Model output discussion 25th Jan onwards

[gottolovethisweather]

Certainly not a common sight to see the depth of cold from the west across the Atlantic

http://www.meteociel.fr/ukmo/runs/2014020412/UW72-7.GIF?04-17

 

steep lapse rates behind the cold fronts would give plenty of snow showers at elevations especially Highlands,Pennines and possibly Welsh mountains etc.

 

That is certainly a trend I see unfolding as well Phil.  In fact last evening there was a little bit of snow which fell towards the SW, albeit at elevation. There have also been other snow days in the last seven to ten days too within this region. I foresee the opportunities of snow at elevation increasing over the coming days and the risk perhaps popping up at lower elevations eventually, say 10th to 11th February onwards. The last time I looked, the GEFS ensembles were hinting at this likelihood, so we can only hope. Beware, fellow snow lovers I am nOT predicting a SNOWFEST with intense cold but every little helps and maybe this trend could lead to something drier and friendlier for the flooded lot in the long-term.

Edited February 4, 2014 by gottolovethisweather

[fergieweather]

Certainly not a common sight to see the depth of cold from the west across the Atlantic

http://www.meteociel.fr/ukmo/runs/2014020412/UW72-7.GIF?04-17

 

steep lapse rates behind the cold fronts would give plenty of snow showers at elevations especially Highlands,Pennines and possibly Welsh mountains etc.

 and even across southern England too, reckon UKMO

[phil nw.]

 and even across southern England too, reckon UKMO

Would this be the Thurs night low coming from the south?

http://www.wetterzentrale.de/pics/Rukm601.gif

 

that would be a surprise if so,based on the DP,s around that period, if GFS modeling is to be relied on

http://www.wetterzentrale.de/pics/Rtavn6610.png

 

possibilities for lower level snow do look better next week if modeling verified.

 

what are the Met seeing Ian?

Edited February 4, 2014 by phil nw.

[Tamara]

As we all know, we've had an upper trough in place extending from the deeply embedded winter time vortex over NE Canada and Greenland into the atlantic for a very long while. I happily and readily admit to liberally using the term 'trough disruption' (within the cyclonic context of the term) during the extended duel with the Russian/Scandinavian High as I think in simple parlance it described our atlantic pattern very appropriately at the time, as the ejected energy bumped up against the cold air to the NE in association with that elusive block

 

The process however simply separated surface troughs from a dominating upper trough and forced them SE'wards against the block to die generally in situ over the UK, and then latterly into Europe, before the Scandinavian/Russian High finally lost the battle as the Canadian sector started further re-energising over this weekend and spilled extra energy further east -  and we have reverted to a flat and very fast pattern through the atlantic sector as a consequence. The hope had been of course, that instead, reduction in strength of the polar westerlies might have been sufficient for an easing of the upper trough and more definitive trough disruptionbeing able to occur, allowing a greater retrograded blocking influence from the NE - alas the complete opposite has occured as stratospheric assistance ultimately proved lacking in our part of the NH.

 

So, the first of the triumverate of very problematic lows modelled through the days ahead is arriving downstream on our doorstep this evening as a culmination of that reinforced energy upstream in the Canadian sector.  Much said about this and the seriousness of the other lows here and in other threads, so no further comment required here.

 

Beyond this protracted very stormy period, there are signs, as other have posted, that the Canadian vortex may shift rather NW'werds with time, and this is indeed in line with longer term ensemble data suggesting some retrograde of the Eastern Pacific ridge that allows this vortex movement to occur. Should this happen, it will force a break (at least temporarily) in the very cold conditions that have been dominating over the eastern US states, and this in turn will assist the jet pattern slowing down as the temperature gradient is reduced. On this basis although the pattern looks to stay generally quite cyclonic, we should start to see lows of less intensity than the coming days

 

With this possible upstream change, then I think this illustrates the fact that no-one is suggesting that the vortex pattern over Canada be stable in situ right through the month, and as, f.e, mooted in a previous post of mine last weekend, breaks in the generally cold outlook in the US were possible that would relieve the intense cyclonic barrage. 

 

However, I would be very wary of taking such a change of hemispheric upper feature re-arrangment as any definitive signal for any cold(er) spell for us in the UK anytime in the foreseeable future.

 

We need to see evidence in stratospheric modelling that not only might ongoing wave activity affect more wholesalely changes in patterns upstream, and move this burden of a vortex far enough away from its downstream influences, but that zonal westerly winds are going to slow down (at least) below 20 m/s - because we already know from experiences of the middle part of January with the attempted trough disruption and failure to lose the upper low to the NW, that this level is likely to be insufficient to permit blocking at any favourably higher latitude or encourage sufficiently far enough westwards those heights now shunted far east into the Siberian/Asian continent.  Clearly, with the recent/current ramping up of all this turbo energy coming from upstream, we have also lost the decent cold pool that had encroached just the other side of the North Sea in the last week or so.

