December 2023 Mid/Long Term Pattern Discussion: Let it Snow!

[Carvers Gap]

Dropping these here for later to see if they verify.....precip is much below normal from the Plateau westward.  It is below normal as well for E TN, but right next to AN...likely signifying snow(snowy areas are sometimes BN for precip on ext models).  Snow track is NE GA to the New England and secondary Midwest.  But give me that 500 pattern, those temps, that HL blocking, and an active El Nino storm track...and let's roll.  Fingers crossed this is legit.   Hard to believe a 46d temp map would be that cold. That would put DJF below normal for eastern areas.

 

[Itryatgolf70]

4 hours ago, tnweathernut said:

Just looking at your ensemble maps at a glance.  The euro and the canadian ensembles look like a recipe for overrunning somewhere down the road.........   Appreciate all the work you put into your thoughts.  I enjoy reading them.  Wish I had more time to dig into things and contribute, but with work I seem to always be pulled in a thousand different directions!

Overrunning will be quite difficult in an El Niño. Not unheard of but not likely imo.

[Matthew70]

1 hour ago, Carvers Gap said:

Dropping these here for later to see if they verify.....precip is much below normal from the Plateau westward.  It is below normal as well for E TN, but right next to AN...likely signifying snow(snowy areas are sometimes BN for precip on ext models).  Snow track is NE GA to the New England and secondary Midwest.  But give me that 500 pattern, those temps, that HL blocking, and an active El Nino storm track...and let's roll.  Fingers crossed this is legit.   Hard to believe a 46d temp map would be that cold. That would put DJF below normal for eastern areas.

 

After the warmup/thaw it will take a lot to erase + temps average across the area for January. Which it’s really not even a thaw.  We have a big soccer showcase mid January here.  Looks like going to be nice temps.  

[Carvers Gap]

1 hour ago, Matthew70 said:

After the warmup/thaw it will take a lot to erase + temps average across the area for January. Which it’s really not even a thaw.  We have a big soccer showcase mid January here.  Looks like going to be nice temps.  

First, the December warm-up is over.  The January warm-up lurks during mid-month, but is not certain.  Details below...

During January, it is much easier to scour out warm air.  It does not want to be warm during Canada during January, and I don't think it will.  Chinooks are not abnormal for Canada, but that has halted.  Canada will be (likely) nearly completely vacated of warm-air by the first week of January and below normal by the second week of January.  It only takes about a week for the entire continent to be flooded with Arctic air.   That means our source regions are likely going to be MUCH different.  

La Nina winters (which you should get next winter) are money for your area - El Nino is tougher but doable w/ your climatology.  Mid-January is a 50/50 call right now in regards to warm or cold.  I would say Jan 12-22 is probably the thaw if pressed....but that NAO develops, all bets are off.   

I had wondered if this would be a thaw when ext LR models hiccuped(as we have to have cold in order to have a thaw).  I think much of E TN will be BN for temps for the next two weeks.  Again, the opening salvo of winter, warm rebounds, and the cold takes hold again....that is what modeling is showing.  Going to be an MJO vs NAO cage match it appears.  We just need to hope the NAO shows up for the fight!

For now, my thoughts on cold are during two time frames:  December28-Jan12 and Jan25-most of Feb.  That can and will change, but those are my thoughts for now.  

[Carvers Gap]

2 hours ago, Matthew70 said:

After the warmup/thaw it will take a lot to erase + temps average across the area for January. Which it’s really not even a thaw.  We have a big soccer showcase mid January here.  Looks like going to be nice temps.  

This is the current run of the 18z GEFS...day one compared to day 15.  IF(stress if) this is correct, that puts much of NA below normal for temps.  More importantly, our source regions will not be where it is red.  Now, keep in mind that those AN temps in Canada are still incredibly cold here at this latitude.  The problem with a warm Canada is that the air modifies more quickly when it originates AN there.  This is a very classic El Nino flip.  How long it lasts is up for great debate!!!!  But I will say that any time it is BN during the heart of our coldest temps, that is very cold air to our north.

 

[Carvers Gap]

Now, I should also add that I am not trying say that we are going to see extreme weather....just maybe seasonal wintry stuff for E TN, and probably slightly BN for points west.  That isn't me being a homer either.  During La Nina winters(unless it is weak), the opposite is true.   Nobody can see the future, so that makes this part of the fun.  But it sure beats tracking what we track last winter which was pretty much a barren wasteland of meh after December.  Again, the MJO and warm phases are a BIG problem if the Atlantic doesn't help.

