Carvers Gap

I have like the Euro control of the weeklies. Meaning that if the ensemble and the control don't match, that is a problem as the control is often right. It spotted the push back on the colder temps for early December. It wasn't completely right, but there was a warm front embedded that the ensemble didn't see. This is this afternoons December map. I don't use these maps verbatim, but just to get a general sense of what is on the table if the 0z Euro was run past 16 days and all the way to Jan 4th! The ensemble shows this general depiction but MUCH more washed out - seasonably cold. It is also important to remember that seasonal cold at range...is probably colder in reality. -15F departures (relative to norms) is insane for a 30 day map. edit: To me, that is showing signs of the stratospheric warming as the latter part of that run is brutally cold in the lee of the Canadian Rockies. We see that often w/ strat warms. Cold dumps west and spreads east. The last week of this run is almost 40 BN in the Rockies. Notice those aren't reflected strongly on this map...it had to eras some warm departures in those places.

MJO stuff...First off, that is not a warm look for December. In fact, it kind of just crawls through the left side of the plot which is not something we have seen in recent years. It seems like the MJO almost defaulted to 4, 5, and 6. How many times have we seen the MJO hit the wall in phase 6 and not move? It looks like this time it might hit the wall while in the cold phases for once. That "could" mean an extended period of cold. If you like really LR thinking, I have to wonder if it can get through the warm phases(before winter fades) if it exits the cold phases in late December or early January. I think it can...and probably by the last third of January. That would give us two decent shots of cold if one assumes winter comes back during that last week of January. But that second cold shot can be difficult, but the QBO may help us in that regard.

It will change, but the 6z GFS shows the potential for the pattern with a slider late in the run.

The 12z GFS and to some extend the 12z CMC were flirting with an anafront. Worth watching as most modeling is now "seeing" this earlier cold front. Jeff mentioned it in the December thread. But I guess we prob should put the actual storm here(if it occurs).

I don't really do hype. I know the winter weight which Dec 2009 carries. The CPC has been using it to balance out their analog package for a few days. I doubt the entire winter matches this analog, but December(at least the first 2-3 weeks of it) looks like a decent match when compared to ensembles and some LR ext modeling. Kind of uncanny. Two different models with similar outcomes in regards to analog matches. In all reality, those are just MJO matches vs actual analog month matches. That said, pretty sure the QBO was dropping or negative during Dec 09-10.

12z CMC ensemble when compared to the surface temp map of Dec 2009.

Some fun stuff. 2009 has been showing up on the CPC analogs for a few days now. So, I thought I would look at the Euro Weeklies and the 2009 500 map. I centered the Euro Weeklies map on d10-40. If I go five more days, the BN mean shifts eastward more. Some differences, but a decent fit overall. We know what happened after Dec 2009. I threw in the GEFS MJO for good measure.

Ok, you all made me break down and look at the MJO. I really hate looking at that metric. LOL. Well, on pretty much every model it crawls into 7(sometimes 8), loops, dawdles, and stalls. 7 is cold when centered on NDJ. 8 is colder. It certainly looks like, as John and Boone and others have noted, that LR ext modeling is being driven quite early by the MJO. That probably is a good thing considering the MJO is in prime real estate by the end of the month. When it actually arrives into 7-8 is open for discussion. Nearly every model gets there w/ the BOMM and EMON being optimal. It just doesn't want to leave the left side of the MJO plot.

Update.....

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.