 

On the basis of predicted zonal energy calculations as suggested, the possible retrograde of the Pacific pattern instead supports a developing NW/SE split perhaps into the second half of February as the worst of the present/upcoming cylogenetic jet streak subsides and adjusts northwards and westwards, but with still too much upper westerly flow to encourage any significant rise in heights to our north, even with the upper trough easing a little further away from our immediate vicinity.

 

I think that stratospheric progress is now being made for the longer term to change the weather pattern finally to a more blocked one, after all these dreadful months, but this remains well beyond our MOD discussion radar, and in my opinion quite conceivably also the radar of the winter season itself with lag time issues also to take into account here

Edited February 4, 2014 by Tamara תָּמָר

[Polar Maritime]

Yes, it's nice to see the GFS showing sign's of something of a change to a weaker blocked Atlantic with the Jet pushing  South over France instead of right over us! as ECM hinted from yesterday also, a lot more rain to come yet this week especially for the South again. At least we have interest of a wintry note.. the further South these Lows swing the better, but a would't get to hung up on every run as there will be lots of swings through-out the models.

Edited February 4, 2014 by Polar Maritime

[Tim Bland]

Patience people, we will get proper northern blocking in the end ...... http://www.meteociel.fr/modeles/cfse_cartes.php?ech=2874&code=0&mode=0&carte=1&run=0

[bluearmy]

Tamara, i read that you feel that we need to see the zonal flow drop below 20m/s in the strat. at what level?  from my perspective, as mooted a couple of weeks ago, the strat conditions are no longer influencing the trop re prevention of HLB and also, without a marked reversal of zonal winds downwelling, re establishment of a strong -AO. 

 

the extended ens means have hinted at a mid month pattern change of sorts and the ops are now playing with solutions whereby we actually see some height rises to our north and northwest. whether these are transient and the jet restarts again soon afterwards remains uncertain.

 

something else thats caught my attention is the uppers on the GEM from the atlantic westerlies. they are continually shown  'warmed out' way west of where the ukmo/ecm/gfs have them. i wonder if  the gem model is missing a connect with sst's in the nw atlantic ??

Edited February 4, 2014 by bluearmy

[Downpour]

You have to laugh really - just when everyone had thrown in the towel, the excellent Ian F, who has been bang on the money all winter, starts highlighting the possibility of snow in the near to medium term.

Many of us will be sceptical of a pattern change as it almost seems like the weather has always been and always will be stuck in this dire pattern.

But at some point it has to change. Still quite a bit of winter left so who knows? Could this winter surprise us after all? The models are hinting that it just might.

[gottolovethisweather]

You have to laugh really - just when everyone had thrown in the towel, the excellent Ian F, who has been bang on the money all winter, starts highlighting the possibility of snow in the near to medium term.

Many of us will be sceptical of a pattern change as it almost seems like the weather has always been and always will be stuck in this dire pattern.

But at some point it has to change. Still quite a bit of winter left so who knows? Could this winter surprise us after all? The models are hinting that it just might.

 

One word will sum their thoughts up I suspect and that'd be TRANSIENT snow at best I imagine, any would be good to see personally but that's just me. Nonetheless, best wait to hear his view. All of this after this and early next week's rain and wind shenanigans. The eventual lessening impact of the raging zonal flow in conjunction with the Jet diving South will perhaps change things for the better before too long.

Edited February 4, 2014 by gottolovethisweather

[snowmadchrisuk]

A few nice Ensemble members starting to creap into the pack , albeit deep FI but still nice to see there starting to come up with different solutions .. A couple of the best ones are below ..

 

 

 

[skadi]

At least we're getting rid of that  Alaskan block that kept pushing the cold air into the US

[bluearmy]

ecm op brings up to 50mm of precip sw of a line aberystwyth to london pre T96 !!  i suspect locally more than that. 

[NorthernRab]

There is a means of clarifying terminology on this forum whereby a dotted line appears beneath a certain phrase and a brief explanation is given when you hover over the term - why not utilise this function more widely? I notice that it appears where acronyms are mentioned, such as the NAO, but it would be beneficial to members of all levels of experience in order to establish a common term and in turn to question its use where individuals feel it is being applied incorrectly. Just a thought

[Captain Shortwave]

Hmm not good, next monday we see another low taking the same track as the one at the end of this week. More rain for the south

 

And another one!!!!

Edited February 4, 2014 by Captain shortwave

[skadi]

hmmm, pressure rising around Nova Zembla...retrograde Russian High?

at t+192

[Man With Beard]

 and even across southern England too, reckon UKMO

Well if that's in connection with this chart, that would be quite some rain to snow event! 

