Model Output Discussion - 23rd Jan - 12z onwards

[Severe Siberian icy blast]

That wasn't really suggested on Ian's forecast last week, it went up to mid-Feb at that point with week three being the first week of Feb, and it suggested a cold period (as we're getting), then a milder period after that, so still much as it was with no prolonged significant freeze, but obviously we're a week further on and the chance of a colder reload later. Obviously Ian's thinking that a Scandi high ridging to the North of the UK isn't how it's playing out, but there really was no suggestion of prolonged cold beyond the first week of Feb.

 

We're heading off topic though, so feel free to drop me a pm if you want a copy of that forecast or to discuss more.

Paul can you have a look at my profile please and turn on my private messages cause iv been looking for 20 damn minutes so I'm either very thick or very tired , can't send any PM's !

[shaky]

The new one is different

not so many embedded troughs and the warm sector seems further west through fri as a small low swings se. ECM has this off the east coast throughout so plenty to firm up on yet, even three days away!

is this a good thing or a bad thing from the ecm?

[blizzard81]

GFS 00z disrupts energy in the atlantic - positive sign but frustratingly, the ensembles have frozen!

[shaky]

GFS 00z disrupts energy in the atlantic - positive sign but frustratingly, the ensembles have frozen!

how do they look up t0 144 hours?

[SNOWPACK]

The charts are still showing rather cold weather setting in from tomorrow. Main snow threat North facing coasts and hills. Mainly dry North Midlands south. Frost at night for most. Any showers dying out as we go through the weekend and into next week.

[craigore]

Thats my take , it seems every time high lat blocking signals are there a few days later they're removed , I understand they still mention ridging toward Iceland so maybe stil a chance but I'm not sure how such strong signals can get blown away in the matter of days

Here , Here.. Ian was very clear on a scandy high , we have never got even close to that forecast , cold spell yes , but absolutely no blocking whatsoever , so whats changed in a very short time...??? hopefully we can benefit from a few disturbances that may develop in this unstable northerly , other wise the south will just be cold but dry as I see it..  

[I remember Atlantic 252]

The charts are still showing rather cold weather setting in from tomorrow. Main snow threat North facing coasts and hills. Mainly dry North Midlands south. Frost at night for most. Any showers dying out as we go through the weekend and into next week.

 

disagree with that, North Midlands looks very wet on Friday not dry

[winterof79]

The charts are still showing rather cold weather setting in from tomorrow. Main snow threat North facing coasts and hills. Mainly dry North Midlands south. Frost at night for most. Any showers dying out as we go through the weekend and into next week.

Disagree with your weekend outlook.Not your standard wishbone northerly this time.Instability is the key.GFS precip charts,although not entirely reliable give a clue.

[nick sussex]

Morning all

 

Well the shortwave ahead of the low over the ne Canada is now causing problems, its no surprise that the post T168hrs outputs are somewhat less exciting this morning as that feature is reluctant to head south/se.

 

The GFS takes ages to eject  this and its only saved because the upstream pattern re-amplifies sufficiently to help eject this, its a close run thing and really very low margin for error.

 

The ECM today takes the shortwave east and runs energy over the top so little chance of developing a decent ridge north of the UK.

 

The UKMO looks better going forward, its difficult to know whats going to happen from T168hrs until the models agree on how and where the shortwave will track and how amplified the upstream pattern might be at that crucial time period.

 

Earlier chances for snow but still some issues with marginality before the Euro troughing edges east whereby a cleaner northerly can edge in.

[Polar Maritime]

A chart to back up posts would certainly help other members understand, At this range any Snow showers & where they will fall be fickle 24hrs out.. 

Edited January 27, 2015 by Polar Maritime

[Kentish Snowman in Yorks]

The charts are still showing rather cold weather setting in from tomorrow. Main snow threat North facing coasts and hills. Mainly dry North Midlands south. Frost at night for most. Any showers dying out as we go through the weekend and into next week.

Rain or snow, at only 48 hours out, this chart does not look dry from the North Midlands south does it?

[i luv snow]

The latest charts show a northerly flow, giving wintry showers, heavy on North facing coasts at times. Scattered further south and inland.

So generally a fine spell of weather coming up with temperatures slightly below normal with night time frosts. Later in the period it's looking like settled conditions may continue with frosts becoming harder but days fine and dry.

 

This isn't what the charts show - they show a deeply unstable westerly/northwesterly/northerly airflow with lots of ppn around this week and again at the weekend, particularly in north and west but across a lot of the rest of the country too. Temps will struggle, and whilst marginal in the far south at times this won't always be the case. Looking at the charts, 'scattered showers' is certainly not the term I'd use. Pinpoint detail, even at 48 hours out, is pointless but there will be lots of instability around and so ppn will be more widespread than just north-facing coasts.

