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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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6 minutes ago, Seasonality said:

Oh definitely Nick! Its all positive for UK cold that much is true.

True , I’d just like to see tonights runs to remove any doubt . I never used to be this cautious ! 😎

Just reading the NCEP extended discussion and I like the sound of it .

Pattern change to a more amplified flow. West USA amplified ridge , down stream mean trough east USA.

This supports high pressure to the ne of the UK, the jet track out of the ne USA should track ne holding back the main PV and allowing the jet cutback sw into the UK.

Edited by nick sussex
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3 minutes ago, lorenzo said:

Well, this looks terrible..❄️

Does it?  What is it?

 

 

 

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1 minute ago, snefnug said:

 

Yes - it looks terrible for the Government and contingency planners and no doubt gritting agencies who are probably under prepared - as they are probably told that it can't happen in the UK anymore by certain people - its the upper air temps at 850mb - time series on every ensemble member for next 2 weeks.

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31 minutes ago, nick sussex said:

True , I’d just like to see tonights runs to remove any doubt . I never used to be this cautious ! 😎

Just reading the NCEP extended discussion and I like the sound of it .

Pattern change to a more amplified flow. West USA amplified ridge , down stream mean trough east USA.

This supports high pressure to the ne of the UK, the jet track out of the ne USA should track ne holding back the main PV and allowing the jet cutback sw into the UK.

Well Nick, with the UK's tendency to snatch mild defeat from the jaws of cold victory then I too advocate extreme caution!

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Well we are getting close to the time the 12z start to fire up, hoping the ICON shifts a little more inline, same as the UKMO which at least did show an improvement.

Also in other news, the storm that is very important to our chances of an easterly (and which the US weather people are watching like a hawk on americanwx) is now in the process of forming over C.N. USA and once that process is complete the models should become more clear.

24hrs at most I think of uncertainties and then we should at least get the easterly/northerly/whatever sorted. What happens after that is still going to need more time however.

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4 minutes ago, Nick F said:

Afternoon all

After some uncertainty with regards to the track of a winter storm over the eastern USA this weekend and how far out into the far north Atlantic it will track and interact or phase with low pressure ahead of it near Iceland diving southeast towards the North Sea Tuesday, it appears the models are starting to converge on the idea of low pressure over North Sea Tuesday dropping southeast across mainland / central Europe into Wednesday, while pressure / geopotential height rises build in to the north of the UK and over Scandinavia

The buckling of the jet over the far north Atlantic ahead of that storm passing Nova Scotia Tuesday and jet stream downwind over the NE Atlantic turning southeast as a result, allows low pressure to dive southeast from Iceland towards the North Sea then into mainland EU and looks to be the main trigger for pressure to build to the north and northwest of the UK later next week.

jet_loop.thumb.gif.e68262ad5ee141a178e1675708f5e063.gif

However, there are also signs, from the ECMWF high resolution, of an arctic high forming over eastern Greenland, I mentioned this yesterday too, perhaps in response to easterly winds starting to propagate down through the troposphere from the lower stratosphere – following the Sudden Stratospheric Warming to start the year.

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EC, with its better vertical resolution, probably get a better handle on the downwelling and how it will affect trop patterns and yesterday's EC stratosphere charts on the Berlin site showing easterly winds finally reaching down into the troposphere by the middle of next week.

ecmwfzm_u_f144.thumb.gif.9c69ed12665471f27ed2438b9b6fe858.gif

06z GFS also has the easterlies reaching down through the troposphere, perhaps a few days later

uwind.thumb.PNG.8b938ab1379c65b768b1081ae1925a93.PNG

This arctic high has, on a few ECMWF runs now, been indicated to drop south to Scandinavia intensifying high pressure there, this and the sequence of events leading to the flow buckling northeast over the Atlantic portending to an easterly or northeasterly flow to develop towards the tail end of next week. 

However, there is still a fair bit of uncertainty how the synoptic pattern will evolve in detail for now beyond Wednesday, suffice to say an increasing risk, say 70%, for very cold air and increasing snow risk to arrive from NE Europe by the end of next week or next weekend. This very cold pattern could be sustained into early January, thanks to the delayed and slow downwelling of easterly winds in the stratosphere impacting circulation in the troposphere but over a protracted period too, so high latitude blocking could persist for a few weeks at least.

Before then, worth keeping an eye on Monday night - active frontal system diving SE with quite cold northwesterly flow immediately behind coming from a very coold Greenland and NE Canda, 00z ECMWF was not overly keen on back edge  snow away from more northern areas, 00z and 06z GFS show back edge snow all the way to southern England. Sleet and snow showers packing in behind across the northwest.

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Thanks Nick, all makes sense in there.

One small typo, you mean into February not January?

 

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Just now, johnholmes said:

Thanks Nick, all makes sense in there.

One small typo, you mean into February not January?

 

Yep, just notice and changed

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This potential cold spell is also going to fall in just about the optimum time for cold as well. The equivalent of big summer heat towards the end of July/beginning of August. It’s all looking good - at the moment!

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Sometimes surprises for snow in short term can happen and I do think there is the chance of snow Tuesday right down to the South Coast.

A very nervous few hours await..

 

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10 minutes ago, kold weather said:

Right everyone, eyes down because the 12z suite are upcoming, starting with the intial stages of the ICON 12z, out to just 12hrs.

Next 4 hours are going to be either very stressful, very sad....or VERY happy.

As long as we continue to see the broad trend of HP forming either to our north or east then the rest will hopefully come in tow.

Best of luck, everyone!

Tis like bingo in here..Well Im hoping for a full house..!!

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ICON has the low MUCh further SE at 108hrs coming out the states, though still worth noting there is a fair amount of lower heights over Iceland this time but looks like a decent start.

Looks like things are further west, for example the upper high is further west to our north (and weaker).

Edited by kold weather
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ICON could be picking up on a new signal but more likely it's a cannon fodder model that just doesn't know how to handle splitting energy..

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I get the feeling the ICON is struggling with this low dropping SE. Guess we will find out with GFS and UKMO shortly 🤞

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9 minutes ago, CSC said:

Sometimes surprises for snow in short term can happen and I do think there is the chance of snow Tuesday right down to the South Coast.

A very nervous few hours await..

 

Not convinced - experience tells me that these marginal events tend to fall the wrong side as they come into the 36-72 range. Rather like tonight's prospects were looking a couple of days ago. Not a problem, as this was only the breadstick course.

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Slightly slower buildup but much better fundamentals than the 06z ICON for sure.

icon-0-138.png?18-12

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42 minutes ago, tight isobar said:

Well for all the talk of brexit etc..

This one up n, coming could put the agenda/issue to the bk of the pack 4 a while...

And our weather could become the main headlines....

Into the freezer we go...

And the rest of europe joins us..

No getting out of this 1 theresa!!!😉

temp4 (3).png

Sorry, I maybe being dumb, but don't those first 2 charts indicate only the West of the UK getting cold conditions and everyone else getting between 0-4c which is cold but nothing out of the ordinary, just typical winter temperatures?

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