winter model output Winter Model Output Discussion -12Z 07/02/13 onwards

[Gibby]

Good evening. Here is the report of the 12z output from GFS, UKMO and ECM for tonight Thursday February 7th 2013.

All models show an occlusion lying North to South down the Western side of the UK embedded in cold air left from yesterdays Northerly flow. The weather will be overcast and cold with some occasional rain, sleet or wet snow over the hills, especially early tonight. The East will stay dry with thinner cloud cover in a continuing light NW breeze. Tomorrow sees little change synoptically with a lot of cloud cover and the chance of further showery bursts of light rain, sleet or snow in the West. Saturday too still shows quiet weather albeit cold as a weak ridge crosses the UK. On Sunday a new front and developing depression is shown to slide SE from the NW towards Southern England and the English Channel on Sunday. The result of this is a spell of rain which will turn to snow in places, especially later in the day and widely on Sunday night with some significant disruption possible. On Monday the Low lies to the South of the UK, still giving snowfall in the South before it slowly clears from the NW through the day. Then on Tuesday it looks like the general consensus between the models is for a ridge to steadily move down from the NW, drying things up but keeping things cold and potentially frosty and icy by night.

GFS then takes us through the midweek period with the quiet weather gradually giving way to a weak front and then more mobility from a SW breeze from the Atlantic with a potential thaw and some rain in places by the end of the week. Then as High pressure remains out to the East and NE the trend for trough disruption remains with a further bout of SE moving Low pressure and potential snowfall in rather cold conditions developing again after the second weekend. The run ends with a large cold and unstable pool of air covering NW Europe including the UK with sleet or snow at times for most.

The GFS Ensembles show fairly good agreement North and South on generally rather cold and unsettled conditions continuing throughout the coming few weeks. The main change from this morning is the upturn in the amounts of precipitation shown indicating a stand off between cold to the Northeast and milder air to the West with the UK being the battleground on various occasions giving rise to copious rain events, some of which will no doubt be of snow given the temperatures.

The Jet Stream shows the current Southward moving flow over the UK breaking up in the coming few days before realigning to a position further South over the Atlantic and SW of the UK where it persists for the coming period.

UKMO for midday on Wednesday shows the cold and snowy NE flow of early in the week having given ground to a stong ridge of High pressure from Scandinavia. The weather would be dry and cold with bright sunny days and very sharp overnight frost, especially over any snow cover.

ECM tonight shows a very wintry start to next week slow to improve from the NW midweek. There will be snow cover likely over many Southern areas once more with a gradual moderation in the conditions midweek as the cold NE flow in the wake of the Sunday/Monday depression weakens as a ridge edges down from the NW. With Low temperatures embedded over the UK midweek a further weak front decayng as it moves East into the UK could give further lighter snowfall around Thursday. However, late in the run the blocking High to the NE gives ground and weakens as the Atlantic winds move slowly East over the UK bringing less cold weather with the chance of rain at times to end the week rather than snow in a much more blustery SW wind.

In Summary the models are maintaining a cold look about them for at least the next week. There looks to be a good chance of some disruptive snowfall in places early next week with nowhere immune from seeing at least a little snow. Longer term it looks like the block to the NE gives way a little to allow troughs to eventually win over from the West bringing less cold conditions for a time with rain in places. If GFS is to be believed it might not last long as further blocking out to the NE develops again and brings back disrupting troughs and cold low pressure.

[phil nw.]

Solid agreement for the diving low across the SW of the UK Sunday with rain turning more and more to snow as the cold air undercuts from the east with the low moving into the channel come Monday.

A slight trend south west with the track on the latest T72hrs Fax compared to the earlier one at T84hrs.

This should bring more areas away from the far south and south west into the snow risk zone either later Sunday or through Monday before the main area of pptn. moves away.

Fine details still to be confirmed but the fax`s and the raw outputs of the other models all look to run this low on a similar track.

Looking into early next week and there`s a definite trend to weaken that Greenland vortex now with those heights to the north becoming more influencial -we can even see some yellow near Svalbard around T120hrs.

http://www.wetterzen...cs/Recm1201.gif

http://www.wetterzen...s/Rtavn1201.png

http://www.wetterzen...cs/Rukm1201.gif

It looks unlikely that any further energy from the Atlantic will do anything other than disrupt and go south east from there with forecasted height anomalies continuing to build across the north

http://176.31.229.22...-0-0-240.png?12

http://www.meteociel...1-240.GIF?07-12

and the 2mtr temps from the 12z GFS

Taken along with the GFS Ens, it looks like we are heading for another cold week following the snowfall.

[Paul_1978]

Disappointing ecm 12z really,azores high moving in on friday.

You mean like, in EIGHT days?

