Jan 6th-7th 2022 Second Chance Storm

[Silas Lang]

That Euro snow map seems unlikely? Like just a weird look, I can not remember too many events where the valley does better than other areas. 

[Carvers Gap]

Weird precip look on the Euro with those streaks.  That has very high bust potential for anyone on either side of those 20 mile wide swaths.  The actual precip maps are much less for 12z.  That said, the run just looks weird.  On WxBell, good/heavy precip rolls right up the eastern valley and Plateau.  Those streaks almost look convective.  IMHO, should have been more precip.  

@Silas Lang, I literally just typed this.  The precip output looks weird.  The actual storm...the way it tracks, 6hr qpf/precip type....they look great.  The map does not match the actual evolution of the storm.

[John1122]

2 minutes ago, Silas Lang said:

That Euro snow map seems unlikely? Like just a weird look, I can not remember too many events where the valley does better than other areas. 

It's going to be cold enough for snow everywhere in the valley except for perhaps the southern edge. The models will just key on different bands at times and it will lead to heavier totals displayed in those areas. Sometimes they key too much on terrain when the system has ample cold for all. 

[Carvers Gap]

Thing is the 12z Euro system completely ran out of gas when it left our region, which is odd.  Both the CMC and Euro cut the qpf.  May just be a one-off, but something to watch.  

[Holston_River_Rambler]

Anyone want to take a stab at the lifting mechanics of this system? The 500mb vort looks strung out and weak. The jet dynamics look weak to me too. I looked at the frontogenesis maps on Pivotal and they didn't look anything like this last system. Is it that fabled lift source, isentropic upglide? 

 

 

 

[John1122]

Take with huge grains of salt as it's at the enc of it's range, the RAP shows a smaller and more compact precip area with the snow falling Plateau/East. It also introduced freezing rain for parts of the forum area around southern middle Tennessee.

 

 

[Carvers Gap]

Noticed with the entire global suite that the system was shifted SE to one degree or another, the CMC/Euro more than the GFS.  Could be the apps sheered it out.  12z is on the left and 6z is on the right.  You can see the difference on the Euro below.  (map from WxBell). My guess is that this system is under-done.  Given rations could be higher, we don't need a tone of precip.

 

[8283 El Nino Baby]

Question related to snow in Tennessee...

As a new resident, I am hoping for a quick education on the geographical areas of Tennessee. I am from California and know that San Jose is considered "Northern California" even though it seems placed in the central part of the state. So when someone on the these forums says "Southern Tennessee, where does that begin? Where does West Tennessee end and Middle Tennessee begin? Where is the upper Cumberland Plateau vs central or southern?

Second question has more to do with snow and altitude. In California, we had storms where it could be in the low 40s and raining in San Jose (80ft), but snowing at 2000 feet in the foothills a couple miles away. Is that same effect present here in Tennessee? Do we get storms where its rains everywhere except for the Plateau and the Appalachian range getting snow? I know in the summer, my location on the plateau  sees temps about 7 degrees lower then McMinnville 30 miles west  of me.

 

 

[Carvers Gap]

I say the system could be under-done(earlier post by me), but it is possible that this system also could run out of gas.  IMBY, I see this from time to time.  The system looks robust to my west, and then just kind of runs out of steam.  @Holston_River_Rambleris correct I think.  This just gets strung out. It may have been shredded by the Apps as the snow axis is almost over the Apps at 12z.  That would cause moisture transport issues.

[TellicoWx]

2 minutes ago, Carvers Gap said:

I say the system could be under-done(earlier post by me), but it is possible that this system also could run out of gas.  IMBY, I see this from time to time.  The system looks robust to my west, and then just kind of runs out of steam.  @Holston_River_Rambleris correct I think.  This just get strung out. It may have been shredded by the Apps as the snow axis is almost over the Apps at 12z.  That would cause moisture transport issues.

It's been on different runs on models, Apps shearing the 850 once it reaches them

[Vol4Life]

Just now, TellicoWx said:

It's been on different runs on models, Apps shearing the 850 once it reaches them

Do we need the 850 to track a little further south to keep this from happening?

[TellicoWx]

1 minute ago, Vol4Life said:

Do we need the 850 to track a little further south to keep this from happening?

No, it's just a weak vort...some have had it shear out over middle TN on prior runs. 

[Reb]

3 minutes ago, Vol4Life said:

Do we need the 850 to track a little further south to keep this from happening?

If it ticks south a little more and cuts just to the SE of the apps, ETN will be in for a jackpot

[Carvers Gap]

6 minutes ago, 8283 El Nino Baby said:

Question related to snow in Tennessee...

As a new resident, I am hoping for a quick education on the geographical areas of Tennessee. I am from California and know that San Jose is considered "Northern California" even though it seems placed in the central part of the state. So when someone on the these forums says "Southern Tennessee, where does that begin? Where does West Tennessee end and Middle Tennessee begin? Where is the upper Cumberland Plateau vs central or southern?

