.802  -1.946  -1.978  -1.763  -1.441  -0.968  -0.508  -0.101   0.324   0.690   1.097
 2017    1.447   1.465   1.268   0.592  -0.267  -1.150  -1.575  -1.925  -1.847  -1.735  -1.548  -1.264
 2018   -1.134  -1.260  -1.320  -1.650  -1.978  -2.118  -2.089  -2.159  -1.979  -1.890  -1.734  -1.700
 2019   -1.725  -1.774  -1.892  -2.226  -2.535  -2.750  -3.045  -3.344  -3.286  -3.001  -2.857  -2.549
 2020   -2.208  -2.029  -1.811  -1.756  -1.891  -1.855  -1.720  -1.586  -1.090  -0.441 -99.990 -99.990
  -99.99
  TNI
  Nina 1.2-Nino4 standardized 

[Fred Gossage]

It was positive as of the weekly ENSO update this week with last week's numbers.  Region 4 was -1.2C and Region 1+2 was -0.8C.  Since then, Region 4 has cooled and Region 1+2 has warmed.

[Fred Gossage]

Looking ahead at longer range stuff, the January analogs from tropicaltidbits.com would suggest an active severe weather season is ahead.  Three of those speak for themselves, but for those that don't recognize 1976 that much:

 

March 1976 holds the record number of tornadoes for any March in the United States in official tornado records.  There were four separate outbreak systems that month alone.

 

The top four of five January analogs there on Tidbits suggest an active and possibly violent Dixie Alley season ahead, and the fifth analog would've been the exact same, but there were STJ interference issues that year.  We are polar jet driven this year.

[Fred Gossage]

 

The pattern through February on the Euro weeklies shows low amplitude suppression will continue, with only flat, low-latitude oriented subtropical ridging as we begin to start March.  That general layout of everything supports the idea that suppression of the pattern doesn't back off until we start heading into spring severe weather season.  That particular pattern there is almost a carbon copy of the February pattern from the two listed analogs above that targeted Dixie Alley in April instead of the late winter. I won't say which two because I don't want to be labeled an alarmist by people on here that may not know me, but the winter pattern so far and what the Euro weeklies show for February does not support the other three analogs on the Tidbits list.

[Fred Gossage]

I will just say that all those analogs above should show that the general large scale pattern is there for a potentially active severe weather season ahead, and not just in numbers but in the potential for a large scale intense event or two.  All four of the years highlighted in the analog chart had high-end days.  When you use certain "celebrity" analogs, people instantly blank out and think you're automatically calling for a repeat of the "celebrity" event, and I'm not, and we're not going there.  Even if you have the exact same setup on the hemispheric or global level, it is up to individual synoptic systems to take full advantage of the background state, and then it is up to the mesoscale of one of those to take full advantage of its synoptic setup.  And that is something we just can't know until we are running up on an individual system.  But with everything in place, I just can't see how we can avoid an active stretch in a few months from now, with a higher-than-usual chance of a headliner type day or two.

[jaxjagman]

Subsurface now looks coldest into 3.4,the standing wave west of the IDL looks to hold at least for now but seeems like their could be some changes upcoming,i wouldnt be surprised to see region 4 get around -1.5 upcoming

[Holston_River_Rambler]

Is it already that time?

 

[Carvers Gap]

2 hours ago, Holston_River_Rambler said:

Is it already that time?

 

What is crazy is how very little thunder we have had in NE TN this winter - not even sure I can name a time where we have had even weak thunderstorms.  I think last January we had a really bad severe event on my end of town - knocked down a bunch of trees.  But yeah, with a ridge temporarily bellying into the center of the country...could happen.  I haven't even been able to use my "thunder in the mountain...snow within ten days" rule this winter - yet.