psuhoffman

I’m optimistic. We will see.

@WxUSAF tonight’s op gfs I think is more indicative of what the ensembles are “seeing” then the bootleg heights issue. From 300-340 there is a full Rex block centered near the southern tip of Baffin with a 50/50 trapped doing loops under it. If anything that should be too much blocking. And yet it rains to Montreal during that period. There is no cold. The flow is blocked. The systems shear out. However...that is the first major longwave trough after the block retrogrades. Imo, like you said, if the blocking persists I think each subsequent wave will likely have a bit more cold to work with. The euro weekly ensembles, however, never quite get to that critical tipping point where there is enough depth of cold to keep storms from either waiting and cutting or shearing out. I agree that’s unlikely. But the gfs shows that it’s a “real” block...and still warm.

Yes...and this is what he was talking about. Get a ridge into the EPO (AK region) and it sends cold continental air down east of the Rockies into the central and eastern US.

I dunno. I’m sure the mean is biased positive some by the warmth near Davis but those are some strong anomalies to get at those ranges from just that. You will never see the ridge signature past 10-12 days due to smoothing on ensembles but when I look at most individual runs and the controls there is legit ridging and even a Rex block at times. Plus with the pac trough where it is we wouldn’t see lower heights into the central and eventually the eastern US in the long range without legit blocking. There would just be a wave 1 signature with full latitude trough on the west coast and a full latitude ridge in the east. I think past day 10 the blocking signature looks real imo. Will it actually evolve that way and can it overcome the pac and a scorched N Amer thermal profile though...?

Agree

We had a nice AO block in Dec though but it was centered northwest of a true NAO block. I respect Tombo and others who are saying it’s just higher heights but I respectfully disagree with that take. First of all it’s impossible to see the ridge in the height lines past 12 days or so due to timing and location differences between members. One might have the block centered over Greenland. Another Baffin. Another Hudson Bay. The ridge meanders around. Those differences smooth it out. Then you add in the outlier members and seeing a ridge signature at that range is not happening. But at the same time those kinds of + anomalies would be unlikely without a ridge somewhere. If it was weak + heights maybe. But to get those kinds of positives at those ranges given the smoothing and outliers would be almost impossible without a ridge somewhere on most members. Also we wouldn’t get lower heights across the CONUS with that pac if there wasnt true blocking. Add in the fact that the control has a true block and when I look at most operationals and individual members they do have blocking the evidence suggests that’s not it. I respect their hypothesis but I don’t see evidence of that. I think the simplest answer is the best. The pac is less then ideal. We begin the period with all of N AM torched. Despite a really good h5 look it thinks we never recover in that regard. History says domestic cold should work in that look. But the eps weekly members obviously think it’s just not going to be cold enough to keep storms from cutting. I think it’s wrong. I’ve seen it run too warm at range. We’ll see

Yea but 82 was very snowy in the mid Atlantic which is more common with a west based NAO block. Sometimes that can favor further southwest then NYC.

I think it’s just smoothing. I’ve never actually seen a strong ridge signature on the height lines past day 12 or so. It’s been the same on ensembles as you pointed out but when I look at the individual members most have a true ridge or even closed Rex block. Take the euro weekly control for instance. These are just a sampling. It pulses and wanes obviously. But looks like real blocking to me most of the run.

Except do you know how many snowstorms we’ve had with that look? We shouldn’t need a PNA ridge and a perfect west based block! Historically a west based block mid winter with a mediocre pac is just fine. I could show you the h5 from our snowiest period ever in 2010. The pac was garbage. I mean at some point all this “well that one thing isn’t totally perfect and that other thing was only 3 standard deviations not 4...” makes us sound like the people in the southeast that have to wait years to hope once every blue moon 25 things line up exactly perfectly to have a chance at snow.

Yea there is a huge disconnect between the h5 and the temps/mslp/precip anomalies/snowfall. Those details all look like a +NAO pattern as I said above. I doubt it goes down that way. But...if we do manage that h5 look and torch with a storm track through the lakes right through it...I think it’s time to be a bit alarmed at what our winter climo might be now.

This H5 equals these temps lol

It's worth noting...the snowfall does NOT align with the H5 look at all...frankly the pattern to the snowfall mean matches a +NAO look more with the greatest +Snowfall anomalies from the upper midwest through Ontario and Quebec. Those are places that usually are warm (for them) and dry in a west based NAO blocking pattern. That said...I will take the H5 look over anything else 100 times out of 100 on a long range prog. Guidance is way more likely to get the large scale longwave pattern correct then any of the synoptic and meso scale details that dictate snowfall. But again...doesn't mean its not worth pointing out the oddity. Let's hope its just an oddity.

Before anyone jumps off a bridge I do NOT take snowfall maps at range seriously....just was posting that for a LOL more then anything else. Of course...come March if we had a west based NAO block all winter and DC doesn't get ANY snow...we can bump this post.

Euro Weekly control manages to have this 30 day H5 look...and not give DC even 1" of snow! LOL I only looked because despite a "weenie" H5 look the snow mean was pretty blah...about 6" in DC and only 10" up here...thats actually below climo snowfall for that 46 day period. So I looked at the control for a clue...I guess if there are runs that manage not to give us ANY freaking snow with that look...lol

The last couple times a SSW obliterated the SPV when the TPV was already weak the ensuing blocking regime lasted quite a while. Even in 2018 when the SSW coupled it set off a -NAO for the next 2 months. Although that was much later so not a great comp. Still I doubt the TPV would recover quickly from this.

All 3 ensembles look the same and pretty good by day 15.

I’m not overly hopeful but wxusaf had a great point the other day. It’s always good when we can see the other side of a bad pattern before it even sets in. And I’ll add it’s always good when we are tracking, even low level threats, during the bad pattern. When I’ve gone back and read threads from good years like 2014 & 2015...there were dead periods and complaining (that should embarrass us looking back) even in those years. I’m not saying this is going to be a good year. But there are signs the base state isn’t totally awful this year.

I’ve noticed the para is a euro clone a lot.

A great look on one side should only require a mediocre in the other.

That's not even cold to boot Ok have it your way

All you do is show 384 hour maps lol That’s not true...sometimes it’s 500 hours

Omg cold anomalies...!!! Lol

They are very unpredictable AND they don’t always couple with the TPV. But when they do it definitely has an effect on the AO. But it’s hard to use something we have such little predictability of usefully for a forecast.

Lot of moving parts. I do think there may be something to this theory. It’s not just Cohen saying it. But it’s also odd that I can remember 4 times recently that a SSW occurred and right before the pattern got suddenly derailed by a huge ridge in the east that originated from the tropical pacific. What just happened this week is eerily similar to what happened in January 2019. What happens after depends though. I’ve read trop coupling is more likely in years with a weak TPV to start so that’s on our side. The last time we had a SSW that coupled in 2018 it initially hurt the progression in Feb (we wasted a strong cold MJO phase wave but then it set up a pretty awesome pattern in March. If we get a similar progression only 5-6 weeks earlier this time...I could live with that! Btw I feel like the end of the 18z gefs needs angel choir music or something. Went all GEPS. Been trending this way for a while but good to see the progression staying locked in time and not getting kicked YET.

I was just ribbing him