December 2020 Medium/Long Term Pattern Discussion.

[nrgjeff]

NAM and ARW have that brief 32 degrees up there in Sequatchie county higher elevations. However the ARW-V2 ICON and hi-res EC do not. I'll side with the latter three. Regardless I figure the NAM version is still a non-event; just too brief.

Unlike northeast Tennessee, southeast Tennessee micro-climates are less likely to produce. We don't get any bleed over of Carolina / Virginia CAD - not even at elevation. 

Oh y'all everything could be worse. Folks down in Chile for a TSE. Narrow cloudy area banked up on the mountains is also the totality path. Sunny lee side Argentina does not allow tourists attm. So 2020!

[Carvers Gap]

4 hours ago, nrgjeff said:

Sorry Judah those are bird farts. Continue jostled but tight strato PV. We'll have to hope for -AO in the troposphere. Sorry I'm in Cynic Mode.

There is still hope for after Christmas into early January. While NWP keeps losing sharp cold waves, it's also losing blowtorch days. Variable can get the job done in January.

Yeah, modeling seems to hint at a trough amplification around or after Christmas.  

[John1122]

I saw someone mention that there was another mountain torque event about to happen in east Asia and that the first is what led to the +PNA after Thanksgiving into early December that brought snow and cold to the area.  Hopefully that comes to pass. 

If we can get the PNA to cooperate in late December vs late November those snow chances should become much more widespread and less elevation dependent. Some modeling also that the TPV gets shunted down towards East central Canada and delivers Siberian cold just up stream. Once you start seeing those -20s and -30s heading for the border you have some better source air nearby.  We pulled off snow in parts of the area in late November and those areas were in the upper 20s above zero. 

[Carvers Gap]

4 minutes ago, John1122 said:

I saw someone mention that there was another mountain torque event about to happen in east Asia and that the first is what led to the +PNA after Thanksgiving into early December that brought snow and cold to the area.  Hopefully that comes to pass. 

If we can get the PNA to cooperate in late December vs late November those snow chances should become much more widespread and less elevation dependent. Some modeling also that the TPV gets shunted down towards East central Canada and delivers Siberian cold just up stream. Once you start seeing those -20s and -30s heading for the border you have some better source air nearby.  We pulled off snow in parts of the area in late November and those areas were in the upper 20s above zero. 

Definitely been seeing PNA and/or EPO combos after Christmas in LR modeling.  They may be just a one or two week event, but that would fit what you have read.  I don't know a ton about mountain torque(makes me wonder what our own mountains do downstream after high wind events?), but had read a little as well over the weekend about that.  

[Carvers Gap]

There have also been signs of the NAO and EPO being negative at the same time later this month.  I think one thing we may have to contend with is the MJO going high amplitude into warm phases in mid-late Jan - but that is way, way out there.  I like Jeff's potential window later this month into early January.   Great comments by John as well.

[Holston_River_Rambler]

I think this may have been the convo. John was talking about earlier, for those who didn't see it:

From Griteater:

 

"Going forward, both Anthony Masiello (HM) and Isotherm are honking for January (these are 2 of the best out there for long range discussion):

Anthony - https://twitter.com/antmasiello/status/1338312081926447117?s=20

Isotherm - https://www.americanwx.com/bb/topic/54035-my-winter-outlook-2020-21/?do=findComment&comment=5732631

Anthony is expecting an MJO orbit through phases 7-8-1-2 late Dec thru January - https://twitter.com/antmasiello/status/1337383148112449538?s=20

Here is what MJO Phase 8 looks like in early January on average - suppressed tropical convection in the Maritime Continent (orange/red/white colors), ridge over Alaska / Western Canada / Greenland, trough east of the Rockies:

 

[Carvers Gap]

The only thing that makes me wary, is at one point we had winter storm after winter storm lined-up on modeling through the 18th - poof.  The good thing is that the 18th appeared at one time to be the demarcation point when winter would flip warm.  Looks like that window will potentially quite brief.  All of that said, I have low confidence going forward with really any ideas.  As noted in an earlier post, the MJO might eventually work in our favor.  However, if it takes the tour...it is going to come back to 4-6 eventually.  That said, some empirical wave proportions charts and OLR stuff looks quite good in the LR.  I can see where some are starting to see cold on the horizon.  I just don't have confidence about duration - would lean cold through mid-Jan with a thaw...and then maybe one last ride in Feb.  I think we could all live with that.  

