CAPE

A had a few flakes a a few weeks ago with some weak thing moving though. It was cold and dry so not much.

35 with big wet flakes mixing in with the the rain here.

That has to happen in order to get anomalous cold into the lowlands of the midlatitudes, in particular places that are moderated by proximity to oceans.

A 'torch' in Siberia in Jan is like -20c

As long as the Mongolian High is intact all is well with winter in the Mid Atlantic.

End of the EPS run has a southern stream shortwave moving east with colder air in place.

I'll take the 13z HRRR. Cold with light rain here in Easton.

Sure

Towards the end of the EPS run a bit of a split flow develops as the NPJ retracts and the western US ridge amplifies- the STJ also links up so there might be a possibility of some energy taking the southern route going forward with colder air in place. Nice jet streak in a decent spot. Looking at h5 there is an indication of pieces of energy in the southern stream flow. NS will be busy but with the -EPO/TPV combo in a Nina that's gonna be a thing.

A legitimate NA (omega) block, amped EPO ridge, and a ridge bridge. Hell yeah. Odds of it verifying...

Some flakes in the air at least, maybe a coating in places. Who would complain about that?

My recollection is we were teased with classic Nino looks and NA blocking on the extended products for months, then ultimately seeing it advertised within a couple weeks on ens guidance when it finally went poof. Regardless, my expectation for the evolving longwave pattern is a significant -EPO developing and persisting for the first 10 days or so of Jan, with the Pacific puke induced Canadian heat ridge evolving into a modest -NAO. Beyond that, we shall see.

But we did see this last year, constantly depicted by guidance in the LR, and it never really materialized. Other variables have influence ofc. Last winter (being a Nino)we didn't have the -EPO. I know some others don't agree, but in a current day Nina that is a key feature imo to bring cold/ flatten the SER tendency. We will need at least some help in the NA to slow/suppress the flow to increase our chances of a wave tracking further south, or a hell of a lot of luck. Hopefully we get a modest -NAO period in conjunction with an EPO ridge- which is what we are seeing at the end of the ens runs/ continuing with the extended guidance. Once the cold is in place, it comes down to wave timing, and maybe we get a little southern stream action as well. Drooling over depicted epic blocking possibilities on LR guidance is a fools errand, as usual, imo. Well timed transient -NAO episodes will have to do the trick, and often do in a Nina when we get moderate snow events.

It was epic is what it was. Proper. It developed early in large part from a retrograding Scandi ridge and persisted. True atmospheric block. Maybe next winter we get the elusive Modoki Nino with blocking, and see how it goes.

I'm rooting for 2009-10 style blocking, but I doubt it happens. Guidance has been depicting a -EPO tendency going back months with the seasonal tools. And its happening. That's the reality. Ofc we don't want a +AO/NAO. But if you go back and look at some of the good snow events of recent Nina years, we did have a transient -NAO in some, which helped. A legit HL block is probably not in the cards this winter, but something bootleg/transient could work. Getting back to the early Jan period, most ens/extended guidance depict a strongly -EPO, with a modestly negative AO/NAO. All these features wax and wane, which is not easily detected on a mean. So as usual, we will need some luck with timing. Also seeing hints of split flow with a bit of a southern stream.

The big 3 global ensembles have a significantly -EPO at the end of their 0z runs. Slightly -AO and NAO. GEFS surface temps still a bit on the warm side but the Euro has about average trending slightly below. Canadian a bit colder.

It's a bit wonky the way it forms and as advertised it doesn't become the classic rex block with a low in the 50-50 position(trough is displaced further out in the N Atlantic). No cold air around until the ridge goes up out west. Lets see how persistent it is as we get colder air in place. If it doesn't block/divert the flow and keep HP locked in to our north with storms tracking underneath then it isn't very useful lol. We have seen this pretty frequently in recent winters.

Its snow on the 12km Other guidance has some precip but mostly rain for our area.

lol NAM Someone should start a thread.

Yeah the EPO ridge is the key to getting cold again. The +heights on the panel from your post are mostly a result of the anomalous warmth that builds across Canada in the days prior. Once the EPO ridge develops and colder air starts to get reestablished, hopefully we see a period with the NAO neutral/slightly negative. The very end of the latest EPS/GEFS hinting at it and the Weeklies are depicting this at least for a time in early Jan. That's probably our first potential window.

A week of above normal isnt a disaster.

Both the GEFS and EPS have high pressure pressing southward along the east coast for much of Christmas week with the last bit of Canadian cold hanging on, while the rest of the continent is overcome by the Pacific onslaught and above normal temps. Lucky us!

Understood. Jan 22 was a pretty good month for a big chunk of our subforum though, not just the eastern part. Again, I think what you are referring to at D15 is essentially something transient that resembles a good pattern- not a Nino like pattern that's going to persist. Take a look at h5 and the North American surface temps on the EPS between Dec 28 and Jan 1. At the end of the run you can see the jet retraction/retrograding NPAC trough and the western ridge start to go up. That is the beginning of scouring out the Pacific air from our source region. Now all the extended products could be wrong- but they continue that pattern progression.

That day 15 look is devoid of cold. Those +heights in the NA are a remnant of the bad pattern leading up to it. We can't snow with that. The pattern needs to progress to the -EPO/TPV combo to bring the cold. The risk is cold and dry, but gotta have the cold. The trough will probably broaden/shift west as the ridge axis does(typical Nina). Keep the EPO ridge and time a wave or 2. That's how we win lately in a Nina. Forget big snow. Forget your 40" climo average. Be content with a few light/ moderate events. Beach chase if there is an offshore bomb.