Model output discussion 25th Jan onwards

[LomondSnowstorm]

Really the GFS is somewhat better overall at D5, with low heights digging further south and ridging a bit cleaner into Svalbard. The main problem is the shape of the low to our west, which means we end up with the trough sitting over us taking an age to disrupt (actually rather similar to the current setup):

A bit more disruption and we've still got the potential for a big battleground snowfall by the end of the week.

UKMO quite different, with a better shaped trough in our vicinity but not digging as far south and getting a bit too far east as well (which to be fair the GFS does as well):

Consequently, cold northwesterlies by +144:

I wouldn't be all that surprised to see us in the same place as we are now by this time next week, although if we can get the next low to disrupt a bit further west it could be a much snowier picture, certainly 'Midlands north'.

[geordiekev]

According to the GFS at T96 T54, the crunch point on Thursday (Tuesday-must learn to read), practically everything 50 degree North of the equator is bathed in cold apart from lonely old UK.

 

However, seeing as the models are struggling with the low/block interactions it is not worth worrying about too much until the actual crunch point between the block on Thursday.

 

 

And later to add insult to injury:

 

Plenty of interesting weather to come before next weekend so some interesting model watching ahead.

Edited January 26, 2014 by geordiekev

[tight isobar]

Maddness once more! Its as though some have taken the GFS 12z and said this is 100% in both evolution and fruition will be exact , on this run!.there realy is a whole lot going on over 2/7 days.

[IDO]

GFS has been consistent in FI when the second slider fails to undercut, in that every run has shown outrageous zonality with potentially 100's of mm of rain:

 

Again:

[Summer Sun]

GFS and UKMO in no agreement at t144

 

 

GEM is missing at t144 currently but t150 is available and it also has a deep low over the UK

 

 

GFS has a low at t150 but not as deep

 

 

So another set of runs and we are no closer to any sort agreement even at day 6, whether ECM can start and follow either UKMO or GFS up-to t144 who knows but some sort of agreement would be nice, known ECM it will take a different route and leave us no further forward

Edited January 26, 2014 by Summer Sun

[J10]

According to the GFS at T96, the crunch point on Thursday, practically everything 50 degree North of the equator is bathed in cold apart from lonely old UK.

 

However, seeing as the models are struggling with the low/block interactions it is not worth worrying about too much until the actual crunch point.

 

 

That chart is for Tuesday.

[Mucka]

Dreadful output so far this evening, in particular GFS with its relentless rain. At least UKMO would offer something wintry for a time but here too the Atlantic is on its way back in.

Let's hope this is a low point for the output and ECM can bring some cheer before what will hopefully be much better output tomorrow for coldies.

Edited January 26, 2014 by Mucka

[IDO]

Although there is disagreement as to specifics the overall trend is to cut off the second slider option and for the Atlantic to come back. The Russian high is then forced east by the PV that shows no sign of losing its oomph.  

 

So the uncertainty is now how wet & horrible the weather is going to be till mid-Feb!!!

 

(based on current output with normal caveats that this is can all change)

Edited January 26, 2014 by i'm dreaming of...

[shaky]

Navgem looks very good!!

[Severe Siberian icy blast]

Although there is disagreement as to specifics the overall trend is to cut off the second slider option and for the Atlantic to come back. The Russian high is then forced east by the PV that shows no sign of losing its oomph.   So the uncertainty is now how wet & horrible the weather is going to be till mid-Feb!!!

That's ridiculous , read the strat thread. Many changes occuring in the near term, we have a cold week to look forward to that's as far as we dare to go

[swfc]

It does look atm moment that the rain totals in the next ten days or so will be making the headlines and not any real wintry weather.Lets hope it changes for our friends in the worst hit areas to something more settled.Very strange atm how badly the models are coping tho at such a short time span be there a block to the east or not!

[EML Network]

So looking ahead of what is likely to be the coldest week of the winter so far...

 

the UKMO 12z goes from Hero to Zero in terms of snow + cold potential in the space of a few days !

 

The GFS is still intent on firing another volley of Low Pressure bombs at us, that makes it about 7,000 this Winter so far..

