Model Output Discussion - 23rd Jan - 12z onwards

[Eskimo]

Brings tears of happiness to ones eyes!   

[Mucka]

Brings tears of happiness to ones eyes!   

 

LOL PS, brings tears of pain to mine. 

I'm sure we can do much better with this synoptic than what GFS offers this morning though the chart you posted in isolation looks good.

[Liam J]

Thats's a very cold W/NW'ly on the 00z for Wed/Thur, a slight upgrade with the uppers with -7 to -9c reaching our shores before mixing out, plenty of snow modelled for the N&W anyway and scope for some back edge snow further south. GFS ppn charts so a pinch of salt needed! Hopefully it'll be cleaner than the GFS evolution for later in the week though. 

 

Edited January 25, 2015 by *Sub*Zero*

[KTtom]

Seems to be a bit of a trend to shift the core of the trough a little further west.....UKMO still promising the wintriest spell for a couple of years..

 

Bottom clinching time with the GFS, you certainly wouldn't want it any further west...all a bit messy really....

 

 

 

UKMO...

Edited January 25, 2015 by KTtom

[Penrith Snow]

In some ways I prefer the GFS as it's more likely to bring precipitation.

The MetO could be bone dry away from the coast.

Either way an interesting week ahead.

Andy

[Captain Shortwave]

Slightly worrying this morning, the evolution at the end of the week seems to be dependent on the position and alignment of the Siberian lobe of the polar vortex. This is due to the good solutions being able to phase the low with the Siberian lobe which makes the low track east and quicker which hence sets up the cleaner northerly. For a few runs now, the GFS has not wanted this nice alignment of the Siberian lobe into Scandinavia and instead we effectively end up with a ball of very low heights moving slower and more in an ESE direction, hence it ends up near Scotland and loiters around.

Models at day 6

GFS

Siberian vortex is nowhere near where we want it to be, hence the slow moving trough over or just east of the UK with a cyclonic pattern, hence less cold.

 

UKMO

Here the Siberian lobe is aligned perfectly and digs well into Europe, hence the main low is centres further north east and allows the cleaner northerly.

 

Last night, the GEM and ECM backed the UKMO solution and hence the GFS was isolated, is it the same this morning?

 

ECM

Half way house, the extension of the Siberian lobe is weaker, but it is sufficient to deliver a cold spell, in fact it is very fun later on as areas of low pressure run into the deep trough.

 

GEM

This is looking more GFS like, and it's overall run reflects this with no real window of cold before the Atlantic rolls in later.

 

Wednesday into Thursday looks good at the moment as the initial PM blast looks very potent for what it is. Beyond that, the models do deviate, ultimately we want the Siberian lobe of the polar vortex to align through Northern Russia into Scandinavia and dig south, this allows the quicker movement of the low midweek and hence a cleaner and better northerly.

[SnowLover2010]

Looking good in to late next week for cold/snow.

Edited January 25, 2015 by SnowLover2010

[winterof79]

No worries from me just variations of a cold theme

 

GFS a wam outlier in the latter stages but who really cares,it is going to get cold and surprise snow events is becoming the winter theme

[Ali1977]

GFS is definitely watering down the Arctic blast, hopefully it's not onto something although that's a few runs now.

[winterof79]

Predicted snowfall from the initial N/Westerly it will not allow for embedded features,which will occur, into the weekend and indeed next week.

 

 

 

[shaky]

Very cold and wintry outputs continue this morning amd ukmo and ecm look coldest of the bunch!! Hopefully gfs turns those 850s colder!! Is it me or is that northwesterly for wednesday/Thursday now tuurning more into a westerly?

[TEITS]

I thought I would take a closer look at Wed/Thurs because beyond this is all rather messy at the moment.

 

A significant drop in temperature is going to occur during Wednesday as highlighted below.

 

http://www.wetterzentrale.de/pics/Rmgfs904.gif

http://www.wetterzentrale.de/pics/Rmgfs934.gif

 

Now as this cold strong W,ly spreads across the UK, showers will start spreading into W parts and could spread across much of the UK although the inland penetration is more likely S of the Pennines. As upper temps could be -8C, dewpoints below freezing then these showers are likely to fall as snow.

