Model Output Discussion 29th December - Into mid-Winter.

[nick sussex]

17 minutes ago, Jason H said:

Please. At least let us drool at the FI eye candy. We'll leave the serious stuff off Euro slugs and shortwaves to the experts

Don't let me stop you! There are two shortwaves, the first circled black manages to run east over the high and not keep any residual energy hanging back, the second stays just enough to the sw to allow the gap to appear to give the Euro slug high room to retrogress. However there won't be any eye candy if that shortwave circled red phases with the low pressure near the UK.

 

The GFS manages not to but given our recent luck low margin for error evolutions are not what we want to see. The GFS then manages to take a high unlikely to get ne at T240hrs and miraculously catapults it ne as the lower resolution kicks in. Anyway lets hope we can have an evolution that's not such a white knuckle ride in future outputs.

PS I hope people don't think I'm being a misery or wanting to drag down the mood but its best to view possible cold set ups in terms of margin for error and how many things need to go right. I'll be happy to ramp any cold when it passes my quality threshold! lol

 

Edited January 4, 2017 by nick sussex

[stewfox]

5 minutes ago, winterof79 said:

Time will tell.The output is getting colder around the 13/14th each run

As I posted before only a matter of time before the high shifts favourably for us.Lets face it,it doesn't have to be a massive westward correction

Its been a pain for a while that's for sure

[karlos1983]

As ever I eagerly await the 12z ecm ensemble due out in 20 mins or so. Hoping for improvements on the last 2 runs.

on a side note, is it just me or is this emoji the most condescending emoji going  

12z not great actually. 

 

Edited January 4, 2017 by karlos1983

[radiohead]

12Z GEM Control manages to produce this but quickly topples it

Edited January 4, 2017 by radiohead

[Snowy L]

10 minutes ago, karlos1983 said:

As ever I eagerly await the 12z ecm ensemble due out in 20 mins or so. Hoping for improvements on the last 2 runs.

on a side note, is it just me or is this emoji the most condescending emoji going  

12z not great actually. 

 

Sizeable cluster going with the GFS OP at least

[karlos1983]

1 minute ago, Snowy L said:

Sizeable cluster going with the GFS OP at least

Yes perhaps but more mild solutions than of late. 

[radiohead]

Control and Op at T192

[Mucka]

42 minutes ago, nick sussex said:

Don't let me stop you! There are two shortwaves, the first circled black manages to run east over the high and not keep any residual energy hanging back, the second stays just enough to the sw to allow the gap to appear to give the Euro slug high room to retrogress. However there won't be any eye candy if that shortwave circled red phases with the low pressure near the UK.

 

The GFS manages not to but given our recent luck low margin for error evolutions are not what we want to see. The GFS then manages to take a high unlikely to get ne at T240hrs and miraculously catapults it ne as the lower resolution kicks in. Anyway lets hope we can have an evolution that's not such a white knuckle ride in future outputs.

PS I hope people don't think I'm being a misery or wanting to drag down the mood but its best to view possible cold set ups in terms of margin for error and how many things need to go right. I'll be happy to ramp any cold when it passes my quality threshold! lol

 

Not at all, things are rarely as clean as the oversimplified GFS FI ramblings.

It will be difficult to get rid of those Euro heights and it won't take much to spoil the SE progression of any trough. Here is the Control for example

Just a waft of PM air in FI by the look of it with salt immune slug to the South.

Edit.

Actually control managed to keep cold air over us for 3/4 days which would go down as a cold snap but it is hardly a convincing one from a passing trough and collapsing ridge - or toppler as we in the snow starved club like to call it.

Edited January 4, 2017 by Mucka

[radiohead]

The majority of the 18Z GEFS are looking pretty interesting in FI at T228. More than the 12Z.

[Mucka]

Hard to see anything other than a transient Northerly 24/72 hrs as long as there is so much spread among the ensembles

 

The North and West could get lucky around the 12th/13th as far as actually seeing a flake of... 

What's it called now?

Damn I forgot.

[nick sussex]

6 minutes ago, Mucka said:

Not at all, things are rarely as clean as the oversimplified GFS FI ramblings.

