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Paul

If you're hunting for cold potential in the model output, this thread is for you. But if you'd like to look more widely at the models, please head over to the general model discussion thread.

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A good ideal there Paul. Think this will be the Cup of Tea for a lot of folk on here chasing a fantasy world of endless cold and snow. Getting excited already !

C

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Nothing really from the overnight ecm run for anyone with a cold bias to get overly excited about with regards to sufficient retrogression of the high pressure cell in order to bring about something distinctly more autumnal. :nonono:

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Whilst your post has some credibility in the fact that the margins of a -EPO high & +PNA high overlap - the loading pattern for a +PNA ridge is a much better teleconnector to an East coast trough than the -EPO ridge as the latter is located further west.

So what is this then?

IMG_5417.thumb.JPG.8279daf541969876a57b518950835b70.JPG

Bottomline, whether the blocking is in the -EPO or +PNA domain, the downstream troughing occurs in Central and Eastern US, with the polar lobe coming down over the Mid West and bringing snow to the Mid-Atlantic/New England.

IMG_5418.thumb.JPG.4e610e5bd7616f67f97029cb9462ad70.JPG

And this further demonstrates the downstream effects.

This is not to say blocking doesn't occur in the Eastern US, during a -EPO. I am just stating that a -EPO is correlated with a trough over the Central and Eastern US.

Quote

In this scenario its 100% clear to see the troughs located in the Northern plains uo to central & you have a fat ridge on the east coast

DDB5B500-59F5-44D7-8EA3-666CBD8506D7.thumb.jpeg.22148bbc36d019730f73e8b32aaf8559.jpeg

That blocking over the Bering Sea isn't what I would call a -EPO, too much leaking into the Far East Siberian region, with the troughing off Western Canada too. That would be the WPO domain.

With a -EPO and +PNA pattern, the below graphic shows Eastern troughing, in combination with other factors.

IMG_5422.thumb.JPG.2066011a7101b217eec7a10593d376e5.JPG

Shows that there can be successful cohesion, which drives troughing on the Eastern half of the continent. 

Quote

Even the teleconnection data shows your wrong

Reanalysis 28 Aug - 10th sept

Huge -EPO RIDGE in a classic Alaska location

Not an east coast trough in sight...

358F4C92-47CF-4186-AD1F-D46BA7114B57.thumb.png.2f01cb60142c657206750afe7c7cc1b9.png

PNA metric

9D6B706E-56D0-4EB9-9B2F-B543418094F4.thumb.jpeg.7753b5412c418dede99de1284e1c1aa8.jpeg

 

IMG_5425.thumb.PNG.07d3d38259183b6f50b44350ea640d8d.PNG

Here was the EPO during your period, first half dominated by a neutral EPO, then a weak-moderate negative phase, then a weakening of the -EPO towards the end. Meanwhile the -WPO was nearly off the charts in strength, so clearly you have picked the wrong domain. The WPO and PNA domains don't cross, nor often correlate. So your statement of "HUGE -EPO RIDGE" is quite misleading.

You also ignored the more -EPO like blocking from the 8-18 Sept this year, which was also a period subject to a +PNA.

IMG_5423.thumb.GIF.3f5801f7e9ccd87dfb40f378f2a707d0.GIF

IMG_5426.thumb.GIF.979066f68a1c4e8153bd988aa51537ed.GIF

 

Edited by Paul
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I sense the first MetO 'epic fail' of the new season might only be a few weeks' away: 'They gave me a red warning and I only saw 45 inches'?;)

Edited by Ed Stone
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Lovely strong blocking high to the west of Ireland next week. This would bring cooler conditions than lately but most importantly would allow the ground to dry out and a lowering of rivers once again after the awful flooding in places here in South Wales last weekend.  

image.jpeg

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Couldn’t resist hacking this (@Paul‘s) thread to add a banner at the top of his original post. :spiteful: 

