Moving on to mid/late November

[snowNH]

Euro brings in winter days 8-10 and keeps it here AMOUT..Has ens support. Nice to see

How can you say it keeps it here at day 10 if the model only goes to day 10?

I don't think there's any question on a shot of winter days 8-10 but the question is whether it stays here past then.. GFS says no right now

[Damage In Tolland]

Transient.

No

AWT

[snowNH]

No

AWT

Lol take your snow-tober souvenir dilusional glasses off

[CoastalWx]

No

AWT

Embrace patience.

12z Ensembles have a transient cold shot, then warms up a bit....then tries to cool down towards turkey day. It's defintely not a torch pattern as the colder wx is right across the border, but it's stubborn to come so far south with such a -PNA. Early on, we have a huge ridge into AK, but then it weakens after day 9 or so. There is some weak riding into Greenland which is probably helping keep any torch at bay because the se ridge is evident. So overall, we are getting there slowly, but it will be a slow step down process. It's a change from next week...no doubt, but just not there yet.

It's a good thing to wait, as the foundation of white gets laid across Canada.

[Damage In Tolland]

I think it's balls in winter pattern by day 11-12 on

[Organizing Low]

Embrace patience.

12z Ensembles have a transient cold shot, then warms up a bit....then tries to cool down towards turkey day. It's defintely not a torch pattern as the colder wx is right across the border, but it's stubborn to come so far south with such a -PNA. Early on, we have a huge ridge into AK, but then it weakens after day 9 or so. There is some weak riding into Greenland which is probably helping keep any torch at bay because the se ridge is evident. So overall, we are getting there slowly, but it will be a slow step down process. It's a change from next week...no doubt, but just not there yet.

It's a good thing to wait, as the foundation of white gets laid across Canada.

[CoastalWx]

That was sort of Tippish. Burgeoning cryosphere.

[ORH_wxman]

Embrace patience.

12z Ensembles have a transient cold shot, then warms up a bit....then tries to cool down towards turkey day. It's defintely not a torch pattern as the colder wx is right across the border, but it's stubborn to come so far south with such a -PNA. Early on, we have a huge ridge into AK, but then it weakens after day 9 or so. There is some weak riding into Greenland which is probably helping keep any torch at bay because the se ridge is evident. So overall, we are getting there slowly, but it will be a slow step down process. It's a change from next week...no doubt, but just not there yet.

It's a good thing to wait, as the foundation of white gets laid across Canada.

The support for the Nov 18-19 cooldown is def a lot stronger today than previously. Very good EPO develops in tandem with -NAO....EPO relaxes a bit and the cold modifies after Nov 20, but then maybe cold again by T-day hopefully.

[Mr Torchey]

This is classic Kevin, emmy award winning stuff. I hope he is right.

[CoastalWx]

The support for the Nov 18-19 cooldown is def a lot stronger today than previously. Very good EPO develops in tandem with -NAO....EPO relaxes a bit and the cold modifies after Nov 20, but then maybe cold again by T-day hopefully.

That EPO is everything. Once that relaxes, it moderates.

[OKpowdah]

Transient.

[CoastalWx]

Canada is cooling so the source is there which is all I care about for now. Somehow, that -PNA needs to relax a bit or have more ridging into the Aleutians and/or AK. But it certainly is a change from next week.

[OKpowdah]

I think it's balls in winter pattern by day 11-12 on

I'll take that bet.

6 pack of Sam Adams

[mitchnick]

I think it's balls in winter pattern by day 11-12 on

OCT snows produce nothing but evil I tell you

[HoarfrostHubb]

OCT snows produce nothing but evil I tell you

I still have a few weenie piles in my yard. Even a little on my back deck, surprisingly.

All will be gone thursday

[ORH_wxman]

That EPO is everything. Once that relaxes, it moderates.

With a good -NAO, it can hold in the cold air for longer duration even after the EPO relaxes, but its kind of inefficient this time of year with the wavelengths...in December we'd probably hold onto a below avg temp regime even after the initial cold shot Nov 18-19 (if it was December)....in a gradient type pattern. You can kind of see it even now, but its too far north as a little bit of ridging tries to pump heights up here...with longer wavelengths we'd probably get away with it easier.