Edited January 27, 2015 by i luv snow

[TEITS]

I note some comments suggesting the S will remain dry during this period. The south will be drier but this does not mean no snowfall. Look at the fax at +48 and you will see a trough approaching Wales that will sweep snow showers across England during Wednesday night.

 

http://www.meteociel.fr/ukmo/fax/fax48s.gif?2

 

Now it is rather unusual to see snow showers from a W,ly but like I said a few days ago these could penetrate well inland. Normally they lose intensity as they move inland but a cluster of snow showers has the potential to cross from Wales to E Anglia.

 

Moving on and the snow risk lessens during Friday but should return during the weekend as a surge of colder N,lys sweep in bringing a renewed risk of snowfall. Beyond and although the evidence points towards this cold spell ending around next Wednesday, I am not yet convinced it will. What could happen is instead of a return to milder W,lys we see high pressure become centred across the UK. Obviously the snow risk fades but the cold temps remain. Another option is an NE/E,ly which cannot be ruled out.

 

I will add much of the above is aimed at S parts of the UK. Some parts of NW England/Scotland/Ireland could see heavy snowfalls.

[Nick F]

Morning, we can only look in wonder at the historic nor'easter blizzard unfolding across the NE USA where some parts there are forecast upward to 30 inches or 2 1/2 feet of snow.

 

As for this side of the pond, something a little more gentle wintry-wise for most from tomorrow, though the NWly flow looks very unstable across the northern half of the UK, GFS suggesting lapse rates of 32C between 850-500mb - so we can expect to see frequent and heavy snow showers for Scotland, N England and N. Ireland later tomorrow and overnight into Thursday - some places, even at lower levels, seeing 5-10cm - more over higher ground. We could see sleet/snow showers blow well inland through the Cheshire Gap into the Midlands too, wintry showers fewer for Wales and SW England, but some snow here in places over higher ground, central S and SE England looking mostly dry.

 

It looks to turn more marginal during Friday and Saturday away from higher ground ans the intial cold blast from the NW gets mixed out, but as winds veer northerly on Sunday, we see another renewed cold blast, this time from the north. The south and southeast may have to wait until this northerly for the best chance of snow as troughs/fronts or polar disturbances move down from the north Sunday and early next week. But generally, before then, it looks like the north and west seeing the lion’s share of wintry precipitation and snow potential.

 

Some uncertainties over how long the northerly will last, the models this morning have the Nly fading by mid-week next week as a ridge of high pressure builds in, but this should be a cold high with sunny days and very cold nights – especially with any snow cover around. I wouldn’t be surprised if this high hangs around until the end of the next week too – locking in the cold.

[Frosty.]

Much better medium range modelling this morning which is what we should focus on, a strong arctic maritime blast is now expected to develop on Saturday and persist well into next week, today's output so far has added at least a few days to the wintry spell compared to 24 hours ago so the trend is very good. In the short term, from tomorrow, squally wintry showers becoming heavier and more frequent, turning to snow, especially across the NW with local moderate accumulations, icy conditions becoming more widespread late tomorrow and through Thursday into Friday, a less cold blip is then followed by that strengthening Northerly flow through next weekend with snow showers spreading south...not bad huh :-)

Edited January 27, 2015 by Frosty.

[marksiwnc]

I note some comments suggesting the S will remain dry during this period. The south will be drier but this does not mean no snowfall. Look at the fax at +48 and you will see a trough approaching Wales that will sweep snow showers across England during Wednesday night.

 

http://www.meteociel.fr/ukmo/fax/fax48s.gif?2

 

Now it is rather unusual to see snow showers from a W,ly but like I said a few days ago these could penetrate well inland. Normally they lose intensity as they move inland but a cluster of snow showers has the potential to cross from Wales to E Anglia.

 

Moving on and the snow risk lessens during Friday but should return during the weekend as a surge of colder N,lys sweep in bringing a renewed risk of snowfall. Beyond and although the evidence points towards this cold spell ending around next Wednesday, I am not yet convinced it will. What could happen is instead of a return to milder W,lys we see high pressure become centred across the UK. Obviously the snow risk fades but the cold temps remain. Another option is an NE/E,ly which cannot be ruled out.

 

I will add much of the above is aimed at S parts of the UK. Some parts of NW England/Scotland/Ireland could see heavy snowfalls.

Yes possibilities are endless even the weekend looks good for us in western wales with a fair few showers according to the last 4 runs.. We seem to do quite well from patterns similar to this.

