Teleconnections: A Technical Discussion - Page 31 - Teleconnections, Atmosphere, Arctic, Climate Change - 33andrain Jump to content
Snowy Hibbo

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1 minute ago, Singularity said:

Hi @33andrain - true that they've got the diving trough across the eastern US, but it's not as sharp (i.e. narrow in west-east span of low heights) as it ought to be - though EPS is arguably still pretty close. The effect is more pronounced for NW Europe as you can see when comparing the three anomaly maps you've shared.

 

Also looking for a stronger HLB signal emerging over the Arctic by the final days of the month; too many ensemble members not really going for this yet hence the mean +ve anomaly is a bit faint.

Got it. As always, thank you for sharing your thoughts!

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Has the +QBO descended down to the tropopause yet(and thus become Westerly as opposed to Descending Westerly)? If not, when do you guys think it will?

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34 minutes ago, Isotherm said:

 

 

 

 

Hi, Mike -- thanks for the kind words. 

 

You and others have been correct that we've definitely seen some positive trends w/ respect to the PNA spike amplitude. To me, more integral is what transpires following the transient spike, and yes, the deamplification as more NPAC energy bombards the coast. This overly active wave-train, in my view, elicited largely from MJO interference, deamplifies the PNA as the 20th short wave is approaching the East Coast [bad timing]. This results in a more "landward" tracking sfc low. If the PNA structure remained stable and amplified upstream during the crucial period of approach toward the east coast, the short wave would be forced to dive farther southeast, before the northward turn. 

 

So, if we see improvements re the wave train and propensity to maintain the PNA longer, we would see better results for the coast. My thinking has been that I doubt it does correct to a major snowfall for the coast, due mostly to the trop. forcing interference.

Understood on all counts. Thanks, Tom. 

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Great post there as well, @Armando S. Glad to see we continue to be on the same page with respect to this pattern.

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1 hour ago, Isotherm said:

 

 

 

 

Hi, Mike -- thanks for the kind words. 

 

You and others have been correct that we've definitely seen some positive trends w/ respect to the PNA spike amplitude. To me, more integral is what transpires following the transient spike, and yes, the deamplification as more NPAC energy bombards the coast. This overly active wave-train, in my view, elicited largely from MJO interference, deamplifies the PNA as the 20th short wave is approaching the East Coast [bad timing]. This results in a more "landward" tracking sfc low. If the PNA structure remained stable and amplified upstream during the crucial period of approach toward the east coast, the short wave would be forced to dive farther southeast, before the northward turn. 

 

So, if we see improvements re the wave train and propensity to maintain the PNA longer, we would see better results for the coast. My thinking has been that I doubt it does correct to a major snowfall for the coast, due mostly to the trop. forcing interference.

 

n4iq0l.png

 

 

Does that also mean the trough could lift out before it has a chance to give Central Florida a freeze next Monday?

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6 minutes ago, Singularity said:

I've been trying to understand what the likes of GFS, FV3 and GEM are up to with the Canadian lobe in the troposphere... in stark contrast to ECM and to a lesser extent UKMO which both follow anticipated trends with time very nicely (well, ECM maybe a bit fast?), they're somehow managing to keep it very dominant with not much in the way of Arctic highs to disrupt it.

 

I read observations from various strat guys on the web it was the Euro that did best in forecasting the reversal and the split.  It appears to have a good handle on things to me.  

 

Seems  from a forecasting view only, the GEFS does well picking up on high lattitiude pattern changes, just as well as the Euro. 

 

As for the Euro being fast,  not sure. Certainly the progression of the Euro/ EPS to the weeklies matches Isotherm's thoughts on the increased blocking and favorable sync in the atmosphere later this month and in Feb.,  and maybe into March. 

 

This morning I see more indications of downward propagation from Judah Cohen thisd morning where he states the GFS is getting more emphatic about downward propagation.  

 

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Some great replies of late...

