Model Output Discussion - 14th Jan 12z Onwards

[Dr. Astro]

Where is that stunning easterly gone i knew this was not a done deal. And still further upgrade and downgrades to come and as for snow not looking as good as warm sectors look to be mixed in so its hit and miss to who gets snow and who gets rain. But looking further ahead into late jan, feb the pv looks on its legs just needs a knockout blow and a bit of luck for us to be on the right side of it.

 

Models will chop and change on each run, the pattern is still there, it's still going to be bitterly cold next week and beyond, with no real way for any milder weather to come back in.

 

I feel some level heads are needed this morning, and there is really no point in pinpointing where it will snow and when until really, Sunday night?

 

Just take note of Fergie's post, no point in looking at too much detail yet.

[snowblues]

If the southern half of the uk is on the wrong side of the slider,there still looks like 2 or 3 days of some good fetched easterlys with -8 uppers to follow,with the flow starting to the north or the uk taking a little while to sink.

[Paul_1978]

Boxing day style a big possibility then? I'll settle for that, although northern areas did better

Boxing Day was rubbish. Not even 1cm here. Hoping for better this time.

well, old GFS 18z looks stunning out to t240, -12 850s a plenty, one things for sure for every one its going to bitterly cold in that flow.

Unless I'm mistaken it's not now the "old" GFS. The GFS is now the 'new' one, ie what was the Parallel.

[Frosty.]

I don't know why there is doom and gloom, the 00z output is a snow making machine next week with cold air becoming entrenched and lows slipping and sliding SE into the cold pool with substantial snow in places, lots of ice and sharp / severe frosts..I despair at some of the comments on here.

[Dr. Astro]

I don't know why there is doom and gloom, the 00z output is a snow making machine next week with cold air becoming entrenched and lows slipping and sliding SE into the cold pool with substantial snow in places, lots of ice and sharp / severe frosts..I despair at some of the comments on here.

 

I think the snowfall of 2010 has done the damage to some people...

 

ECM is also worth a shout - heights around Scandi at the end of the run and the UK in a slack NE feed, keeping the cold weather with us for longer.

 

One thing is for sure Frosty, it's going to be very cold next week, when & where snow fall will end up is anyone's guess at the moment.

 

 

[Paul]

18z running now, so good time to ask for some help.

 

It's going to be very busy in here tonight and for the next week or so at least by the looks of it, and at these times this thread can be fun, informative and absolutely buzzing. It can also be frustrating - particularly when people don't keep their posts on topic. 

 

So please, if you're not discussing the models, make your post elsewhere - the model banter/moans and ramps thread is an active thread for random semi-model related stuff and reactions to the output:

https://forum.netweather.tv/topic/81281-model-banter-moans-and-ramps-autumnwinter-201415/

 

The regional threads will also be very busy with local chat, info on any snow and so on:

https://forum.netweather.tv/forum/142-regional-discussions/

 

And with the strong winds during the next 24 hours or so, the severe weather area is the spot for discussing the impacts of that.

https://forum.netweather.tv/topic/82219-atlantic-storm-14th-15th-january/

 

Taking just a few seconds to consider where your post fits best will really help keep this thread running smoothly.

 

Thanks

 

Paul

 

Just repeating this - please take a moment to consider what you're posting and whether it is model discussion.

[Penrith Snow]

I don't think the charts are a downgrade at all more a moving around of weather systems that alter conditions at the surface.

Essentially a cold spell is coming but a severe cold spell wasn't really on the cards yesterday and still isn't, how long it lasts is still up for grabs.

My approach is to divide the spell into 3 and concentrate on each at a time.

1. The weekend north westerly and where snow falls as features move south, west looks best here and Wales best of all.

2. The sliders early next week, far to early to predict any snow locations so don't even bother but will make for tense model watching and plenty of IMBY posts as some get rain, some get snow and some (probably me) stays dry.

3. Later next week on beyond, what happens after the sliders? Easterly or back to zonality? Again far to early to tell but I reckon the MetO favour a return to zonality but only by a short margin.

