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Model output discussion - 7th January onwards


Message added by 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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13 minutes ago, bluearmy said:

just a reality check .... it might be worth thinking about some of the decent cold spells of the past decade and then viewing the archived runs that were being thrown out for the week two period back then. It’s very unusual to see the verification live up to the levels of deep cold etc that were being shown 9/13 days ahead .....what is important to see is the potential longevity of the pattern .... the more bites at a potential snow event we get, the more chances we have of one sticking ..... especially once we have surface cold in ...

onto the 12z’s ....... don’t expect to see anything in particular ......just enjoy the ride for the time being ....

That's interesting, because the extent to which the cold air is moving to the south of Europe also looks pretty outrageous at this stage. Is this likely to modify too?

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So a rather long post ( Will also clip into the winter forecast thread ) However just an update on saturdays post, a large debate around models - & I took the day 6 UKMO & GFS charts to c

I assume the overnight ECM has (temporarily at least) put an end to the glass half empty stuff from some posters yesterday. I'm sure the next variation in op run will bring them back out - but if you

It's all good folks - we are about to get slammed ? Think March 2013 imprinted on the middle of winter - what's not to love ! The slider solutions are dialled in as the wave guide changes, N

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12 minutes ago, Alderc said:

Beware, remember the great model backtrack from a couple of winters ago when at day 5/6C there were -10C - -15C uppers banging on the door for a sudden seismic and almost instant flip in the models and we ended up with mild westerlies? Not saying that will happen but with so many inter/intra model variances there's still a lot of up and downs to through yet. 

Being in pretty much the least snowiest place in the country I'm trying not to look at the precip charts, down here we are sheltered by a long land track from any direction north or west/east if that makes sense and have a warm body of water directly south such inevitably quick raises wet bulb temps with a flow from the sea. Hopefully as we get closes to the middle and end of next week some of little polar lows will start churning westwards which I would have thought is good possibility or better still a proper channel low.

I'm not a big cold or snow fan but if got to happen this is the best time as most optimal for cold and snow so it can go hard or go home as far as im concerned!! 

I'd say with the SSW impact there'd surely be less of a chance (of a backtrack) but you never know

Edited by CanadianCoops
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26 minutes ago, bluearmy said:

just a reality check .... it might be worth thinking about some of the decent cold spells of the past decade and then viewing the archived runs that were being thrown out for the week two period back then. It’s very unusual to see the verification live up to the levels of deep cold etc that were being shown 9/13 days ahead .....what is important to see is the potential longevity of the pattern .... the more bites at a potential snow event we get, the more chances we have of one sticking ..... especially once we have surface cold in ...

onto the 12z’s ....... don’t expect to see anything in particular ......just enjoy the ride for the time being ....

Funnily enough I was looking at 10/11/12 Feb 1994 recently. A great easterly but not a lot of snow of I remember rightly. However we seem to have the potential for undercuts and approaching fronts this time, which we didn’t in ‘94. 

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A multi model flip seems unlikely this time in terms of a definite cold spell. Such a strong signal for this to be the case over at least the next fortnight.

Biggest concern is where the precip will fall and how much. Too early to say of course, but the longer we stay cold/very cold, the greater the potential opportunities arise.

I'd prefer a week of cold and plenty of snow, rather than a fortnight of showers/light stuff. Give me those 50p size flakes!!!

Anyone know whether AROME/ARPEGE/HIRLAM is most trustworthy for precip types/amounts?

Edited by Runcible Spoon
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10 minutes ago, helentheroberts said:

That's interesting, because the extent to which the cold air is moving to the south of Europe also looks pretty outrageous at this stage. Is this likely to modify too?

Invariably - yes

the models tend to show stuff further out that’s simply so unprecedented that it just won’t verify - obviously there are occasions which contradict this like last feb/March where the deep cold pool survived its arrival at the Baltic Sea and made the long track across - but the strength of the reversal wave was exceptional as was seen by how far into the Atlantic it got ....

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1 minute ago, Runcible Spoon said:

A multi model flip seems unlikely this time in terms of a definite cold spell. Such a strong signal for this to be the case over at least the next fortnight.

Biggest concern is where the precip will fall and how much. Too early to say of course, but the longer we stay cold/very cold, the greater the potential opportunities arise.

I'd prefer a week of cold and plenty of snow, rather than a fortnight of showers/light stuff. Give me those 50p size flakes!!!

Anyone no whether ARMOE/ARPEGE/HIRLAM is most trustworthy for precip types/amounts?

50p flakes means things are marginal, what you really want is tiny, dry powder snowfall, when that type of snow falls you know you’re in a cold spell!

All the models have their flaws.. I tend to use EURO4/APERGE blend but it depends how they fit in with the other Hi-Res models. 

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At 144h the GFS and ECM solutions are rather different, and I know what I'd put my money on at that range. And although it has been done to death I'm convinced there is at least a grain of truth in the US shutdown affecting the accuracy of the GFS output. Very sad to see the full implementation of the FV3 has been delayed.

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13 minutes ago, Paul_1978 said:

Funnily enough I was looking at 10/11/12 Feb 1994 recently. A great easterly but not a lot of snow of I remember rightly. However we seem to have the potential for undercuts and approaching fronts this time, which we didn’t in ‘94. 

You must have got belted on that overnight Monday into Tuesday from that front coming up from the South West.

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5 minutes ago, Seasonality said:

At 144h the GFS and ECM solutions are rather different, and I know what I'd put my money on at that range. And although it has been done to death I'm convinced there is at least a grain of truth in the US shutdown affecting the accuracy of the GFS output. Very sad to see the full implementation of the FV3 has been delayed.

Both are great solutions . We’ve seen variations of where any high is between outputs which is normal at this stage .

If the Euro troughing holds to the se then cold remains locked in for the UK.  There is no other set up which is so overwhelmingly correlated with UK cold .

 

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15 minutes ago, Paul_1978 said:

Funnily enough I was looking at 10/11/12 Feb 1994 recently. A great easterly but not a lot of snow of I remember rightly. However we seem to have the potential for undercuts and approaching fronts this time, which we didn’t in ‘94. 

Later Feb '94 was though! the days ruled, 22-24th, sure I had 72 hours continuous snow! the days when Atlantic air failed to win against the cold air! and result snaw

archives-1994-2-24-0-0.png

Edited by I remember Atlantic 252
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Just now, nick sussex said:

Both are great solutions . We’ve seen variations of where any high is between outputs which is normal at this stage .

If the Euro troughing holds to the se then cold remains locked in for the UK.  There is no other set up which is so overwhelmingly correlated with UK cold .

 

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

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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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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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