theweatheroutlook

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nickl
07 December 2017 13:32:16


Talking of the Azores High, the NAO is forecast to head negative although there's a lot of uncertainty.


 



yesterdays output rob - all ens suites are now going for a neutral/weakly positive NAO.  note latest Exeter 30 dayer actually stating high pressure establishing after week 2. coldies hoping that gets some purchase to get north of the uk. signs of the nw pacific ridge retrogressing towards the Aleutians with time which opens up the possibility of some cross polar ridging in time. just a possibility mind ..............


Originally Posted by: Rob K 

tallyho_83
07 December 2017 13:48:56


It's the strong Azores high, ridging towards Newfoundland, that allows the jet to dive SE into Europe with a much increased chance of Arctic outbreaks - if it's weak and flabby, it often extends into Europe (Euro or Bartlett high) and sends warm SW winds over us and into the Arctic.


May the Azores high remain strong with ridging NW and repeatedly swinging and pointing towards Greenland to provide essentials for building the Greenland High.


Originally Posted by: polarwind 


 


I thought the Azores HP is bad news as it strengthens the zonal westerlies!?

Home Location - Kellands Lane, Okehampton, Devon (200m ASL)
---------------------------------------
Sean Moon
Magical Moon
www.magical-moon.com


Maunder Minimum
07 December 2017 13:57:06


 


 


I thought the Azores HP is bad news as it strengthens the zonal westerlies!?


Originally Posted by: tallyho_83 


Surely that depends on its precise location, orientation and intensity?


Normally it is bad news, since it prevents a southerly tracking jet.


But when there is no Jet to speak of, it can ridge northwards as we see it doing in the charts.

New world order coming.
polarwind
07 December 2017 15:22:09


 


And May the Azores High swing in this direction of the UK once we get to next summer.


Originally Posted by: johncs2016 

Can't disagree with that…...

"The professional standards of science must impose a framework of discipline and at the same time encourage rebellion against it". – Michael Polyani (1962)
"If climate science is sound and accurate, then it should be able to respond effectively to all the points raised…." - Grandad
"The whole problem with the world is that fools and fanatics are always so certain of themselves, and wiser people so full of doubts". - Bertrand Russell
"Science is the belief in the ignorance of the experts" – Richard Feynman
"A consensus means that everyone agrees to say collectively what no one believes individually.”- Abba Eban, Israeli diplomat
Dave,Derby
Rob K
07 December 2017 15:46:25
12Z GFS - the low looked a little further south on the approaches but it's coming in a bit more W-E than NW-SE so milder air gets a tad further north in fact.
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
polarwind
07 December 2017 15:50:01


 


Surely that depends on its precise location, orientation and intensity?


Normally it is bad news, since it prevents a southerly tracking jet.


But when there is no Jet to speak of, it can ridge northwards as we see it doing in the charts.


Originally Posted by: Maunder Minimum 

A strong Azores high, I would have thought, influences the strength of the jet and if the orientation (ridging), is towards the NW Atlantic, then the jet is influenced strongly to travel over the top of the cell and more deeply into Europe. (it's got to catch its tail) Furthermore, the pressure over the NW Atlantic is generally higher and the tendency to get northerly winds on our side of the pond is increased.


 

"The professional standards of science must impose a framework of discipline and at the same time encourage rebellion against it". – Michael Polyani (1962)
"If climate science is sound and accurate, then it should be able to respond effectively to all the points raised…." - Grandad
"The whole problem with the world is that fools and fanatics are always so certain of themselves, and wiser people so full of doubts". - Bertrand Russell
"Science is the belief in the ignorance of the experts" – Richard Feynman
"A consensus means that everyone agrees to say collectively what no one believes individually.”- Abba Eban, Israeli diplomat
Dave,Derby
Rob K
07 December 2017 15:56:29

Interesting: a spell of snow on Monday for the previously snow-starved SE on this run.


 



 


Starting to look as though there could be a second bite of the cherry as the low pulls away to the south.

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
roger63
07 December 2017 16:03:54

Before the GFS 12h kicks off a glace to the longer term.


At both 240h and 360h the ratio of cold:mild members is 60:40


Will see how 12h compares

Ally Pally Snowman
07 December 2017 16:04:28

ukmo looks much better for the south at 72 and 96

Bishop's Stortford 85m ASL.
Rob K
07 December 2017 16:15:07

Anyone with snow would do well to enjoy it quickly as it looks almost certain to be washed away by Wednesday morning!


 


Edit -  although there could be more for high ground on Thursday 

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
moomin75
07 December 2017 16:17:06

Anyone with snow would do well to enjoy it quickly as it looks almost certain to be washed away by Wednesday morning!

Originally Posted by: Rob K 


Indeed. For the first time in the semi reliable GFS flattens the pattern and goes a bit zonal as way as Wednesday.

Witney, Oxfordshire
100m ASL
Rob K
07 December 2017 16:19:04


 


Indeed. For the first time in the semi reliable GFS flattens the pattern and goes a bit zonal as way as Wednesday.


