Pattern The Great December Dump

[Webberweather53]

But that's assuming the GEFS way out at the unreliable hour 312 is even close to being right. Look at the major changes that occurred much earlier in the run. That in itself makes this 312 hour map even less reliable than normal.

As for "major" changes that occurred earlier in the run, we're going towards a stronger +EPO as the TPV gets absorbed towards Alaska but the -NAO is also getting stronger at most if not all time steps, so this big -NAO later in the run isn't occurring by chance.









These trends in the GEFS also match the mean height pattern anomaly for the same period which means it's probably more legit than usual.

 

[Ollie Williams]

FWIW the 12z Navgem has a storm in the favorable position

850s say it's now snow though

Link if you want to play around with it
https://www.fnmoc.navy.mil/wxmap_cgi/cgi-bin/wxmap_DOD_area.cgi?area=nvg_conus&set=All

 

[Webberweather53]

As for "major" changes that occurred earlier in the run, we're going towards a stronger +EPO as the TPV gets absorbed towards Alaska but the -NAO is also getting stronger at most if not all time steps, so this big -NAO later in the run isn't occurring by chance.

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These trends in the GEFS also match the mean height pattern anomaly for the same period which means it's probably more legit than usual.

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Without a coherent tropical forcing signal (a nascent one in the Maritime Continent atm) there's no doubt though that this upcoming period thru virtually the end of December is going to be highly tumultuous and unpredictable. The fact that we're getting a negative NAO without any help whatsoever from tropical subseasonal forcing speaks volumes to how favorable our base state is for -NAO (for once). If we continue ticking towards a +EPO in the extended some warm spells would be abound but the northern & central US would likely bear the brunt of the warmth (anomaly wise)

 

[Webberweather53]

The last 4 12z Euro runs have been a total gong show in the eastern US.

Gotta love the continuous flip-flopping from deathly cold to torch near the Great Lakes.

 

[BirdManDoomW]

At least Florida and south Texas is modeled cold consistently. Most weather social media outlets never show them below average.

 

[WxWatch]

More thoughts about the 21st/22nd system. Looking at the GEFS, 500mb heights, it still shows a developing Gulf coastal low that eventually intensifies on the southeast coast.



850mb temp anomalies would support snowfall along and east of the Appalachian Mountains.


2m temp anomalies look to be marginal or slightly below during the 21st/22nd time window. I'd like to it trend colder, but the southeast can still score with snowfall with marginal temps.


Comparing the images above, the ridge over the Rockies would allow mild air to be in place just west of the Appalachian Mountains while the cold air is over Eastern Coast. So, if this were to hold true, there probably won't be much snowfall west of the mountains with the 21st/22nd system. Overall, I think most of the higher accumulating snowfall would be along and east of the Appalachian Mountains (again, if the 21st/22nd does bring snowfall.)

While I was looking over the 12z GEFS MSLP anomalies, I noticed a low develops down in the Caribbean on the tail end of a frontal boundary. This had thrown me off because the GEFS 500mb height anomalies chart does not show this feature. The MSLP anomaly doesn't even show the Gulf low that the GFS/GEFS has been showing. So, will the low develop and track on the Gulf coast? or develop over the Caribbean and intensify off of the southeast coast? Bottom line, the indications of a strong storm system intensifying off or on the southeast coast is present for next weekend. Will it be a snow storm, rain storm? we just don't know yet, but I still wouldn't completely write off a strong east coast snowstorm.



What do you all think about this?

 

[Brick Tamland]

People are freaking out over a pattern like this?

Lol ok.

Most of us would kill to see this pattern coming knocking at our doorstep around Christmas. A pretty classic Miller A pattern is being shown here verbatim.

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this that type of pattern where if things go right, you could get a nice big dog, especially if phasing occurs, easily get amped up storms with that -NAO, just the problem like always in the SE is cold, but we have days to figure that out

I think some are just looking for anything that could possibly go wrong. That's the nature of living here and enjoying snow. But to me it continues to look like we have a lot more to be optimistic about than usual for the remainder of the month if we want to get a winter storm. We have a good team out there, just have to see if they can win the game now.

 

[NickyBGuarantee]

Womp...That’s not what you want to see if you’re hoping for BN temps for the month of Dec.


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Womp...That’s not what you want to see if you’re hoping for BN temps for the month of Dec.


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It was always suppose to be above normal so I’m not too bummed about it .. the chance it ends up below normal is just cool to track

 

[Rain Cold]

I think some are just looking for anything that could possibly go wrong. That's the nature of living here and enjoying snow. But to me it continues to look like we have a lot more to be optimistic about than usual for the remainder of the month if we want to get a winter storm. We have a good team out there, just have to see if they can win the game now.

There are definitely more reasons to be optimistic about this winter than previous recent ones. I think that point has been pretty well made. But discussing the negative or what-could-go-wrong side, is part of the process as well. It's how you learn and how you get more accurate, if either of those are your goal. You like Greg Fishel. One of his primary rules in evaluating winter weather prospects around here was starting with what could go wrong. That is wise. Being negative just to be negative is as silly as being positive just to be positive. You're just wishcasting at that point.