[bluearmy]

Hmm not good, next monday we see another low taking the same track as the one at the end of this week. More rain for the south

 

 

 

And another one!!!!

 

 

interestingly, the ecm op has mondays precip only affecting se uk and leaving some snowcover (possible but likely?). thereafter, the feature coming west to east leaves decent snowcover over the hills (inc exmoor/dartmoor). as steve alluded earlier, once we have a slack deep trough, as long as the systems dont deepen and mix out the layers, we could see snowfall at any time, even on low ground. settling would be quite another matter !

Well if that's in connection with this chart, that would be quite some rain to snow event! 

 

 

i think ian is referring to the showers that follow in the coldr lee flow rather than the back edge of the rain (although over high ground thats feasible)

[Bristawl Si]

Well if that's in connection with this chart, that would be quite some rain to snow event! 

No hints at all on bbc weather this eve for Friday or weekend re snow down here - still talking about copious amounts of rain.

I know some on here comment on their forecasts sometimes being behind the curve, but even with Ian's earlier comments are we really looking at a rain to snow event.....just yet?

[A.J]

No hints at all on bbc weather this eve for Friday or weekend re snow down here - still talking about copious amounts of rain.

I know some on here comment on their forecasts sometimes being behind the curve, but even with Ian's earlier comments are we really looking at a rain to snow event.....just yet?

At the risk of sounding off topic, I feel folk are over analyzing and second guessing his words....Ian will no doubt appraise us on the Meto's thoughts at some stage this evening (won't be right now as he's probably on tv giving the points west forecast).....until such time best to concentrate on the actual output that we can interpret

[Severe Siberian icy blast]

interestingly, the ecm op has mondays precip only affecting se uk and leaving some snowcover (possible but likely?). thereafter, the feature coming west to east leaves decent snowcover over the hills (inc exmoor/dartmoor). as steve alluded earlier, once we have a slack deep trough, as long as the systems dont deepen and mix out the layers, we could see snowfall at any time, even on low ground. settling would be quite another matter ! i think ian is referring to the showers that follow in the coldr lee flow rather than the back edge of the rain (although over high ground thats feasible)

Yes I have to admit when I looked at the ECM for early next week , with upper around -3/4 under a slack low pressure , especially if you have snow cover on any higher ground , may well end up quite a wintry week for some , higher the better obviously but things look to be going in the right direction , finally !

[cooling climate]

For well over a week now I have been touting a pattern change to one of more blocking or

amplification to the north and lows tracking further south with hopefully a decent continental

feed bringing cold uppers and finally a taste of winter. This is now starting to show in the model

output and is brought about by the ongoing strat warming.

Plenty of changes to come in the output as the models get to grips with this with the strongest

period of blocking probably the last two weeks of the month.

I know if I could take one week of proper cold wintry weather, laying snow etc from this awful

winter I will be happy.

[Polar Maritime]

There is the chance of Snow over the spine of the country tomorrow afternoon.

 

[SMU]

Without putting to much insight into the models there really is high potential for snow & snow cover in the models tonight- again though more especially over the hills of the midlands & pennines etc-

 

ANY shallow low that tracks across the UK in this type of set up-

http://www.meteociel.fr/modeles/ecmwf/runs/2014020412/ECU1-192.GIF?04-0

http://www.meteociel.fr/modeles/ecmwf/runs/2014020412/ECU0-192.GIF?04-0

 

With heights around 508 DAM & thickness around 528 DAM, will always be a recipe for snow over hills-

 

The UKS best chance of the winter for snow presents itself this weekend & more especially early next week.

Also Scotland looks very cold - with circa -4c air, low heights & thicknesses as well with a gentle southerly breeze.

 

S

[Stuie]

Without putting to much insight into the models there really is high potential for snow & snow cover in the models tonight- again though more especially over the hills of the midlands & pennines etc-

 

ANY shallow low that tracks across the UK in this type of set up-

http://www.meteociel.fr/modeles/ecmwf/runs/2014020412/ECU1-192.GIF?04-0

http://www.meteociel.fr/modeles/ecmwf/runs/2014020412/ECU0-192.GIF?04-0

 

With heights around 508 DAM & thickness around 528 DAM, will always be a recipe for snow over hills-

 

The UKS best chance of the winter for snow presents itself this weekend & more especially early next week.

Also Scotland looks very cold - with circa -4c air, low heights & thicknesses as well with a gentle southerly breeze.

 

S

True Steve, early next week a chance for nearly all of the UK. No doubt enough precipitation about or knowing our luck, zero.

 

Edit: Oh maybe ;-)

Edited February 4, 2014 by StuieW

[SMU]

http://www.meteociel.fr/modeles/jma/runs/2014020412/JN192-21.GIF?04-12

 

Decent JMA -  nice chart.

 

Need some of these eye candy charts to get to 72 & 96............

 

S