Second question has more to do with snow and altitude. In California, we had storms where it could be in the low 40s and raining in San Jose (80ft), but snowing at 2000 feet in the foothills a couple miles away. Is that same effect present here in Tennessee? Do we get storms where its rains everywhere except for the Plateau and the Appalachian range getting snow? I know in the summer, my location on the plateau  sees temps about 7 degrees lower then McMinnville 30 miles west  of me.

 

 

Question 1.  Everything to the east of the Plateau is E TN.  Everything from the western portion of the TN River to the Plateau is M TN.  Everything west of the western portion of the TN river and to the Mississippi is W TN.  The Plateau is the border between E TN and M TN.  The eastern portion of the TN river runs through the middle of E TN and is not a demarcation line.  

Question 2.  And yes, the Plateau gets a crap ton more snow than anyone else outside of places like Mountain City and Roan Mountain which are in the Apps.  Both levation makes a and latitude make a lot of difference.  Also on the Plateau, you all are likely on the upslope which is a HUGE bonus.   The Upper Cumberland Plateau is also home to one of the most famous Americans of all-time, Alvin C York.  Beautiful, and in some places, remote country up there.  

[Holston_River_Rambler]

7 minutes ago, Carvers Gap said:

I say the system could be under-done(earlier post by me), but it is possible that this system also could run out of gas.  IMBY, I see this from time to time.  The system looks robust to my west, and then just kind of runs out of steam.  @Holston_River_Rambleris correct I think.  This just gets strung out. It may have been shredded by the Apps as the snow axis is almost over the Apps at 12z.  That would cause moisture transport issues.

Yeah that’s what is confusing me. The models are showing some steady if not dramatic lift. Sort of an overrunning scenario. I would have thought that that would have been frontogenetic since presumably there’s a front nearby but pivotal maps don’t show much in the way of that. There’s something (we probably several things) subtle going on in different levels of the atmosphere that are lifting the moisture. No one culprit, slow but steady. Honestly I kind of like that approach more than the drama of the last storm. At least for my part of the plateau. 

[John1122]

10 minutes ago, 8283 El Nino Baby said:

Question related to snow in Tennessee...

As a new resident, I am hoping for a quick education on the geographical areas of Tennessee. I am from California and know that San Jose is considered "Northern California" even though it seems placed in the central part of the state. So when someone on the these forums says "Southern Tennessee, where does that begin? Where does West Tennessee end and Middle Tennessee begin? Where is the upper Cumberland Plateau vs central or southern?

Second question has more to do with snow and altitude. In California, we had storms where it could be in the low 40s and raining in San Jose (80ft), but snowing at 2000 feet in the foothills a couple miles away. Is that same effect present here in Tennessee? Do we get storms where its rains everywhere except for the Plateau and the Appalachian range getting snow? I know in the summer, my location on the plateau  sees temps about 7 degrees lower then McMinnville 30 miles west  of me.

 

 

Look up the Grand Divisions or look at the CWA for each NWS office. To me, southern Tennessee is basically the two or three counties along the southern border of the state. You will often see I-40 used as a guide, because snow/mix/rain line seems to happen right around it quite often. The Northern Plateau is basically Fentress, Scott, Morgan, Campbell, NW Claiborne.  Crossville and a county or two south is Central imo. Everything else is southern Plateau. 

Yes, there are times when the Plateau/Mountains see snow when everywhere else sees rain. It's actually pretty common. 

[Carvers Gap]

@8283 El Nino Baby, I should add that southern TN could be in any of those Grand Divisions.  Northern TN could also be in any of those Grand Divisions.  I live in NE TN about 5 miles from Virginia and likely live remarkably close to @1234snow . If you are on the upper Cumberland Plateau, you are in the snow jackpot most winters.  Great thing about TN is that snow is temporary.  

[TellicoWx]

I would set that 12z Euro to the side...it does run an almost convective type cells starting on the southern plateau up the valley. I dont see that type of dynamics to support it as @Holston_River_Ramblerpointed out.

[Carvers Gap]

13 minutes ago, Holston_River_Rambler said:

Yeah that’s what is confusing me. The models are showing some steady if not dramatic lift. Sort of an overrunning scenario. I would have thought that that would have been frontogenetic since presumably there’s a front nearby but pivotal maps don’t show much in the way of that. There’s something (we probably several things) subtle going on in different levels of the atmosphere that are lifting the moisture. No one culprit, slow but steady. Honestly I kind of like that approach more than the drama of the last storm. At least for my part of the plateau. 

The precip map does not fit the 6hr/preciptype map at all.  I am just tossing the precip map this run.  Overall trend is slightly (edit) south and east.  Seems like models are sensing that cold front more.  With modeling just now dialing this in, I suspect a slight uptick in precip. Would not be surprised if the precip in the northern stream is under modeled.  