 

[Webberweather53]

This 12z EPS run is giving a nod to the GEFS (again) in the extended. This huge ridge it was showing east of the Rockies by Christmas is getting beaten back significantly (shocker).

There's probably going to be some sneaky northern stream waves that slide underneath this beautiful Baffin Bay block/west-based -NAO that recharge cP air masses into the east-central US during this period around Christmas. These air masses probably won't be extremely cold but might be just marginal enough for climatologically favored areas of the upper south to potentially have a chance if they play their cards right.

Late December imo looks transient & rather uncertain as I noted in an earlier post with potential for cold shots, Miller As/coastal cyclones, and even brief respites/breaks, but hardly looks like a torch.

This is arguably one of the best patterns we've seen at this time of the winter since 2010, which obviously may not be saying much, but I'll gladly take it.

 

[Jimmy Hypocracy]

There are definitely more reasons to be optimistic about this winter than previous recent ones. I think that point has been pretty well made. But discussing the negative or what-could-go-wrong side, is part of the process as well. It's how you learn and how you get more accurate, if either of those are your goal. You like Greg Fishel. One of his primary rules in evaluating winter weather prospects around here was starting with what could go wrong. That is wise. Being negative just to be negative is as silly as being positive just to be positive. You're just wishcasting at that point.

The funny thing is, if you’re negative just for the sake of being negative you’ll still be right more than the snow goober. Like the great PackBacker on the other forum. He was the ultimate miser but was right 90% of the time

 

[Rain Cold]

The funny thing is, if you’re negative just for the sake of being negative you’ll still be right more than the snow goober. Like the great PackBacker on the other forum. He was the ultimate miser but was right 90% of the time

True....but you also have to consider the fact that trying to find ways for things to suck is kind of like wishcasting suckiness. Packbacker was just pointing out what the pattern was showing as opposed to bittercasting it.

 

[deltadog03]

The last 4 12z Euro runs have been a total gong show in the eastern US.

Gotta love the continuous flip-flopping from deathly cold to torch near the Great Lakes.

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When the models are flipping and flopping on every run it tells me really only 1 thing..........Changes are coming, and the pattern is about to get super active.

 

[wxdaniel]

When the models are flipping and flopping on every run it tells me really only 1 thing..........Changes are coming, and the pattern is about to get super active.

Agreed I was hoping someone would say that. Last time the models didn’t stay consistent from run to run it was a significant pattern change in 2016 and the word poller Vortex enter the mainstream media


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[Brick Tamland]

When the models are flipping and flopping on every run it tells me really only 1 thing..........Changes are coming, and the pattern is about to get super active.

Yes, that's why I said a while back that the back and forth on the models is a good thing. We have seen plenty of times where they go from having a storm to not having one, then another model picks it up, and then the former jumps back on board. The back and forth COULD be a good indication of strong possibility of a storm coming our way. I'd much rather see that then all of them showing nothing at the same time.

 

[Webberweather53]

When the models are flipping and flopping on every run it tells me really only 1 thing..........Changes are coming, and the pattern is about to get super active.

Like HM/Masiello, I have always been under the impression that once the +IOD decays & the West Pac forcing takes the driver seat that things could get real interesting around here, what we're seeing now is without any help from the tropics & just a reflection of what's a favorable low frequency base state for -NAO and one that's more receptive to cold.

I've felt this proverbial change of hands in the tropics would probably happen sometime in early January but that remains to be seen.

 

[Tarheel1]

2d m xx

Like HM/Masiello, I have always been under the impression that once the +IOD decays & the West Pac forcing takes the driver seat that things could get real interesting around here, what we're seeing now is without any help from the tropics & just a reflection of what's a favorable low frequency base state for -NAO and one that's more receptive to cold.

I've felt this proverbial change of hands in the tropics would probably happen sometime in early January but that remains to be seen.

How’s the MJO looking? Forecast? If we got phase 1,2,8, and a -NAO, at the same time, that should be epic?

 

[BHS1975]

I just hope the models don’t troll us like last year.


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[pcbjr]

Like HM/Masiello, I have always been under the impression that once the +IOD decays & the West Pac forcing takes the driver seat that things could get real interesting around here, what we're seeing now is without any help from the tropics & just a reflection of what's a favorable low frequency base state for -NAO and one that's more receptive to cold.

I've felt this proverbial change of hands in the tropics would probably happen sometime in early January but that remains to be seen.

 

[GaWx]

"The pattern evolution past the 11-15 Day period are very different depending on the model of choice. The ECMWF Weeklies projects a +EPO pattern with a trough over Alaska and warm ridging over much of North America. Alternatively, the CFS model projects the opposing –EPO, with a ridge over Alaska and a trough centered over Canada. This differing look echoes the lower forecast confidence at longer ranges, especially along the Northern Tier. The differences are not only among the weekly climate models, but in the mid-range Euro and GFS ensembles with respect to the EPO pattern." from Maxar