 

http://www.wetterzentrale.de/pics/Rmgfs1022.gif

http://www.wetterzentrale.de/pics/Rmgfs1028.gif

 

Areas that could do rather well here are Wales, W Midlands especially N Wales. However like I say its pot luck here and many could see snowfall. infact you could argue Wed night/Thurs morning has the greatest potential for snowfall for the entire period of this coming cold spell.

[tinybill]

http://www.meteociel.fr/modeles/gfse_cartes.php?mode=2&ech=6

 

well things  might get a bit interesting on Wednesday if you go along  with the  models

 

 

[Optimus Prime]

For those who are looking at the 850hPa temperature profile and determining that it won't be cold enough for widespread low lying snow;

 

 

London was hit by heavy snowfall that day and record low temperatures followed over the coming days.

[IDO]

No worries from me just variations of a cold theme

 

 

 

GFS a wam outlier in the latter stages but who really cares,it is going to get cold and surprise snow events is becoming the winter theme

 

 

Fair enough but it has been obvious for a time the cold is coming via a Euro trough so that is not really an issue. We have moved on to what can we make of this 5-7 day cold period (and will it last a bit longer). 

 

GEM has joined the GEFS trend from yesterday of shortening the cold spell and by D9: 

 

The GFS op and Control still remain promising for a continuation of the cold spell after D10 and they have been consistent in  that regard so although different to the ECM pattern wise it gives us options going forward. The GEFS are still against the Atlantic Ridge holding on and by D10 the GEFS uppers mean confirms that with a return to average uppers:

 

 

Some push the trough east and a cluster like the control topples the Atlantic Ridge for a MLB over the UK and slack easterly:

 

 

It is about a 40% cluster but the Control was one of least complicated in that regime. That would easily be the best outcome in FI if the ridge does not hold and bearing in mind at no time has the GEFS suggested it would be more sustainable than the 5-7 day window, it is a good move away from the Atlantic moving back in.

 

ECM has not surprising backed down on the uppers from last night and they are now in line with the GEFS take for the south with less than marginal uppers (-2 to -4c) for 48 hours or so around D5:

 

 

With that core low crossing the UK at that time the GFS had consistently washed out the uppers so it was a surprise when the ECM sat the SE in a cold pool! Again the ECM is messy after D7 so I am not sure I have any confidence in it from there:

 

 

The UKMO does not impress me in these pattern change situations and has been playing catch up most of this winter. Compare it's D7 chart yesterday morning to this morning and you can see how slow it is to adjust to the short wave spoilers:

 

Yesterday for the 30th:  Today for the same time: 

 

So the upcoming spell looks like giving uppers of 2-4c below average, so nothing like a real Arctic blast, though with the wind chill, likely to feel a lot colder than that. Snow mostly as showers to the NW and West with potential elsewhere for something at short notice. From the weekend models and ensembles deviate, so how the Atlantic Ridge breaks down still to be determined.

Edited January 25, 2015 by i'm dreaming of...

[bluearmy]

The solution of the trough now certain and the models will deal with it differently run to run. hence the mood on here will swing up (with runs like yesterday's ECM 12z) and down with those that are messy with it and keep it close to the east of the uk at the outset.

as far as the solution for next weekend and beyond is concerned, that depends on two things and they are related. The behaviour of the upstream n American trough which is ostensibly an extension of the Canadian lobe and how the Siberian lobe develops and subsequently interacts with it. the Siberian segment will be affected by the Alaskan ridge and other events in the n pacific. again, the fi ops dealing with this differently, run to run. I would expect the ens will also be quite spread. No easy answer on this although the favourite in the longer term (10 days +) is going to be a flattening out of the Atlantic. the gefs seem keen to build the Azores ridge ne across nw Europe which is feasible but mainly predicated on a big e Canadian vortex master. there is no guarantee on that so I would be continuing to look at developments in week 2 with caution until that polar profile becomes clearer.

Incidentally, the gem day 10 is of interest in the way it builds heights over the pole from the Alaskan ridge to cut off the Canadian vortex. that is the expectation of joe b and I think the ex 32 for weeks 3/4. if the Canadian op is overdoing the transfer of vortex from Siberia to Canada in the mid term, imagine what that day 10 chart would look like? ( the clue being that IDO wouldn't have used it in his post!)

Edited January 25, 2015 by bluearmy

[Frosty.]

