The Weather Outlook

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polarwind
17 December 2021 20:38:17

Broad pattern remains good if you want cold.

Details such as how far north that LP moves, how fast it weakens, what attack angle won't be resolved for a while so the rollercoaster ride will continue for a while yet!

 

Originally Posted by: Quantum 

Yes - 'The Broad Pattern' - that is exactly what needs to be kept in mind - any model forecast and especially as the time ahead increases, is a conjecture, whether it turns out right or wrong. 

The broad pattern is 'good if you want cold'.

"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

polarwind
17 December 2021 20:41:27

I note a lot of the rampers have vanished.  The way people abandon the MO thread when there's some bad runs in hunting down a cold spell puts me in mind of the way the Deatheaters vanish in the climax of The Deathly Hallows pt II when old Volders is clearly losing his powers.

Originally Posted by: Whether Idle 

Yes, but I wouldn't put a bet on them not coming back soon.wink

"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

Polar Low
17 December 2021 20:46:33

Rampers of today are nothing to what it was a few years ago Younger Dryas put so many snowflakes up at the pure sniff of a cold spell inbound Brian even got pissed off

 

Yes, but I wouldn't put a bet on them not coming back soon.wink

Originally Posted by: polarwind 

Hippydave
17 December 2021 20:53:37

ECM ens continue to be a rather mixed bag IMBY, with the op being at the top of a warm cluster on Xmas day, with plenty of colder members on offer too.  

ECMWF 14-day ensemble weather forecast for Royal Tunbridge Wells | Weather.us

ECMWF 14-day ensemble weather forecast for Royal Tunbridge Wells | Weather.us

Longer term and there's a reasonable cold cluster 26-30/12 but something of a slight minority with more members going milder.

All in all I imagine it'll take 2-3 days before things settle down yet and maybe a couple of days beyond that for the post Xmas period. When you look at charts like the UKMO T168 and how close the ECM op is to a very good setup nationwide* there's reason for optimism if you're after cold, although I'd be more optimistic personally if I was a few hundred miles further North

*It is of course pretty good for parts of Northern England and Scotland already, just to balance out some of the IMBYism I've been posting lately

Home: Tunbridge Wells

Work: Tonbridge

Polar Low
17 December 2021 21:07:03

Have a look at the Dec 20 2010 fax chart uncanny similar  but we got a way with it

https://www.wetterzentrale.de/reanalysis.php?map=1&model=bra&var=45&jaar=2010&maand=12&dag=20&uur=0000&h=0&tr=1440&nmaps=24#mapref

 

By the way

That is a very strong temperature gradient.

If you want a good frontal snow event, this is the kind of thing you want to be seeing. Weak fronts produce drizzle, strong fronts produce snow even if the temps seem slightly too high on paper.

 

And roughly the heaviest snow probably corresponds to roughly where the -2C isotherm is.

But since this is so far off this could move north or south so the location isn't really all that important.

 

Originally Posted by: Quantum 

nsrobins
17 December 2021 21:16:57
If it’s of any interest, 18Z ICON had adjusted south at 120 by about 100 miles.

Small steps.

Neil

Fareham, Hampshire 28m ASL (near estuary)

Stormchaser, Member TORRO

White Meadows
17 December 2021 21:20:46

If it’s of any interest, 18Z ICON had adjusted south at 120 by about 100 miles.
Small steps.

Originally Posted by: nsrobins 

I noticed this too. Possibly due to the increased / extended HP ridging over Iceland. 

Polar Low
17 December 2021 21:23:41

Yes Dave good post, even gfs members still sniffing -10 850 London some a bit sooner so it’s still up for grabs we just don’t want a major flip of the complete set

https://www.meteociel.fr/modeles/gefs_table.php?x=0&y=0&lat=51.5085&lon=-0.12574&run=12&ext=1&mode=0&sort=0


ECM ens continue to be a rather mixed bag IMBY, with the op being at the top of a warm cluster on Xmas day, with plenty of colder members on offer too.  

ECMWF 14-day ensemble weather forecast for Royal Tunbridge Wells | Weather.us

ECMWF 14-day ensemble weather forecast for Royal Tunbridge Wells | Weather.us

Longer term and there's a reasonable cold cluster 26-30/12 but something of a slight minority with more members going milder.

All in all I imagine it'll take 2-3 days before things settle down yet and maybe a couple of days beyond that for the post Xmas period. When you look at charts like the UKMO T168 and how close the ECM op is to a very good setup nationwide* there's reason for optimism if you're after cold, although I'd be more optimistic personally if I was a few hundred miles further North

*It is of course pretty good for parts of Northern England and Scotland already, just to balance out some of the IMBYism I've been posting lately

Originally Posted by: Hippydave 

SJV
17 December 2021 21:25:10

Yes it's a lot better, isn't it?

 

Edit: low too round but in a better position.

