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

[knocker]

Huge potential!

[Ali1977]

1 minute ago, knocker said:

Huge potential!

For your squirrel to freeze to death? Potential for what?

[Banbury]

4 minutes ago, swfc said:

sorry????

do you not mean 6z

No GFS 12z , ends up with a massive Easterly

[northwestsnow]

Personally, i suspect ecm will go on to be cold after 240 but not the deep cold from the east, more an inversion cold as we see an extensive southern scandy/Benelux block.For me there is to much energy going over the top to allow for a true scandy high.

[ghoneym]

2 minutes ago, West is Best said:

Nope stunning Scandi high, bitter easterly with astonishingly low temps, followed by a classic boundary attack which can brilliant results.

This is the Scandi high in Question from the 12Z. -10 850's, easterly / south easterly winds

[swfc]

2 minutes ago, Banbury said:

No GFS 12z , ends up with a massive Easterly

its 14 days away !!!! granted it looks ok but more chance of elvis doing a gig in sheffield!!! lol

[SMU]

The ECM day 10 into 11 would certainly move into a more favourable position for cold -

Atlantic low closer to iberia, the high building & shearing NE & low euro heights forcing cold west so within the EPS expect day 11 to be the 'cold' meeting point of all before they mix out to seperate solutions

in terms of the OP post day 11 it woukd certainly be cold circa -8c air in the SE but questionable whether there would be a direct easterly flow creating snow showers- it would more than likely be light NE..,

Anyway not to bad but not the 06z blockbuster

expect the OP to be at the midpoint of the runs @ day 10 with plenty of sub 0c thereafter & plenty -5s... maybe a few cobras as well...

Steady as she goes-

S

[Geordiesnow]

10 minutes ago, mountain shadow said:

It is not potent and not sustained before it topples/sinks.

2nd attempt going the same way unless you believe the GFS over ECM/UKMET

Will the third amplification bring in an Easterly though? More runs needed

 

1st Northerly not potent? Uppers ranging from -5 to -10 looks pretty potent to me although the GFS does tend to overdo the uppers but the fact is, its a pretty strong Northerly to my eyes if albeit rather brief affair.

I do agree there still not much sign of HLB unless you believe the GFS which as we know tends to overdo blocking situation in the medium to longer range. 

[Methuselah]

Okay then...

Unless something almost meteorologically 'impossible' happens between now and Sunday, a 2/3-day-long and reasonably potent Northerly looks odd-on: if it isn't then we might as well all give up now?

Around January 6-7, what could be a prolonged spell of colder weather looks increasingly likely. But likely does not mean certain (we are after all all in the UK!) so it 'could' always still go the way-of-the-pear - so prepare for the worst and hope for the best ought to be good advice?

My personal preference? As snowy as but not nearly as cold as what the 06Z was suggesting...Are daytime maxima of -10C really what folks want to see? Wouldn't -2C do?

[chionomaniac]

3 minutes ago, northwestsnow said:

Personally, i suspect ecm will go on to be cold after 240 but not the deep cold from the east, more an inversion cold as we see an extensive southern scandy/Benelux block.For me there is to much energy going over the top to allow for a true scandy high.

I think that extent of WAA and position and angle of the building block is better with the ECM at T+240 than the GFS at the same time frame. And look what the GFS produced from there. The ECM would nudge everything a bit further west. All FI conjecture of course. I like all output tonight - even the UKMO at T+144 I think that would drag the block further west still (eventually)

[mountain shadow]

8 minutes ago, northwestsnow said:

Personally, i suspect ecm will go on to be cold after 240 but not the deep cold from the east, more an inversion cold as we see an extensive southern scandy/Benelux block.For me there is to much energy going over the top to allow for a true scandy high.

Agreed. The pivot of the UK high is to far South, for a true Easterly we would want the high to pivot at least as far North as the Northern Isles, in this case the pivot is over the UK, the coldest air would therefore be France bound.

[Lampostwatcher]

Whats the latest for NYE weather front

 

[blizzard81]

Just now, northwestsnow said:

Personally, i suspect ecm will go on to be cold after 240 but not the deep cold from the east, more an inversion cold as we see an extensive southern scandy/Benelux block.For me there is to much energy going over the top to allow for a true scandy high.

What worries me about the ecm is that the day 9 and 10 charts often end up being way too amplified. This has happened a few times this season. I remember commenting on one of it's day 10 charts a few weeks ago. It showed a jan 47 esq chart with the UK high migrating to meet it's arctic cousin. The reality was very different. I am now expecting high pressure to be situated over the UK in 10 days time and it could stick there for quite some time. Here in lies the problem with this winter - no appetite for "enough" amplification. Note the word "enough". At least it will be cold though. All this ties in with the last few meto updates.