[CoastalWx]

With a good -NAO, it can hold in the cold air for longer duration even after the EPO relaxes, but its kind of inefficient this time of year with the wavelengths...in December we'd probably hold onto a below avg temp regime even after the initial cold shot Nov 18-19 (if it was December)....in a gradient type pattern. You can kind of see it even now, but its too far north as a little bit of ridging tries to pump heights up here...with longer wavelengths we'd probably get away with it easier.

Yeah I was talking earlier about that..glad you see it too. Would be nice to have in about a month from now.

Those temp anomalies on the east slopes of the Canadian Rockies are really impressive.

[ORH_wxman]

Yeah I was talking earlier about that..glad you see it too. Would be nice to have in about a month from now.

Those temp anomalies on the east slopes of the Canadian Rockies are really impressive.

Euro puts -24C at 850 in British Columbia. That is absolutely frigid for this time of year. That's impressive a month from now.

In Dec you probably see that stuff bleed a lot more efficiently over the lakes and into New England with the longwave pattern we have progged.

[40/70 Benchmark]

i'd rather see that frigid cold build in n/w/c canada for now. conducive to a good snow pack and solid source region later on. no sense in having it drop down into the lower 48 and modify into 45F daytime highs.

This.

I'm fine with what we are seeing....get the source region in shape...I can do without 45* and windy.

Warmth is comfy this time of year.

[weathafella]

I think it's balls in winter pattern by day 11-12 on

Day 22-25 maybe,

[weathafella]

Back in Boston. It's warmer than DC.

[Typhoon Tip]

Back in Boston. It's warmer than DC.

Jer',

That is actually kind of common for these autumn return flow scenarios... The reason this happens less in Summer is because the sun is so intense that what we gain in well mixed conveyor up here, they make up for in insolation. But not always! If the Bermuda sfc ridge is displaced a few degree lat N of normal, they can end up with a S wind up the Del Bay and get ventilation that way; meanwhile, Boston roasts as said wind turns WSW up this way. However, at this time of year pretty much everyone N of ~ ATL, GA is frucked for sun, so the regions are far more guided by advection terms for determining their respective temperature trends. In this case, DCA is closer to the ridge center, where subsidence is limiting vertical mixing.

That is also why sometimes in the winter you can have a low for the day at 11am and high at 11pm - particularly in "blue cold" scenarios that is true. The core of the coldest air passing through drives the thermometers regardless of whether the feable sun is shining or not.

Scott, I dig on the EPO idea; I've been saying for years now that the -EPO relay into N/A is better for getting cold into source regions, whereas the NAO is better at tapping the sap so to speak.

Will, I agree, the -EPO ridge on the ECM ensemble mean from 12z is clear. It is also about 10dm of geo gradient from establishing an bona fide cross-polar transit - not sure that was mentioned or not. It remains to be seen if this signal gets louder in the future means. I would note that the GFS' mean from 12z was also similar in structure, but with less amplitude. Who knows which is right, but the blend is encouraging for loading winter guns. The -NAO aspect has been in the GFS ensembles for awhile now. Going back a few days the nightly comps at CDC have indicated modest to at times moderate (-1 SD) values persisting until after the 20th of the month.

There is a lot of cold air not far away! -30C at 850 covers quite an expanse up N.

I mentioned this in the cryosphere thread... still, I don’t know about “hold” – per se…. Seems rarer, really, to get a 45 straight days of negative anomaly like last year.

That said, I still think that after the 15^th of the month we start to break colder – whether that happens in stages or in a big badass whack remains to be seen.

The lowering NAO however small, still offers a plausibility for lowering the latitude of the westerlies along the eastern Seaboard as a starter.

One note about the EPO. Although the means are negative by D8, currently it is being heavily corrupted by that historically large and powerful extra-tropical cyclone crunching through its domain… So it is hard to get a longer term coherent idea on what the index is up to; when this storm wanes, the index could slip into something perhaps only currently masked - that would likely affect the outlooks in the means shortly there after. It will be interesting to see what takes place. Before this storm though CDC was flagging a colder signal by diving.

The PNA is indeed negative until further notice, but perhaps belying a colder signal because from ~ the 13^th of the month through the end, it rises from -3, to -.5… That is an upward mode change of 2.5 standard deviations! That is giant amount of mass correction for a domain space that it truly awesome in size. In the minimum, it offers less resistance to a –NAO, possible –EPO gang up on the middle latitudes over N/A. (ice storm?)

