Carvers Gap

Don't know if I trust ensembles or not...but the Euro AIFS ensemble and GEFS at 18z make a lot of sense, though different on several levels. The 18z Euro deterministic AIFS actually ends up w/ a strong EPO/PNA ridge with split flow. Maybe that is where this is headed. If so, Canada would restock w/ very cold air in days, and set the stage for Cosgrove's last third of January to be frigid. Those seeds seem to be in place in LR modeling. I think we have chances prior to that, but just commenting for Jan 15-31st. Either way, it looks some HUGE back and forth cold/warm swings could be in play....I still kind of think Jan 2 is being under modeled in regards to cold. I will try to update one more time as ensembles finish running....with individual members in an effort to sift through this.

18z (EURO AIFS, GFS, and AIGFS)...yuck. Ensembles appear steady, but that is a big time warming trend across deterministic modeling at 240. I wouldn't call if a flip, but welcome to wx model watching this winter. Yet again, we are likely dealing with feedback...this time w/ an Alaskan vortex which cuts off our cold air supply. That kind of makes sense, but the downstream effects are just model chaos. Do I think it spins up that strong? Nope. It probably is a legit player, but like so, so many other features this winter past d8...it is likely over amped to a point it just ruins the run from a rigor standpoint. Also, we are seeing a trend for the NAO to simply evaporate. That could happen. It is very difficult to model. The good trend is that there is a trend for a western ridge by Jan10. A reasonable model bias(and not feedback) is to break down the NAO too quickly. I am guessing that is in play. But the 18z deterministic suite is about as ugly as it gets, and a complete flip from 0z and 6z. Thankfully, most of that is in fantasy land.

I have always understood that after d10, modeling can be woefully incorrect. However, modeling would still produce a lot of plausible solutions. I just can't escape the idea that something seems really off about wx modeling since late November. I don't know if they are struggling w/ the MJO which is kind of indiscernible at times, or if the cold air is a problem. But we have seen feedback (sometimes really bad at times) and patterns after d10 which make zero sense at all. It literally looks like Jackson Pollack has taken the wheel. I do think the threat of Canada being scoured of cold is growing with each run...right as our pattern gets right. Such is life, and not uncommon during recent winters. But let's remain patient. When modeling is spitting out stuff like this....do we really trust their ouput? Yes, I know it's way out there, but again....even prior to November modeling was at least creating solutions which made since. With the images below, none of that teleconnects. Even spookier, the Euro kind of produced something similar at 12z.

From the MA forum pattern thread...Interesting about the +NAO bias. I am pretty sure that Jon Wall was/is a longtime poster on the SE forum.

I don’t post a lot of tweets, but this saves me from having to cut/paste the analogs and allows me to source the information all in the same post…this is from MA thread.

This is not a bad look for a 30 day mean. The NAO is over the Davis Straits. There is an EPO ridge. BN temps over the northern half of the East with cold centered just a bit to our NE. The Weeklies have been shaky lately so I hesitate to share, but hey…

Thank you. Yes, there are so many great posters here. If I started naming all of them, I would miss someone. They make this subform the great place that it is. Many thanks to them and to you both as well!

This is a really good look IMHO from the 12z suite. The NAO shifts to west based. Ridge forms out West w/ a trough east of Hawaii. Cold source in Alaska. The EPS does go AN for much of Canada, but it doesn't scour it like the deterministic. Plus, medium and LR models haven't been stellar in "seeing" cold. Overall, decent agreement at 500 w/ details obviously scarce at this range. I kind of blend all of those together. Considering everything will be really washed out at this range...not bad.

The 12z Euro...I don't even know what it is doing after 300. In my mind, I am kind of just tossing crazy looks. Hopefully, I am not tossing something that is going to actually happen. But the overall trend at 12z on both deterministic and ensembles is to slide the NAO towards the Davis Straits, build some type of ridging in the NAO/PNA region, Alaska stays cold(good thing I think this time around), and an evolving storm track along the East Coast. I would be really surprised not to see some sort of Arctic outbreak during January. The good thing is there is a bit more juice (precip) to squeeze since about 0z overnight. As @John1122noted, we definitely have to beware of Canada getting scoured. We have seen that during recent winters. I freely admit that could happen. I do kind of think we may see a chunk of that cold get dislodged southward and get trapped under a block until the cold just spins and burns out. I could easily be wrong. If that happens, Canada would stay cold enough.

Kind of a yin and yang look. But if I showed you this....not a bad look. When I toggled to a 5 day 500 pattern, this is what I got. Kind of like putting it in the blender and washing out the craziness. That will work, and it is cold. That storm signal is almost perfect with the low inside Hatteras.

You can see the pattern evolve to coastals on the Euro. I suspect what we see is some sort of TPV get trapped under an EPO/NAO block which bridges across. I just think modeling isn't quite there yet. Models are so very close at 12z. I think we keep the cold...but again, January seasonal will get it done.

I wonder if the reason some of the better winters flirt with the Aleutian high...is that it allows Canada to fill with cold. As you note, the GOA low often floods Canada with PAC air if it isn't far enough west. The good thing is most deterministic modeling is putting a ridge in the EPO region after d10...so maybe the Alaska situation is temporary. The other great thing is modeling is just slaw after 120 hours right now. LOL. I mean it is choose your own adventure. As you note as well, that block "should" get it done. With it being January, we can get by with Canadian cold. A lot of modeling is very close to something good during that first and second week of January.

The fly in the ointment for the 12z Euro (which has a better 500 patter) is the lack of a decent cold source for NA. Both the GEM and GFS don't evacuate all of that air. I "think" we are about to hit a pretty good time frame...but we don't want to lose that cold source.

After 240, the NAO has simply taken over the pattern on the 12z Euro. Really good run after a meh-run by the 12z GFS.

Not sure how I am out to 258 at 500 on WxBell w/ the surface graphics lagging...but that looks like winter storm.