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Gusty
19 December 2014 06:29:20

It appears to me to be the low of tropical origin over the Azores at 144 hours that has caused the problems by sending a fairly sizeable chunk of warm air advection north to form a new high pressure cell over Spain.


This prevents clean retrogression to Greenland.


Instead the low then manages to squeeze through the gap of the two high pressure cells between Spain and Greenland, interacts with the jet and then forms a deep atlantic depression just in the place we don't need it.


It just goes to show how you can get a strong -NAO and still end up on the warm side of the trough.


Longer term..who knows ? The signal for heights is still present over the Greenland area and it may just take this pesky depression to clear eastwards to allow the arctic northerlies to flood in 2 or 3 days later than originally progged a couple of days back.


More jam tomorrow ? Maybe yes. 

Steve - Folkestone, Kent
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Whether Idle
19 December 2014 06:51:12

Another walk on the mild side. No change from me this morning, the trough of low pressure sets up too far N and W and leaves us on the mild flank and we bathe in Tm air. Too much high pressure to our S, obviously, and the HP over Greenland does not  extend far south east enough.


Time to start scanning beyond the pale horizon again.

Dover, 5m asl. Half a mile from the south coast.
warrenb
19 December 2014 06:52:13
Or time for you to scan beyond just the Gfs
Tonbridge 45m 
Whether Idle
19 December 2014 06:56:06

Or time for you to scan beyond just the Gfs

Originally Posted by: warrenb 


take your pick.

Dover, 5m asl. Half a mile from the south coast.
Retron
19 December 2014 07:03:48
ECM continues its trend of showing blocking (in the vicinity of Greenland) with the UK on the battleground between mild and cold. This time the dividing line is a little further north, but the trend of a cold plunge + potential for a real dumping of snow somewhere across the British Isles remains.

I would expect the ECM ensembles to continue to paint a cold outlook today, although there may be a bit more scatter in FI than yesterday.

GEFS is showing, by day 10, a right old mixture as you'd imagine. However, the vast majority have a cold plunge over or very close to the UK by day 10 - and a few show genuine blizzards over the UK.

Anybody writing off the cold spell at the moment is very premature IMO.

(What I think will actually happen is that there will be a couple of "bites at the cherry" before a low finally moves far enough eastwards to envelop the whole of the UK in cold air).

Leysdown, north Kent
doctormog
19 December 2014 07:10:15

ECM continues its trend of showing blocking (in the vicinity of Greenland) with the UK on the battleground between mild and cold. This time the dividing line is a little further north, but the trend of a cold plunge + potential for a real dumping of snow somewhere across the British Isles remains.

I would expect the ECM ensembles to continue to paint a cold outlook today, although there may be a bit more scatter in FI than yesterday.

GEFS is showing, by day 10, a right old mixture as you'd imagine. However, the vast majority have a cold plunge over or very close to the UK by day 10 - and a few show genuine blizzards over the UK.

Anybody writing off the cold spell at the moment is very premature IMO.

(What I think will actually happen is that there will be a couple of "bites at the cherry" before a low finally moves far enough eastwards to envelop the whole of the UK in cold air).

Originally Posted by: Retron 


It is very good to read your analyses again Darren.


A glance at the GFS op run and a good look at all the data paint different pictures.

Aberdeen
Current conditions (personal WS) 
Whether Idle
19 December 2014 07:21:20

ECM continues its trend of showing blocking (in the vicinity of Greenland) with the UK on the battleground between mild and cold. This time the dividing line is a little further north, but the trend of a cold plunge + potential for a real dumping of snow somewhere across the British Isles remains.

I would expect the ECM ensembles to continue to paint a cold outlook today, although there may be a bit more scatter in FI than yesterday.

GEFS is showing, by day 10, a right old mixture as you'd imagine. However, the vast majority have a cold plunge over or very close to the UK by day 10 - and a few show genuine blizzards over the UK.

Anybody writing off the cold spell at the moment is very premature IMO.

(What I think will actually happen is that there will be a couple of "bites at the cherry" before a low finally moves far enough eastwards to envelop the whole of the UK in cold air).

Originally Posted by: Retron 


Darren, what I am thinking is that the post Christmas cold spell that some output displayed 2-3 days ago in FI has gone, and that we are again scanning beyond. Day 10.  It may be the case that we need another bite at the cherry, but that second bite is back in FI again, and hence my comments. I do not think that is premature, it is to me realistic!

Dover, 5m asl. Half a mile from the south coast.
nsrobins
19 December 2014 07:35:40


 


Darren, what I am thinking is that the post Christmas cold spell that some output displayed 2-3 days ago in FI has gone, and that we are again scanning beyond. Day 10.  It may be the case that we need another bite at the cherry, but that second bite is back in FI again, and hence my comments. I do not think that is premature, it is to me realistic!