Whichever way you look at it it's better than a 10 day Bartlett!!!

Andy

[Man With Beard]

Reasonable agreement in assessment of 00z UKMO and other output for the scope of Mon-Tues evolution but still only broad-brush detail possible. Without describing all the rationale and diagnostics, we expect essentially a risk of (perhaps significant) snow Wales/Midlands northwards. Marked uncertainty how long the cold weather lasts before a return to around average temperatures.

Perhaps some southerners will be disappointed with this post, but no need ATM. If the trough sinks into Europe later next week and there is an easterly, the SE is in prime position to benefit from snow. The SW could do with another depression heading in from the Atlantic but sliding under the block with cold in situ a la April 2013

[TEITS]

I don't know why there is doom and gloom, the 00z output is a snow making machine next week with cold air becoming entrenched and lows slipping and sliding SE into the cold pool with substantial snow in places, lots of ice and sharp / severe frosts..I despair at some of the comments on here.

Have to be honest Frosty that is not the outlook for everyone.

 

Personally I cannot be bothered to look at the detail with regards to the slider LPs and im more focussed on what occurs afterwards. What is fairly clear to me is the slider LP clears S of the UK bringing an E,ly flow, however it could take a while before the really cold upper temps spread from the E. The 18Z GFS was perfect because we did see -10C upper temps spread into the UK. However this is not guaranteed and it could be that we lose the E,ly flow before the really cold air has chance to back W.

 

So just to warn members this cold spell could turn out to be just a few days of marginal snowfall followed by an E,ly that isn't cold enough to bring convective snow showers which is when quickly replaced by a return  of W,lys. On a positive note it could also turn out to be far more prolonged and colder than currently indicated if we do see much colder, sustained E,lys. This is why I am more interested in the period after the slider LPs!

[Smiler1709]

Horrible downgrades this morning for Midlands south, hopefully the models don't water all this down to wet icy dross. It just shows that were far from certain to have a good cold spell, last nights easterly on the ECM has all but disapeared and the 850 uppers have retreated back east.

Lots of wintry weather for the North again but for us southerners, if it plays out this way then I for one will not be excited about rain interspersed with frosts and ice. Basically it will be like living in the Falklands which for who that have never been its the most depressing place on the planet, cold, wet and windy.

Fingers crossed for a few upgrades again but I'm not holding my breath.

[chionomaniac]

I don't know why there is doom and gloom, the 00z output is a snow making machine next week with cold air becoming entrenched and lows slipping and sliding SE into the cold pool with substantial snow in places, lots of ice and sharp / severe frosts..I despair at some of the comments on here.

Well I kind of disagree with your broadbrush comments here Frosty. The 00Z does give us a cold pool to play with - and a significant amount of people will see snow. I won't look at the precipitation charts just yet - but the intriguing thing about this set up is that it will be characterized by marginality by those further south and even at lower elevations further north, so whereas there may be substantial snow in places, if I was living anywhere south of the M4, west facing coasts - or even some lower lying ground to the north I would be watching and waiting to see how this pans out. 

 

I think though we would all rather be in this situation than last years - at least it looks like we have a handful of lottery tickets to enter the lottery with, rather than none at all.

[Great Plum]

Morning all,

Even as a southerner, I'm not worried about 'upgrades' and 'downgrades' at the moment... It's a dead cert that it will be colder next week but trying to find out where it will snow is a fruitless exercise... A 50 mile difference in the positioning of the low makes a huge difference and it will change over the next 5 days...

Also, the GFS 0z ensembles show that around the 20 Jan, the run is warmer than the mean, I would expect the mean to show greater snow prospects further south...

In addition, I think this is the first time this winter that the ensemble mean has remained below average throughout...

http://www.wetterzentrale.de/pics/MT8_London_ens.png

Enjoy the ride!

[MPG]

The GFS looks a mess to me, the -5 850 coming and going being mixed out, looks like a mixed bag of rain, sleet and snow as systems push down from NW.

[MPG]

Have to be honest Frosty that is not the outlook for everyone.

