December 2021 Medium/Long Range Discussion Thread

[nw baltimore wx]

24 minutes ago, Interstate said:

Didn't Potter lose in the end?

Only if you consider getting $8,000 handed to you in 1945 and no one knowing losing.

[Eskimo Joe]

5 minutes ago, nw baltimore wx said:

Only if you consider getting $8,000 handed to you in 1945 and no one knowing losing.

Also, with Potter not having to buy Bailey's Building & Loan, no toxic assets were inherited by the bank. Double win.

[jaydreb]

Safe to say that the 12z Euro wants no part of whatever the GFS is smoking.  

[MJO812]

2 minutes ago, jaydreb said:

Safe to say that the 12z Euro wants no part of whatever the GFS is smoking.  

It's wrong

There is a huge block up north. Nothing is cutting. 

[Interstate]

26 minutes ago, nw baltimore wx said:

Only if you consider getting $8,000 handed to you in 1945 and no one knowing losing.

I guess you didn't see the extended version when they find out and he is thrown in jail and loses everything.

[nj2va]

12 minutes ago, jaydreb said:

Safe to say that the 12z Euro wants no part of whatever the GFS is smoking.  

Yeah, with a massive -NAO that its showing, I'd be surprised if things are cutting like that.  

Also looks like GFS and Euro both showing a -EPO developing (if I know how to read a 500 map correctly).

[Weather Will]

MJO rotates through 7 much slower on the EURO.  GFS has been faster.  At least we may have things to keep half an eye on starting next week.  I have barely seen a sprinkle in weeks!

[Eskimo Joe]

Good news is that it appears the Canadian and GFS ensembles have the cold lasting into early/mid January. Looks like they're trying to get the Pacific to cooperate more, or at least it isn't as hostile. This would imply that we aren't going to wobble back and forth between Lows 50s and Mid 60s for highs....sustained at or below normal temperatures. 

[CAPE]

31 minutes ago, MJO812 said:

It's wrong

There is a huge block up north. Nothing is cutting. 

Yeah must be. It's a meteorological impossibility with a deep trough out west and a flat ridge in the eastern third of the US. Unheard of.

[WinterWxLuvr]

3 hours ago, Wonderdog said:

Brother, I think you should start the thread; call it the Festivus Christmas Storm!

Haha there it is!!! Storm killer

[cbmclean]

2 hours ago, WxWatcher007 said:

Congrats Raleigh?

If you insist, well take it off your hands.

[psuhoffman]

59 minutes ago, CAPE said:

Yeah must be. It's a meteorological impossibility with a deep trough out west and a flat ridge in the eastern third of the US. Unheard of.

We went through a very similar progression to this last winter.  Last year we got a raging Ak vortex for 2 weeks that destroyed all the cold in N America though. This year we’re in better shape if a similar progression happens.  But it requires patience. 
 

Remember in January when we had a similar pattern at range things were cutting only to end up suppressed. We got teased each time around day 4-5 as the south trend happened. Not saying everything will be exactly the same but I wouldn’t discount squashed with that Atlantic look. Doesn’t mean snow though. Things will be deamplifying so it takes a perfect thread the needle track and we’re talking likely more minor threats.  Being downwind the apps hurts even more when a storm is weakening so the gulf and Atlantic moisture are mostly out of the game. 

Good news is what “could” come next.  If this pattern takes the natural typical progression…as the NAO continues to retrograde it will eventually link up with the North Pacific ridge.  Once that happens the trough will end up in the east.  
 

This happened last year but we lacked the necessary cold for DC to cash in.  Imagine a replay of last year but 5 degrees colder.  DC has a 15-20” season easy and that’s a big win in a Nina.  When I talk about how this could work Im still being relative to the fact we’re in a Nina.  If we get a median to avg snow winter there a top 10% Nina outcome and a win imo  

 

[CAPE]

9 minutes ago, psuhoffman said:

We went through a very similar progression to this last winter.  Last year we got a raging Ak vortex for 2 weeks that destroyed all the cold in N America though. This year we’re in better shape if a similar progression happens.  But it requires patience. 
 

Remember in January when we had a similar pattern at range things were cutting only to end up suppressed. We got teased each time around day 4-5 as the south trend happened. Not saying everything will be exactly the same but I wouldn’t discount squashed with that Atlantic look. Doesn’t mean snow though. Things will be deamplifying so it takes a perfect thread the needle track and we’re talking likely more minor threats.  Being downwind the apps hurts even more when a storm is weakening so the gulf and Atlantic moisture are mostly out of the game. 

