Carvers Gap

The 12z Euro is about to send it late in that run....

Amplified patterns with an NAO and cold…definitely worth watching.

Well, the Tenn sub-forum wins the internet today. You all did good, Flash! Cute as a button. So, if flash is up watching the 0z runs…we know Flash is on the midnight baby shift!!!!

If the cold air mass for Dec 28-Jan 1 verifies, ensembles across the board missed that cold air mass outside of day 7. To me it looks like another one is right after that(roughly Jan 6-7). As John noted, the late December cold snap looks like a dry frontal passage. I would guess higher elevations probably see some upslope if the CMC is correct. It would make sense that the atmosphere would wring out some moisture. One thing in weather, we are rarely going to get perfect placement of every feature on the map. What we want is the feature(which is in our favor) to be the driver. Outside of climatology Jan10-Feb10, it really doesn't want to snow at lower elevations in the Upper South. The base pattern is rain. So, we generally need a little bit of help outside of that window. As is, the pattern in the weeks 2-4 is likely going to have some cold shots, and some warmups. Timing and intensity of any longterm cold snap when/if it returns is TBD. That is why we are tracking what happens after the cold shot to end this year and begin the new one. My guess...models are handling the NAO poorly (duration, intensity, placement). That has occurred more times than I can count. As LC noted, it makes it difficult for models and forecasters to get a handle on things. That is creating wild swings in modeling. It does make sense that at some point, things line-up just enough to send a lot of cold air into the east at some point during January. But really, that is a pretty easy call - it is our coldest month! LOL.

And honestly, after like 20ish days of BN temps....we were long overdue for some warmer weather. I kind of roll with LC. I don't think the MJO is actually having an impact right now...just a really washed out and conflicting signal. I think Nina climatology is driving this. The trough should pull back west for part of the winter due to Nina climatology alone. Then, as the pattern relaxes at some point in January, it may all rush eastward. Very, very complicated pattern in the week 2-4 timeframe right now. The duration and strength of the NAO is likely key. The good thing is that we now know that model feedback has caused two pretty significant errors this winter in the week 2-4 range. As one met noted in another thread yesterday, when models start flipping back and forth....can't really trust that until it settles down. The potential NAO and HL has upended things. We are really one good cutter or coastal from having a pretty massive cold air mass slide all the way to New Orleans. I think we will have a better idea by around Christmas time...

Cutters would help. Where the Aleutian sets up shop as I noted yesterday is what matters. Lots of noted uncertainty ahead. That is what make the hobby both challenging and fun.

The Euro Weeklies control...the majority of that is Jan 10-11. IF that trough slides east due to the NAO, there is a window for strong amplification which we talked about earlier. Just a control run...so TIFWIW. At least two runs in a row of cold temps. If that cold in Canada can ever make its way to the Gulf....sparks are gonna fly IMHO.

I guess the overall trend I am seeing at 12z is the tendency to amplify a trough over the eastern half of the United States. Some models are doing this on the 29th(Euro). Others are doing it with the next system just after New Year's(GFS and CMC). I can see the path to a warmer pattern, but it sure looks like the cold is going to be pay-me-now or pay-me-later...ie the cold is coming with the NAO block in place and it is a matter of time.

The normally warmi-sh Euro at 12z rolled this for the Music City Bowl...I truly hope that is wrong, but it looks like a cold front will possible slide in the evening of the 28th. I am still waiting on my warm-up - I need a short warm-up! This morning is the first morning I haven't run with gloves in a long time...so that is a start.

One other thing LC noted last night was that the MJO has no real clear signal - at least that is how I read it. He has cautioned multiple times about using it recently. He noted it was almost impossible to decipher the phase it was in. He did add that there is room for cold and snow further south after January 20th. I think he has likely nailed this. When I read his original forecast back in the fall, I was like, "Wow. That is really sound reasoning, but it conflicts with so many of the other social media seasonal forecasts." Heck, it conflicted with mine which came out during June of last summer. Veteran forecasters are savvy. And the great thing about the human brain....it doesn't tend to get caught in feedback loops. I think we have some circles of thought where opposing ideas are not allowed to be cultivated. That leads to group think. Back in the fall, Cosgrove produced a forecast where he cautioned that those waiting on winter would have to be patient. It is hard not to look at the deterministic runs at noon, and think they are not gonna be in a good place by the second week in January.

