Carvers Gap

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.

I "think" the ridge in the east kind of retrogrades westward....pops, gets beat down, pops up westward until about Jan 8-10 when it hits the best location. I am hoping with that AR out of the way, the trough which forms in the GOA is far enough west to allow the PNA or EPO to form.

After a pretty ho-hum first 240 hours...the 12z Euro slides a slp along the low road.

And you know the blocking is having an effect on modeling when it is trying to snow in Louisiana, Mobile, AL, and in the Panhandle of Florida late in the 6z Euro AIFS deterministic run - this also found on ensemble members of the 6z GEFS and 6z Euro AIFS ensemble. Cold shots like that have not been an uncommon occurrence during recent Nina winters, and is a bit of a thorn for those of us who have been well below snow climatology for several years in eastern sections of the forum. Haha! The 6z Euro AIFS even has snow to the South Carolina coast. So, that should give you all an idea of where modeling went overnight and at 6z.

If we just need things to worry about(other than latitude and elevation), the cold source in Canada is less w/ overnight runs. That means we have to score w/ Canadian and not Arctic air. Thankfully, we are talking January and not mid Feb. The STJ was a bit more active overnight, but a dry pattern would be still on the table I think. The 6z GFS put 4-6" of snow over most of E TN w/ the exception of SE sections. The mountains got nearly 3 feet on that run.