[Dennis]

CFS shows cold more west in first days Jan 2017

[blizzard81]

9 minutes ago, chionomaniac said:

I think that extent of WAA and position and angle of the building block is better with the ECM at T+240 than the GFS at the same time frame. And look what the GFS produced from there. The ECM would nudge everything a bit further west. All FI conjecture of course. I like all output tonight - even the UKMO at T+144 I think that would drag the block further west still (eventually)

If the ecm was bias corrected, I bet that WAA up through Iceland would be much less pronounced or even non existant.

[stewfox]

So reviewing the last 24hr

For clarity

I may quote some folk as i dont write propper but remember the quotes are taken at that time and may not reflect on further updates. Something happened with GFS 6z that added 8 pages in 4 hours on the morning of 29/12/. A ‘stellar’ run.

See theory re cold and pages here

https://www.netweather.tv/forum/topic/86580-model-output-discussions-06z-041116/?page=189#comment-3483019

Yesterday evening inc pub run

Not a down beat affair.

We have had two northerlies at the start of Jan ie cira 1/1 and repeat 7/1.

The ECM T240 was great for collides.

Notable that at T240 the GEFS mean 500mb height anomalies are very similar to the ECMWF ENS anomalies. So there appears to be all round support for a cold northerly flow around the 7th January!

Back edge snow more pronounced on the latest 18z GFS run. Parts of the Midlands, especially those on hills will get something this relates to the first cold incursion 1/1.

18z trending is towards ECM better height rises toward Greenland.

GFS is a pretty decent one at that with -12c uppers into Scotland and -10c pushing down across the country re 7/1.

So first week of Jan not too shoddy although no price rises for snow shovels at Tesco yet

Morning

Morning starts with some low-key discussions over tea and toast over the two northerly incursions, nothing has changed since last evening.

Weak topper has potential to bring the goods as we welcome in the new year for snow to some regions. Some discussion over where the block will end up day 10.

The 0z GFS P keeps the general trend of Atlantic amplification in the day 7-11 range.

Just the slightest suspicion a period of enhanced amplification may be coming onto the extended range (mid to late Jan) via uptick in angular momentum tendency (beyond what models are advertising)

Then to 06z GFS came out

SM summed it up nicely

Where the f*** did that come from

 6z is brill high never sinks holding to the colder air longer now a reload incoming

screaming jet going southwards- & deep cold moving west.

By 264 we have deep snow cover and bitterly cold temps, -7 across the north.

-14c uppers touching the NE coast @ 288… operational run support.

The whole of the UK sub -10c BIBLICAL charts, run of the century etc

The 9 pages of ramping !!!!  someone said “””””its just one run””.

Afternoon

The GFS 12z perhaps the most waited for model update ever?.

Folk hit PF5 100 times to speed up the GFS 12z, life stands still, make your own F**** tea.

 

T0000001  winters over post is deleted

T72 is that a secondary trough ??

Comment on each 3 hr updates (4 pages)

012z not as ‘stella’ as 06z how could it ? similar to 168 (we get the two northerlies)

Less pronounced ridging on the 12Z GFS Day 10 mean compared to the 06Z.

ENS, a still supports the second cold spell/snap and GFS 12z offers easterly in la la

UKMO causes some concern T144.

Evening (pre pub run)

Eyes down for ECM we don’t want it to trend to UKMO and a flatten pattern, we want that Atlantic amplification.

ECM halfway between GFS and UKMO as far as retrogessing Euro heights West.

Vortex in Greenland is night and day ECM miles better also ECM more amplified.

ECM very similar to yesterday 12z at 168, just slightly less amplified. 

Can we please not post one liners is followed by 6 one liners and how bad its got.

Cold 5/10 ( a lot of potential and some split stella).

Gritters will be out in force so buy screen wash.

Cold is coming how long how severe to be decided, try not to over analyse every run or take too much into account from the one liners. New year day doesn’t start too bad.

Edited December 29, 2016 by stewfox

[mulzy]

28 minutes ago, knocker said:

Huge potential!

With high pressure dominating between days 6-10, it will be cold at the surface.