The other thing is that something mysterious (for lack of better word) is going on… The NH, despite having a lag in sea-ice, is currently boasting the greatest snow cover in decades. It’s everywhere, too. Siberia, Eurasian, western N/A…all in positive anomaly snow.

TPC noted in their 3^rd discussion regarding tropical cyclone Sean that the deep layer temperature structure of the middle and upper levels are unusually cool over the cyclone. This is effectively shifting the feasible tropical sounding down the scale.

It was noted prior to the recent "1 in an 500" October snow storm, the atmosphere over eastern N/A was below average in similar characteristic. I checked the Satellite soundings and this certainly appeared to be the case.

What all this means is that the NH is breaking cold regardless, and somewhat if not out rightly, doing so anomalous with respect to what daily teleconnectors would suggestion.

This is a HUGE intangible …what that means I am not sure is entirely understood. Intuitively, it is a factor that may have some kind of proxy on the pattern at large.

[Ji]

OCT snows produce nothing but evil I tell you

What the hell are you doing in here?

[snowNH]

Interesting tidbit I found from VAwxman about the EPO 4 years ago. Whats interesting is that it was in 2007 as well.

--------------------------------------------

Most folks in the eastern half of the nation focus on the NAO as far as geting things cold, and that is obviously a very important piece of the puzzle, but what often gets overlooked is the ability of ridging in the EPO position to just overwhelm the influence of the SE ridge. Take a look at these 500 mb anomalies forecast for Saturday evening.

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At first glance, you would likely say, wow, what a warm pattern from the Plains eastward, but think again. Let's look lower at the 850 mb anomalies.

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Some impressive cold shown in the Dakotas, but nothing major elsewhere. Take note especially of the anomalies from Kansas City to Chicago... above normal both places. Now lets go to the surface map.

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Whoa! Both Kansas City and Chicago are both in the 20s... well below normal... not to mention the 15-20 below normals farther northwest in places like Des Moines and Minneapolis! Even into the Lakes and Northeast, the cold is way more impressive that one would think from the 500 mb anomalies. This is a classic example of how the Pacific pattern can trump the SE ridge in many areas, outside of the immediate Southeast. A strong ridge in the EPO position with a vortex in eastern Canada and a general positive tilt trough back into the Southwest is ideal for this, as it builds very high pressures over Canada, and these highs push low level cold underneath the ridging aloft (northerly flow in the low levels, but southwesterly aloft). So you have to obviously look at much more than the 500 mb pattern, and as always, watch your source regions!

As a side note, this type of pattern screams overrunning with enhance potential of significant ice storms. See Jan-Feb 1994. No this is not going to be that extreme, but the general setup is not far off, though the ice threat is shifted farther north and west with the current pattern since the SE ridge is stronger this time.

Another side note... The cold air often presses farther south than what models initially show, especially in the mid continent, so something to keep in mind also. Fun forecasting ahead!

[dryslot]

What the hell are you doing in here?

Probably the same thing you could ask yourself..........

[CoastalWx]

snowNH, the NAO can be overrated too. The EPO is what really can drive the cold into the US. However, the NAO is a much needed adversary to beat down a se ridge too.

[mitchnick]

What the hell are you doing in here?

Because I love you.....

[Snowstorms]

I updated my blog on the possible weather pattern thru late November. I tried to make it nice and simple.

http://weatherintoronto.blogspot.com/2011/11/weather-pattern-thru-late-november.html

Any questions or comments will be nice.

[ORH_wxman]

snowNH, the NAO can be overrated too. The EPO is what really can drive the cold into the US. However, the NAO is a much needed adversary to beat down a se ridge too.

Also, a lot of it has to be kept in context for the time of year. A lot of these teleconnectors are muted in the fall vs Dec/Jan/Feb.

[CoastalWx]

Also, a lot of it has to be kept in context for the time of year. A lot of these teleconnectors are muted in the fall vs Dec/Jan/Feb.

Yeah exactly. Wavelengths can be an issue and sometimes the NAO won't mean much if eastern Canada isn't that cold. Obviously, that is more of an issue this time of year.