[Itryatgolf70]

1 minute ago, Carvers Gap said:

Now, I should also add that I am not trying say that we are going to see extreme weather....just maybe seasonal wintry stuff for E TN, and probably slightly BN for points west.  That isn't me being a homer either.  During La Nina winters(unless it is weak), the opposite is true.   Nobody can see the future, so that makes this part of the fun.  But it sure beats tracking what we track last winter which was pretty much a barren wasteland of meh after December.  Again, the MJO and warm phases are a BIG problem if the Atlantic doesn't help.

A true SSW event will trump the mjo, especially if it sends some of it here and mjo isn't higher amplitude imo

[Carvers Gap]

1 minute ago, Itryatgolf70 said:

A true SSW event will trump the mjo, especially if it sends some of it here and mjo isn't higher amplitude imo

That is a debate which could go three pages!  It is highly dependent on which area of the forum one lived as to whether that worked out for them during the last three winters.  The warm phases of MJO were toasty in NE TN during the last three winters - and those were with some version of SSWs.  I was in shorts while you all were trying to keep the lights on.  LOL.

[Itryatgolf70]

3 minutes ago, Carvers Gap said:

That is a debate which could go three pages!  It is highly dependent on which area of the forum one lived as to whether that worked out for them during the last three winters.  The warm phases of MJO were toasty in NE TN during the last three winters - and those were with some version of SSWs.  I was in shorts while you all were trying to keep the lights on.  LOL.

SSW events are exciting if they happen here. Tough to decipher this far out. Southern sliders can benefit us all when they happen. 

[Carvers Gap]

2 minutes ago, Itryatgolf70 said:

SSW events are exciting if they happen here. Tough to decipher this far out. Southern sliders can benefit us all when they happen. 

Yep.  All true.  

[Carvers Gap]

@Holston_River_Rambler, were global ensembles even colder overnight?  Looked to me like a ridge rolls through on the ~9th, and then a colder air mass right after that.  The CFSv2 (I used that to extrapolate past global ensembles) has a warm-up and then brings temps almost twenty-five degrees below normal for early Feb.  I think that must be the strat warm effect.

[Holston_River_Rambler]

Been trying to think if I have anything to add or build on what @Carvers Gap said yesterday, and I just can't add much. Kind of burnt out on models right now. There is just a ton of volatility at range. Yeah that's normal, but there just seems to be some like hemispheric pattern swings out in fantasy land. To me it seems normal to have storms come and go, but I feel like models are decent at the general pattern. IDK, maybe it is the SSW projected is now flopping and that is screwing with things? 

FWIW there is still a minor split, but not at the levels most people look at and show on social media (i.e. 10 mb)

 

I'll also add that recent long range runs are trying to make a second run at a warming. Definitely on the table as much as anything is, but still in fantasy land. 

 

Further down in the atmosphere we've gone from having these hugely anomalous HL blocks the second week of Jan. (NAO, I'm looking at you)

To this look at the end of the 6z GFS:

And look, I at least think I get it. These are OP runs at basically max range, of course they're going to be wrong and flip flop. But that is like a 360 degree flip. Maybe I should lay off the OP juice and stick to the low gravity ensembles, but, IDK, I wonder if there is some sort of pattern shake up in the works around the second week of January. I don't necessarily men locally, but big picture, N. Hemisphere type stuff. 

WRT the MJO, I'm kind of hoping toward dying in phase 3 right now.

Although models kept trying to COD it when it was in 4 and 5 earlier in the month, it did eventually pitter out in 6. TBH, I'm still not sure exactly what the MJO is. Is it a planetary scale process that involves the earth's rotation and Coriolis effect at the equator that is enhanced or suppressed based on SSTs and ongoing convection? I mean I think I kind of get why tropical convection matters, but I guess I just wish there was a way to see where the MJO was based purely on satellites. 

 

 

[Holston_River_Rambler]

Sorry @Carvers Gap what I was writing might seem really weird in light of what you asked before I finished typing it, lol.