All three deterministic 12z runs bring the trough eastward w/ a mega strong -NAO in place. Larry Cosgrove mentioned that cold could be coming back east by the New Year, but also noted the forecast is incredible difficult during that time frame. We have seen this exemplified as models are swinging wildly from one solution to the other. He notes the NE would take the brunt of this. I do think we are seeing December 28-29th as a step off point towards another cold front of the seasonal variety. That could have a decent amount of amplification with it, so it will need to be watched. It is what happens immediately after that which I think will determine the first weeks of January. 12z has a good look. I think the NAO is making its presence felt on modeling now. I normally defer to ensembles, but maybe not this time. I think ensembles are way behind the curve on this pattern right now. It is unusual for that to happen, but it does occur w/ complex setups. The Euro control and its ensembles(for the Weeklies) were night and day yesterday. I think this is one of these patterns which would be easy to over analyze. For now, I just admire the wild solutions that are out there. Kind of fun! I personally think the end game of this is very cold air getting dumped into the Lower 48. The mechanism is in place to unload a majorly cold airmass southward. We may not have a long lead for when this occurs. Things to watch as we go forward....strength and duration of the NAO. It is the counterbalance to the Aleutian low.

The 0z Euro, 0z CMC, and 6z GFS all move a trough into the East which looks to possibly have some staying power. The CMC is much quicker and the GFS is the slowest. But they all get tend get to a similar point. Starting to be concerned the Music City Bowl is going to be cold.

@John1122atmospheric river alerts are posted for Mammoth later in the week. The webcams should be hopping.

The 18z GEFSAI and EuroAI are the first ensembles for flip. Let’s see if they stay that way - much cooler since yesterday I think.

The Euro Weeklies control had an EPO ridge, NAO, and trough east of Hawaii.

The control run of the Weeklies looked like this…the best run of the season for the control,

FWIW, the Euro control Weeklies looked just fine…even bullish on cold.

The good thing is the Weeklies have been pretty awful this winter so far. I don’t think ensembles will handle this pattern well quite yet. Reference my post above.

FTR, I don't think we go 1985. That is its own benchmark kind of like March 1993. We perch that year on the mantel and just take it down to look at when we get bored or want to reminisce. I have had that in the back pocket for several, several days. It is why I simply refuse to let the likely brief chinook bother me. A raging NAO took over that pattern above just after the New Year, and brought the hammer for two weeks. It was the one time in my life that I was ready for spring at the end of January. I think what is coming has yet to be defined by d10+ modeling. If the NAO takes over, we are good. If it is one-hit-wonder, the rotten Pac could take back over. But the NAO is so difficult for models to handle. It is interesting tracking with it on the table. To me, I kind of think a back-and-forth pattern witch some strong cold shots looks likely.

And if I showed you all this December analog, you might not be enthused. I can only imagine the number of folks who would have canceled winter had the internet been around. It looks almost identical to the last 10 days models for this December. That is ->

Jan and Feb 1996....I don't mind ridging into the Aleutians. Recently, that hasn't been a good thing. Historically, it isn't bad. January 2015 had it. But look at January of 1996. We kind of want hp to not be centered on top of the Aleutians. But AN heights in the Aleutians can be really good as long as it is centered to one side. The ticket is getting a trough to slide in over Hawaii or just to the east of it. A lot of great patterns flirted with disaster at times(torch).

Here is the difference between the mean and actually what the individual members depict. As is, that not a slam dunk warm pattern. Many of those are BN for temps or headed that way within the next slide or two. When you look at the mean, it is easy to assume that we are headed for a warm pattern. It is why the deterministic models have to be given a bit more weight than normal.

IDK. There are definitely some colder winters with it there. I was surprised when I went and looked last year. There has to be Atlantic help to overcome it. It is the rex block which it creates which is the problem, and that (to the best of my knowledge) doesn't form every time. There are some crazy good winters with teleconnections which are out of whack.

If you created a median(and not mean) of temps after d10, it would look MUCH different than the mean on the GEFS. Roughly 5/30 crazy warm members are skewing the temps warm. That means ensembles are stuck in catchup mode.

I really like the BOMM MJO which is shown on the CPC today. It rotates the MJO rapidly through the warm phases. It is sitting in phase 3/4 around NY and that isn't always a bad spot for snow. I don't see any model camping out in 6...maybe 48-72 house at the most. There is a bit of trend in modeling to dry out the MC if I heard JB correctly. The signal will still likely be weak. That means other drivers could take over the pattern. That also means the Aleutian Ridge is probably on the clock now.