[The Beast From The East]

I think you could be right about high pressure moving over us later next week. Looks like what BBC weather are going for as well.

I note some comments suggesting the S will remain dry during this period. The south will be drier but this does not mean no snowfall. Look at the fax at +48 and you will see a trough approaching Wales that will sweep snow showers across England during Wednesday night.

 

http://www.meteociel.fr/ukmo/fax/fax48s.gif?2

 

Now it is rather unusual to see snow showers from a W,ly but like I said a few days ago these could penetrate well inland. Normally they lose intensity as they move inland but a cluster of snow showers has the potential to cross from Wales to E Anglia.

 

Moving on and the snow risk lessens during Friday but should return during the weekend as a surge of colder N,lys sweep in bringing a renewed risk of snowfall. Beyond and although the evidence points towards this cold spell ending around next Wednesday, I am not yet convinced it will. What could happen is instead of a return to milder W,lys we see high pressure become centred across the UK. Obviously the snow risk fades but the cold temps remain. Another option is an NE/E,ly which cannot be ruled out.

 

I will add much of the above is aimed at S parts of the UK. Some parts of NW England/Scotland/Ireland could see heavy snowfalls.

[Gibby]

HERE IS MY LATEST ANALYSIS FROM THE OUTPUTS OF THE WEATHER COMPUTER PREDICTION MODELS FOR TWO WEEKS FROM 8AM TODAY TUESDAY JANUARY 27TH 2015.

 

NEXT UPDATE WEDNESDAY JANUARY 28TH 2015 08:00

 

THE CURRENT GENERAL SITUATION A strengthening SW flow ahead of active cold fronts crossing SE over the UK tonight and tomorrow will be followed by an increasingly cold and windy westerly flow tomorrow.

 

MODELS-2 WEEK HEADLINE Becoming colder with snow showers or snow at times before becoming less cold and changeable again later next week.

 

THE JET STREAM ENSEMBLE FORECAST The Jet Stream Forecast shows a week long spell with a deep trough over Europe keeping the flow well South of the UK in NW winds. In week 2 the pattern flattens markedly over the Atlantic and Europe with the flow returning North across the UK between High pressure re-established to the South of the UK and Low to the North.

 

GFS OPERATIONAL The GFS operational today continues to illustrate the colder theme of weather now for the rest of this week, the weekend and the start to next week with cold West, NW then North winds with wintry and snow showers affecting all areas at some point across the UK with the exposed areas facing NW and North. A marked wind-chill will accompany the cold period. Then as we move through next week milder air will try to dislodge the cold from the Atlantic and a messy mix of rain and snow will accompany that before a slow return to milder SW winds and occasional rain arrives later in the run.

 

THE GFS CONTROL The GFS control run is not fully available at time of publish but as far as it goes show a lessening of the cold spell as we move into next week from the West.

 

THE GFS CLUSTERS The GFS Clusters also are only available up to 132hrs today and show a cold and wintry NNW flow across the UK in total domination at that point.

 

UKMO UKMO this morning continues to show the UK in a very cold Northerly flow to start next week with plenty of snow showers flooding South across the UK with only Central inland areas of Southern Britain least at risk.

 

THE FAX CHARTS The Fax Charts show plenty of troughs feeding South and SE in the cold flow from tomorrow giving rise to plenty of instability sufficient to give many areas the risk of either wintry or snow showers, the latter especially at the weekend as the flow turns more Northerly.

 

GEM GEM today continues to show the dissolve of the cold weather early next week in the wake of less cold but very unstable westerly winds with heavy rain and gales likely at times with wintry showers at times too, these especially in the North.

 

NAVGEM NAVGEM today keeps the cold going over the UK into next week with a ridge eventually cutting off the cold North flow by Tuesday but with the likelihood of it remaining cold with the possibly of a battleground snow event towards the West by midweek

 

ECM ECM this morning looks very messy as the cold northerly flow dissolves away early next week. Temperatures are shown to steadily rise by day at least as a broad ridge crosses the UK from the West. Frosts are still likely at night though and it would likely stay largely dry.

 

ECM 10 DAY MEAN The 10 Day Mean this morning looks like broadly setting the UK back on it's default position later next week as Low pressure lies well to the NW and High pressure to the South with broadly westerly winds likely across the UK and a much less marked trough over Europe.

 

NOTABLE TREND CHANGES FROM PREVIOUS RUNS The trend remains for much colder and windy weather later next week and through next weekend. The longevity of the spell has firmed up somewhat on milder conditions returning from the West as we move deeper into next week.