 

[Holston_River_Rambler]

I'll take anything to get some cold back in Canada:

EPS:

GEFS:

 

Here is the run-to-run change on the GEPS 850mb temps, don't know how useful one run to run change is, but I decided to try weatherbell, so we can have those gifs now:

[Daniel Boone]

9 minutes ago, Carvers Gap said:

@Holston_River_Rambler, were global ensembles even colder overnight?  Looked to me like a ridge rolls through on the ~9th, and then a colder air mass right after that.  The CFSv2 (I used that to extrapolate past global ensembles) has a warm-up and then brings temps almost twenty-five degrees below normal for early Feb.  I think that must be the strat warm effect.

Yeah, as most of us know, an SSW really fouled us up just as a great pattern was setting up a couple times the last several years. Timing of occurrence I suppose. 

[Carvers Gap]

46 minutes ago, Holston_River_Rambler said:

I'll take anything to get some cold back in Canada:

EPS:

GEFS:

 

Here is the run-to-run change on the GEPS 850mb temps, don't know how useful one run to run change is, but I decided to try weatherbell, so we can have those gifs now:

Yeah, that is it.  Great stuff on all fronts.  I "think" modeling is picking up on the Lower 48's first Arctic outbreak of the winter - maybe right after the 12th.  That may well be the consequences of the SSW disruption which began a few weeks back.  Looks to me like we may well get some of the coldest air in the norther hemisphere to work into the NA pattern.   We are going to see some model chaos.  La Nina's would normally park a SER over us in that pattern...but without the Nina driver, it may well just come in waves.   I think we see a warm-up right after that, a reset, and then very cold air after that.  

I am actually good with just jostling the spv and the tpv.  I don't know if this makes sense, but vs the Arctic just jettisoning all of the cold at once...I prefer it rolling to lower latitudes in waves.  That said, I am growing a bit more concerned that all of it heads south somewhere in a window of Jan25th to Feb 10th.  

[Holston_River_Rambler]

13 minutes ago, Carvers Gap said:

I don't know if this makes sense, but vs the Arctic just jettisoning all of the cold at once...I prefer it rolling to lower latitudes in waves.

I agree 100%. 

[Carvers Gap]

And tomorrow will likely feature lots of snow showers over the forum area with minor accumulations(elevation advantage) as @Holston_River_Rambler pointed out earler.  The 3k NAM definitely has widespread, light snow showers for much of the forum area.  Streamers reach into the northern third of Alabama.  It wouldn't surprise me to see some of this fall as a mix or even light rain, depending on the time of day.  

From MRX this morning:

On Friday, the center of an upper level closed low will be situated
across northern Kentucky/southern Indiana with a surface wave across
central Illinois. An inverted sfc trough will be aligned across
Eastern Tennessee. This upper level low will move east through the
day Friday before elongating in response to phasing associated with
a northern branch north of the Great Lakes. As the past few
discussions have pointed out, this system is fairly moisture
starved. Colder temperatures aloft will promote some instability and
shower activity across the region Friday into Saturday. Coverage
appears to be scattered at best given the lack of moisture. It will
be cold enough for snow showers, especially across the Cumberland
Plateau, southwest Virginia, and higher elevations of East
Tennessee. Snow total amounts remain mostly unchanged with just a
few tenths of an inch across most locations. Slightly higher amounts
(1-2 inches) may be found across the highest elevations where
temperatures will remain colder for most of the event. Eventually
this system will exit the region Saturday afternoon with decreasing
chances of precipitation.

[Holston_River_Rambler]

I was about to post about the NAM 3k. It's a lot more widespread than other models at least to my eye. 

[Carvers Gap]

1 hour ago, Holston_River_Rambler said:

Been trying to think if I have anything to add or build on what @Carvers Gap said yesterday, and I just can't add much. Kind of burnt out on models right now. There is just a ton of volatility at range. Yeah that's normal, but there just seems to be some like hemispheric pattern swings out in fantasy land. To me it seems normal to have storms come and go, but I feel like models are decent at the general pattern. IDK, maybe it is the SSW projected is now flopping and that is screwing with things? 

FWIW there is still a minor split, but not at the levels most people look at and show on social media (i.e. 10 mb)

 

I'll also add that recent long range runs are trying to make a second run at a warming. Definitely on the table as much as anything is, but still in fantasy land. 

