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Next week's major storm and beyond


OKpowdah

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i think it blew one inside of 36 hours, honestly. i agree it has had a rough go of it here and there vs. our expectations on the model in recent history.

obviously you know this, but i think sometimes we either 1) over-emphasize what the models do/are and 2) expect the euro to *always* be right and the GFS to *always* be wrong.

they all have their respective values, strengths, weaknesses blah blah.

Strongly agree.

High expectations + Direct effects on sensible weather IMBY. That's what has some people up in arms about the Euro

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John,

1- As depicted by model guidance this is a clear pattern change. It doesn't always have to affect the domain of all your indices. Right now, the change is simply shifting the zonal mean zonal wind maximum equatorward, by a possible split and displacement (at the very least, distortion) of the polar vortex. As you say, we're still in a zonal pattern, but we're shifting the continental-mean gradient south. The NAO and PNA fields will do what they're going to do, and will dictate the evolution of the next several weeks *within* this new base state. If anything, the base state will help to decrease the NAO to near neutral (as the ensembles show).

2- I never said the event next week triggers the pattern change. I said it's a component of the pattern change ... First, the trough amplifies as upstream ridging punches into the vortex over Alaska. Second, as the trough breaks northward, it pulls / consolidates PV energy southward over Canada,

Agree in principle.

My post wasn't really directed at you - though I realize it seemed that way... hehe. No, it was aimed at the general consensus - seems there's an idea out there that "it is a pattern changer"; more at answering to that.

"Bifurcation" (favorite word of mine, nyuk nyuk) of the polar vortex is probably also from a purely statistical point of view expected - The thing is, the PV rarely stays strong for longer than 45-60 day periods and it's run is about up in keeping with that linear argument. Whatever the cause...sure, bring it on. But as I was once discussing with a Dr. of Met - who agreed with me - the AO can also help lead PNA and the way it works is that when the mid latitude gradients increase in response to cold loading, the spatial and temporal placement of storm genesis can then force L/W progressions. It's essentailly the same as tropical forcing from the south, but obviously not related to convection - duh.

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Agree in principle.

My post wasn't really directed at you - though I realize it seemed that way... hehe. No, it was aimed at the general consensus - seems there's an idea out there that "it is a pattern changer"; more at answering to that.

"Bifurcation" (favorite word of mine, nyuk nyuk) of the polar vortex is probably also from a purely statistical point of view expected - The thing is, the PV rarely stays strong for longer than 45-60 day periods and it's run is about up in keeping with that linear argument. Whatever the cause...sure, bring it on. But as I was once discussing with a Dr. of Met - who agreed with me - the AO can also help lead PNA and the way it works is that when the mid latitude gradients increase in response to cold loading, the spatial and temporal placement of storm genesis can then force L/W progressions. It's essentailly the same as tropical forcing from the south, but obviously not related to convection - duh.

Haha, I don't mind it being directed at me. It's how I stay accountable for what I write ;)

I love that word too lol. I wonder what the statistics of the PV strength are stemmed to. In general, strong westerlies provide a wave transport, acting to break down the PV, so there's at least some sort of negative feedback to provide a periodic nature. But yeah... whatever haha.

That's a really interesting idea about the AO leading the PNA. As the gradient increases, we move toward lower wave numbers. So in that sense, it shakes up the longwave distribution. I don't know how to determined how that specifically interferes with the antecedent wave pattern, but something interesting to consider.

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weird...the GEFS mean does not seem to have significant high anomalies over Greenland...maybe the analogs are skewing it?

Yes, I agree those anomalies are too high in Greenland. But it sort of drives home the point of the vortex being surrounded. I think the NAO will be more positive than that.

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FWIW the GEFS was programmed by Steve.

post-33-0-45134800-1325706249.gif

:lmao: in what universe...

Maybe something to consider ... analogs suggest that the modeled developing changes from the North Pacific toward the Pole are historically inherently linked to changes extending toward the Atlantic side...

But actually what the analog mean is showing is bridging a ridge from the North Pacific to Greenland ... where there is no ridge to bridge (Dr. Seuss can jump in anytime now ... lol). The ensemble mean bridges the North Pacific over to the ridging over Russia (which stands alone in the analog mean)

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:lmao: in what universe...

Maybe something to consider ... analogs suggest that the modeled developing changes from the North Pacific toward the Pole are historically inherently linked to changes extending toward the Atlantic side...

But actually what the analog mean is showing is bridging a ridge from the North Pacific to Greenland ... where there is no ridge to bridge (Dr. Seuss can jump in anytime now ... lol). The ensemble mean bridges the North Pacific over to the ridging over Russia (which stands alone in the analog mean)

FWIW I can buy the ridge bridge to a point. It may be a weak draw bridge near the Pole, but I can see that...even the euro ensembles have it weakly. I don't buy a -NAO anytime soon.

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FWIW I can buy the ridge bridge to a point. It may be a weak draw bridge near the Pole, but I can see that...even the euro ensembles have it weakly. I don't buy a -NAO anytime soon.

So you're saying a smidge of a ridge bridge? Could put us in the fridge ;)

Anyway, yeah I have no problem with a bridge; that's part of how I see this evolving, but not into Greenland, into Russia.

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So you're saying a smidge of a ridge bridge? Could put us in the fridge

You are poetic today.

Yeah I can buy that to a point. It's possible the vortex may not allow a total bridge, but I don't think it would change the sensible outcome. 12z EC ensembles rolling out now so we'll see if they continue.

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But will it keep sliding E? Or can it park it's spinny self right over HB

I just want to talk about a storm that will happen in the next days when that happens, all this pattern change jargon, transient, displaced, gradient, etc etc etc, which is about as boring as it can get, will disappear. When this thread is busy it means there is nothing else to talk about. A noreaster would be nice.

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I just want to talk about a storm that will happen in the next days when that happens, all this pattern change jargon, transient, displaced, gradient, etc etc etc, which is about as boring as it can get, will disappear. When this thread is busy it means there is nothing else to talk about. A noreaster would be nice.

True. A lot of this should go into the pattern change thread.

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The EP vectors are still not ideal on most guidance but we are beginning to see some real good signs even down to 50 hpa. These things can take two-three weeks to downwell so I assume we will begin to see some more changes on modeling Day 10 and beyond.

This is not a SSW by "definition" but more of a moderated development which eventually should be the demise of the big vortex over Central Canada.

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The EP vectors are still not ideal on most guidance but we are beginning to see some real good signs even down to 50 hpa. These things can take two-three weeks to downwell so I assume we will begin to see some more changes on modeling Day 10 and beyond.

This is not a SSW by "definition" but more of a moderated development which eventually should be the demise of the big vortex over Central Canada.

How is it defined, then -

Looked like an abrupt insert of both temperature and geopotential flux to me. Interesting.

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