[syed2878]

i made a comment yesterday regarding ian brown's posts and it was removed by the mods. So il say it again its confusing for new people who's trying to learn making statements with out backing it up doesn't help those of us who trying to learn, so plz ian b at least explain your statements. Thanks.

[weather eater]

Can’t say I can see much signs of Atlantic dominance, however from mid week on I do see lots of nothing in particular, cold nights where sky’s clear, mainly dry cool days, pretty uneventful weather, the GFS holds far more interest going forward than the ECM does at present.

[johnholmes]

As promised my view of what the upper air pattern and surface weather may be in the 6-15 day outlook

[Ian Brown]

i made a comment yesterday regarding ian brown's posts and it was removed by the mods. So il say it again its confusing for new people who's trying to learn making statements with out backing it up doesn't help those of us who trying to learn, so plz ian b at least explain your statements. Thanks.

What are you wanting me to explain ?

[Bristawl Si]

Difficult to say at the moment.

At this stage many will see this start as rain but there is a chance those towards the N&E stand a better chance of seeing all snow and this is especially true with elevation. Currently it appears around Sunday night into Monday is when rain will turn to snow at lower levels with this initially occuring in the Midlands/N England and slowly moving S. I would say based on the output locations such as the Midlands are ideally placed. Some will ask why not N England/Scotland and my reply would be that a shift SW of the LP remains a possibility.

Compare the ensembles at my location with the mean at -5C.

http://cdn.nwstatic.co.uk/ensimages/ens.20130207/12/t850Cambridgeshire.png

Gloucestershire stands at 0C

http://cdn.nwstatic.co.uk/ensimages/ens.20130207/12/t850Gloucestershire.png

What hasn't been mentioned yet is the period between Tues into Wed. Once the band of cloud associated with the LP clears away a brief window when heavy convective snow showers will spread W across England. This period could give more snowfalls than the LP itself!

So for the moment the best location in my opinion is anyone who lives in the Peak District, worst anyone in the far SW.

Cheers TEITS

We (imby) just seem to have been on the 'wrong' side of the division between cold and less cold air this winter, bar a couple of snow events.

[johnholmes]

What are you wanting me to explain ?

Ian I think all of us would like to see you explain your view with links to the charts which you feel show what your post suggests. Nothing more than that in my view.

Is that too difficult for you to do as those new to here have suggested?

[Jason M]

This thread is pretty dire tonight :-(

If people don't agree with Ian Brown or anyone else for that matter why can't they at least be polite in doing so? Maybe the mods should consider a major culling. We even have one line posts criticising others for one line posts!? I bet the mods can't wait for spring.

Anyway, whilst this weekend may or may not be a damp squib, the signal for a potent cold spell continues to build in the GEFS. The best may come last this year.

As for the weekend, my reading of things is that this wont be entirely unlike the fabled Monday snow event that was meant to kick of the last cold spell. Everything looks very marginal to me and I wonder if the biggest issue will actually be laying snow. It's all very well to get 20cm worth fall from the sky, but if temps and or dew points are above zero it won't accumulate.

Jason

[Summer Sun]

Disappointing ecm 12z really,azores high moving in on friday.

Well short term its far from disappointing if its cold and snow you like especially if you live midlands north.

Longer term yes the Atlantic is shown to push in bringing milder weather, If I remember correctly ECM was the first model to pick up on the mild start to January before the others finally came on board

The first hints of something less cold start on Thursday with the cold uppers getting shifted east

This process continues through the rest of the run as it turns milder, windier and wetter

Edited February 7, 2013 by Gavin.

[Long haul to mild]

Some differences between the models even at 96 hours re the depth of the low:

UKMO

ECM

GFS

GFS and UKMO are best for snow chances. We don't really want the ECM's round version if it's widespread snow we are looking for. It's so dartboard, I reckon Phil Taylor would be eyeing it up

I still think the low will not be as deep as shown on the ECM and still believe that at this range it's the UKMO and FAX charts we need to be following.

Edited February 7, 2013 by Chalk Serpent

[MR EXTREMES]

What are you wanting me to explain ?

how the alantic is dominating or even close to moving in even after a week?

[Grimsby Snow Lover]

Well short term its far from disappointing if its cold and snow you like especially if you live midlands north.

Longer term yes the Atlantic is shown to push in bringing milder weather, If I remember correctly ECM was the first model to pick up on the mild start to January before the other finally came on board

The first hints of something less cold start on Thursday with the cold uppers getting shifted east

This process continues through the rest of the run as it turns milder, windier and wetter

What is quite positive though in my book is that the colder air is modelled to shift east in around 7 days time, which in weather terms is not that reliable. As during the previous cold spell we could quite easily see the cold hanging on for a day or two longer. On the other hand the milder uppers could move in sooner. The point I'm trying to make is that what will happen in 7 days time is very likely to change between now and then.