 

Further down in the atmosphere we've gone from having these hugely anomalous HL blocks the second week of Jan. (NAO, I'm looking at you)

To this look at the end of the 6z GFS:

And look, I at least think I get it. These are OP runs at basically max range, of course they're going to be wrong and flip flop. But that is like a 360 degree flip. Maybe I should lay off the OP juice and stick to the low gravity ensembles, but, IDK, I wonder if there is some sort of pattern shake up in the works around the second week of January. I don't necessarily men locally, but big picture, N. Hemisphere type stuff. 

WRT the MJO, I'm kind of hoping toward dying in phase 3 right now.

Although models kept trying to COD it when it was in 4 and 5 earlier in the month, it did eventually pitter out in 6. TBH, I'm still not sure exactly what the MJO is. Is it a planetary scale process that involves the earth's rotation and Coriolis effect at the equator that is enhanced or suppressed based on SSTs and ongoing convection? I mean I think I kind of get why tropical convection matters, but I guess I just wish there was a way to see where the MJO was based purely on satellites. 

 

 

I read from a met in the MA forum who cautioned their forum (if I interpreted those comments correctly) not to buy-in to MJO rotations into the warm phases quite yet.  He noted that might be an error in the same vein that modeling was in error last winter when trying to rotate the MJO into phases 8-2-1.   Modeling is definitely struggling with rotating past phase 3.  I think it will, but it is no slam dunk.  One thing the met noted was that as modeling gets closer, it adjusts better as maybe modeling doesn't handle the MJO well during d10-15, but corrects once inside of d10.  That swords cuts both ways...meaning the near range may be colder than originally modeled(much higher amplitude into phase one than was forecast), but w/ the MJO flirting with warmer phases in the longer range...the LR  (d10-15) may not be "seeing" the MJO rotation into warmer phases.  

If the MJO fails to rotate out of the COD (while in the warm phases), and treks back into 7-3, then we may be looking at a significantly long period of cold weather.  That is spitballing on my part, and could be an error.

[Carvers Gap]

Just tagging onto Holston's 3k gif for tomorrow, there is quite a lot on the table in modeling in the short and medium ranges.  I think it is more nickel and dime stuff, but there are some decent passes that a very short NW jog could change to something better.  There are three pieces of energy rotating through next week alone.  The 6z GEFS has this for the full-run snow mean.  Sometimes, I look at the long range, and fail to mention the potential closer at hand.  Not a bad look....and probably means that some members have those slp running inland instead of off the coast.  

 

[Carvers Gap]

And one last map, and it probably deserves to go into banter, but hey, it's the holidays.  This is last night's full-run of the ext GEFS (control).  I don't know what somebody did in south-central TN to make wx model programmers mad, but....LOL.  Anyway, that is the map through Jan 31.

 

[*Flash*]

21 minutes ago, Holston_River_Rambler said:

I was about to post about the NAM 3k. It's a lot more widespread than other models at least to my eye. 

I'm rooting for the 3k to verify. Just seems too bullish. 

[Daniel Boone]

34 minutes ago, *Flash* said:

I'm rooting for the 3k to verify. Just seems too bullish. 

Much of the moisture in the mid/ upper levels was used up with last System , as KMRX noted. However, alot of low level RH so, may be picking up on that being lifted. 

[Carvers Gap]

Another little system rolls through Monday.  It is small, but could have some snow with it north of I-40 in E TN.

[Carvers Gap]

Stellar look on the 12z Euro at 168.

[tnweathernut]

29 minutes ago, Carvers Gap said:

Stellar look on the 12z Euro at 168.

No fair, you are ahead of me.  lol  

Good to see a duck or two on the pond after catching up to you.

 

[Silas Lang]

4 hours ago, Holston_River_Rambler said:

I was about to post about the NAM 3k. It's a lot more widespread than other models at least to my eye. 

Weird, as usually the 12k is more robust due to lower resolution, but it's the opposite this time. From the looks of this, most in Tennessee will at least see some flurries or a snow shower sans the Southern valley. 

[Holston_River_Rambler]

1 hour ago, Carvers Gap said:

Stellar look on the 12z Euro at 168.

Doesn't get more TN Valley than that track

[Holston_River_Rambler]

5 minutes ago, Silas Lang said:

Weird, as usually the 12k is more robust due to lower resolution, but it's the opposite this time.

Yeah that's the weird part of those runs. The only thing I can think of is that the higher resolution is doing something with RH from the still almost entirely unfrozen Great Lakes. 

 

The 18z NAM 3k has pretty good RH values up through 750mb and even in a few select locations in west and southern middle TN up to 500mb: