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Joe Bloggs
23 February 2018 17:19:32

Mean at T+192.


No real end in sight.


http://www.wetterzentrale.de/maps/GFSAVGEU12_192_2.png


 


Manchester City Centre, 31m ASL
doctormog
23 February 2018 17:20:08


The deep cold to the NE on the +144 UKMO is capable of acting like a blocking high of its own.


It even generates its own higher SLP because it's so dense - hence a lot of models now showing a narrow surface ridge aligned with it by Fri-Sat.


It adds a fascinating twist to things just when we'd otherwise be at the mercy of an evolving west-based negative NAO setup - although I'm not sure given stratospheric signals that the blocking high will actually go so far away. 



The elongated shape of the LP to the south on the +144 UKMO suggests it is continuing to follow the (very!) southerly-tracking jet into the Med. more than break away N in the style of GFS.


I would actually expect, going forward, to see the LP continue across to Italy or thereabouts, with deep cold still moving across the UK from the E or NE albeit not at such brisk pace as earlier in the week, leaving us wondering if the polar vortex will pay us a visit from Siberia way before the remnant cold pooling had even had time to clear away.


That last part depends on how the second bout of anomalies propagating down from the stratosphere happen to orientate, so not worth getting too interested in at this time - especially given what we've got to deal with next week!


Originally Posted by: Stormchaser 


A typically great post there SC.


On a different note GFS ensembles look a bit colder than the 06z set so far (the ten day mark).

Aberdeen
Current conditions (personal WS) 
David M Porter
23 February 2018 17:21:33


12z GEFS means. You can see why the pro's are now referring to the potential for a historic cold spell.


http://www.wetterzentrale.de/maps/GFSAVGEU12_96_2.png


http://www.wetterzentrale.de/maps/GFSAVGEU12_120_2.png


http://www.wetterzentrale.de/maps/GFSAVGEU12_144_2.png


Direct hit. Sensational. 


Originally Posted by: Joe Bloggs 


Hells bells!

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
SJV
23 February 2018 17:23:20


 


Well if we have "English channel effect snow" then it will turn milder for sure for a time. The snow would be heavy south of the M4 (makes a change). But then again of the low takes a more southerly track then at least we stay in the cold easterly and will enjoy powdery snow flurries and showers for longer!?


Originally Posted by: tallyho_83 


As some have alluded to we get a better scenario on the control with the low taking a more southerly track, preventing marginality for the south coast and also helping beef up the snow coming in off the N Sea 


Once again: upgrades! 


 


edit: BTW thanks to Joe, Rob and later James on their excellent thoughts on the UKMO latter stages :)

Russwirral
23 February 2018 17:23:26

Interesting how this cold spell could really spell the end for the people who post in February "Winter is over"


 


This could really be the antidote to alot of trolling on here for years to come.


Weather station:
https://www.wunderground.com/personal-weather-station/dashboard?ID=IWIRRAL24#history 
Rob K
23 February 2018 17:23:42


The deep cold to the NE on the +144 UKMO is capable of acting like a blocking high of its own.


It even generates its own higher SLP because it's so dense - hence a lot of models now showing a narrow surface ridge aligned with it by Fri-Sat.


It adds a fascinating twist to things just when we'd otherwise be at the mercy of an evolving west-based negative NAO setup - although I'm not sure given stratospheric signals that the blocking high will actually go so far away. 



The elongated shape of the LP to the south on the +144 UKMO suggests it is continuing to follow the (very!) southerly-tracking jet into the Med. more than break away N in the style of GFS.


I would actually expect, going forward, to see the LP continue across to Italy or thereabouts, with deep cold still moving across the UK from the E or NE albeit not at such brisk pace as earlier in the week, leaving us wondering if the polar vortex will pay us a visit from Siberia way before the remnant cold pooling had even had time to clear away.


That last part depends on how the second bout of anomalies propagating down from the stratosphere happen to orientate, so not worth getting too interested in at this time - especially given what we've got to deal with next week!


Originally Posted by: Stormchaser 


Thanks for that explanation SC!


 


Meanwhile I see the control run has a second crack at a breakdown. The first was all snow, the second turns to rain for a time in the SE before dumping more snow in the Midlands. 


 


Very 1980s these repeated attempts at introducing mild air!

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
Ally Pally Snowman
23 February 2018 17:26:04


12z GEFS means. You can see why the pro's are now referring to the potential for a historic cold spell.


http://www.wetterzentrale.de/maps/GFSAVGEU12_96_2.png


http://www.wetterzentrale.de/maps/GFSAVGEU12_120_2.png


http://www.wetterzentrale.de/maps/GFSAVGEU12_144_2.png


Direct hit. Sensational. 


