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Paul

Please keep this thread solely to discussing the model output. The model banter thread is available for more loosely model related chat, ramps and moans.

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Gfs still different in the initial evolution to Euro/UKMO but both still cement a low over Europe. 

Snow for Scotland from Wednesday and for the south west and Ireland probably around fri/sat.

For the rest of us the Euro/UKMO would probably move us towards an easterly of some sort.

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8 minutes ago, tinybill said:

http://www.meteociel.fr/modeles/cmc_cartes.php?code=15&ech=192&carte=1

i know its cherry  picking but their some their juicy charts that could come our way in fantasy world

It's only cherry picking if you select a run that is largely unsupported by the ensemble suite. The charts you have chosen are perfectly plausible as they sit within a decent sized cluster. Go for it!

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1 minute ago, Optimus Prime said:

Similar to 2010?

If your're talking 2010 Dec then i think 2010 would have had more around or slightly below -10c by then but still great.

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Clear the diary,walk the dog keep the wife happy (not easy I know). I have a feeling Boom charts from 3.30pm on the 12z.I am looking forward to that placement of that slider on UKMO🙂

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The ECM op is the best case scenario from my perspective. 

My thoughts are that we want the Canadian PV lobe to discharge in one continuous strong flow. This will suppress the Azores/Atlantic High(s) and enable a smooth transition of an NW to SE flow into a Euro trough. Hopefully squeezing the Atlantic Ridge further west, so when the lobe is weak we can see a ridge creating better long term blocking. That far west will put the UK in the comfort zone for cold and snow.

The first push at D5 is where the models diverge, that system stalls on the ECM allowing wedges to develop on its Eastern flank, whereas the GFS joins that low with the low-pressure systems to our east, with the mini-ridge on the west flank. The Atlantic Ridge then oscillates too far east with a repeating pattern of failing ridges.

Thankfully we are aware of the bias of the GFS, so more than hopeful that the ECM will be much closer to the outcome. There is a small cluster in the GEFS supporting the ECM take and the GEFS FI continues to trend towards the interesting for long term cold. I think all doors lead to cold and snow, but some of those doors you will need to dig yourself out, let's hope we open one of them!

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3 minutes ago, snowice said:

Clear the diary,walk the dog keep the wife happy (not easy I know). I have a feeling Boom charts from 3.30pm on the 12z.I am looking forward to that placement of that slider on UKMO🙂

I can certainly see the potential for UKMO and Euro to upgrade the timing. Euro killed the initial splitter and needed the second attempt, GEM shows that it could be done on the first attempt.

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4 minutes ago, Catacol said:

Fascinating to see 2 such starkly different interpretations as to the passage in around 7 days. ECM op much more amplified initially - GFS gets there a day so later....and the end product is cold of a very different setup at 240h. ECM slider scenario that I'll post again is front edge snow and probably lots of it.

ECM1-240.thumb.gif.7b838db360591a46464ce13a4b731053.gif

GFS is harder to call - certainly strong convective showers for all in N and E parts - but with pressure strong out west fronts may fizzle as they try and work their way east to west.

gfs-0-240.thumb.png.17477d6143ddf7b41edb6b526212128a.png

Each model sees the tilt of the trough as exact opposite - but both very definitely cold and cyclonic.

ECM I think gives more snow more widely - so glad it out punches GFS in the stats - but the beauty from a forecasting angle as that you can see it is quite difficult in the current conditions for us NOT to end up with a wintry product in around 10 days time. A meridional circulation thanks to the strat downwell means the only scenario that would prevent a positive outcome would be one which sees the high pull back west and then ridge slap bang over the UK again. I don't see it, however. Pattern change means change - and that means both wavelength and amplitude of the atlantic pattern. In this context - without being an expert in waves from the physics perspective - I think it highly unlikely that the ridge could essentially remain where it is. One way or another we are heading for a European trough, whether positively or negatively tilted, and this means snow.

I just told someone that snow is coming. Apologies if I've jinxed it.

 

Euro is fairly useless for the bulk of England but the prize is the attempted easterly once it undercuts enough.

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2 minutes ago, summer blizzard said:

Euro is fairly useless for the bulk of England but the prize is the attempted easterly once it undercuts enough.

It won’t verify exactly like that though ......it’s the trend that’s important and we need the op to get on the same page as the mean to guide us re the actual route to the cold set up we expect to get to. hopefully the ec op is in the same ballpark days 7/10 later to give us some more clues. If it’s an outlier (as yesterday’s runs were) then it’s a pretty useless tool! 

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I've only seen one 'negative' so far today: the GFS's suggestion that warmer uppers may invade from the east, towards the end of its run...?

But even that (should it, by some unpleasant quirk of fate, actually transpire) is not really that negative, is it: After traversing hundreds, if not thousands, of miles across deep snowcover, to get here, temps at 2m would hardly be mild?