[MR EXTREMES]

This thread is pretty dire tonight :-(

If people don't agree with Ian Brown or anyone else for that matter why can't they at least be polite in doing so? Maybe the mods should consider a major culling. We even have one line posts criticising others for one line posts!? I bet the mods can't wait for spring.

Anyway, whilst this weekend may or may not be a damp squib, the signal for a potent cold spell continues to build in the GEFS. The best may come last this year.

As for the weekend, my reading of things is that this wont be entirely unlike the fabled Monday snow event that was meant to kick of the last cold spell. Everything looks very marginal to me and I wonder if the biggest issue will actually be laying snow. It's all very well to get 20cm worth fall from the sky, but if temps and or dew points are above zero it won't accumulate.

Jason

to be fair if the alantic is not dominating or running our weather then why make the statement in the first place its miss leading its also not correct and is very much in my opion what we hear most winters and then we hear nothing when the cold is apon us.

[Tamara]

The variations continue with the location of the low for Sunday - and these variations determine the crucial aspects of temperatures, dewpoints and distribution of precipitation and in terms of the interest in this thread, who gets snow. Its all going to come down to the weekend itself and when the NAE and micro modelling high resolution models are within range

Further out, more uncertainty, but one would place their bets with further amplification of the jet stream upstream and favourable Scandinavian and atlantic ridge profile. Maybe the NOGAPS model is onto something? (instead of being on something) Joking aside, it has become much better and far less erratic of late

[lord stratus]

Some differences between the models even at 72 hours re the depth of the low:

UKMO

ECM

GFS

GFS and UKMO are best for snow chances. We don't really want the ECM's round version if it's widespread snow we are looking for. It's so dartboard, I reckon Phil Taylor would be eyeing it up

I still think the low will not be as deep as shown on the ECM and still believe that at this range it's the UKMO and FAX charts we need to be following.

I agree, as we move into the weekend it's best to keep a close eye on the ukmo and ECM. I believe there will be a south and west correction over the next couple of days which will mean a change in the snow risk areas.

[mcweather]

Whilst a few people in here seem to be getting deflated before sundays fun and games even start I thought I'd just let people know what can happen when a moderately deep low pressure slips southeastwards from northern Ireland towards the English Channel as sundays low is progged to do by the latest ukmo and ecm.

The paragraph is from One of the best books ever written about the UK climate. namely The Weather of Britain by the late Robin Stirling.

25-27the December 1927:

A depression from the atlantic moved from Ireland to the English Channel and across France. It caused a great snowstorm in Southern England. About 1800hrs Christmas day rain in the south turned to snow so heavy that all roads were hopelessly blocked by midnight. and a train was snopwbound between Alton and Winchester. Even in London travel ewas difficult with 6 inches of snow falling in central London. The storn raged all the 26th. On Salisbury Plain drifts were 6 metres deep. A very impressive sight was snow blowing out to sea from the cliffs of Devon, Dorset and the Isle of Wight which seamen on passing ships thought to be fog!!!

[cooling climate]

The ECM could of course be overplaying the shortwave feature that halts the

westward regression of the high but with pressure wanting to rise around the

Greenland area at t168-192 then we could very well see an outcome more in

line with the GEM model and more undercutting. The only problem I see is lack

of cold pool in the extended period to the east.

I am still hopeful of a visit from the beast and with northen blocking likely to

persist if not strenghen and the GFS model has already toyed with bringing the

much deeper cold over eastern Russia westward.

Still to far out imo to put any bones on what will happen over the weekend as

there are signs that things may well back further west and south and of course if

it does then so will any precipitation.

It does look though as if there is a 24-36 hour window for some nice convective

snow showers and accumulations later monday and into Tuesday and if some

places further east do come up trumps with the snow Sunday and Monday then

they could see some quite impressive snowfall totals.

[bradymk]

Whilst a few people in here seem to be getting deflated before sundays fun and games even start I thought I'd just let people know what can happen when a moderately deep low pressure slips southeastwards from northern Ireland towards the English Channel as sundays low is progged to do by the latest ukmo and ecm.

The paragraph is from One of the best books ever written about the UK climate. namely The Weather of Britain by the late Robin Stirling.

25-27the December 1927:

A depression from the atlantic moved from Ireland to the English Channel and across France. It caused a great snowstorm in Southern England. About 1800hrs Christmas day rain in the south turned to snow so heavy that all roads were hopelessly blocked by midnight. and a train was snopwbound between Alton and Winchester. Even in London travel ewas difficult with 6 inches of snow falling in central London. The storn raged all the 26th. On Salisbury Plain drifts were 6 metres deep. A very impressive sight was snow blowing out to sea from the cliffs of Devon, Dorset and the Isle of Wight which seamen on passing ships thought to be fog!!!

Chart for midnight boxing day on that date!

Not to dissimilar to now with low moving south eastwards with rain to begin with before drawing in colder NE winds once the low started to pull away.