Originally Posted by: Joe Bloggs 


Will be interesting how much snow the UK gets because you could not hope for better output really. Good luck to everyone. 

Bishop's Stortford 85m ASL.
SJV
23 February 2018 17:28:37


Interesting how this cold spell could really spell the end for the people who post in February "Winter is over"


 


This could really be the antidote to alot of trolling on here for years to come.


Originally Posted by: Russwirral 


Positives from upcoming cold spell:


3) unprecedented deep cold


2) huge snow potential


1) no more WIO trolling in Feb 


Arcus
23 February 2018 17:29:02

The control gives insane amounts of snow to the East especially.

Originally Posted by: NickR 


The control also aligns very well with the GEFS 12z mean IMBY on the 850s as far as 5th March.

Ben,
Nr. Easingwold, North Yorkshire
30m asl
Stormchaser
23 February 2018 17:29:33


 


Thanks for that explanation SC!


 


Meanwhile I see the control run has a second crack at a breakdown. The first was all snow, the second turns to rain for a time in the SE before dumping more snow in the Midlands. 


 


Very 1980s these repeated attempts at introducing mild air!


Originally Posted by: Rob K 


Always welcome  


I have been wondering whether the polar jet might stay stuck way down south for longer than the models are tending to edge toward in the 7-10 day range, as the full magnitude of continued forcing from the stratosphere may be alluding them.


It really is speculation at this point in time though. Plenty of freezing cold air to get through in the meantime 

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tallyho_83
23 February 2018 17:31:35


 


As some have alluded to we get a better scenario on the control with the low taking a more southerly track, preventing marginality for the south coast and also helping beef up the snow coming in off the N Sea 


Once again: upgrades! 


 


edit: BTW thanks to Joe, Rob and later James on their excellent thoughts on the UKMO latter stages :)


Originally Posted by: SJV 


Just comparing the two:


Yes I see the Control gives all of southern England including the south coastal areas in the snow zone where as the Op run has it as a marginal rain/snow esp for the south and south east.


GFS Control run



 


GFS Op


Home Location - Kellands Lane, Okehampton, Devon (200m ASL)
---------------------------------------
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Rob K
23 February 2018 17:35:27
p20 is interesting on the GEFS. It runs a shortwave down southwards over the UK through the block in the early stages of the run but this doesn't mess things up. Instead it gives an early dump of snow and then the cold is even more intense behind!
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
IanT
  • IanT
  • Advanced Member
23 February 2018 17:38:59

All looks good for a fascinating week, but I can’t help but be a little worried that the “focal point” (by which I mean the time with the highest snow potential) seems to have slipped seamlessly from the early part of the week, to Wednesday and now to Friday. When we’ve chased these events before, disappointment has often followed.

Hands up that this might be somewhat IMBY, but I think the observation stands for a large part of the country in terms of population.

Woking, Surrey. 40m asl.
LeedsLad123
23 February 2018 17:40:54

All looks good for a fascinating week, but I can’t help but be a little worried that the “focal point” (by which I mean the time with the highest snow potential) seems to have slipped seamlessly from the early part of the week, to Wednesday and now to Friday. When we’ve chased these events before, disappointment has often followed.

Hands up that this might be somewhat IMBY, but I think the observation stand for a large part of the country.

Originally Posted by: IanT 


Monday and Tuesday look like the snowiest days of next week to me, with hefty showers moving in from the N Sea. 

Whitkirk, Leeds - 85m ASL.
Rob K
23 February 2018 17:42:25

All looks good for a fascinating week, but I can’t help but be a little worried that the “focal point” (by which I mean the time with the highest snow potential) seems to have slipped seamlessly from the early part of the week, to Wednesday and now to Friday. When we’ve chased these events before, disappointment has often followed.

Hands up that this might be somewhat IMBY, but I think the observation stand for a large part of the country.

Originally Posted by: IanT 


I don't think that's true at all. The focal point i.e. The start of the easterly slipped by a day or two from Sat/Sunday to Monday but it has stayed rock solid since then. The initial easterly was never going to be the main snow event other than the usual favoured spots. You'll always get more widespread snow from frontal features. 

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
IanT
  • IanT
  • Advanced Member
23 February 2018 17:44:03


 Monday and Tuesday look like the snowiest days of next week to me, with hefty showers moving in from the N Sea. 


Originally Posted by: LeedsLad123 


Maybe, but I think we’re looking more at the impact of the low moving up from the south on Friday. For me this is a long way off and very likely to happen differently to the way modelled at this range.

