Carvers Gap

Been up late at a veterinary hospital and up early! Things this AM look much better than 12z yesterday in regards to the LR pattern. Ensembles are workable. A lot of this hinges on which area of AN heights is stronger. Need both to weaken or the NAO to be stronger. Most importantly, need the big area of AN heights in the PAC to weaken or move closer to the coast. Those two scenarios bring the cold eastward.

The 0z GFS, and I have low confidence in any model right now due to huge swings, is basically showing what occurred last winter. The cold presses and multiple waves run it. That is the best run of the season so far. And with a block in place, that is the potential that is there...suppressed storm track with cold coming eastward in waves.

The 0z GFS is how one would expect that type of pattern to be...cold with multiple chances for ice/snow.

Honestly, that is super close to an long duration over running event. Not quite there yesterday, but a strung out front with ample precip. Night and day to earlier runs.

0z GFS is a vast improvement through 300. Snow(minimal but was a ridge earlier)threat for KY and SW VA on the 30th.

The 18z GEFS is how you would draw up a great winter wx pattern. NO IDEA if it stays there. Prob will change several times more. High in the GOA and building into Canada. NAO is textbook. There is some connection between the Alaskan and NAO block.

I use Pivotal, WxBell, and TT to name a few. I usually watch the models run on Wx Bell, because it is easier to watch trends. The 18z GEFS is a great winter weather pattern after 300. Flipped back from 6z/12z to 0z. Not often you see large scale features bouncing around that much over NA on an ensemble.

Not through with the run yet, but looks like the cold is going to get kicked eastward on the ensemble.

Models have no idea how to handle those two areas of blocking at this range. If the -NAO is stronger, the Pacific is likely weaker. Flip that around and the NAO is weaker. The 18z GEFS definitely accentuated the NAO this run, and temps are much cooler. Actually, the 18z would work really well. One thing that we have to consider is that there is some likely feedback over the West. I

I don't sweat temps(LOL) after d10. Pretty much just look at the trends at 500. Out to about 294, the -NAO is the dominant feature with the are of AN heights in the Pac being weakened. Hints of AN heights in Alaska which is a big change.

Thanks, it was your previous post I remember that from.....knew I had read that somewhere. Any thoughts on the models bouncing around? I do believe this year we see a repeat of November. Fall was warm during the first half and then the cold pattern of November slammed the door shut on that. Almost seems like that is repeating.

GEFS is still running. Looks like both blocking areas are less strong. We will see where that leads. Pac is substantially less strong. Honestly, modeling is just going to be nuts for a few days. I thought it would settle down once the typhoon dissipated. Nope.

7 is tricky for January. I hear it is slightly different for La Nina. The CPC map is cold for 7 when the three month time frame is centered during December, but gets warmer for January. Again, Nina may well be slightly different. Major reshuffle in modeling. No idea where this ends-up. So, 12z flipped warm and 18z flipped crazy wild with a huge EPO ridge. Pattern shake-up likely under way...again, no idea where this heads but it could get wild. Have a good one. If you get a good tweet, feel free to share. Not much to talk about at present as we get ready to ride out a warm-spell after Christmas.

The 18z is the ying to the 12z's yang. If you watch the global wind pattern at 200-300mb, you can see each deepening of the western trough is progressively eastward. Why is that important if true? That means the pattern is progressing eastward. The 18z features a monster GOA positive height anomaly late in the run. No idea where this is headed, but models are all over the place. Likely culprits are a strat warm(no necessarily a split) and also bitterly cold air over the western Canada(likely a feedback problem). Been a wild day of model watching!!!!

When you see a ridge over the mid-latitudes(especially over eastern NA) hook-up with a -NAO....we have seen this for several years, and it nearly always precedes major changes in stratospheric anomalies. The consequence of that coupling is model mayhem and extreme cold dropping into either EurAsia or NA. That is all I have on that. Let's see if that trend continues.

I strongly suspect we are about to see some MAJOR happenings in the stratosphere if that run is even 25% correct. I should have caught that at 12z when the models made an about face. We have seen great patterns during prior years just go poof...usually the strat is getting HOT!

Wild run by the 18z GFS underway just in terms of how cold it is to the previous run. Again, it doesn't hurt to repeat that the ultra cold air in this pattern is playing havoc in concert with two very strong anomalous blocking regimes. Could be a wild next month of weather in terms of extremes in both North America and our forum area.

That was what was said last winter....always safer to go warm. Last winter saw historic cold and snow in western parts of the forum area. I think we will be ok.

If looking for positives, the end of the 12z EPS run looks plausible. I still like the Dec 20-30 as a transition time frame, especially at high latitudes. Jan 1-10 looks cold-ish though I am less confident after the 12z suite. Warm-up third week of Jan, and then maybe we see true winter later in January. Again, similar to last winter for those just to my west. Almost looks like the EPS didn't flip warm as much as it delayed the cold by 48 hours. I can hear the eye roll and understandably so as I share the same concern - cold pushed back again and I agree. But, not uncommon for that to occur. I like the timeframe around New Year's for a transition to seasonal cold with some warm interludes for sure. As Jeff notes, the SER is going to fight all winter. I also agree that the NAO at some point will hook into the wester Pac ridge. I think that is when we score a decent pattern. The EPS has this late.

Looks like the GEFS/GEPS are accentuating the western Pac ridge. Almost looks like a feedback error. My guess is that modeling is not even close to having a solution for the first ten days of January. Not good trends at 12z but a ways to go. Seems like whichever area of blocking is accentuated(even in the slightest), it is moving the trough around by thousands and thousands of miles. On the plus side, the CFSv2 is much colder this run. I just think things are going be all over the place. Reminds me A LOT of last winter.

Same trends on the 12z EPS so far. Might be time to tune-up the lawnmower!

I hear ya. This pattern is an extreme pattern. Just tough to know if we have the bear or if the bear has us! I think we see some cold and snow...maybe a lot of it at times. Warm Decembers usually lead to one of two outcomes - non-winters or big winters. Looks like this is going to be a year when Canada is really cold. I think we see maybe 1-2 severe surges of cold. I suspect the MJO got wonky on the GFS at 6z. CPC's MJO stuff is not available for some models(don't know if those are connected or just a tech issue for them). Saw where Robert had a new post on WxSouth. Anyone have access to it? Not looking for a repost, but just if he thought it might get cold. It won't take but a small adjustment for it to get really cold here. Oddly, I don't want to be in the bullseye for cold right now.

Boy, we had better hope the 6z and now 12z GEFS are not right. 12z GFS never went BN for the entire run. 12z GDPS looks great. I don't think the American suite is handling the block well. Crazy how the model sees it first, and then tries to break it down so quickly. Once the block retrogrades into the Davis Straits and the model gets inside of d12....should see some more cooling in the model. Though admittedly, this feels almost exactly like last winter without the Christmas cold snap. But as Cosgrove mentions, at some point this pattern could send brutally cold air southward.

Bring on the rain in NE TN, it is badly needed. La Nina is doing the work here in terms of low rainfall. I think remember that the Ohio Valley can get a lot of rain during La Ninas. That might be helping middle TN. Rain yesterday helped, but our urban streams are still quite low (as of last night). Not even a trickle was going over the dam at Bays last week.

That is wild. With November being so cold, would have thought they would have recorded at least a trace. Higher elevations here have recorded some.