 

Personally I cannot be bothered to look at the detail with regards to the slider LPs and im more focussed on what occurs afterwards. What is fairly clear to me is the slider LP clears S of the UK bringing an E,ly flow, however it could take a while before the really cold upper temps spread from the E. The 18Z GFS was perfect because we did see -10C upper temps spread into the UK. However this is not guaranteed and it could be that we lose the E,ly flow before the really cold air has chance to back W.

 

So just to warn members this cold spell could turn out to be just a few days of marginal snowfall followed by an E,ly that isn't cold enough to bring convective snow showers which is when quickly replaced by a return  of W,lys. On a positive note it could also turn out to be far more prolonged and colder than currently indicated if we do see much colder, sustained E,lys. This is why I am more interested in the period after the slider LPs!

 

Think you have it bang on. As the METO have said, 3 maybe 5 days at max with return of the Atlantic. The North could do ok from this, but futher south looks like cold rain with any PPN.

[Great Plum]

Think you have it bang on. As the METO have said, 3 maybe 5 days at max with return of the Atlantic. The North could do ok from this, but futher south looks like cold rain with any PPN.

Have they said a 3 to 5 day spell? I can't see that from this:

'Dry, cold and clear for much of central Britain on Monday and Tuesday with showers affecting many coastal counties away from the south, readily falling as sleet and snow. There will be a widespread frost overnight and some localised patches of freezing fog which may be slow to clear through the day. Through the rest of next week, the general cold conditions will persist bringing an ongoing risk of snow, more especially in northern and eastern areas. Temperatures will be generally below average with overnight frosts, locally severe. Towards the end of the period there looks to be a possible return to more generally unsettled conditions with rain, strong winds and temperatures perhaps nearer to normal for the time of year.'

In addition, the ECM says yes to a 7+ day cold spell...

http://www.wetterzentrale.de/pics/Recm2401.gif

Even the GFS ensembles that I posted just now remain below average throughout...

[chris55]

The overall trend into next week is a very interesting one IMO. Remember this time last week there was hardly a sniff of anything interesting in the models. The evolution with regards to the sliders and possible easterly flow thereafter will need plenty more runs to nail down any details. Any one writing off a return to westerlies or an easterly at this point is ahead of themselves, more runs needed. Exciting model watching period for me.

[BLAST FROM THE PAST]

So from trumpets blowing and MetO/BBC saying coldest spell for 2 years to a 3-5 day marginal colder period?  Really is a funny thread this

 

 

BFTP

[Troubleatmill]

Horrible downgrades this morning for Midlands south, hopefully the models don't water all this down to wet icy dross. It just shows that were far from certain to have a good cold spell, last nights easterly on the ECM has all but disapeared and the 850 uppers have retreated back east.

Lots of wintry weather for the North again but for us southerners, if it plays out this way then I for one will not be excited about rain interspersed with frosts and ice. Basically it will be like living in the Falklands which for who that have never been its the most depressing place on the planet, cold, wet and windy.

Fingers crossed for a few upgrades again but I'm not holding my breath.

 

Twinned with West Lancashire I believe? As chio said after yourself Smiler its not only the south that suffers in marginal set ups,

 

 I am hoping to see the slider low further west (but not too far) so the west can get in the action then the east can when the easterly sets in there after. 

 

Must admit though when you look at the ensembles we should be happy, not seen this for a couple of years, its going to turn cold  

Edited January 15, 2015 by Nicholas B

[Gibby]

HERE IS MY LATEST ANALYSIS FROM THE OUTPUTS OF THE WEATHER COMPUTER PREDICTION MODELS FOR TWO WEEKS FROM 8AM TODAY THURSDAY JANUARY 15TH 2015.

NEXT UPDATE FRIDAY JANUARY 16TH 2015 08:00

THE CURRENT GENERAL SITUATION A deep depression near Northern Scotland will fill slowly over the next 23-48 hours as it drifts slowly NE. A cold and showery Westerly flow will become established across the UK.

MODELS-2 WEEK HEADLINE Cold and frosty with chances of showers or longer spells of rain, sleet or snow.