Ecm 0z is gorgeous this morning, even better than yesterday's peachy output. The initial cold blast is now at T+72 with an exceptionally cold westerly, sst's rather lower now so much higher risk of snow showers than earlier in the season, and then the flow veers around to pure Arctic. the cold heart of winter 2014 / 2015 is just around the corner. Time to throw caution to the wind, it's going to turn much colder with snow, frosts and ice, and with strong winds at times, drifting snow, I just love drifting snow..bring it on!

[Biggin]

A notable cold spell immenent.850hpa's and the like are at this (fork) cartoon synoptics..it shouts at thos juncture a prolongend' spell.lets gets (L)driver before we are road worthy!

Im sorry, is there something wrong with your laptop?? Or mine ?? The above comes up on my comp as jibberish.

[bluearmy]

Ecm 0z is gorgeous this morning, even better than yesterday's peachy output. The initial cold blast is now at T+72 with an exceptionally cold westerly, sst's rather lower now so much higher risk of snow showers than earlier in the season, and then the flow veers around to pure Arctic. the cold heart of winter 2014 / 2015 is just around the corner. Time to throw caution to the wind, it's going to turn much colder with snow, frosts and ice, and with strong winds at times, drifting snow, I just love drifting snow..bring it on!

Yes and no Karl.

Yes, it brings colder uppers in the latter part of its run but it's drier as a result. Could be ok with troughs in the flow.

No, the front at day6 is accompanied by higher DP's than yesterday. It would not give decent lying snow to much of the uk as yesterday's did.

[nick sussex]

Morning all

 

Well first the bad news, get that out of the way, the models seem to be moving to a middle ground solution with the Euro troughing, normally its the eastwards progression of a pattern that can frustrate here the pattern initially is too far west with the low centre too close.

 

This is not a 5 star northerly or indeed anything like this and I fear expectations won't be met with the set up as shown, I've seen countless similar set ups and this is not an all snow event from day 4, regardless of the low heights the depth of cold is simply not good enough.

 

It doesn't mean theres not snow opportunities but that this will be marginal at times and temps don't look anything out of the ordinary. I know this post probably won't go down well but rather than setting up people to be disappointed its best to be realistic and err on the side of caution.

 

Okay now that I've become public enemy number one, the good news theres more scope today to extend the cold, the ECM in terms of the orientation of the PV at day ten looks ripe for some ridge extension further ne, indeed the coldest air could well come at this point.

 

The GFS operational run again different but with potential as it drops that low south from Greenland, the GEFS seem to be more bullish about an earlier breakdown so some divergence of opinion there.

 

So overall a messy Euro trough scenario to begin with, after this a better chance of seeing some deeper cold.

[bluearmy]

Yes nick, the spread is a Greenland ridge (or at the very least a displaced mid Atlantic high)

Nw American ridge, Azores ridge mid Atlantic orientation, sceuro trough. Fill in the blanks.

[Duane S.]

For those who are looking at the 850hPa temperature profile and determining that it won't be cold enough for widespread low lying snow;

 

 

London was hit by heavy snowfall that day and record low temperatures followed over the coming days.

Absolutely. The 850mb temp profile is only one aspect. Here's a chart I wheel out every year to show it is not the be all end all. This fairly innocuous looking chart produced insane amounts of snow for areas in the south and south west, right onto the coast, I can still remember it as a kid.

I'm not trying to draw any similarities to the upcoming cold spell, just pointing out not to simply look at the upper temps and assume yay or boo to whether it will snow in your garden. They are a good guide, probably the best single guide but too simplistic to rely on solely

[nick sussex]

Yes nick, the spread is a Greenland ridge (or at the very least a displaced mid Atlantic high)

image.jpg

Nw American ridge, Azores ridge mid Atlantic orientation, sceuro trough. Fill in the blanks.

Thanks BA, I like those spreads! You never know I may even cheer up if that verifies! I look forward to seeing the extended ECM ensembles.

[Ali1977]

Ian Fs latest tweet says by Thurs nearly all showers will be of snow - that doesn't scream marginal...Be nice to hear what the METO are thinking for the next weekend. Temps /precip especially.

[Cloud 10]

Another "everything but the kitchen sink" chart from the ECM this morning at 120 hrs.

 

 

 

Ecm mean at day 10 continues the cold spell.