Also shows that -8c 850hpa is not needed for snow

Edited February 7, 2013 by bradythemole

[lorenzo]

On this run Ian called for another slider to reinforce the Euro trough and back the Azores west, prior to that calling the Atlantic in before the first trough disruption.

So perhaps a case of repeated Azores calls leading to confusion depending on which shout for the Atlantic folk are referring to, as the run unfolded the NW-SE trajectory gets lost and goes to a stalemate position.

It will be interesting to see what the postage stamps look like for the suite at 144 > 168 to see where the clusters go.. the run from mid-range 168 as BA stated is lacking direction, or in other terms, continued shortwave drama.

GEFS mean was mentioned earlier and looking at also the Jet, operational, control and a decent cluster of runs maintain the energy drifting south post day 10. 48 hours from then the mean delivers little or no energy into the Atlantic, some charts here on what shurely ish the subject of the day.

Plenty to watch just now, MJO round to a favourable phase for cold, i.e having been around phase 8 now into 1/2 with the lag included for continued height rises to the North. Perhaps more of a visible influence will pull through without the strat over riding the Canadian sector.

[Long haul to mild]

The variations continue with the location of the low for Sunday - and these variations determine the crucial aspects of temperatures, dewpoints and distribution of precipitation and in terms of the interest in this thread, who gets snow. Its all going to come down to the weekend itself and when the NAE and micro modelling high resolution models are within range

Further out, more uncertainty, but one would place their bets with further amplification of the jet stream upstream and favourable Scandinavian and atlantic ridge profile. Maybe the NOGAPS model is onto something? (instead of being on something) Joking aside, it has become much better and far less erratic of late

Yes, whilst it is fun to discuss what may happen in terms of snow this coming weekend, it's not in reliable precipitation forecasting range yet, so people shouldn't get too hung up on where may or may not get snow. I am still plumping for the UKMO option as its record at that range is well known and it doesn't over deepen lows like GFS and ECM are often prone to do.

I agree, all eyes on the NAE from tomorrow re precipitation type and distribution, but even that may well change as it gets closer.

[Jason M]

to be fair if the alantic is not dominating or running our weather then why make the statement in the first place its miss leading its also not correct and is very much in my opion what we hear most winters and then we hear nothing when the cold is apon us.

It's his view, and Ian along with Steve Murr, John Holmes, TEITS, GP, Chiono amongst many others have their views. I personally follow all these posters and whilst I often disagree with Ian as I do with Steve I rarely if ever feel the need to rubbish their input. We all have an ignore button, so if someone is winding you up, use it.

I get the impression that Ian isn't all that enamoured with this weekends cold spell. If thats the case, Tbh I share his views! but I respect others on here who don't agree (and obv hope they are correct and not me).

I'm not having a go at you, or saying you we're disrespectful, its just unfortunate that I'm replying to your post :-)

Sorry mods! I'll say nothing else on this now and feel free to delete :-)

Jason

[Ian Brown]

It's his view, and Ian along with Steve Murr, John Holmes, TEITS, GP, Chiono amongst many others have their views. I personally follow all these posters and whilst I often disagree with Ian as I do with Steve I rarely if ever feel the need to rubbish their input. We all have an ignore button, so if someone is winding you up, use it.

I get the impression that Ian isn't all that enamoured with this weekends cold spell. If thats the case, Tbh I share his views! but I respect others on here who don't agree (and obv hope they are correct and not me).

I'm not having a go at you, or saying you we're disrespectful, its just unfortunate that I'm replying to your post :-)

Sorry mods! I'll say nothing else on this now and feel free to delete :-)

Jason

I think Sunday and Monday are potentially very interesting, although of course the 'event' will be rain to begin with. It's very complex for forecasters as such a situation always has been.

[80sWeather]

Whilst a few people in here seem to be getting deflated before sundays fun and games even start I thought I'd just let people know what can happen when a moderately deep low pressure slips southeastwards from northern Ireland towards the English Channel as sundays low is progged to do by the latest ukmo and ecm.

The paragraph is from One of the best books ever written about the UK climate. namely The Weather of Britain by the late Robin Stirling.

25-27the December 1927:

A depression from the atlantic moved from Ireland to the English Channel and across France. It caused a great snowstorm in Southern England. About 1800hrs Christmas day rain in the south turned to snow so heavy that all roads were hopelessly blocked by midnight. and a train was snopwbound between Alton and Winchester. Even in London travel ewas difficult with 6 inches of snow falling in central London. The storn raged all the 26th. On Salisbury Plain drifts were 6 metres deep. A very impressive sight was snow blowing out to sea from the cliffs of Devon, Dorset and the Isle of Wight which seamen on passing ships thought to be fog!!!

Yes fantastic book, the description about the great south west blizzard is mindblowing!