THE JET STREAM ENSEMBLE FORECAST The Jet Stream Forecast shows the flow remaining South of the UK for the foreseeable future. In the first half of the period it drifts SE towards the Meditteranean maintaining the UK on the cold side of the flow, though depressions deepening North of the UK later will change the airflow to polar maritime variety later with rain and stronger winds from the west bringing more in the way of rain rather than snow away from the hills.

GFS NEW OPERATIONAL The GFS operational projects a week to 10 days of rather cold and unsettled weather as the UK lies under a cold trough fuelled by a Jet stream South of the UK and sinking Low pressure troughs down from the NW. The pattern then flattens through Weeek 2 as the Jet flow moves back North in a West to east flow across the UK powered by deep Low pressure back north of the UK with rain and showers for all in nearer to average temperatures.

THE GFS CONTROL The GFS control run shows a very similar sequence of events as Low pressure disrupting SE across the UK brings unsettled and cold conditions with sme snow in the North and East and cold rain elsewhere. Later in the period the pattern flattens as deep low pressure North of the UK drives less cold West winds across the UK with a return to polar maritime type conditions with rain and wintry showers at times thereafter..

THE GFS CLUSTERS The GFS Clusters show good support for the UK to lie under strong Westerly winds with rain at times two weeks from now with colder showery periods mixed in between milder and wetter periods. There is a 10% chance only of a strong Scandinavian Anticyclone with the balance of the rest of members supporting cold NW winds and wintry showers.

UKMO UKMO this morning shows cold weather as we move into next week fuelled by Low pressure slipping South just to the West of the UK and bringing a risk of sleet and snow to Northern and Eastern parts though more likely to be rain over Southern and Westernmost parts.

THE FAX CHARTS The Fax Chartsshow a cold and eventually quite slack flow across the UK. Troughs meandering around the sea waters around the UK will meander South affecting inland areas at times with a push of milder Atlantic winds towards Western parts on a front as we move into next week.

GEM GEM today also shows a cold and unsettled period lasting up to a week or more as cold Low pressure areas sink SE across the UK through next week with rain and snow at times. The model then shows a High pressure ridge crossing SE with cold and dry weather gradually becoming less cold from the NW ;ater as more westerly winds start to encroach down across the UK at then end of the period.

NAVGEM NAVGEM shows Low pressure sliding down across the UK next week ending up South of the UK with an easterly flow on the Southern flank of a ridge of High pressure developing across the North. So some rain and snow for many next week gradually drying out from the North later next week as the ridge extends it's influence South later.

ECM ECM this morning is arguably the best run for longevity of cold weather across the UK as it pulls cold Low pressure down over the UK next week in already cold surface air with a real risk of appreciable snowfall in places, though rain probable for a time in Southern and Western parts. Later in the period a strong ridge linking an Atlantic High to an European High sets up cold and unstable Easterly winds across the South late in the run with no doubt snow showers across the East and South and widespread severe frost for all.

ECM 10 DAY MEAN The ECM 10 Day Mean Chart at first sight shows a strong ridge across the UK to Scandicavia. This is most likely to be made up of a mixture of options as Low pressure is still held over the Meditteranean and weak Low pressure to the NW. To me this indicates a rather cold pattern still with only a muted chance of Atlantic Westerlies returning in the timescale. For continued cold beyond Day 10 though we need Low pressure maintained down over the Med to act as a catalyst in keeping the Jet flow well South over Europe.

NOTABLE TREND CHANGES FROM PREVIOUS RUNS The trend this morning compared to my previous report yesterday morning has increased the chances of a rather longer cold spell next week. There is still strong support for a resurgence of the Atlantic Westerlies later ending the spell though ECM goes for a more sustained cold period lasting several weeks.

