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Rob K
23 January 2015 16:50:22


 


 


Wrong.  Try the Alps


Originally Posted by: soperman 


This is true. Many a time I have sat out on a mountain terrace with the air temperature below freezing but the hot sun on my face and felt comfortable in a light jumper or even a T-shirt.

Northerlies very rarely deliver snow in the south. Only if there  is an incredibly potent front, as in the thundersnow event 10 or 12 years ago.


We also got a bit of snow from a northerly (northwesterly really) at Xmas 2004.


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
doctormog
23 January 2015 16:56:20
If people are trying to decipher what is in the charts from this thread, I would like to summarise:

Cool/mild/cool/mild until midweek next week as Lows pass close by. So alternating between cooler and showery and milder and cloudier with the chance of rain.

Beyond then (in the latter half of next week) it looks like becoming increasingly unsettled with a NWly cyclonic picture. So in that time period I would expect some very windy conditions and turning increasingly colder with wintry precipitation for many NW parts and possibly a few others as the wind direction moves round to the north.

This is a brief summary of the 12z GFS op run but it also seems to reflect the majority of the recent model output.
Rob K
23 January 2015 16:56:26

This sums it up really... -10C down the spine of the country - couldn't be a better aligned hit (and will of course be further east come the day)

http://www.wetterzentrale.de/pics/Rtavn2282.gif

Delivers daytime maxes of 3-7C in the south

http://www.wetterzentrale.de/pics/Rtavn24017.gif


 


If I lived in the NW I might start thinking about snow showers though.


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
doctormog
23 January 2015 17:02:36
The UKMO 12z run looks like it would support a similar picture to the GFS output

http://www.wetterzentrale.de/pics/Rukm1441.html 
Gusty
23 January 2015 18:00:49

If people are trying to decipher what is in the charts from this thread, I would like to summarise:


Beyond then (in the latter half of next week) it looks like becoming increasingly unsettled with a NWly cyclonic picture. So in that time period I would expect some very windy conditions and turning increasingly colder with wintry precipitation for many NW parts and possibly a few others as the wind direction moves round to the north.

Originally Posted by: doctormog 


Memories of yester-year would suggest that you will do very well out of this Michael, if the current pattern being modelled verifies ? 


Steve - Folkestone, Kent
Current conditions from my Davis Vantage Vue
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soperman
23 January 2015 18:02:14


 


This is true. Many a time I have sat out on a mountain terrace with the air temperature below freezing but the hot sun on my face and felt comfortable in a light jumper or even a T-shirt.

Northerlies very rarely deliver snow in the south. Only if there  is an incredibly potent front, as in the thundersnow event 10 or 12 years ago.


We also got a bit of snow from a northerly (northwesterly really) at Xmas 2004.


Originally Posted by: Rob K 


Thanks Rob and my the same token 5c next week will feel freezing with a brisk northerly blowing. The charts appear to be throwing up some seiously stormy weather.

Retron
23 January 2015 18:09:39

drool... (from one of the GEFS ensembles)



Whacko cold outliers aside, it's interesting to see such high snow percentages on the short GEFS this evening.


http://www.meteociel.fr/cartes_obs/gens_display.php?x=306&y=141&run=12&ville=Londres&runpara=0&type=0&ext=0


 


Leysdown, north Kent
JACKO4EVER
23 January 2015 18:13:32
MetO now on board for the LP moving east bringing a NW blast- perhaps quite stormy for a time? Northern Britain may get a fair few snow showers, but can't see much for Southern England in such a setup. It will feel raw for sure.
hobensotwo
23 January 2015 18:31:42


drool... (from one of the GEFS ensembles)



Whacko cold outliers aside, it's interesting to see such high snow percentages on the short GEFS this evening.


http://www.meteociel.fr/cartes_obs/gens_display.php?x=306&y=141&run=12&ville=Londres&runpara=0&type=0&ext=0


 


Originally Posted by: Retron 


At last a decent cold pool to tap into, shame its virtual reality.


Has a chart like this ever verified in modern times?

Charmhills
23 January 2015 18:52:45



Cold and wintry from the ECM 12z so far.


Loughborough, EM.

Knowledge is power, ignorance is weakness.

Duane.
Gooner
23 January 2015 18:56:40
Gooner
23 January 2015 18:58:06

http://www.meteociel.fr/modeles/ecmwf/runs/2015012312/ECH1-240.GIF?23-0


Ends with a very promising chart


Very much in FI though


Remember anything after T120 is really Just For Fun



Marcus
Banbury
North Oxfordshire
378 feet A S L


Charmhills
23 January 2015 19:02:31


A possible snow to rain event as the system hits the colder air across the country.


