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Late autumn, early winter model mayhem


Typhoon Tip

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5 minutes ago, Typhoon Tip said:

Which is why a -NAO may and may not be so useful for winter enthusiasts here... 

This is a good opportunity to elucidate my point ... -NAO isn't well-enough understood (for other reasons, like that you stated right there..) and the folks really shouldn't blanked assess things based upon it.  Actual 'blocks' in the NAO domain, particularly west versus east, do decidedly different forcing numbers on the flow compared to large amplitude ridges in that/those vicinity.   

It's probably true for any of those, but the problem with the NAO is that it's effect is "back drilling" ... It more than just seems modeling has trouble assessing how downstream events "back-log" forcing as opposed to when said forcing is driving thing going west to east.  

I keep coming back to a hypothesis that I have where we've been looking at the NAO wrongly all along - it's not the -NAO ..it's stuff going on upstream from NE of Japan all the way to the Alaska sector and then across mid-latitudes of N/A that's doing it, and the NAO just happens to be exhaust (for lack of better words); we keep seeing the exhaust and thinking that's what's doing it. 

I was being snarky and droll earlier, and folks took it the wrong way in this super uptight nervy touchy bastion of emotion co-dependence of winter climate (understood) but I definitely believe the standard model of NAO that stemmed(s) from the 1980/'90s needs some polish. 

Yeah I agree, I think it's better to just look visually at the pattern rather than getting worked up in the numbers of the different indices. If we see a meridional pattern out of the Northwest territories/Yukon with some sort of mechanism for confluence over eastern Canada...whether it is an actual NAO block or just some big vortex stretching its legs down into Labrador/New Foundland....then we can be pretty confident that the bias or "correction vector" as you often like to call it (and it's a useful descriptive term I might add) will point toward the colder/stormier solutions more often than not.

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In any case ... the CDC teleconnectors (as I'm sure some are aware) as of this morning, with the notable exception of the WPO, are really impressive ...heading into the 2nd week of December.  The WPO is off kilter though ... fyi -

I'm sure those that have insider perspectives based upon the EPS can shed light from that source, but the above refers to the GEFs derivatives. 

The CPC's are also very intriguing.. The AO falls off the bottom of the graphical range ...that's really interesting with an on-going neutral/negative temperature anomaly in the stratosphere.  The behavior of the curve(s) almost looks like a warm penetration into the tropopause forced a pancake event ... There have been no antecedent SSWs of any kind; if the mean of the GEFs are correct, that's pretty intriguing what's forcing causing that type of oscillation.  The PNA is less impressive at CPC as the CDC so ...not sure what to make of that.  

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5 minutes ago, Typhoon Tip said:

In any case ... the CDC teleconnectors (as I'm sure some are aware) as of this morning, with the notable exception of the WPO, are really impressive ...heading into the 2nd week of December.  The WPO is off kilter though ... fyi -

I'm sure those that have insider perspectives based upon the EPS can shed light from that source, but the above refers to the GEFs derivatives. 

The CPC's are also very intriguing.. The AO falls off the bottom of the graphical range ...that's really interesting with an on-going neutral/negative temperature anomaly in the stratosphere.  The behavior of the curve(s) almost looks like a warm penetration into the tropopause forced a pancake event ... There have been no antecedent SSWs of any kind; if the mean of the GEFs are correct, that's pretty intriguing what's forcing causing that type of oscillation.  The PNA is less impressive at CPC as the CDC so ...not sure what to make of that.  

Does a closed ULL in the sw states in a split flow, with ridging to the north, cause a fake out in the PNA index?

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17 minutes ago, ORH_wxman said:

Yeah I agree, I think it's better to just look visually at the pattern rather than getting worked up in the numbers of the different indices. If we see a meridional pattern out of the Northwest territories/Yukon with some sort of mechanism for confluence over eastern Canada...whether it is an actual NAO block or just some big vortex stretching its legs down into Labrador/New Foundland....then we can be pretty confident that the bias or "correction vector" as you often like to call it (and it's a useful descriptive term I might add) will point toward the colder/stormier solutions more often than not.

Bingo... both are blocks, ...we just think of 'blocks' in a narrow bandwidth of visualization but a 'trainwreck' works just as well - haha. 

seriously though, my 4th favorite winter of all time 1993-1994, that was like a +NAO that was so dominating that it back drilled it's circulation and sent spokes around that hooked up with flat waves out of the Miss. Valley that kept doing crazy prolific overrunning 2"-10" deals. I may not be totally right about that characterization of that winter but my memory always hearkens to the great +NAO winter of all time.  That was the year that we were up in the weather lab and we had a 10, 000 ' tall sleet column in a storm where it was like 12 F .. there were OES streaks coming into the sleet column - I haven't really seen that since.  

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6 minutes ago, RUNNAWAYICEBERG said:

Does a closed ULL in the sw states in a split flow, with ridging to the north, cause a fake out in the PNA index?

Actually .. no. 

Believe it or not...there is a vague statistical correlation for SW continental "tucked" depressions when the PNA/ridging is bulging in to the NE Pacific.  The problem with that the EPO also has an even more robust SW low correlation (teleconnection) - particularly earlier in the year when wave lengths are still relatively shortened. 

Anyway, a PNA ridge will tend to have a weakness in the geopotential medium in the SW... In fact, if you look at a lot of Kocin et. al. evolution, they often are ally-oops.  An outside or inside slider gets stuck in the SW with the PNA surging over top, and then...later on, it gets eject out (days later sometimes even..) and that runs through the S with the ice storm in Texas and warning in ST L.... then, if we are lucky and timing a polarward wave, look out!   

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PNA ridge is more amplified too on the EPS than last run. The NAO def trended better, but it's considerably more east based than those runs from 2-3 days ago. Not that east based NAOs are bad...we often do very well on them, but not to be confused with bringing back west based blocking.

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Just now, ORH_wxman said:

PNA ridge is more amplified too on the EPS than last run. The NAO def trended better, but it's considerably more east based than those runs from 2-3 days ago. Not that east based NAOs are bad...we often do very well on them, but not to be confused with bringing back west based blocking.

I don't know much about my region as far as what a NAO can do. Is a east block good for my area?. I am from New Glasgow, Nova Scotia Canada.

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1 minute ago, ORH_wxman said:

PNA ridge is more amplified too on the EPS than last run. The NAO def trended better, but it's considerably more east based than those runs from 2-3 days ago. Not that east based NAOs are bad...we often do very well on them, but not to be confused with bringing back west based blocking.

Less suppression possibilities-we take.

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10 minutes ago, leo2000 said:

I don't know much about my region as far as what a NAO can do. Is a east block good for my area?. I am from New Glasgow, Nova Scotia Canada.

I would say an east based block is def better for your area than west based.

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