 

Just a few thoughts and comments, but with mid-winter, meteorologically speaking, now here I think what needs to be acknowledged is despite the understanding and importance of the AAM/GWO/GSDM (take your pic) in the winter, just like any aspect of forecasting it has the ability to be wrong. There seems to be something of an underlying theme that the AAM etc is the 'be-all-and-end-all' when NWP output isn't really being of much use. Clearly, the theories and physics behind the AAM and how it can influence the evolution of the tropospheric patterns can't be discounted of course, that's not what I'm suggesting at all, but, again, there's still room for this to be wrong. That seems to have been the case, at times, this winter. With such 'strong' background signals at times, especially around the mid-December period, looking forward to the period we are in now, overall some predictions haven't become reality. One primary one that stands out to me is the lack of amplification of the GWO so far this winter...

 

image.png.2104f4cd743122caf7cdd266e583a4b5.png

 

Given a number of posts regarding EAMT and spikes in AAM which clearly have occurred, at times, in recent weeks the end result hasn't always been as predicted. As can be seen from the last 40 days of GWO plots, despite the whole situation of the GWO only taking Relative AAM into consideration, that, to me is a poor plot against what was forecast and what was possible. Perhaps, at times, that has combined with the particularly slow downward propagation of the SSW to influence winter predictions and forecasts, especially with half of January now gone. 

 

Looking forward and, indeed, the MJO and Pacific developments continue to support favorable blocking patterns when using analogs, but these have also failed at times this winter too. That being said with the MJO now moving through P4-5 and likely into 6 then this does indeed support further +AAM trends, perhaps supported by additional +MT events as well. However, the $64,000 question is can we get a greater GWO amplitude, finally, to help the cause? I'm not so sure now...

 

From a UK perspective what has been a pain in the ass is the remnant vortex over N/NE Canada that continues to be a thorn in the side of NWP output, especially now that deep troughing and cold is taking place over the CONUS with resultant cyclogenesis. This is creating all sorts of downstream issues with regards to potential WAA up to the W of Greenland (or not) and how that helps to build pressure within the N Atlantic domain. I won't post all the usual MJO and GWO analogs which match what may well occur over the next 7 to 14 days, the majority on this thread will no doubt have them and know what they portray, clearly, there's one in the last post anyway.

 

There is a lot of winter left, but, again from a UK/NW Europe perspective time does quickly run out and you need a more significant cold synoptic to bring the cold weather that the cold lovers want, I included.  A -5C to -10C 850mb air mass in an N or NE'ly flow in late Jan will have more potency than compared with late Feb/early Mar, for example, that's the way it works over here. Clearly, from a US perspective, that type of air mass is 'peanuts' and easily achievable.

 

It'll be good to review the winter, come late Feb/early Mar just to see how it has panned out against predictions and teleconnection backgrounds. Despite my knowledge of the subject being inferior to others on this forum, I am currently being left underwhelmed, somewhat, by the AAM and the GWO this winter and how it could have or, should have influenced the patterns. The disclaimer here, particularly from a UK point of view is it is always 'close but no cigar', one could argue that between Christmas and essentially present day the blocking regimes have been there, but just a few hundred miles has made all the difference, I certainly appreciated that and understand that of course. It has been a particularly boring winter period, but despite all the background signals at the start of the winter, much of the UK has now progressed to mid-winter without even seeing a signal flake of snow and that includes higher elevations of N England and Scotland. There has been an unusual lack of winter weather which, even in a more zonal winter may well have made an appearance in association with temporary N or NW'ly flows. Blocking regimes are one thing, but it's all about getting them in the right place which I don't think likes of the AAM, MJO et al will help provide the answers, or not IMO.

 

I just do hope, even for my own sake, that between now and the 28th of February some 'proper' winter weather arrives and the synoptics develop as the likes of the AAM, MJO and the SSW suggest that should/could do. I reserve further judgment until the end of the winter period. Equally, once the winter is over I have a great interest in reviewing how the AAM/GWO can influence summertime synoptics, where there links and connections between the AAM the what happened across the UK, last summer, for example, and the extreme blocking pattern there which lead to the warm and very dry summer. But that's for further down the line and another learning curve...

 

Kind regards to all, Matt.

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Thanks David!

I was looking at these this morning and hoping for some input in the forum. 😊

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