Originally Posted by: Whether Idle 


Thanks again Darren. It's good to see some decent analysis rather than emotive comments based on one OP run.


The clusters are as you say useful and there is a decent cold cluster on GFS today, with both Control and OP away on the mild fringes.
Yes the Boxing Day shot has all but dissolved but that was on it's way yesterday. What happens after with the rise in heights to our NW is still on the table.

Neil
Fareham, Hampshire 28m ASL (near estuary)
Stormchaser, Member TORRO
JACKO4EVER
19 December 2014 07:40:21
Morning all. Quick scan through this morning and I think we are shaping up for a bit of a battle. With quite a lot of cold air up north it wouldn't take much to drag this into the mix and possibly end up with quite a snowstorm for Scotland and those with elevation up north. It's more in doubt for lowland England and Wales, though as Darren points out in his excellent post above it's the ens clusters that need to be followed now, not mean flows or specific runs. Very interesting period coming up, but I do have that feeling that the "action" for those down South is perpetually put back to the further reaches of FI with more "jam tomorrow" hints.
Retron
19 December 2014 07:40:40


 post Christmas cold spell that some output displayed 2-3 days ago in FI has gone,


Originally Posted by: Whether Idle 


It's been shown continuously by ECM for days now, which I find interesting.


Here's last night's 12z EPSGram for Reading:


Nope. Tinypic's not working for some reason.


So instead:


Median max 25: 6C


26: 5C


27: 3C


28: 2C.


I would imagine today's will be similar.

Leysdown, north Kent
Brian Gaze
19 December 2014 07:40:50

Plenty of interest mid to longer term regarding a cold spell. The problem with that is it's a bit like saying the England football team can still qualify if they beat Holland and Italy and the Faro Islands beat Germany.  

Brian Gaze
Berkhamsted
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jondg14
19 December 2014 07:44:12
I was hoping that by this morning the operationals and ensembles would be in better agreement which each other for the few days after Christmas but they are still out of kilter! The ensembles are clustering best around cold 850s but the operationals keep bringing milder air into the mix. It's hard to call but the ECM ens have been pretty keen on a UK wide cold spell for a couple of days now.

Just a quick aside to say thank you to the forum stalwarts for their ongoing excellent posts. I'm learning more each day and I really enjoy reading the great analysis and insights.
Matty H
19 December 2014 07:44:49


Plenty of interest mid to longer term regarding a cold spell. The problem with that is it's a bit like saying the England football team can still qualify if they beat Holland and Italy and the Faro Islands beat Germany.  


Originally Posted by: Brian Gaze 


You're saying there's no chance whatsoever?

Yate, Nr Bristol
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Brian Gaze
19 December 2014 07:52:08


 


You're saying there's no chance whatsoever?


Originally Posted by: Matty H 


Yes I was a bit harsh.  


Not gone through the ensemble data yet, but at 10 days the ECM, GFS & GFSP all are lowering heights over Greenland. GEM shows more mid Atlantic and Greenland blocking. I suspect we will see a cold snap or spell this winter, but it has apparently been impending according to some since mid November.  It's worth remembering that despite the chatter on the web the December CET is now slightly above average.

Brian Gaze
Berkhamsted
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Richard K
19 December 2014 08:10:49

It seems to me that these ensembles have looked broadly similar for the last few days now and what changes is whether the operational is on the colder side or the warm side. It looks as though the course is set by about 24-25th so hopefully in the next day or two the situation should clarify a lot.


http://www.wetterzentrale.de/pics/MT8_London_ens.png

Saffron Walden, NW Essex, approx 70m above sea level (when the tide is out)
Rob K
19 December 2014 08:11:36
An immense amount of scatter on the GEFS this morning. Basically just about anything is on the table by New Year, from -11 to +9. Even at Christmas there is still a 10-degree spread.

http://www.wetterzentrale.de/pics/MT8_London_ens.png 
Yateley, NE Hampshire, 73m asl
"But who wants to be foretold the weather? It is bad enough when it comes, without our having the misery of knowing about it beforehand." — Jerome K. Jerome
Gooner
19 December 2014 08:16:51

Morning all. Quick scan through this morning and I think we are shaping up for a bit of a battle. With quite a lot of cold air up north it wouldn't take much to drag this into the mix and possibly end up with quite a snowstorm for Scotland and those with elevation up north. It's more in doubt for lowland England and Wales, though as Darren points out in his excellent post above it's the ens clusters that need to be followed now, not mean flows or specific runs. Very interesting period coming up, but I do have that feeling that the "action" for those down South is perpetually put back to the further reaches of FI with more "jam tomorrow" hints.