Good news is what “could” come next.  If this pattern takes the natural typical progression…as the NAO continues to retrograde it will eventually link up with the North Pacific ridge.  Once that happens the trough will end up in the east.  
 

This happened last year but we lacked the necessary cold for DC to cash in.  Imagine a replay of last year but 5 degrees colder.  DC has a 15-20” season easy and that’s a big win in a Nina.  When I talk about how this could work Im still being relative to the fact we’re in a Nina.  If we get a median to avg snow winter there a top 10% Nina outcome and a win imo  

 

I am ok with the pattern progression potential as advertised on the means. Around Xmas though we aren't quite there yet, and a range of possibilities from a storm cutting west/north, to a perfectly timed 'thread the needle' moderate wave, to dry/shredded pos in NW flow are all viable at this juncture. I was just dragging his ass for that stupid post. 

[poolz1]

12z euro ens show the western trough weakening toward the end of the run with the 50/50ish trough becoming dominant.  West based block still going strong....  

 

[BristowWx]

2 minutes ago, poolz1 said:

12z euro ens show the western trough weakening toward the end of the run with the 50/50ish trough becoming dominant.  West based block still going strong....  

 

Who knows….at least it’s not boring.  Every model run is fun to look at…that makes it 100x better than last year

[brooklynwx99]

That much of an anomalous west-based -NAO on a 10-15 day mean is just insane. We should start to see some chances around Christmas into the New Year with shortwaves rolling underneath the block (like the 12z GFS). It might warm up for a bit as the SE ridge pumps for a day or two in that timeframe, but that will be transient if it happens. Models often take a while to see the full effect of the block on the longwave pattern, and the EPS has generally done a horrible job from the start determining the strength of the block to begin with, so I'm not so sure I trust its depiction of the pattern over the CONUS as much as the other ensembles.

The progression of tropical forcing will allow for the PNA region to become much more favorable for larger snowfall chances heading into early January. The GEFS and GEPS show this well as the trough focuses more towards the Rockies and cold air begins to spill into the E/C US as ridging begins to move towards the WC:

That would be all this pattern needs to go from a bit better than average to something with huge potential, and it looks to be progressing that way as of now.

Also, I've been hearing a lot of complaints about temperatures not being cold enough yet (not here, just generally), and I don't think that's as big of an issue as many make it out to be. Usually, when we see these big -NAO patterns, we're late in the season and climo is much more unfavorable temps-wise. However, we're in peak climo, and above normal 850mb temperatures are still cold enough to snow. We don't need big negative departures:

Most of the NE/MA is either at normal or very slightly below average at 850mb, but temperatures are more than cold enough for any system going south of the region. With a pattern that'll allow for that, this is all that's needed to see snowfall events. 

[Eskimo Joe]

@brooklynwx99 great post, very informative. Thank you for your thoughts.

[brooklynwx99]

1 minute ago, Eskimo Joe said:

@brooklynwx99 great post, very informative. Thank you for your thoughts.

thanks! I usually post in the NYC subregion but I figured that most of the time my thoughts are just as applicable down here

I really am quite optimistic about this pattern to close out the month. it's not perfect by any means, but it will provide chances and that's really all you can ask for in late December. early January could be nuts though if the WC only gets a touch better with that -NAO. it wouldn't have to be a big shift at all

 

[midatlanticweather]

As has been the challenge this year, whatever disturbance is coming through @ Christmas time on the GFS seems to be anemic on moisture so we do not see much of anything on this run. I mean, there is some ripple of energy/low pressure.. but moisture starved. I know we need to be watching the pattern, but it would be cool to see something come to fruition from these GFS mirages!

Now, let's see if the pattern looks favorable and not this little wave.

 

[BristowWx]

18z looks similar to the 12z Euro…you gotta laugh.  8 days out.  Who knows

[StormchaserChuck!]

Hey, December 2010 was the most -PNA by a lot, only really comparable to this year since the early 1900s. This was Jan 2011

[psuhoffman]

1 hour ago, StormchaserChuck! said:

Hey, December 2010 was the most -PNA by a lot, only really comparable to this year since the early 1900s. This was Jan 2011

That’s where this is heading Imo.  Most of the analogs to the current pattern point to that being the end of this progression.  Makes sense logically. The ridge that starts in Europe eventually retrogrades until it links with the pacific ridge. Question is do we take more advantage of it than Jan 2011. History of Nina’s with this progression suggests we get snow, probably one “good” storm…but this isn’t a Nino. 96 was an outlier even for an extreme blocking event in a Nina. I have tempered expectations vs what we might expect if this was a neutral or Nino with more stj being likely. So if we set the bar realistically and just root for a good result “for a Nina” I think this will likely perform. But it’s still a Nina so if anyone expects a 2010 type outcome it’s going to be frustrating.  

[StormchaserChuck!]

GFS ensembles is reloading/strengthening -NAO at hr384 and it's reloading -PNA too. I think the reloading -PNA at 384hr is good because otherwise we may default quickly to +EPO. -PNA also keeps a lot of cold air in N.America (,but although that it sometimes than true, more times than not ~60% of the time SE ridge amplifies when that is the case). I do think we will see the Pacific shift in January, maybe Jan 5-10, and I mean as much of a flip as is possible with predominant -PNA cycle present. We seem to be in this law of averages-evening out thing, so there may be a +PNA period in Jan.

 

Don't broadbrush the whole thing because it's Nina, just maybe expect less precip, as that has been the trend since the Summer anyway. 

[BristowWx]

23 minutes ago, StormchaserChuck! said:

GFS ensembles is reloading/strengthening -NAO at hr384 and it's reloading -PNA too. I think the reloading -PNA at 384hr is good because otherwise we may default quickly to +EPO. -PNA also keeps a lot of cold air in N.America (,but although that it sometimes than true, more times than not ~60% of the time SE ridge amplifies when that is the case). I do think we will see the Pacific shift in January, maybe Jan 5-10, and I mean as much of a flip as is possible with predominant -PNA cycle present. We seem to be in this law of averages-evening out thing, so there may be a +PNA period in Jan.

 

Don't broadbrush the whole thing because it's Nina, just maybe expect less precip, as that has been the trend since the Summer anyway. 

You are smarter than me but with a -PNA won’t we see lows cutting continuously regardless of the NAO.  This may not matter for the NE…but the MA will be on the losing side more often than not.  Seems like the -NAO is just keeping a full blown torch at bay.  

[psuhoffman]

47 minutes ago, StormchaserChuck! said:

Don't broadbrush the whole thing because it's Nina, just maybe expect less precip, 

Agree…except that’s kinda the thing.  There is this perception that Nina’s are warm.  But there are 2 distinct types of ninos. Type one is with a flat pac ridge and no blocking.  The flat fast pac flow is related to the lack of blocking.  Those are all out torches across all N America and the worst winters.  See below composite of those Nina’s in the last 30 years. 

but those are actually the minority of Nina’s. About 40%. Most have a more poleward pac ridge at times and or some blocking.  Those Nina’s are actually typically avg to below avg temps here. Below composure of those Nina’s in last 30 years  

But other than 1996 they all had kinda lackluster snow (considering the pattern and temps) because they were DRY!  Warm wasn’t the issue. 
 

Actually…this is a composite of all non Nina winters in the last 20 years WITHOUT the 3 modoki ninos. Those are really the only “guaranteed to be good” enso phase. The type 2 Nina’s are preferable to THIS…

 

If we could ever get either an anomalously active stj in a Nina OR lucky with a few miller b’s like we did in 96, we could see what happened in 1996 again. I just wouldn’t bet on it. But we get plenty of Nina’s where it’s cold enough. Just not wet enough. 

[psuhoffman]

21 minutes ago, BristowWx said:

You are smarter than me but with a -PNA won’t we see lows cutting continuously regardless of the NAO.  This may not matter for the NE…but the MA will be on the losing side more often than not.  Seems like the -NAO is just keeping a full blown torch at bay.  

If the pac ridge shifts east into the epo and you get a epo and NAO ridge then you can get a full conus trough.  

[WinterWxLuvr]

6 minutes ago, psuhoffman said:

Just not wet enough. 

This

[psuhoffman]

Decent agreement for early January 

[Weather Will]

6Z GFS says winter is still on hold.  I guess another two weeks of patience is needed.  Looking back to Thanksgiving, there was a subset of meteorologists that thought the pattern to colder weather would have happened by now.  I won’t say Lucy is holding the football for Charlie Brown yet, but if we get to NYE weekend and we are punting another 2 weeks, I will become skeptical of this pattern change.

[CAPE]

The rest of the month after this weekend should average around normal. That has been the expectation based on the h5 look the ensemble means have been advertising. Take a trip north if you want to experience cold and snow the next 10 days or so.