Loughborough, EM.

Knowledge is power, ignorance is weakness.

Duane.
doctormog
23 January 2015 19:18:33


 


Memories of yester-year would suggest that you will do very well out of this Michael, if the current pattern being modelled verifies ? 


Originally Posted by: Gusty 


Thanks Steve. 


Yes, there is potential for a few places including here, but I remain very cautious. With a bit of luck they will verify and throw in a few surprises across the board. There is a little bit of everything in outlook at the minute and the potentially for some interesting after the next few "rollercoaster days". 


Medlock Vale Weather
23 January 2015 19:26:13


 


At last a decent cold pool to tap into, shame its virtual reality.


Has a chart like this ever verified in modern times?


Originally Posted by: hobensotwo 


Wasn't much different in March 2013



 


 


Alan in Medlock Valley - Oldham's frost hollow. 103 metres above sea level.
What is a frost hollow? http://www.weatheronline.co.uk/reports/wxfacts/Frost-hollow.htm 
Stormchaser
23 January 2015 20:04:32

Okay... a bit more cold air to work with down south on the latest runs, which is good, but not much to bring precipitation as things stand unless the air is cold enough to develop disturbances in the flow capable of hanging on all the way down across the UK. Still not ripe for a significant snow event, but better than nothing 


 


What actually catches my eye more are signs that this northerly is just a small part of something bigger. Admittedly there were similar hints being dropped prior to the cold spell we're moving out of now, but these were largely dependent on getting a second trough disruption event that in the end only materialised briefly in the output before vanishing again. We then saw the upstream pattern become mobile sooner than originally predicted, cutting the cold easterly down as well.


 


Anyway, this time it's largely down to developments in the stratosphere, with the vortex heavily displaced to Siberia right out to day 10, helping to focus the low heights in the troposphere to that region rather than across Canada.


This was brought about by a warming event that's currently focused across Canada. If only the stratosphere and troposphere were strongly connected over there - the Canadian vortex would be going AWOL very soon indeed.


As it is, that lobe does look like weakening gradually over the coming week or so, as that warming event attempts to propagate down toward the troposphere.


Meanwhile, a new warming event looks to emerge over East Asia/the Western Pacific, and this has been looking increasingly strong with each new set of model runs. It looks to be close enough to the displaced vortex to really interfere with it, the results of which are likely to be complicated - and not well handled by the models.


In light of this, any output showing the focus of low heights shifting back to our N or NW in the 10-15 day period, while possible, has a higher than normal chance of being total b*l**ks 


 


Realistically though, there's no ignoring the tendency so far this winter for low heights to find a way to hang on in some guise to our NW in the face of even quite substantial pressure.

Perhaps we will be relying on the primary (Siberian) vortex being displaced and weakened enough to allow some decent height rises across the pole, aligned in the right way to keep the remains of the Canadian vortex away from Greenland for as long as possible.


For this, the ECM 12z op run is a good effort 


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Stormchaser
23 January 2015 20:21:40


May as well enjoy the 'op run of the day' from a persistent cold pattern perspective  (just don't go placing bets on it!)


The low that ECM feeds across on day 10 moves through on day 9 of this CMA run and also tracks further SW. The pace of things is probably too fast, but the SW track has a perfectly reasonable cause; the Canadian vortex lobe is displaced further into Canada, away from Greenland, at that time - this allows higher heights across Greenland which start disrupting the Atlantic jet.


The day 10 chart shows disruption taking place SW of Greenland which is a good way to feed the UK a snow event while allowing high pressure to persist to our NW.


 


GEM is remarkably similar, and GFS wasn't far away really - just becomes too progressive upstream. Interesting that ECM turned out so well for day 10 in terms of the polar heights, considering it keeps the Canadan vortex closer to Greenland for days 8 and 9.


Generally speaking, this Chinese model (CMA) has been proving quite entertaining since it's introduction and since a recent upgrade it has had a few successes - it was among the first to suggest trough disruption for Monday/Tuesday this past week - so worth keeping an eye on I reckon 


If you have any problems or queries relating to TWO you can Email [email protected]

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2023's Homeland Extremes:
T-Max: 30.2°C 9th Sep (...!) | T-Min: -7.1°C 22nd & 23rd Jan | Wettest Day: 25.9mm 2nd Nov | Ice Days: 1 (2nd Dec -1.3°C in freezing fog)
Keep Calm and Forecast On
Gavin P
23 January 2015 20:36:34


 


The seasonal models, NAO signal and background seasonal fluctuations have been more useful than the strat etc. in forecasting this winter. I'll leave others to judge my forecast, but would say the MetO and those who've not relied on the latest fashions have performed quite well. This winter is only proving a 'shock' to those who relied on the OPI and Cohen etc. Those who used the former (or indeed on common sense of what a typical British winter is like) have managed to build a decent innings. Those who went down other routes saw their middle stump being knocked out of the ground early on.