Originally Posted by: JACKO4EVER 


 


Wasn't it dead in the water yesterday though

Remember anything after T120 is really Just For Fun



Marcus
Banbury
North Oxfordshire
378 feet A S L


Sevendust
19 December 2014 08:25:47

An immense amount of scatter on the GEFS this morning. Basically just about anything is on the table by New Year, from -11 to +9. Even at Christmas there is still a 10-degree spread.

http://www.wetterzentrale.de/pics/MT8_London_ens.png


Originally Posted by: Rob K 


If anything, the situation on GEFS is more messy than yesterday with splits evolving quicker.


I would say that although potential for a decent cold spell remains, there is huge uncertainty as things stand

Gooner
19 December 2014 08:30:50

O/T apologies


 


Tweet for Ian Fergusson


W COUNTRY F'cast confidence good to Xmas Day but post-26th tricky. Expected colder than average to New Year. Periods of severe weather poss.


Find it a bit odd he would be talking about New Year so far out.......................I wonder what he has been looking at

Remember anything after T120 is really Just For Fun



Marcus
Banbury
North Oxfordshire
378 feet A S L


Retron
19 December 2014 08:36:14
Just a quick post - ECM ensembles show, as expected, a cold spell but with more scatter.

Median values for Reading:

25: 5C
26: 4C
27: 4C
28: 3C
Leysdown, north Kent
marting
19 December 2014 08:37:28
ECM and GFS ensembles still looking good to me. Worth considering what things looked like a few days back.
Martin
Martin
Greasby, Wirral.
idj20
19 December 2014 08:43:07


O/T apologies


 


Tweet for Ian Fergusson


W COUNTRY F'cast confidence good to Xmas Day but post-26th tricky. Expected colder than average to New Year. Periods of severe weather poss.


Find it a bit odd he would be talking about New Year so far out.......................I wonder what he has been looking at


Originally Posted by: Gooner 



"severe weather", as in terms of cold and snow or stormy wet weather? (I suspect the latter will be much more likely).

That is one of the many things I hate about Twitter is that info are condensed so tightly packed into as "tweets" that they are rendered rather useless to the layman.

My gut feeling (I know, that shouldn't be allowed as its not scientific enough) is this winter being January 1984 all over again (wet 'n' wild to the south, frequent snow north of the Midlands) associated with a cold zonal pattern.

Folkestone Harbour. 
David M Porter
19 December 2014 08:43:51


O/T apologies


 


Tweet for Ian Fergusson


W COUNTRY F'cast confidence good to Xmas Day but post-26th tricky. Expected colder than average to New Year. Periods of severe weather poss.


Find it a bit odd he would be talking about New Year so far out.......................I wonder what he has been looking at


Originally Posted by: Gooner 


Something that we don't have access to, I would imagine.

Lenzie, Glasgow

"Let us not take ourselves too seriously. None of us has a monopoly on wisdom, and we must always be ready to listen and respect other points of view."- Queen Elizabeth II 1926-2022
Brian Gaze
19 December 2014 08:48:59




"severe weather", as in terms of cold and snow or stormy wet weather? (I suspect the latter will be much more likely).

That is one of the many things I hate about Twitter is that info are condensed so tightly packed into as "tweets" that they are rendered rather useless to the layman.

My gut feeling (I know, that shouldn't be allowed as its not scientific enough) is this winter being January 1984 all over again (wet 'n' wild to the south, frequent snow north of the Midlands) associated with a cold zonal pattern.


Originally Posted by: idj20 


I don't like second guessing Ian F either, but I suspect he means stormy conditions are a possibility generally, and there is a chance of blizzards in the north, mostly over higher ground.

Brian Gaze
Berkhamsted
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"I'm not socialist, I know that. I don't believe in sharing my money." - Gary Numan
roger63
19 December 2014 08:51:33


 


If anything, the situation on GEFS is more messy than yesterday with splits evolving quicker.


I would say that although potential for a decent cold spell remains, there is huge uncertainty as things stand


Originally Posted by: Sevendust 


Agree it is messy!The GFS op is broadly an Atlantic dominated pattern.The GEFS tells a much more diverse story.


At 144h Xmas day, 60% of ENS have a fairly vigorous north  westerly with the remaining 40% having a HP closer to the south and a slacker WSWesterly flow.


By 240h 70% of ENS are dominated by HP.of which  half are Mid Atlantic HP, a third Greenland HP and  a couple pf Scandi hp.Thses conatin a number of quite cold options.


At 360h 60% 0f ENS are Hp related with the location of HP being  40% Scandi/Iceland,followed by another 40% which are Mid Atlantic/Greenland. 


To ge ta significant cold spell going an easterly is the most stable so will be hoping for an increase in the number of Scandi HP ENS (though of course the Atlantic has a knack of winning through in uncertain times!


 


 

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