Apart from that, everything looks amazingly positive...And, when one considers the likelihood of a significantly lengthy cold spell; even more positive than they did, immediately following last-year's SSW!:cold::santa-emoji::yahoo:👍🎆

Edited by Ed Stone
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16 minutes ago, Catacol said:

ECM I think gives more snow more widely - so glad it out punches GFS in the stats - but the beauty from a forecasting angle as that you can see it is quite difficult in the current conditions for us NOT to end up with a wintry product in around 10 days time. A meridional circulation thanks mostly to the strat downwell means the only scenario that would prevent a positive outcome would be one which sees the high pull back west and then ridge slap bang over the UK again. I don't see it, however. Pattern change means change - and that means both wavelength and amplitude of the atlantic pattern. In this context - without being an expert in waves from the physics perspective - I think it highly unlikely that the ridge could essentially remain where it is. One way or another we are heading for a European trough, whether positively or negatively tilted, and this means snow.

I just told someone that snow is coming. Apologies if I've jinxed it.

 

00z EC quite dry but rather cold past Thursday, exception is the island of Ireland and NW Scotland - where it shows snow or a wintry mix week commencing 21st Jan.

But like bluearmy says, plenty of room for change, with fronts perhaps making more inroads east.

Edited by Nick F
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3 minutes ago, Nick F said:

00z EC quite dry but rather cold past Thursday, exception is the island of Ireland and NW Scotland - where there could be snow or a wintry mix week commencing 21st Jan.

But like bluearmy says, plenty of room for change, with fronts perhaps making more inroads east.

Different time scales here Nick. Yes - for next weekend the EC is quite dry - but the slider scenario is not come Tuesday. Timelines can get confusing - but I was very definitely talking about day 9/10

All this assumes, of course, we get a slider in the first place. GFS has a different solution. Hours of fun model watching to come this week!

Edited by Catacol
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Some long range eye-candy from the 06z GEFS.⛄

 

Maybe hinting on where we are headed into February?

 

gensnh-5-1-384.thumb.png.3dda4bc4acc61a05a3f31be8d353340d.pnggensnh-8-1-384.thumb.png.b3dedad644c010ed95e25be9c8580c87.pnggensnh-9-1-384.thumb.png.bc4ba5090cc139d85fe260f5b7d76985.pnggensnh-19-1-384.thumb.png.9c13d59dbe9380aefde831441859ef9a.pnggensnh-15-1-360.thumb.png.0bfc2cd971d5d0b593077b01b091edaf.png

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9 minutes ago, Catacol said:

Hmm. Check the 6 Feb 1996 and then snowfall totals for many parts on that day before you write off the initial impact of the slider. The synoptic similarity between the ECM 240 and that Feb 6 chart is very striking. If I'm allowed not to post a chart here - and quote from the Dark Side of the online weather community worth perhaps noting this:

"On the 6th, an occlusion system approached the west of the UK threatening a change to much milder weather across the UK. However, pressure began to increase to the east of the UK and this prevented the occlusion advancing and the system became stalled over the west of the UK on the evening of the 6th. Heavy snowfalls fell right across western and central parts of the mainland but conditions were particularly severe in SW Scotland and parts of Cumbria, where depths of snow were approaching 50cm. A state of emergency was declared in SW Scotland and many drivers stranded on the A74 had to be rescued. Whitehaven in Cumbria was virtually cut off and workers at the Sellafield nuclear reprocessing plant had to spent the night as they were stranded. Conditions elsewhere were less severe but the inevitable travel chaos ensued. By the evening of the 7th, the snow finally died out and it remained cold and snowbound until the 9th with further snowfalls at times before a vigorous depression finally brought a thaw and milder temperatures. The snowfalls turned out to be some of the heaviest in the west since the winter of 1947."

Admittedly the east did less well on that occasion. But "useless"? Don't think so 🙂

 

My all time fav snowfall.. I would give me left proverbial for a repeat of that. 

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1 minute ago, bluearmy said:

Gefs 06z at the back end ..... if ec46 is right then we should be expecting to see a greeny ridge appear on the fi output ......if the low res gefs are picking it up then that’s a great sign ...…

And given the operational output bringing the cool down forward slightly to Thurs/Fri any ridge developing to the NW - which has been the talk of the broad teleconnections since New Year and actually a bit before that - would be doing so with cold already well established over Europe. No need to wash the warmth out of ground or surface air by then - just the need to get the boundary between trough and block in the right place for precipitation. No easy watch of course that - we all know from an IMBY perspective that local weather conditions can vary enormously over only a few miles....and so luck without doubt will be needed for snow hunters on this forum - but from a macroscale perspective odds would be much more favourable than in many a winter gone past.

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