 

A nice snug fit slap bang on top of the UK from the GFS so start next weekend >>

 

UKMO for the same day...

couldn't further away if it tried. 

 

In fact the only thing the 2 charts have in common is that neither paints a particularly cold picture, although it could be worse I suppose. 

 

The only shred of comfort is that the 12z GFS, does give us a SSW very late in the run...

 

 

Maybe the snow gods will look upon the UK in pity and say ''OK here's a nice big fat SSW  what you lacked in cold and snow this winter we will deliver unto you for the final 2 weeks of Feb and you can all enjoy 10 weeks worth of snow in 14 days'' 

 

in the words of Dwayne Dibley... ''You never know'' 

Edited January 26, 2014 by EML Network

[cooling climate]

Although a real freeze was never at any time modeled for later this week.

I think it is becoming very apparent in fact it has been for quite a while

now.That the only chance of us seeing any prolonged sustained very cold

wintry weather this winter rests with the upcoming strat warming that has all

the hallmarks of 2009 abeit some 2weeks later than then.

By my reckoning then we are looking give or take a couple of days the 7th of

February onwards for some real cold and wintry weather with robust HLB's and a

tanking AO.

As for the near term you can not rule out the chances of some snowfall over the

UK later this week especially if there is a little more disruption of the

lows and fronts from the west and also if there is a little more correction west

with the Scandinavian high. It would not take a lot a tweek here and there to

give some snowfall although at the moment the north looks the best bet.

[weather eater]

I’d like to say something positive but the only thing I can think of is that the pattern will continue to evolve, so who knows what the next couple of days will bring. For me the telling sign is that despite four runs a day the GFS has never really gone for the idea of anything more than a brief easterly feed, whereas I would have expected it to have pulled at least the odd rabbit out of the bag, but then it is very progressive with the Atlantic so maybe that’s to be expected. As for the UKMO I have never trusted its 120hr and 144hr output, still it may yet prove me wrong, the ECM is out in a while but I have little faith in how it models blocking on our side of the pond.

It looks like my summery is

Don’t trust the ECM with blocking

Don’t trust the UKMO at 120 and 144hrs

And don’t trust the GFS as it’s too progressive

A long term positive could be that apparently the little Ice age was proceeded by three extremely wet years, so expect some serious snow about 2017

[Timmytour]

Much as most of us want the East to gain ascendancy in the forthcoming battle, it concerns me that the GFS has been slowly diminishing the prospects of snow as far down as London for next Wednesday. Yes we hope the block proves to be stronger that the models are currently portraying it to be, and that wouldn't be a first if it did happen. But such events where it has happened have often been preceded by the models slowly backtracking from progressive runs, not making them more progressive.

If the GFS 12z were to verify out into deepest FI, I think a lot of families looking at going skiing in the Alps for the half term might be nervously looking at the snow reports...

[weather eater]

That's ridiculous , read the strat thread. Many changes occuring in the near term, we have a cold week to look forward to that's as far as we dare to go

The Stat could throw a spanner in the works that’s for certain but unfortunately it’s not a guarantee of cold for the UK.

Edited January 26, 2014 by weather eater

[karlos1983]

The Stat could throw a spanner in the works that’s for certain but unfortunately it’s not a guarantee of cold for the UK.

 

It's probably a month too late though, could end up only seeing the changes from a SSW 6 weeks after it, i.e. mid March

[weather eater]

Thought the saying was get the cold in first then see what happens afterwards ? We don't know what is going to fall tonight never mind next weekend heads up coldies

That usually apply when we get a cold continental feed for several days from a very robust block, then you have all the fun and games of snow showers off the north sea and potential slider lows running up the channel, unfortunately we can’t get to base one and its difficult at the moment to see how that’s going to evolve at the moment.

[Mucka]

As poor as the output has been so far this evening we should remember things are still in the balance. When I say dreadful output I am talking about GFS in particular and what that would mean should it verify - I am not saying it will verify - just to make that clear. 

