Carvers Gap

The 12z Canadian has similar set up in terms of cold. I would not be surprised to see an anafront system develop if the cold is that strong. The AIFS is 3-4 days later. Modeling is picking up on a strong cold front...timing TBD. The Tenn-Vandy game would be pretty frigid if the 12z GFS/CMC were to be correct.

The 6z Euro AIFS has some company.

Well, well, well...look what the 12z GFS just drug in.

6z Euro AIFS FTW....been wanting to post that all morning. Cloudfare had other plans. Thankfully, systems are slowly coming back online.

D8-14 analogs from CPC today. Really pulling for the Dec 09 thread to be THE analog. 19851121 19561203 19851116 19721207 19641123 20051202 19961113 20081214 20091207 19801203

I recommend unpinning this thread and pinning John's December thread. All deterministic threads(as John notes) have December within their sites.

Thanks, man. Good points as well.

The Weeklies do mirror what @John1122shared earlier in the winter or fall thread(from Grit).

The can kicking has paused...and the control and ensemble are now singing the same song as noted above. They have recently been on opposite sides of things with the control winning the battle! I say that, because we kind of hope the control might be right today. Here the 32 day control run - temps are accentuated BN by heavy snow which falls after the 20th. In general, temps are 10-15 BN regardless of snow cover. This would rival any December cold outbreak. The second is the 7 day ensemble mean which is centered on Christmas. The 500 pattern is nice, especially after the first week of December. LONG way out there, but fun to look at... For those of you who are new OR are visiting from other forums, we often put maps to brainstorm/discuss, admire, or just for future reference. They are NOT forecasts at this range. I prob should have placed this in the winter thread! But.....I already have this ready to go, so will leave it here. If a mod wants to switch it to winter, no problem. Anyway, for new folks (or visitors) we kick a lot of stuff around in this forum. We are often not afraid to be wrong which I think is what makes this a great place. You can take a risk. Another great thing about this subforum is that we have no incentive to drive numbers with posts that you will see on social media which are designed to get clicks. If you see us post a map, we are just adding to the conversation. Never be afraid to ask a question. Unless the poster has a red tag(an actual meteorologist! thank you to those folks!), the rest of us do this as a hobby. Now, we do have a couple of folks here who have chosen not to get a red tag who are also mets. You will figure out who they are pretty quickly. I am definitely not one of those folks - just a fun hobby.

It looks like we "might" (famous last words) have some consolidation w/ the Euro Weeklies. It looks like the cold is delayed, but now holding for the last three weeks of December. Christmas(for now!!!) looks very cold on both the ensemble and control. It has been a while since the ensemble and the control have been singing the same song.

All I can say is this...if you don't see me commenting about the LR pattern, there is a reason for that. LOL. The trend has not been our friend over the weekend. But it is the LR, and things can(and likely will) change again. I still think we go cold, but I don't have a lot of model support nor a lot of confidence in that. Cosgrove has to be feeling good about now - he made a good forecast. No idea if it is right, but it is well supported, and he made that when modeling said otherwise. If forced to make a call for December(and this could change), I would say: Week 1: AN to normal Week 2: transition to normal or cold Week 3: BN Week 4: choose your own adventure book

Fall started early here, then paused, everything turned a muted color of normal fall colors, and then the leaves were blown off with several wind events. And yes, I did my leaves on Thursday and Saturday as well. By Sunday...couldn't even tell the difference! The wind was howling. I did look at the wind forecast prior, but Sunday's wind caught me off guard. I am not doing leaves prior to a wind event in the future. LOL.

I like Grit's posts. Good share. I tend to think we see a warmup in there, but recent LR ext modeling trends definitely support Grit. Interestingly, the analogs we looked at the other day maybe(off the top of my head without looking) seemed to support a mid to late cold outbreak.

We take this and run with it.

Deterministic runs are starting to pick up on a decently cold shot right after Thanksgiving. Still plenty of uncertainty, but cold enough for snow if we time it right.

The CFS seasonal today was wall-to-wall cold for DJF.

