Model output discussion - 5th December 2016 - Into Winter we go

[Mucka]

1 hour ago, CreweCold said:

UKMO at day 6 doesn't follow the script this morning

GFS at day 6 a lot better than the UKMO as it maintains that wedge of heights between the LPs that Steve was talking about earlier

So...still no resolution to this one

 

 

Yeah the problem is that Azores low moving North and phasing with the trough. It is a possible fly in the ointment but hopefully it doesn't happen.

The good news is that only a few GFS ensembles go for anything close.

GFS is decent. If the pattern was a little further NW in FI it would have put the forum into meltdown. As it is, it is cold but essentially dry.

 

Edit.

Obviously a lot going on and very difficult to predict what might happen in FI until the the pattern in the more reliable is tied down, but I'd say the current form horse is for a ridge just to the West of the UK around day 10. If that is the case then how far West it is backed and how far North it can reach will determine snow chances. Either way the potential of an Easterly setting up second week of January currently looks better than it has all winter to me.

Edited December 29, 2016 by Mucka

[IDO]

It looks like the GEFS are firming up on that second shot from the next heights push and the mean highlights a good consensus for that as the next play. Again even if it hits the U.K. And some members do, it looks like a mobile pattern, with U.K. HP back in afterwards. 

Another few runs to pinpoint the troughs dive for around D8. From then will the next wave from the Azores enable the high to sustain, rather than flatten, so we get at least a solid mid to high latitude block? Looking at the PV setting up in NE Canada before it slowly drains again, retrogression is unlikely till after D16 IMO. 

Again a cold first half of January the continued theme, but dry and cold rather than wintry seemingly  the favorite.

[MR EXTREMES]

well the early bird catches the worm lol.

anyway im not convinced of any atlantic onslaught but heres 3 of this mornings charts from 3 models gem gefs gfs.

its knife edge stuff and im more convinced of cold heights over the uk with more unsettled to the north but not above average temp wise.

gefs strikes me as a nice run fingers crossed.

 

[snowangel32]

As we look far ahead into FI chasing out next pot of gold we miss what is right in front of us and shows even a weak topper has potential to bring the goods as we welcome in the new year.

If we get that colder air to dig in sooner a lot of people could see a bit of the white stuff and after what we have had so far I would happily Bank.

As we look into the realms of FI the form horse looks to be our limpet high will fall back over us and cold and dry theme will stay in place but there is still a long way to go with this saga. 

 

[knocker]

A quick general overview of the GEFS this morning. Essentially nothing has changed since last evening.

The 6-10 sees an adjustment of the Aleutian ridge which strengthens and realigns more over the Pole, Which, along with the Canadian vortex initiates an Arctic plunge over North America. This in turn initiates a new Atlantic wave which produces renewed amplification and some quite sharp ridging in mid Atlantic. This in turn facilitates troughs dipping SE over the UK to produce some transitional wintry weather towards the end of the period with snow on the hills and temps a bit below average for a time.

The wave then plays out and as per usual amplification diminishes with a ridge settling down adjacent to the UK and more settled weather with temps still a little below average.

Edited December 29, 2016 by knocker

[Ali1977]

Looks like the ECM is following last nights which is great news, WAA getting fired North to Greenland at day 8 - maybe not quite as strong though so Day 10 may see it toppling.

Edited December 29, 2016 by Ali1977

[SMU]

morning

The ECM has moved away from the Greenland high scenario & more towards the scenario I was trying to highlight last night, deep cold moving west @ day 10-11 the same as last nights control... GFS op on a similar page.

Also the front developing a wave along it with a solid undercut @ 102

This is the HRes GFS

S

Edited December 29, 2016 by Steve Murr

[That ECM]

8 minutes ago, Ali1977 said:

Looks like the ECM is following last nights which is great news, WAA getting fired North to Greenland at day 8 - maybe not quite as strong though so Day 10 may see it toppling.

Not as good but the trend is there. Far to early to see where the exact position of the block will be. A second northerly looks on the cards tho, after that, who knows...

[That ECM]

6 minutes ago, Steve Murr said:

morning

The ECM has moved away from the Greenland high scenario & more towards the scenario I was trying to highlight last night, deep cold moving west @ day 10-11 the same as last nights control... GFS op on a similar page.