It will be difficult to get rid of those Euro heights and it won't take much to spoil the SE progression of any trough. Here is the Control for example

Just a waft of PM air in FI by the look of it with salt immune slug to the South.

Yes that's why I'll be much happier when the slug leaving is within T168hrs. The upstream pattern has just kept it in place for weeks and its kept any deep cold out of reach. To put that slug in context  the last time we saw some heavy snowfall for the mountains was the 23rd November,  the only rain since then came before Christmas which delivered a pitiful 4cms of new snow for the ski resorts. We've had though more frosts already this winter than the whole of last seasons woeful effort and if you like sunshine you'd love it here.

[Scandinavian High.]

no big freeze on way just yet just standard winter weather for uk .

Edited January 4, 2017 by abbie123

[Man With Beard]

Well the 18Z confirms a lot of other model output today, which is that there is at least a route to deep cold coming up. 

The key is getting a depression in the Atlantic to disconnect from the main PV and drop over the North Sea (a la T192 on GFS 18Z).

As it does, we need the Siberian high and the Atlantic high both to be in position to try to fill that gap.

If they can meet over Scandinavia - BINGO.

Current window of opportunity: T192-T264ish.

If it fails, there will always be the chance of more PMs to come.

 

[Man With Beard]

Just now, Rocheydub said:

Haha, Brilliant!

 

Seriosly though Man With Beard, that's looking for a lot of ducks to swim in a row! I'd be amazed and delighted if it was fulfilled! 

Indeed. Unlikely. But yet again the GEFS is buying it tonight, well 8 of them anyway! Is it just a case of thinking - our time will surely come??

[Connor Bailey Degnan]

In our dreams v reality 

#justforalaugh

[northwestsnow]

Hmmm fergies tweet doesnt inspire confidence.A lot of this potential is not stemming from high lat blocking which for me means any route to cold is going to be frought with potential spoilers.

Id happily take my chance with an ECM evolution.

I do hope we get a decent polar north westerly, but at the same time im expecting spoiler complications on the 00z runs..

[Mucka]

GFS Op doesn't offer much encouragement with it's love affair with the Azores high but fortunately UKMO is a bit more interested in squeezing it West and putting us in a decent PM flow at least.

For once we want the more progressive solution of UKMO phasing the two lows through 120/144 to flatten the ridge and force the pattern West for any Northerly down the line as the first whiff of PM air will be a waste of time anyway

Looks better upstream as well which, along with the trough being further South and West than GFS, would give a chance of a decent Atlantic ridge building.

So let's hope GFS is on one and UKMO onto something. 

 

Edit 

Just to illustrate why we want the lows to phase and power up the trough here are 2 extreme examples from withing GFS ensembles.

The first example, with more separation between the lows at 144 which allows the 2nd low to extend the ridge

 

The second example, the lows phase and create a deep trough.

It should be said the most members offer something between these two examples.

Seems odd rooting for the opposite of what we usually want but there you go. Any amplification/ridging through the mid term is now more likely to be a hindrance than a help.

 

Edit 2

GEM phases the lows

and goes on to produce a wintry if unlikely trough.

UKMO is actually slightly better at 144 IMO though impossible to know how long it could sustain a cold PM flow.

 

Edited January 5, 2017 by Mucka

[knocker]

There is not much to add this morning vis the GEFS anomaly that wasn't said last evening. Still looking at transient Pm incursions from the NW, more particularly near the end of the ten day period as some upstream pattern changes are occurring which leads to some brief Atlantic amplification and a depression tracking down the North sea.

We are still looking at much energy tracking around the HP and a 160Kt jet but certainly not to forget that a significant amount is also tracking SE and topping up the upper low to the south which maintains it's role of keeping the HP honest but also slips in the odd shortwave that effects the UK

.From now until Monday, apart from a weak front tracking SE on Friday, high pressure in charge but then sees the onset of depressions tracking east between Iceland and Scotland with associated fronts running SE across the UK as the HP is pushed SW and winds veer NW. This is really the onset of a few days of more unsettled weather although still more inclined to effect the north, terminating in a quite shallow depression running down the North sea. Temps around average but perhaps a little cooler in the Pm air. Still pretty dry apart from the NW

Edited January 5, 2017 by knocker

[mcweather]

Afraid to say I remain far from convinced by the midweek model madness.  Same thing happened a week ago only for major backtracking away from the coldest options to occur on the Thursday. Something both the gefs op and control seem to doing again this morning.  As with any stellar charts that come along Unless they'come within 120 hours then treat them for what they. Winter porn and nothing more.