 

MY THOUGHTS The cold period is almost upon us now and remarkably the models have held firm on it's evolution of this spell from the weekend. However, the models have found it less easy to agree on the end of the spell which is looking likely towards the middle of next week. In the meantime there is concrete support for a cold and windy West, NW then North wind over the coming 5-6 days starting tomorrow with snow and sleet opportunities for many on all days though as always the hills of the North and West will probably fair best. I know we shouldn't be looking for the end of the spell before it arrives but I wouldn't be giving my report much credibility by not and it does look like there is very good support for less cold conditions to move across from the West by the middle of next week give a day or two. The way that happens is shown by most models to be a real cocktail of options at the moment but the likely scenario is for Westerly winds to regain a foothold across the UK by next weekend with rain at times. GEM shows a more extreme version of this with gales and heavy rain on a strong Westerly flow and the ECM 10 day Mean chart is ugly if it's continued cold your looking for. However, the operationals over the last few runs have shown much volatility in their range of options so I feel the ensembles tell a truer picture and that suggests milder weather as we progress through next week. Nevertheless we have a period of 5-6 days when there is some good opportunity for snow even in the South and though inevitably some will see little or none there will be some who see a lot with disruption and news coverage likely but overall by this time next week I think we will be seeing a moderation in the cold and a gradual return to a more default position we have been in for much of this Winter.

Edited January 27, 2015 by Gibby

[nick sussex]

Can we order the ECM control run for this evening:

 

 

The control run looking at the wind directions brings in an easterly for Holland and more than likely the UK also:

 

http://www.weerplaza.nl/15daagseverwachting/?r=midden&type=eps_pluim

[EML Network]

I think you could be right about high pressure moving over us later next week. Looks like what BBC weather are going for as well.

 

She looks like she's trying to squeeze one out. 

 

But yes the favored option is for High pressure to push in towards the UK next week, looking through the ensembles this morning though it seems to be ditching that idea and instead going for an all too quick return the westerly's.  but this is just one run and the theme for the past few days has been for High pressure to nose in from the west

 

wouldn't take much of a Westward movement for that Low over Italy to come into play though

 

[sebastiaan1973]

Can we order the ECM control run for this evening:

 

eps_pluim_tt_06260.png

 

The control run looking at the wind directions brings in an easterly for Holland and more than likely the UK also:

 

http://www.weerplaza.nl/15daagseverwachting/?r=midden&type=eps_pluim

Yes, that would mean we could skate on the other side of the North Sea!

[nick sussex]

Yes, that would mean we could skate on the other side of the North Sea!

Yes its been a long time since you've been able to do that in Holland. Fingers crossed tonights ECM operational run picks up the control run tonight.

[bluearmy]

Yes its been a long time since you've been able to do that in Holland. Fingers crossed tonights ECM operational run picks up the control run tonight.

Nick - the control amplifies the ridge which then becomes a general n euro block. Transferring East and maintaining surface cold with the Atlantic eventually getting through around day 12/13. No screaming easterly i'm afraid. Infact, I do wonder if a standard return to the Atlantic might just bring another reload of sorts within a week?

Anyway, what do you think re the spreads on ecm. Uppers look like the Atlantic getting well in whereas heighs look like a n Atlantic ridge. I'm confused although the uppers must mean the heights spread reflects deep systems to our nw.

[nick sussex]

Nick - the control amplifies the ridge which then becomes a general n euro block. Transferring East and maintaining surface cold with the Atlantic eventually getting through around day 12/13. No screaming easterly i'm afraid. Infact, I do wonder if a standard return to the Atlantic might just bring another reload of sorts within a week?

Anyway, what do you think re the spreads on ecm. Uppers look like the Atlantic getting well in whereas heighs look like a n Atlantic ridge. I'm confused although the uppers must mean the heights spread reflects deep systems to our nw.

Lol! Maybe I'm a bit slow today but trying to decipher those spreads is doing my brain in!  It seems straightforward upto T192hrs, the spread seem to have a slightly more amplified upstream troughing, a shortwave runs south/se between T168 and T192hrs. I think BA the spread to the nw is low pressure at T240hrs I think the Azores high is nosing into the sw, some low heights remain over northern Italy.

 

What do you think?

Edited January 27, 2015 by nick sussex

[The Enforcer]

Dewpointwatch update (number of GFS frames above freezing for South Midlands area between Wednesday 3pm and Sunday 9pm:

 

25/1/06z - 10

25/1/12z - 1

25/1/18z - 2

26/1/00z - 7

26/1/06z - 12

26/1/12z - 9

26/1/18z - 4

27/1/00z - 7

 

Less favourable period for snowfall remains on Friday and Saturday's has been enlarged again.

 

Before that, dewpoints look OK Thursday evening:

 

but NMM isn't having any of it: