Carvers Gap

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.

Today's 8-14 analog package from CPC... 19611207 20001106 20001111 19521122 19831124 19671210 20041119 19981106 19711115 19691110 The one that really stands out is the 83-84 winter due to the cold which came early during that winter. It was just brutal. I remember riding to town in our Toyota, and the windows froze up on the inside! @John1122will have to fill in the blanks for the 1960s. Generally, if I see winters from the 1960s showing up...those are gonna have some decent analogs(not all). We may have some others with knowledge of those winters as well. Keep in mind, these analogs are centered-on a warm time frame. So, let's see where these go as we get deeper into winter, and see if we see a particular analog which survives from week to week. I like to look at analogs during forecasted warm-ups. If they turn cold later on, that may tell us something.

We are starting to sporadically see deterministic modeling (at very long range) spotting the potential for a massive EPO/PNA ridge. The 12z Euro is just the latest iteration. That ridge connects to a ridge over into eastern Asia. Europe goes into the ice box which teleconnects well to a cold eastern half of NA. That is the type of nechanism which can send bitterly cold air into North America, particularly the East Coast. Way out there and huge grains of salt.