Originally Posted by: moomin75 


Not really, this has been showing for a while - the pattern flattens briefly before the ridge builds north at the end of the week.  I wouldn't call it "zonal", it's just the bottom of the curve.

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
roger63
07 December 2017 16:23:02


 


Indeed. For the first time in the semi reliable GFS flattens the pattern and goes a bit zonal as way as Wednesday.


Originally Posted by: moomin75 


on GFS 12h The wed/thu slider is no longer a slider but a west to east movement.


Rob K
07 December 2017 16:28:33


 


on GFS 12h The wed/thu slider is no longer a slider but a west to east movement.



Originally Posted by: roger63 


 


Seems similar to what has been showing for a while now. The milder blip mid week has been there for a few runs.


The ridge that follows looks a bit stronger on this run although that chunk of low heights in NE Canada also looks quite fierce.

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
backtobasics
07 December 2017 16:32:22
not forgetting the short term picture the 12Z again picks out a more organised band of snow albeit I suspect fairly light through the midlands overnight tonight, seem to recall someone posted a fax earlier which showed this trough. Might give a dusting overnight for some ?
Rob K
07 December 2017 16:36:09

not forgetting the short term picture the 12Z again picks out a more organised band of snow albeit I suspect fairly light through the midlands overnight tonight, seem to recall someone posted a fax earlier which showed this trough. Might give a dusting overnight for some ?

Originally Posted by: backtobasics 


 


I've noticed that also picked up on eg the HIRLAM model.


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
kmoorman
07 December 2017 16:43:15

https://www.theweatheroutlook.com/twodata/gfs.aspx?run=12&charthour=207&chartname=mslp500&chartregion=na-region&charttag=500hPa%20GPDM

Top right of this has my attention

Originally Posted by: ballamar 


 


and yet it failed to deliver.   

Home: Durrington, Worthing, West Sussex. (16 ASL)
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Saint Snow
07 December 2017 16:55:47

 


and yet it failed to deliver.   


Originally Posted by: kmoorman 


 


Failed?


It remains a feature throughout the second half of the run, linked to the GH by the end. The huge chunk of the PV sat over Canada has an annoying way of farting shortwaves, though, which spawn into full, eastwards-trundling lows that stop the cold properly building south to us.


However, the formation & track of shortwaves/lows is impossible to forecast at such a range, and I'd rather be seeing very pretty building blocks of serious HLB over Scandinavia/Greenland, than a transient feature that may deliver colder temps in the short-term but not be sustainable.


 


Martin
Home: St Helens (26m asl) Work: Manchester (75m asl)
A TWO addict since 14/12/01
"How can wealth persuade poverty to use its political freedom to keep wealth in power? Here lies the whole art of Conservative politics."
Aneurin Bevan
moomin75
07 December 2017 17:10:16
The UKMO 12z seems to be following a similar pattern to GFS at 144hrs.
Witney, Oxfordshire
100m ASL
polarwind
07 December 2017 17:15:19

https://www.theweatheroutlook.com/twodata/gfs.aspx?run=12&charthour=207&chartname=mslp500&chartregion=na-region&charttag=500hPa%20GPDM

Top right of this has my attention

Originally Posted by: ballamar 

The high pressure or perhaps the extremely dark and threatening blue blob coming our way??

"The professional standards of science must impose a framework of discipline and at the same time encourage rebellion against it". – Michael Polyani (1962)
"If climate science is sound and accurate, then it should be able to respond effectively to all the points raised…." - Grandad
"The whole problem with the world is that fools and fanatics are always so certain of themselves, and wiser people so full of doubts". - Bertrand Russell
"Science is the belief in the ignorance of the experts" – Richard Feynman
"A consensus means that everyone agrees to say collectively what no one believes individually.”- Abba Eban, Israeli diplomat
Dave,Derby
The Beast from the East
07 December 2017 17:19:29

www.meteociel.fr/modeles/gefs_cartes.php?code=20&ech=216&mode=0&carte=0


hope pert 20 is a trendsetter, but a lot of uncertainty in the GEFS


 

"We have some alternative facts for you"
Kelly-Ann Conway - special adviser to the President
Rob K
07 December 2017 17:20:54

ARPEGE 12Z. You can see why the Met are talking about some places getting cut off.


 



 


Over a foot in parts of mid Wales if the accumulation charts are to be believed.

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
Gandalf The White
07 December 2017 17:24:52

Arpege 12z has a potentially messy scenario for the eastern extent of the precipitation band, with initial light rain and sleet then snow as the intensity picks up and then back to a wintry mix and drizzle.


Intensity and elevation are likely to be important factors here - once the track is better resolved.  That’s still some way off given the competing forces.

Location: South Cambridgeshire
130 metres ASL
52.0N 0.1E


tallyho_83
07 December 2017 17:31:15

Still in colder air stream but not bitterly cold up until 15th.


Milder Tuesday 13th. So much uncertainty.  



 

Home Location - Kellands Lane, Okehampton, Devon (200m ASL)
---------------------------------------
Sean Moon
Magical Moon
www.magical-moon.com


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