Originally Posted by: Brian Gaze 


I did put the OPI (well rapid increase in snow cover really) Into my winter forecast, but l'm  pleased I "off-set" it with the NAO, seasonal models and solar activity (all of which never looked great for this winter) 


I think my winter forecast has been ***quite* good so far, but I'm rapidly approaching the tricky bit (a colder, blocked pattern for February)


Rural West Northants 120m asl
Short, medium and long range weather forecast videos @ https://www.youtube.com/user/GavsWeatherVids
tallyho_83
23 January 2015 20:40:21

Just a question please? - Why is it so mild for a brisk northerly wind +7c!? - Surely this doesn't have Atlantic influence and it's not like the winds are moving around the HP in the Atlantic!??




 


 


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


Gavin P
23 January 2015 20:44:49

Well that's just a projection, over one week away, from one model.


However... The thing with northerlies is that it always takes a few day's for the cold to really "bed in" which is why the south tends not to get much snow in the "toppler" scenario, because no sooner is the proper cold arriving, then it's being cut off by the next Atlantic low.


When you get into a "locked in" blocked pattern like December 2010 then northerlies can be as good as easterlies for snow, even in the south.


Rural West Northants 120m asl
Short, medium and long range weather forecast videos @ https://www.youtube.com/user/GavsWeatherVids
Ally Pally Snowman
23 January 2015 20:55:32

I don't think its a toppler. Looks like a long period of northerly winds progressively getting colder and certainly cold enough for snow in the south. Should be plenty of showers around with such a deep area of low pressure to our East. 


http://www.wetterzentrale.de/pics/Reem1681.html


http://www.wetterzentrale.de/pics/Reem2401.html


Bishop's Stortford 85m ASL.
Stormchaser
23 January 2015 21:00:38

Well by some measures (or at least my own) the GEFS 12z is the coldest set of the season so far (only runs since 2015 began visible below though):


No chart available for the selected hour. Many charts start at 3 hours ahead, so if you have 0 hours selected try stepping forward or selecting a later hour.


The strength of the signal at such range is beyond anything I can recall so far this season, more typical of spells driven by strong high latitude blocking rather than a major trough dropping into Europe. Shows just how large in scale and influence the event is now looking to be. This time yesterday the signal was still chaotic for the 29th Jan-4th Feb period, so the agreement is in it's early stages right now - prone to coming undone at short notice, so be wary!


 


If you have any problems or queries relating to TWO you can Email [email protected]

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2023's Homeland Extremes:
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Keep Calm and Forecast On
Ally Pally Snowman
23 January 2015 21:04:08

Good updat from the Meto man


Ian Fergusson NW


Hang about! That's totally incorrect. Indeed only a couple of days ago I *specifically* cautioned re possible longevity.
Reason? Because we could see need for caution from the more pessimistic (i.e. colder for longer) EC-EPS and MOGREPS members.
And we still do. Our story remains consistent: growing risk of a more potent, windy outbreak of cold weather; longevity, disruptiveness and scope of which continues to be very uncertain.


Bishop's Stortford 85m ASL.
kmoorman
23 January 2015 21:11:01


Good updat from the Meto man


Ian Fergusson NW


Hang about! That's totally incorrect. Indeed only a couple of days ago I *specifically* cautioned re possible longevity.
Reason? Because we could see need for caution from the more pessimistic (i.e. colder for longer) EC-EPS and MOGREPS members.
And we still do. Our story remains consistent: growing risk of a more potent, windy outbreak of cold weather; longevity, disruptiveness and scope of which continues to be very uncertain.


Originally Posted by: Ally Pally Snowman 


 


Sounds...  intriguing 


Home: Durrington, Worthing, West Sussex. (16 ASL)
Work: Canary Wharf, London
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White Meadows
23 January 2015 21:25:42
Before everyone starts talking about 'inevitable' downgrades we should all bear in mind the clustering has today has continued consolidation toward a solid cold theme from month end.
How the initial low is being handelled of course crucial to the outcome. But I do feel this time will either be misjudged poorly by the models and monumentally fail OR end up seroiusly cold and memorable, with slimmer Chance for a middle road/ blended solution than previous cold shots this winter.

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