[Mucka]

37 minutes ago, bluearmy said:

Whilst the GEFS chop and change their orientation with each run, the eps seem pretty consistent with their op. The run pretty well as I expected it and I don't think that ridge will back much further west tomorrow mucka (though a few hundred miles feasible) 

the trough over n America at day 8/9 much sharper than the previous run and drives that Atlantic trough downstream a bit further south than might be likely. Whilst the op fits with the ens, it's good for later week 2 re the undercutting of the ridge. 

Joking aside, you may well be right Blue, depends on how quickly we drain those Euro heights and orientation of ridge but a few hundred miles is all we need. 

Personally I believe there is enough wiggle room to get that few hundred miles we need to draw in colder uppers later.

I hope so because rather jam tomorrow Northerly than jam next week Easterly though it is nice to have the potential easterly as a fall back in case the pattern is forced East and the Northerly is short lived.

Of course the dream is to get prolonged N/NE flow followed by the Easterly.

 

I will be watching the mornings outputs nervously to see if the UKMO gets on board and GFS, ECM maintain the theme - as you say backing the pattern West would be a bonus to any renewed amplification.

 

Edited December 29, 2016 by Mucka

[knocker]

2 minutes ago, mulzy said:

With high pressure dominating between days 6-10, it will be cold at the surface.

Precisely. Potential for quite severe ground frosts.

[Seasonality]

32 minutes ago, West is Best said:

Nope stunning Scandi high, bitter easterly with astonishingly low temps, followed by a classic boundary attack which can brilliant results.

Astonishly low? It looks cold I'll give you that but is that not a little hyperbolic? Please don't take this as a dig, just trying tobe realistic.

[northwestsnow]

Well the EC ens will be interesting thats for sure. Would be nice to see some clustering in the easterly camp post day 10...

[Derbyshire Snow]

First post since Christmas and what a complex situation we have now. The constant west to east jet stream in December and the high over Europe constantly trying to extend westwards to no avail has at last been binned and we have now a completely new set up to work on. In my opinion i am finding  it really difficult to predict what will happen next,but all the models are predicting some sort of cool/cold spell but how cold and how persistent   is the real question. The first colder spell from January1st looks certain but i expect it to be just a normal cold snap with some snow showers in far north and down the east coast. The key to a longer more severe cold spell is this high pressure in the Atlantic.Thankfully low pressure near the Azores should stop the high sinking and maybe drifting in to France ( worst possible route allowing the jetstream to be similar to December).

By far the best way to a lengthy severe spell are for heights to develop over Greenland and hopefully this should encourage the Atlantic high to ridge northwards and build in  intensity, strong enough to   either split the jetstream and sending low pressures to west of Greenland or deflect the jet  much further south. If this happened then because of little heights over Europe the lows to the north of the British Isles would drift over Scandinavia and maybe in to North Europe resulting in possibly a very large unstable north and north easterly airstream, so many possibilities of severe cold from this position. Scandinavian High! Polar troughs! would be mouthwatering

What happens in the next 7 days i think could decide our weather for January. All i can say its great model watching. The building blocks are there but lots of luck required as usual for our islands.

[East_England_Stormchaser91]

44 minutes ago, West is Best said:

Nope stunning Scandi high, bitter easterly with astonishingly low temps, followed by a classic boundary attack which can brilliant results.

A case of 1947 type snow events on the 6z and a carbon copy of Feb 1991 on the 12z! Couldn't ask for a better choice really! 

The ECM run could've been much much worse too. The 240 timeframe shows a loaded gun of sub -20 uppers ready to be blasted out of scandi to my viewing. 

[Banbury]

40 minutes ago, swfc said:

its 14 days away !!!! granted it looks ok but more chance of elvis doing a gig in sheffield!!! lol

of course it is 14 days away no one is disputing it wont occur , we could say that about most charts beyond 144 but as its the MOD thread WIB mentioned it

Onwards and upwards old boy

[Man With Beard]

43 minutes ago, blizzard81 said:

What worries me about the ecm is that the day 9 and 10 charts often end up being way too amplified. This has happened a few times this season. I remember commenting on one of it's day 10 charts a few weeks ago. It showed a jan 47 esq chart with the UK high migrating to meet it's arctic cousin. The reality was very different. I am now expecting high pressure to be situated over the UK in 10 days time and it could stick there for quite some time. Here in lies the problem with this winter - no appetite for "enough" amplification. Note the word "enough". At least it will be cold though. All this ties in with the last few meto updates.

I really don't think this has happened since the upgrade at the end of November, though - if anything, it has under-amplified on occasions (ok, all bar one run which split the vortex quite ridiculously). It looks like it will have made excellent calls on both of the upcoming northerlies from way out at D9/D10. So I see no reason why it is going to be far off tonight