Carvers Gap

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.

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.

Ensembles are also starting to show a bit o a snow signal. @Knoxtronmentioned that yesterday, and that has increased overnight. As early as....Something to watch is the 6z GEFS is picking up a mid-south slider around New Year's. I can't find that at on other modeling, but several 6z GEFS members have it. I wouldn't put too much stock in that one, but it was worth a mention. January 2 still has some BIG differences across deterministic runs. If a model doesn't send it on Jan 2, I am seeing a trend to send it Jan4-5. Pay me now or pay me later type of stuff. Ensembles still have this timeframe as cold as does the GFS/AIGFS suite. Honestly, there are too many winter events to screenshot across deterministic, AI, and ensemble runs this morning. Let's see if that continues as a trend. Definite trends by deterministic models late in their runs to build a western ridge.....Let's see if we can get some of this inside of 5 days.

These are the d10-15 maps, 5 day maps. The transition to this occurs much earlier. If those western Atlantic heights back into the Davis Straits and hook into the EPO.

Really good trends in overnight modeling. Modeling has multiple winter storms. The 0z Euro pretty much goes eastern trough after the Jan 2 cold front w/ one ridge rolling through.

The 0z AIGFS has these maps. Sorry, it doesn't have clown maps or precip types. Use your imagination. Looks like it has a clipper and a WAA event.

Check out this front as it comes through Sunday night...Some places could well have single digit wind chills by Tuesday morning.

I may post slightly less over the weekend(Saturday and Sunday). I am gonna sit back and enjoy watching model run chaos. So, if you see fewer posts...don't assume the modeling has been poor. But I will leave you with this. Some things I see and then I don't post about(hard to believe, right?!). I think at some point, there is a good chance that we see this. LC has been banging the drum for late January into early February. Low and behold, the control shows this today. Have a great weekend, everyone!

Interestingly, one of the most useful models I can find right now is the Euro Weeklies control. It is basically a 4 week extension of the 0z Euro deterministic run after day 15. It has been doing really well if one accounts for its biases - the ensemble weeklies not so much. I haven't been discussing the weeklies as much lately due to their errors and inconsistencies. But again most models past 120 hours are struggling mightily. They are all over the map. One thing the weeklies are signaling is that we are possibly about to enter a very dry time frame. Now, that might sound bad and it could be. However, many of the areas which get snow...that signal will show up as dry. I noticed the CPC analogs are almost all from the 2020s. That probably isn't unwise on their part, but it probably means they are going to be wrong. This winter doesn't remind me of 2020s winters at all. This one has a bit of old school in her bones. And no, I don't want an ice storm either. I don't mind a mixed bag, but I like my lights on. After Helene knocked us out for several days...I am not a fan of running a generator 24/7. During the winter, "no power" is about ten times worse. Pipes freeze. There is no heat. There is no travel.

I don't trust a model past 120 hours right now though I talk plenty about them - that is the fun of tracking, right? As for snow climatology, I am actually AN. Many of you are exactly at normal as climatology hasn't supported snow yet. I know it easy to see places like Indiana, Illinois, and Ohio get snow. That would be like Atlanta comparing their snow climatology to here. Mid-West climatologyis definitely NOT our climatology or standard here at any time of the year - not even close. Until models get the NAO/AO/EPO/PNA situation worked out....gonna be a slog in regards to figuring things out. My rule of thumb right now is that if any model sees a cold front...it likely verifies. Again, go to ensembles members and count them. Try to find the median for a run (not the mean which could be skewed) and look to see if that number increases as time gets closer. Right now, the GEM and counting ensemble members is about the only way to go. As for Nina...again, middle and west Tenn have taken E TN to school during the past several Nina winters. Nina winters have tempered the snow drought in those areas which had been huge. NE TN is in a significant snow drought as are portions of SW VA. Members this way just don't say much about it. Weak Nino and Nina winters(this is one!) are when NE TN peeps score....so I think this winter might end up differently due to the QBO. Remember, the end of January and February is a month when wavelengths shorten. That adds more opportunities than the dead of winter. I think the biggest obstacle going forward is below normal precip and not temps. So, if you need something to worry about...that is the fly in the ointment and has been for several days on modeling. @Holston_River_Ramblermentioning the STJ as key is an underrated post. I think we have a warm-up sometime after the 6th, but I can't really perceive when as that window is probably a good snow window as well. For now, it looks like several cold fronts dropping down. Most of these fronts have been correcting southward and stronger as the day nears - let's see if that trend continues. But again, until we know the duration and intensity of the NAO and any subsequent ridge out West...very tough call but I lean seasonal right now w/ a mix of warm and cold days. In about two weeks, seasonal will get the job done. The "now you see it and now you don't" Aleutian ridge runs are not helping models after day 8!

Just uncanny that you all talked about the 1982 ice storm, and the 18z GFS rolls with that slider w/ ice on the south side. FWIW, the 12z GEM had almost the exact solution. Long way out there at 200 hours, but it is inside of d10.