 

Looking at GFS ensembles out to 120 the operational was among the more progressive solutions and worth noting that about half the ensembles still have us in the cold at 144, even if that won't be reflected by low 850's, which is far as is worth going (and perhaps not even that far)

 

I would much rather see the output trending toward more blocked than Atlantic driven today but there is plenty of wiggle room still for things to turn back in our favour but If something like GFS verifies you may hear the distant sound of a single gun shot.

Edited January 26, 2014 by Mucka

[weather eater]

It's probably a month too late though, could end up only seeing the changes from a SSW 6 weeks after it, i.e. mid March

That’s true as well although I don’t think there are hard and fast time rules when it comes to initial event and then effect. March could still be decent in an IMBY way, certainly last March I saw some of the deepest snow that I’ve seen since 1987 but I doubt that will float many other people’s boats.

[Thundery wintry showers]

The main issue next week will be that the Scandinavian block is too far east and pressure is too high over south-eastern Europe.  If we take the GFS 12Z chart for T+72, follow the isobars and note where our winds are coming from:

http://nwstatic.co.uk/viewimage.pbx?type=gfs;date=20140126;time=12;ext=72;file=h500slp;sess=f813c911bdc3f9b06109855b856e354f;

 

Yes, they're coming up from southern Europe.  The import of ex-Russian air that we're going to get from the east will be subject to considerable mixing with warmer air from the south-east, and the airmasses in the upper levels of the atmosphere will not be particularly cold, although it will be quite cold near the surface.

 

The forecast skew-t chart for East Lothian shows a considerable "dry lid" at 800hPa which suggests only shallow convection over the North Sea.  I'm expecting mostly dry cloudy weather around midweek with stratocumulus trapped underneath the cap.

http://cdn.nwstatic.co.uk/gfsimages/gfs.20140126/12/84/sound-EastLothian-84.png

 

The main point of interest for snow lovers is likely to be possible frontal snow on Friday as the Atlantic weather systems push in, and some of the polar maritime incursions that are being modelled around T+120-168 are looking quite potent, but unless we see some toning up of the potential cold blasts, it looks like low-lying areas will mostly be on the warm side of marginal for lying snow.

[UV-RAY]

Who'll be a pro forecaster when you have a week like the upcoming one, gawd knows what we will end with from the latter part of this week onwards, none of the models have got this in the bank yet and we may have to wait until midweek before we start too see a path forward, perhaps!

Edited January 26, 2014 by Sceptical Inquirer

[IDO]

Yes the GFS op is a milder run (as appears to be its trend of late). It appears to be dragging the ens with it, so I am not sure we can dismiss it:

 

London short:

 

However the coldest run is the control and look at the surface conditions:

 

T168:  T192:

 

Just another possibility on the op theme.

 

 

[bluearmy]

Can someone explain why if the GFS models a significant warning why it still shows a solid PV. IF the warning is accurate modeled then surely so is the rest of the Synoptics that go with it?! I know it can take a while to have an effect but surely by the last few days of the run we would see something? By late feb early march we need a very rare set up to get a sustained cold and snowy setup. What we saw last march could well be a on e in a lifetime event

The ssw is relevant at 10hpa tim. Its a long way down to the trop from there. The fastest i recall a quick response over the years has been about 5 days for the siberian vortex to begin to head this way. Where i do agree with you is that the current lower strat wind profile doesnt look like it reflects a steaming trop vortex in week 2. The siberian vortex looks strong but the remainder of the hemisphere doesnt have a strong canadian segment as the run progresses. Problem we have is that whatever is left over canada is in a bad place to lead to a quieter atlantic.

[Mucka]

Yes just to reiterate the 850 temps may be a little deceiving if we just look at the graphs for these because we are unlikely to be able to draw the deep cold upper air in but many of these ensemble members will still have a slack continental flow where the 2m air temperatures are quite cold so even though we might see -3 or 4C 850's or higher the ground temps will also be low and perhaps lower than the upper air. So for example a run that has us in just -3c 850's could still be a wintry run because the ground temps and DP's would be low also with a continental feed.

All that will become academic once this is resolves one way or the other but it is worth baring in mind when looking at the ensemble 850's and basing a probability of outcome on those alone would be a mistake.

Edited January 26, 2014 by Mucka