Edited January 5, 2017 by mcweather

[snowbunting]

11 minutes ago, mcweather said:

Afraid to say I remain far from convinced by the midweek model madness.  Same thing happened a week ago only for major backtracking away from the coldest options to occur on the Thursday. Something both the gefs op and control seem to doing again this morning.  As with any stellar charts that come along Unless they'come within 120 hours then then treat them for what they. Winter porn and nothing more.

In agreement with you there. Until longer term teleconnections signals firm up, it is pointless looking beyond +144 hrs on any model. Thats twice now the GFS has sent a signal of a great Nly down around 7-10 days and twice its now ended with a deep low and a not budging euro high. Watching the Greenie high by the way. I have been watching the CFS for trends in runs and whilst there are a few who might slate it.. one thing it has picked up on... no Nly blocking trend. Its right so far. 

[IDO]

Very hard to get excited by the output as it firms up on mid month onwards. No change in that a cooler background is forecast but there appears to be little chance of any sustained forcing in the Atlantic or Pacific to build heights north for a prolonged cold spell. Basically the Atlantic profile remains as per the past month or so, therefore for us down south any zonal phases will be colder rain than December's!

The D8 mean NH shows the problem we face; the waves from the Atlantic -v- PV to the N/NW: 

There is little to no chance of any HLB'ing for the UK under this scenario and with the heights holding their own, getting a cold trough encompassing the UK looks a hard call.

The D12 mean still has the main PV lobe over the NW so chances of the heights building further north to mid latitude. However with the jet firing off that lobe any ridging likely to be flattened by the jet:

I am sure some FI charts will have a few colder outcomes but we have learnt this winter that they rarely get close to D8 let alone T0.

There of course remains uncertainty so a colder phase is possible though not sustainable IMO. Once the Pacific Ridge collapses after D8 and we see how the PV moves from there we will have a better idea of that potential. At the moment any break off wedges of heights are ejected away from the polar region which only means the PV is squeezed away from the Asia/Siberia side of the NH. Those wedges get warmed out by about D12 so that is the next sign post for the shifting sands of the PV. The GEFS at D13-D16 offer no guidance yet. 

So we are looking at the last third of January for any pattern to swing to cold.

 

[Weathizard]

PV over greenland/eastern canada + Euro/Azores high =  unfortunately based on recent years this is the norm, luckily enough this winter it's been boring but at least it's been set up in a way that keeps is predominantly dry.

ECM 192 is a rather strange chart, we desperately need the PV to pull its anchor out and move to Siberia

[knocker]

The ecm varies in detail from the GFS next week. Midnight Tuesday it has a depression 984mb over the Faeroes and wet and windy for N.  Scotland  With the strong jet looping SE over Ireland (it just emphasizes how little adjustments to the pressure distribution alter the detailed outcome vis the UK) the next trough later in the period pops down just to the east of  the UK brifly veering the surface wind northerly before the next resurgence of the HP from the SW.

[Dennis]

22 minutes ago, Weathizard said:

PV over greenland/eastern canada + Euro/Azores high =  unfortunately based on recent years this is the norm, luckily enough this winter it's been boring but at least it's been set up in a way that keeps is predominantly dry.

ECM 192 is a rather strange chart, we desperately need the PV to pull its anchor out and move to Siberia

its attention on what will grow soon in the strato ; zonal winds are diving quick next days

Edited January 5, 2017 by Dennis

[terrier]

So the pub run last night whipped everyone up into a frenzy. And this morning the models bring us back down to earth with a bang

Edited January 5, 2017 by Paul
Removed the off topic stuff