07ED35D1-83E5-4CDD-B524-4786E6884163.png

Edit: something thing to add (and not sure if there’s been any posts on the particular model): the 00Z GEM attempts to go for a Northerly right at the end of its run with High Pressure amplifying in the Atlantic, though it looks as though the main part of the Northerly dodges the U.K. to the East:

48549534-5912-4E23-9447-772C247C42B5.thumb.png.c3be03032e0ca53ef29c0ca25b1c75e8.png

0842CB46-56E1-462E-B720-603D0393731F.thumb.png.1cd6ac8ee8b0175801c55965e41e9553.png

Perhaps close enough maybe for a high-ground wintry shower or two over Northern and North-Eastern areas. Looks a bit similar to yesterday’s 12Z ECMWF run - albiet that had stronger amplification in the Atlantic and the pattern seemed a little bit further West. 

Mostly for a bit of amazement really as it will, no doubt, change again on the next GEM run.

Whether a Northerly occurs or not within the next ten days will, I think, partly depend how much High Pressure in the Atlantic can amplify. Helped also by upstream troughing/Low Pressure systems digging far enough South to the West of the Atlantic High so the Low Pressure doesn’t steam roll over it. This, along with any Lows that swing down from the North-West on the Eastern side of the Atlantic High going far enough South to the East of the UK into mainland Europe, to provide an Arctic blast for the cold weather fans to drool over. 💦

 

Edited by DiagonalRedLine
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3 hours ago, Snowy Hibbo said:

So what is this then?

IMG_5417.thumb.JPG.8279daf541969876a57b518950835b70.JPG

Bottomline, whether the blocking is in the -EPO or +PNA domain, the downstream troughing occurs in Central and Eastern US, with the polar lobe coming down over the Mid West and bringing snow to the Mid-Atlantic/New England.

IMG_5418.thumb.JPG.4e610e5bd7616f67f97029cb9462ad70.JPG

And this further demonstrates the downstream effects.

This is not to say blocking doesn't occur in the Eastern US, during a -EPO. I am just stating that a -EPO is correlated with a trough over the Central and Eastern US.

Thanks Snowy - yes - this is my take on RJS's early season descriptor and on the pattern as I see it related to the current shape of Nino and AAM trends. Beyond November is really tough at the moment: we dont have a handle yet on the vortex (though Recretos' diagramme in another thread is really interesting, suggesting 2 key long range models seeing a warming again...) and for followers of Cohen's theory it is also 2 weeks too soon to draw a conclusion.

A mid atlantic ridge giving us some frosty conditions into November would be a good start. I'm not particularly keen on the idea of November snow - I've only ever seen it once in lowland England close to me (and it was the last few days of the month) and it lasted less than 36 hours. Let's not waste good synoptics on November! Mid December following a continental cooldown is the start of the sweet spot.. :-)

Steve - I hope you are having a better day today!! All I posted yesterday was a personal opinion based on a starting point of Roger's strong sense that a cold start to the Canadian arctic season is likely to produce a downstream cold East US trough and from there a mid atlantic ridge under high AAM conditions supported by Nino and a high orbit GWO. Let's see if it transpires that way. If November doesnt pan out that way then we havent lost any of the "real" winter season...so everyone stays happy..

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5 hours ago, carinthian said:

 excited already !

C

You won’t be when we are all booking trips to come stay with you due to the mild mush ! I jest ! Fingers crossed for a real winter season ! 

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4 hours ago, Snowy Hibbo said:

 

 

The high pressure over Alaska in September teleconnected to a ridge on the East coast.

Catacol inferred relating to Rogers post & that it would be the default winter pattern a downstream trough on the coast. when infact the east coast had no troughing.

Simple as. Which was incorrect.