The EPS is on an island right now. The Euro Weeklies, after being locked-in for weeks, have flipped to AN temps for week one of December and normal for week 2. It is definitely "can kicking." On the other hand, the GFS and Canadian ensembles and LR ext models have assumed the Euro Weeklies former "cold is king" spot. Welcome to shoulder season modeling. The CFSv2 at lunch was just ridiculously cold w/ the ridge heights and trough lows. We are talking subtropics to the NP. That is not a stable pattern, and probably why we see differences. But....that is a pattern which could deliver insanely cold air into the Lower 48. The December which Boone referenced and 89 would be on the table as ensembles. I "think" cold is coming, but going into battle with the Weeklies flipping doesn't give me great confidence. I often wonder if the Euro Weeklies are about 1-2 days ahead of other LR ext models w/ better data. With the Weeklies trending away from a cold start to December, I would think other LR ext models will do the same during the next couple of days - if they are actually going to flip. BTW, the 500 pattern isn't terrible on the Euro Weeklies, but it isn't cold either. The SSW....has screwed up more than one great cold snap during the past decade. That event often wrecks havoc on modeling and can inflict damage on what looked like a promising event. The SSW....most likely we are looking at modeling bouncing around due to low level cold air being underneath those 500 patterns. Might as well drop a cat in a bathtub - cause all you know what is gonna break loose. Overall, I think cold is coming just after thanksgiving, but with a strong word of caution. FWIW, I generally like the CMC when cold is in the forecast at medium and long range. It often over-does the cold, but it actually "sees" it. I would feel a bit better if the Euro and EPS hadn't been right about this last system, and "at range" to boot. But the GEFS was sneaky good as well - just not the GFS. The GEFS looks like a good compromise for the two weeks after Thanksgiving.

Whew. Not often that I see an ensemble look that cold at range. The 12z GEFS looks similar, but with lighter blues. That is most of the continent. 384 map...so proceed with caution.

The 0z GEPS and 6z(edit...) GEFS are frigid at the ends of their runs today. The EPS is lagging as it kicked the can by about 3-5 days yesterday. It still "should" get there, but have to be careful for the Charlie Brown football deal. When ensembles get that cold, chances start to go way up. Those ensembles are cold for about 75% o NA and almost all of the Lower 48. Pretty impressive.

Just checked. Nope, not December 2020. Though this current projected cold looks remarkably similar in its progression. I am looking for the year where an epic December(way better than what weeklies have now) delayed by about three weeks. It might be that late December/early January cold snap where it didn't snow much - 17 or 18'? I remember sitting in a movie theater and seeing the Weeklies flip warm. I know...get a life right? I had been banging the cold drum for weeks, and it was like someone turned the lights off! LOL. Seems like it has been 7-10 years since that time. I can remember really two places where I connect weather models going nuts(good and bad) and a specific location. The other one(besides the movie theater) is in Hampton. We had been back in the boondocks with no cell service. When we got to the hill overlooking Hampton, I got several texts from @tnweathernutw/ snowmaggedon maps that originally included us. To this day, I hate missing a 12z suite because of that. Those maps were flat out nuts. DC got most of our snow, but the model runs for a few days were epic.

I honestly don't use the MJO much in November and early December. I wonder if modeling is over-emphasizing it. Either way, a delay would probably allow for the cold to last into early January - good recipe! I will say that I track an "eastern" cold shot only to have it dump West...and then come eastward around Christmas. It was delayed by about three weeks. I need to check the thread, but that might be the Christmas Eve anafront year.

The Euro Weeklies today use the first week as a transition week(as opposed to full blown cold) and repay us with cold the rest of the month. I am seeing a bit of a trend to dump cold in the west and then it spreads eastward. We have seen this trend on modeling(and it be correct) more times than I can count during the past decade. The 12z GEPS absolutely slams the cold into the West and it quickly spreads eastward. With all the bouncing around today, this may be a very wicked shot o cold air - lots of bouncing around with very cold air. It is worth noting that the Canadian model suite will often "see" the extreme of cold air first. While the Euro is sidestepping a bit, the GEFS and Canadian ensembles at 12z are quite cool. Remember it is shoulder season and possibly VERY cold air in the mix for December....so no surprise today.

Thanks, @John1122. Great stuff. And JP Estrella looked good last night!

All three 0z global ensembles show the transition to an EPO and/or PNA ridge by very late this month. Operationals don't have it at 0z, but that could easily change. Ensembles are the choice for now. Hopefully, we see further runs over the next 2-3 days which sporadically show major cold out breaks at least heading SE out of Canada along with big highs.