MY THOUGHTS The interest on this morning's output will no doubt hinge on how the upcoming period firstly develops cold weather over the UK and how it maintains or ends it later in the output period. Despite a lack of the usual ingredients of a Scandi or Greenland High it does look the UK will fall under a very cold spell next week as cold Arctic winds from the North slip down across the UK. Inland winds will be often light and this will allow deep cold to develop especially where any snow lies with severe night frosts. Near coasts there will be a lot of unstable air aloft snow showers will be prevalent and as disturbances in the flow sink South these could be drawn inland at times almost anywhere. Then as we  move through the early days of next week all models support a disruption in a push of Atlantic air towards Western Britain which leads to the risk of snow for some. On current thinking Southern and Western parts could be just on the too mild side to see snow from this with rain more likely at least for a time but parts of the North and East could see a lot of snow as the milder air engages the cold in the shape of low pressure sinking SE away from the South into NW Europe later. It all depends on the track and depth of the Low which will be determinate in where and how much snow falls. In any event later next week pressure rises to the North, NE and NW which may well give several days of cold East winds for all with snow showers for the East in particular. Then many of the longer term projection models indicate Atlantic Westerlies may regain control though ECM does look best for longevity for cold today as in 10 days time the UK lies locked in an Easterly flow with a strong ridge to the North along with a relatively inactive Atlantic. So all in all it's been a long time getting here but cold and snow lovers should be quite happy with the output today as we see our best chance yet of cold and for some snowy conditions than we have seen for several years and lasting for a week or so at least.

[chris55]

This is a loaded chart!! Massive cold pool to the east, low pressure over Europe, nice north easterly flow. Not a Barlette in site lol.

All the people having a moan should just step back and actually look at the output.

Edited January 15, 2015 by chris55

[karlos1983]

Well the output hasn't changed that much, and can swing back. Last night was about as good as it could get in the current setup and downgrades were much more likely than upgrades, which is good as it leaves room for improvement now. Personally I'd prefer upgrades to arrive later today/tomorrow. As long as the theme continues.

But just in case, think I'll book a meeting in the north Midlands somewhere with an overnight stay on Monday! :-)

[BristolBaggie]

I don't know why there is doom and gloom, the 00z output is a snow making machine next week with cold air becoming entrenched and lows slipping and sliding SE into the cold pool with substantial snow in places, lots of ice and sharp / severe frosts..I despair at some of the comments on here.

I think Fergie's post about snow Midlands north next week has dampened southerners spirits aswell

[IDO]

Looking at the GFS snow accumulations, 8 day: 

 

Obviously caveats aside (one run, etc) but south of Oxfordshire just trace amounts of snow. The SW, south and eastern coast zero. The main snow looks for hills and mountains.

 

As for how long it will last, the GEFS suggests till around D8-9 and the ECM mean also now trending in that direction:

 

 

An easterly from a block to the east not looking likely. The ECM clusters at D5 have six clusters so to say that there is uncertainty is an understatement. ECM may be consistent but looking at its members the op is in cluster 2 (same as cluster 3, 10 members) now, so not even the main outcome. The GEM ensembles are also consistent for a trough but with variation within that theme.

 

All the ensembles are in agreement that no solution after Sunday is yet guaranteed within the cold upper flow and the sliding low scenario.

Edited January 15, 2015 by i'm dreaming of...

[winterof79]

Well I kind of disagree with your broadbrush comments here Frosty. The 00Z does give us a cold pool to play with - and a significant amount of people will see snow. I won't look at the precipitation charts just yet - but the intriguing thing about this set up is that it will be characterized by marginality by those further south and even at lower elevations further north, so whereas there may be substantial snow in places, if I was living anywhere south of the M4, west facing coasts - or even some lower lying ground to the north I would be watching and waiting to see how this pans out. 

 

I think though we would all rather be in this situation than last years - at least it looks like we have a handful of lottery tickets to enter the lottery with, rather than none at all.

Hope the odds are better Chio

Edited January 15, 2015 by winterof79

[Roadrunner]

Question for the more knowledgeable eg. Our resident easterly expert Dave (TEITS) or someone else with experience - although not guaranteed or easily predicted perhaps in such situations, but from experience is it more likely that the trough will sink into Europe next week and allow an easterly flow? Just trying to understand what would normally be expected to happen in this sort of scenario.

Cheers.