White Meadows
17 December 2021 21:26:06

Stav’s beeb forecast emphasised:
A ‘massive headache’
‘Models not agreeing’
‘Huge uncertainty’

DPower
17 December 2021 21:55:18

I am trying to see why (after such strong signals for cold) it has gone P.Tong!? Is it the High in wrong place? WHat caused such a shift to exceptionally milder weather which we could now well get!? The high is/was clearly over Greenland and also there is a substantial amount of cold air just to our east. Both AO and NAO are going negative too I saw the Met Office update saying colder further south etc then I see such balmy zonal and mild charts. I am so confused. We see this time and time again with the models and the Op isn't a mild outlier this time either! :/

Originally Posted by: tallyho_83 

Apologies if this has been said already but it looks to me as if the low pushing out into the north sea from norther Scandinavia is moving west taking the really cold air with it. We need this to drop south this will allow for better trough disruption and much colder air spreading south as well. 

A step in the right direction from the Icon with the Atlantic low a good  4 to 5 hundred miles further south than the 12z. The low over Scandinavia still looks to cause problems though. I am still very confident though that the uk will see the models trending colder and snowier over the coming days. It sure would be a massive disappointed weather wise if we failed to see a significant cold spell out of this especially when looking at say t120 and then wondering how it all went so wrong.

CField
17 December 2021 22:04:04

Well not looking so favourable for a festive Xmas in the south but while the models show the possibility then that’s what I will be chasing! Looks like some northern areas will be in with a good chance. Longer term looks like we could be in for an unsettled period, then hopefully the chance for countrywide cold will reappear. Perhaps the GH will inflate and push everything further u

Originally Posted by: ballamar 

   

Late 78 was a great example of that.....wouldn't rule it out at some point this winter as cold intensifies....

Favourite snowstorm

Famous channel low

Dec 31st 1978

Hastings East Sussex

Foot of level snow severe drifting

Next day max temp -4 degrees Celsius

Rob K
17 December 2021 22:32:16
Boxing Day storm for the south on the 18Z. A bit colder for the north but a bit milder for the south. Still pretty horrid.
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
17 December 2021 22:42:15

A totally different pattern in the 18z by Boxing Day, with a deep LP off the Eastern Seaboard spinning up and pushing a burst of WAA up through Greenland and on towards the Pole.

Location: South Cambridgeshire

130 metres ASL

52.0N 0.1E



Gandalf The White
17 December 2021 22:44:55

We’ve been through the entire rainbow of options and are now back to a mid-Atlantic ridge and a broad northerly flow by T+240

 

Location: South Cambridgeshire

130 metres ASL

52.0N 0.1E



Polar Low
17 December 2021 22:46:28

Nice gate is open 


We’ve been through the entire rainbow of options and are now back to a mid-Atlantic ridge and a broad northerly flow by T+240

 

Originally Posted by: Gandalf The White 

Gooner
17 December 2021 22:48:12

Settle for that 

 

Remember anything after T120 is really Just For Fun



Marcus

Banbury

North Oxfordshire

378 feet A S L



glenogle
17 December 2021 22:55:03

Heavy snow around the 27th with that low around the M4

https://www.theweatheroutlook.com/twodata/gfs.aspx?run=18&charthour=225&chartname=preciptype&chartregion=uk&charttag=Precip%20type

https://www.meteociel.fr/modeles/gfse_cartes.php?mode=0&ech=204

 

Originally Posted by: Polar Low 

And a quality 24hrs+ of festive day snow in the central belt.

UserPostedImage LLTNP 105m asl 
Polar Low
17 December 2021 23:03:54

Definitely a southwards correction amongst many no 19 lol

https://www.meteociel.fr/modeles/gefs_cartes.php?code=19&ech=156&mode=0&carte=0

 

 

DPower
17 December 2021 23:19:38

Perturbation 3 sending the low south instead of west. Big, big ramifications to weather on the ground. That would be a Christmas day to remember.

https://www.meteociel.fr/modeles/gefs_cartes.php?ech=6&mode=0&carte=1&code=3

springsunshine
18 December 2021 04:26:13
Huge uncertainty in the models re xmas period.Will be interesting to see/hear Gavin P's weekly forecast this week. Having watched his latest xmas update all models have dramatically changed over the past few days.Its looking like a north/south split with things progressively turning milder and more unsettled.

We badly need a prolonged wet spell now.

CField
18 December 2021 06:28:48

We’ve been through the entire rainbow of options and are now back to a mid-Atlantic ridge and a broad northerly flow by T+240

 

Originally Posted by: Gandalf The White 

thesedays this option is more likely to verity for UK...followed by sliders..

Puzzled by reluctance of lows to head south over Scandinavia thesedays must be stronger heights to south....

Favourite snowstorm

Famous channel low

Dec 31st 1978

Hastings East Sussex

Foot of level snow severe drifting

Next day max temp -4 degrees Celsius

Whether Idle
18 December 2021 06:47:40

ECM trending south this morning.  Still a LOT of uncertainty regarding the big day.  If I were north of the M4 Id feel I was in the game!  Good luck guys!

Dover, 5m asl. Half a mile from the south coast.

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