Woking, Surrey. 40m asl.
Nordic Snowman
23 February 2018 17:44:43


All looks good for a fascinating week, but I can’t help but be a little worried that the “focal point” (by which I mean the time with the highest snow potential) seems to have slipped seamlessly from the early part of the week, to Wednesday and now to Friday. When we’ve chased these events before, disappointment has often followed.

Hands up that this might be somewhat IMBY, but I think the observation stands for a large part of the country in terms of population.


Originally Posted by: IanT 


I am sure the snow shower activity will ramp up once we get into Mon/Tuesday. The METO warnings will always go on the side of caution too; the likelihood is that there will be some locations that will see substantial falls and with much disruption.


I can just see Sky News reporting on it now 

Bjorli, Norway

Website 
Rob K
23 February 2018 17:47:29


 


Maybe, but I think we’re looking more at the impact of the low moving up from the south on Friday. For me this is a long way off and very likely to happen differently to the way modelled at this range.


Originally Posted by: IanT 


Woking is reasonably well placed for snow streamers from the Thames as long as there is a decent easterly (tick) and a cold enough pool of air (tick). Streamers are always a lottery but I wouldn't be surprised to see a few in Surrey and even Hampshire as early as Monday.


For us though a frontal attack is always going to be more likely to give a good dumping (e.g. Jan 2010, although that was a low coming down from the northeast, so less risky!)

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
SJV
23 February 2018 17:50:05


All looks good for a fascinating week, but I can’t help but be a little worried that the “focal point” (by which I mean the time with the highest snow potential) seems to have slipped seamlessly from the early part of the week, to Wednesday and now to Friday. When we’ve chased these events before, disappointment has often followed.

Hands up that this might be somewhat IMBY, but I think the observation stands for a large part of the country in terms of population.


Originally Posted by: IanT 


Disagree.


We've got a lot of weather before Friday and the prospect of numerous disturbances/troughs etc enhancing an already volatile easterly flow over the N Sea. Snow showers will be packing in from Mon afternoon onwards. 

LeedsLad123
23 February 2018 17:52:56


 


Maybe, but I think we’re looking more at the impact of the low moving up from the south on Friday. For me this is a long way off and very likely to happen differently to the way modelled at this range.


Originally Posted by: IanT 


I'm not really interested in that projected low - it's too far out to be taken seriously. Eastern and central parts of the country can get significant snowfalls during 'sea effect' snow, and that's what many of us are interested in.

Whitkirk, Leeds - 85m ASL.
IanT
  • IanT
  • Advanced Member
23 February 2018 17:54:07


 


Woking is reasonably well placed for snow streamers from the Thames as long as there is a decent easterly (tick) and a cold enough pool of air (tick). Streamers are always a lottery but I wouldn't be surprised to see a few in Surrey and even Hampshire as early as Monday.


For us though a frontal attack is always going to be more likely to give a good dumping (e.g. Jan 2010, although that was a low coming down from the northeast, so less risky!)


Originally Posted by: Rob K 


 


Yep - the streamer in (I think) December 2010 gave us a level 30cm. It’s easy to see that this might be replicated.

Woking, Surrey. 40m asl.
Devonian
23 February 2018 18:02:29


 


Positives from upcoming cold spell:


3) unprecedented deep cold


2) huge snow potential


1) no more WIO trolling in Feb 



Originally Posted by: SJV 


'Imo, it's going to snow because of X, Y or Z' = positive post?


'Imo, it's not going to snow because of X, Y or Z' = trolling?

Whether Idle
23 February 2018 18:04:43


 


Monday and Tuesday look like the snowiest days of next week to me, with hefty showers moving in from the N Sea. 


Originally Posted by: LeedsLad123 


There is large variation in snow amounts and distribution from run to run and model to model.(Under-statement mode employed)  The best guide IMHO is the Met O and the SWW they have issued this far.  

Dover, 5m asl. Half a mile from the south coast.
Deep Powder
23 February 2018 18:06:00


 


 


Yep - the streamer in (I think) December 2010 gave us a level 30cm. It’s easy to see that this might be replicated.


Originally Posted by: IanT 


Ian I can't be sure for your location, however, you are very close to me and we had a streamer in Feb 2009 that gave 40cm+ of falling snow. Thenone on 30th November 2010 that gave a foot of snow and even on the morning of the 30th (8am) was not forecast. Things can and will pop up at very short notice.......👍🥃

Near Leatherhead 100masl (currently living in China since September 2019)
Loving the weather whatever it brings, snow, rain, wind, sun, heat, all great!
Shropshire
23 February 2018 18:09:25


 


In my view after T+144 the Iberian Low will continue its journey ENE giving us continued cold weather (NE'lies) with a continued snow risk. 


Originally Posted by: Joe Bloggs 


 


Having studied it I agree with this, so the limited T168 will be interesting later.

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