[John1122]

6 minutes ago, Carvers Gap said:

@8283 El Nino Baby, I should add that southern TN could be in any of those Grand Divisions.  Northern TN could also be in any of those Grand Divisions.  I live in NE TN about 5 miles from Virginia and likely live remarkably close to @1234snow . If you are on the upper Cumberland Plateau, you are in the snow jackpot most winters.  Great thing about TN is that snow is temporary.  

 

This, and the difference here (N. Plateau) vs NE Tennessee, even at similar elevations, is that you're more likely to see 15+ inch snow events there than here. Here you are more likely to see more different days where snow falls. Tazewell is on the edge basically of the NETN valley and NE section of the Cumberland Plateau. It's the snowiest non-mountain/plateau city in the state with an official reporting station.  

[John1122]

Double post.

[Carvers Gap]

This is probably one of those winter systems(since the cold air is in place) that we could prob use a last minute NW jog.  Though to be sure if it doesn't, I would be 100% fine with Chattanooga finally getting a snowstorm!!!!  One more tic south, and Chattanooga is in this.  It might be already with that Hi-res Euro run.

[TellicoWx]

Here's the sounding over those 3" per hour cells...maybe some of you guys can see what caused it.

[John1122]

28 minutes ago, 8283 El Nino Baby said:

Question related to snow in Tennessee...

As a new resident, I am hoping for a quick education on the geographical areas of Tennessee. I am from California and know that San Jose is considered "Northern California" even though it seems placed in the central part of the state. So when someone on the these forums says "Southern Tennessee, where does that begin? Where does West Tennessee end and Middle Tennessee begin? Where is the upper Cumberland Plateau vs central or southern?

Second question has more to do with snow and altitude. In California, we had storms where it could be in the low 40s and raining in San Jose (80ft), but snowing at 2000 feet in the foothills a couple miles away. Is that same effect present here in Tennessee? Do we get storms where its rains everywhere except for the Plateau and the Appalachian range getting snow? I know in the summer, my location on the plateau  sees temps about 7 degrees lower then McMinnville 30 miles west  of me.

 

 

Here's a video that gives a very basic explanation.

https://www.wbir.com/video/weather/explaining-horseshoe-snow-forecasts-in-east-tennessee/51-5f97bf74-5944-4211-948a-e572cf82db2f

[Carvers Gap]

3 minutes ago, TellicoWx said:

Here's the sounding over those 3" per hour cells...maybe some of you guys can see what caused it.

I don't look at those a lot, but upper level winds are humming along.  Maybe those cells are under the entry point of the jet into the forum area? With winds moving like that, lots of energy in that front.  Kind of out over my skis on that one.  Do you know the answer?

[TellicoWx]

3 minutes ago, Carvers Gap said:

I don't look at those a lot, but upper level winds are humming along.  Maybe those cells are under the entry point of the jet into the forum area? With winds moving like that, lots of energy in that front.  Kind of out over my skis on that one.  Do you know the answer?

I'm actually not sure why it keyed in on those

[fountainguy97]

20 minutes ago, TellicoWx said:

I would set that 12z Euro to the side...it does run an almost convective type cells starting on the southern plateau up the valley. I dont see that type of dynamics to support it as @Holston_River_Ramblerpointed out.

Is it possible those intense cells are hindering the moisture transport into the rest of the precip shield? Similar to what happens when a Miller A gets strangled dry by a line of intense storms along the gulf. (I remember a few heartbreakers that fizzled for Eastern NC because of this) That could be the reason behind the euros pretty weak QPF besides the swath of .5+

[Carvers Gap]

I always like looking at trends once we get within 48 hours or so.  Here are side-by-side comparisons of the 6z and 12z snow and precip totals from the EPS.  Slight move to the south and east.  Snow totals are more robust.  Otherwise, the ensembles didn't change much which is good.  Only downside, at this range the operational would likely catch a trend first.  12z on the left.  6z on the right.

 

[TellicoWx]

2 minutes ago, fountainguy97 said:

Is it possible those intense cells are hindering the moisture transport into the rest of the precip shield? Similar to what happens when a Miller A gets strangled dry by a line of intense storms along the gulf. That could be the reason behind the euros pretty weak QPF besides the few tracks of .5+

Possible...i would think the precip shield would be larger, could see moderate returns..not what the Euro spit out

[TellicoWx]

3 minutes ago, Carvers Gap said:

I always like looking at trends once we get within 48 hours or so.  Here are side-by-side comparisons of the 6z and 12z snow and precip totals from the EPS.  Slight move to the south and east.  Snow totals are more robust.  Otherwise, the ensembles didn't change much which is good.  Only downside, at this range the operational would likely catch a trend first.  12z on the left.  6z on the right.

 

Looks more realistic than the OP