Of note the Weeklies look good for 3-4 weeks before flipping decidedly warm in the East....take with a grain of salt as they have been pushing pack the warm-up.

[Carvers Gap]

There are continued hints right now of a strong amplification of an eastern trough between Christmas and Elvis's birthday - that has been discussed by many including Jeff.

[Mr. Kevin]

Hi Carver. This is my opinion. Of course I'm no weatherman but I believe if we can keep the mjo out of amplitude in warm phases, we should be ok. Maybe. It's a very interesting pattern for sure. Of course people will go default to warm in a niña, especially moderate niña, but on occasion we can get a shakeup that tends to not happen like most people think. Not saying it will happen like that but its something to consider. 

[BNAwx]

I believe Carver said (correct me if I’m wrong) that we need a fresh shot of colder air into our area for these currently borderline systems to produce wintry weather outside of the favored elevated areas.  I believe we’ll get that around Christmas give or take a few days.  The question is how long it sticks around and will any trough that develops be oriented in a way that allows the cold AND moisture into our area.  I personally would like any trough to line up SW to NE to give us an overrunning type set up.  I think that’s a good setup to get a board-wide wintry event.   Having a low with a January 1988 path is a lot to ask for these days but it certainly would be nice.

[BNAwx]

Courtesy of griteater.  Euro control Jan 2nd - 29th

Lawd have mercy...

https://mobile.twitter.com/griteater/status/1338685577621872646

[Daniel Boone]

1 hour ago, Carvers Gap said:

There are continued hints right now of a strong amplification of an eastern trough between Christmas and Elvis's birthday - that has been discussed by many including Jeff.

Thank you,  Thank you very much !

[Holston_River_Rambler]

Is Sandy Claws a comin' to town? Is he bringin' his old Polar magic with him?

0z Dec. 25th: 

 

[weathertree4u]

6 minutes ago, Holston_River_Rambler said:

Is Sandy Claws a comin' to town? Is he bringin' his old Polar magic with him?

0z Dec. 25th: 

 

We dont want super cold - wont that shunt all the systems south of the TN Valley?

[Holston_River_Rambler]

12 minutes ago, weathertree4u said:

We dont want super cold - wont that shunt all the systems south of the TN Valley?

It's been so long, I don't remember any more. 

[Holston_River_Rambler]

This is what we really want, always and forever:

 

 

 

 

 

[PowellVolz]

I didn’t look at the date and I was showing my buddy.....”man if that happened we would be talking March 93’ type snow”


.

[Carvers Gap]

8 hours ago, Daniel Boone said:

Thank you,  Thank you very much !

Underrated post right there.  

[Holston_River_Rambler]

I just about cropped it without the date, but thought better of that, lol. It's from Tomer Burg's twitter, I just have it saved to my gifs, for those....special.... moments, when I need a pick-me-up. 

 

To be more serious about the question (cause I kinda feel bad now). After the last couple of years, (and the couple of marginal systems so far this year), I'll take the cold first, and roll the dice with the energy's track. We almost had a bona fide 1 - 3 or 2 - 4" clipper system on one run of the GFS last night.  That would be nice, to have a clipper track across I-40, with no concern for precip type. I really feel like Huntsville, AL needs to not be worrying about precip type, for those of us outside of 2500 feet plus or extreme NE TN and SW VA, to also not worry about there being a problem. 

The 6z GFS was also close to something a little more spectacular around Christmas:

(Compare that to what I posted above). On the surface it looks similar, but it is A LOT messier and uglier than the beautiful phase in 1993. Now that I have been looking at these H5 energy maps for a while, there almost something beautiful or atmospherically perfect about that energy phase in 1993. (many of you will respond, "well no duh," lol)

But the gif in this post, if there was a messy phase of those 2 pieces of energy and it stayed south of us as it went negative, it would likely get the job done. 

 

If you look in the gifs posted by Griteater of the Euro Control (link in BNA's post above) there are some nice opportunities for energy to get south of us again, with the northern stream.  suppling the cold. 