CCC21A09-B49E-4ACA-AD2C-72017CF7B36B.thumb.jpeg.4d4e95e7dcd6620fb581f23d5fe1ac7b.jpeg

 

Edited by Paul
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⬆️ Come on guys, let’s keep

this thread friendly please. Cheers. :) 

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1 hour ago, Catacol said:

Thanks Snowy - yes - this is my take on RJS's early season descriptor and on the pattern as I see it related to the current shape of Nino and AAM trends. Beyond November is really tough at the moment: we dont have a handle yet on the vortex (though Recretos' diagramme in another thread is really interesting, suggesting 2 key long range models seeing a warming again...) and for followers of Cohen's theory it is also 2 weeks too soon to draw a conclusion.

A mid atlantic ridge giving us some frosty conditions into November would be a good start. I'm not particularly keen on the idea of November snow - I've only ever seen it once in lowland England close to me (and it was the last few days of the month) and it lasted less than 36 hours. Let's not waste good synoptics on November! Mid December following a continental cooldown is the start of the sweet spot.. 🙂

Steve - I hope you are having a better day today!! All I posted yesterday was a personal opinion based on a starting point of Roger's strong sense that a cold start to the Canadian arctic season is likely to produce a downstream cold East US trough and from there a mid atlantic ridge under high AAM conditions supported by Nino and a high orbit GWO. Let's see if it transpires that way. If November doesnt pan out that way then we havent lost any of the "real" winter season...so everyone stays happy..

Hi @Catacol

Im having a great day thanks -

I guess for me- there was a differentiator in the patterns highlighted yesterday -

The Alaska high / Canadian trough for the East coast is a bit like the West based NAO for the Uk - The cold 'can' get all the way to the east however usually where the high sets up - in this case alaska, the trough digs a long way south through the central Plains then lifts out along the ridge up the east coast- so the jet exit point for a high based over Alaska is certainly more often than not warm for the east coast -

Where the arguement may ensue is that where people actually think the loading pattern is to measure the EPO pattern - If you overlay into the PNA to much then you cannot differentiate or reanalise either pattern with clarity- & certainly a +PNA is a better fit ( in the round ) for east coast cold than a -EPO

Same as ENAO is better for the UK than WNAO but WNAO can still deliver -

FWIW I believe there will be 2 super high pressures this winter dominating the pattern across Northern US & for Europe it would either be Scandi or Greenland -

For me the link ( again in the round ) is more likely to be

-EPO / -PNA encouraging more atlantic / Greenland blocking 

+EPO / +PNA encouraging more scandi high pressure - 

Again all relating to the jet exit off the states- The first being more NNE then second being more East then being forced to recurve....

Thanks

Also the is picture for a loading pattern is really badly worded

EF0EC8D5-B43D-45BF-8511-F76B0E855B59.thumb.png.9a5639f29c41ab31ded8bf3bfc6056f7.png

The Trough is in Canada.... !

Remember when we get one of these super high pressures like Sept they will distort the eastward flow & send the main trough south. so with either pattern the stronger the index of -EPO / + PNA will distupt the jet towards the atlantic

Edited by Steve Murr
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13 minutes ago, prolongedSnowLover said:

The GFS 12z run looks like a bore fest although with some potentially nice crispy frosty mornings 😐

Yes it's a run dominated by high pressure (s) so at least predominantly settled with some pleasant sunny spells and light winds with some crisp frosty early mornings as you say..still a chance of a Northerly but on this run it misses the uk to the east.

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Strap yourselves in folks...it’s going to be a long 6 months 😍☃️

59586E4F-B315-43BA-B808-301E191FC083.jpeg

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Get out the shovels - it's time for the Cold Rush!

Edited by Ed Stone
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Quite a benign Ecm 12z with lots of high pressure / ridging bringing predominantly settled conditions with variable amounts of cloud and sunshine, feeling pleasant in the sun but where skies clear overnight, a risk of frost and fog..crisp quiet mid autumn weather for most of the uk.☺🌞

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15 minutes ago, Daniel Smith said:

If nobody objects i’d like to put an order in for P16

4345924D-3D57-411B-BED1-299B453512FD.thumb.jpeg.e9e57d0878ca2d86c79dbb1972efb30a.jpeg

Oh I just love this time of year! 

Do you have an 850Hpa chart for that?

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