 

 

[Carvers Gap]

LOL.  I enjoyed the Euro Control yesterday so much, I put my comments in the observations thread...BNA has it covered above, so here is my post from yesterday from the obs thread:

Then entire control run(Weeklies) was lit...cold and pretty much built a glacier over E TN.  Incredibly strong NAO signature.  I think the control was pushing 20" over NE TN.  The mean is less enthused...but I am riding the control - LOL.

Give me the Euro Weeklies control for the 500 pattern....like the entire run.

 

•  

[Carvers Gap]

11 hours ago, Carvers Gap said:

The only thing that makes me wary, is at one point we had winter storm after winter storm lined-up on modeling through the 18th - poof.  The good thing is that the 18th appeared at one time to be the demarcation point when winter would flip warm.  Looks like that window will potentially quite brief.  All of that said, I have low confidence going forward with really any ideas.  As noted in an earlier post, the MJO might eventually work in our favor.  However, if it takes the tour...it is going to come back to 4-6 eventually.  That said, some empirical wave proportions charts and OLR stuff looks quite good in the LR.  I can see where some are starting to see cold on the horizon.  I just don't have confidence about duration - would lean cold through mid-Jan with a thaw...and then maybe one last ride in Feb.  I think we could all live with that.  

Of note the Weeklies look good for 3-4 weeks before flipping decidedly warm in the East....take with a grain of salt as they have been pushing pack the warm-up.

I don't have a ton to add to yesterday, so I am going to bump my comments from yesterday.   Bout where I am at the moment....

[Daniel Boone]

Where I've not been in the game like I used to be due to health reasons,  I lost touch somewhat on Model "upgrades".

       From what I've seen so far at this juncture of the cold season, the latest GFS upgrade was way overdone in the modification of its flaws. As someone else noted, it is now the Dr. No..  

       Even with cold air advection and 528 to 534 DM line over our area with -8 850s , 2m T of 1C.  it'll  somehow manage to paint rain .?.. I, of course know that the great Valley does cause us to get the short end of the stick often but, not to the degree of the example here. Maybe it sees the Valley as all Chatt..j/k

      With the latest "upgrade"" I'm really curious to what was programmed into it and where that info/data came from . Mainly pertaining to our area.

      

[jaxjagman]

[Carvers Gap]

MBY is at about 730 days - I think since the last time I have had more than 2" fall at once (off the top of my head).  Not even sure I have seen a decent storm pattern in a couple of years...I may go dig back through the threads.  December 2018 is my last decent storm I believe.  I might have gotten 1/2" with that deal a couple of weeks ago, and that is not a winter storm in my book.   I don't agree with that 13 at lower elevations where people live - nothing against you, Jax, just whoever made that map.  Definite lack of Miller A tracks evident there.

[Carvers Gap]

12z GFS and CMC are really cold later in their runs.

[tnweathernut]

16 minutes ago, Carvers Gap said:

MBY is at about 730 days - I think since the last time I have had more than 2" fall at once (off the top of my head).  Not even sure I have seen a decent storm pattern in a couple of years...I may go dig back through the threads.  December 2018 is my last decent storm I believe.  I might have gotten 1/2" with that deal a couple of weeks ago, and that is not a winter storm in my book.   I don't agree with that 13 at lower elevations where people live - nothing against you, Jax, just whoever made that map.  Definite lack of Miller A tracks evident there.

I sure don't remember being in a winter storm watch up here in northeast TN, but it's possible i missed it with work keeping me busy.

I figured the mountains were the only ones under winter storm watches for the system a couple of weeks back.

[Carvers Gap]

As a caveat, this is not a forecast, but just providing an example of what a cold air delivery system looks like.  This is the very end of the CMC(GFS is very similar)...PNA/EPO ridge(kind of a hybrid), riding into Alaska, AN heights over Greenland.  This opens the door for very cold air.  Again, this is an example and just one option of many which are on the table.  

 

 

 

 

[Carvers Gap]

Ya'll falling down on the job with regard to the Euro.  Is that a cold front inducing snow(and not even going to put the jinx on what day that is!)?   

 

 

[Carvers Gap]

I think these WxBell snow algorithms are way off.  Shows snow on the surface map, but no accumulations....

[Carvers Gap]

Quite the block showing up between d8-10 on modeling over Greenland.