Also the front developing a wave along it with a solid undercut @ 102

This is the HRes GFS

S

Hi Steve. Help me out here please. How does the deep cold move west day 10/11 when the days prior push it east? All I see is the whole pattern edging slightly east each frame and I am struggling to see how we get hp ne and drag the cold back. 

 

Cheers

[Dennis]

I do see so many options these days that i decide to watch only 24 hours forecasts  started from day 1 in 2017

[northwestsnow]

Happy with Gfs0z and to my eyes the GEFS look decent too.Ecm offers plenty of interest for cold lovers with a scandy trough in the mix longer term.UKMO though looks poor in comparison so will hope for an improvement this evening! All in all coldies have to be pleased.

[knocker]

Nothing to suggest this morning that the ecm det is vastly different to to the GEFS with the new wave producing mid Atlantic amplification that tracks east thus also allowing a transitional wintry interlude as new troughs swing SE and phase with the trough to the east At least that is the percentage play  as the run signs off.

Surely news of deep cold is exaggerated ?

 

 

 

Edited December 29, 2016 by knocker

[SMU]

53 minutes ago, That ECM said:

Hi Steve. Help me out here please. How does the deep cold move west day 10/11 when the days prior push it east? All I see is the whole pattern edging slightly east each frame and I am struggling to see how we get hp ne and drag the cold back. 

 

Cheers

 Once that block stops the atlantic at day 10 then the motion of the jet is screaming south ( just to our east ) it will pull the little lows south & the ridge will build NE over the top sending the cold west-

S

[knocker]

7 minutes ago, Steve Murr said:

 Once that block stops the atlantic at day 10 then the motion of the jet is screaming south ( just to our east ) it will pull the little lows south & the ridge will build NE over the top sending the cold west-

S

That's one theory. Another would be that the ridge is quite strong from the south west up to Iceland which stops any great eastern movement of the southern arm of the jet and most of the energy is thus directed around the north of the ridge thus nudging it east and curtailing it's development north

[jvenge]

1 hour ago, knocker said:

Nothing to suggest this morning that the ecm det is vastly different to to the GEFS with the new wave producing mid Atlantic amplification that tracks east thus also allowing a transitional wintry interlude as new troughs swing SE and phase with the trough to the east At least that is the percentage play  as the run signs off.

Surely news of deep cold is exaggerated ?

 

 

 

Hi,

Yes, it seems so. The cold spell recently experienced will be similar to the one coming just after New Year. The next one is on the edge of the ECM run, where things can still change (either way, I might add). 

 

[northwestsnow]

Judging by the ecm mean i suspect a decent set of ECM ens..

[radiohead]

0Z ECM Day 10 mean looks very similar to the 12Z. Ridge slightly further east.

[frosty ground]

32 minutes ago, knocker said:

That's one theory. Another would be that the ridge is quite strong from the south west up to Iceland which stops any great eastern movement of the southern arm of the jet and most of the energy is thus directed around the north of the ridge thus nudging it east and curtailing it's development north

Wouldn't your theory be backed by evidence thou and therefore the more likely one.

[knocker]

25 minutes ago, jvenge said:

Hi,

Yes, it seems so. The cold spell recently experienced will be similar to the one coming just after New Year. The next one is on the edge of the ECM run, where things can still change (either way, I might add). 

 

Of course that is true, nothing is anywhere near set in stone at that range but I can find little evidence to suggest indications of a different evolution. The ext EPS continues a known theme of weak ridging adjacent to the UK with negative anomalies stretching from the SW to SE where the two troughs are situated. It would appear at the moment that the trough in the western Atlantic will become a little more influential as it moves a tad east perhaps backing the upper flow SW. So generally the UK under the auspices of the HP so mainly dry with temps a little below average.

Just my take on things

Edited December 29, 2016 by knocker

[knocker]

9 minutes ago, frosty ground said:

Wouldn't your theory be backed by evidence thou and therefore the more likely one.

See my reply above.

[Nick F]

Looking at the GEFS z500 mean/anomalies days 7-11 and 11-15, there seems little impetus to push the mean N Atlantic block SE into Europe as per some of the operational runs yesterday, thanks to cold air / low heights draining down from NE Europe into central Europe

Stunning 00z EPS mean days 11-15, can't show them, but picture the troughing beginning to undercut near the Azores at day 10 on chart below spreading further east into SW Europe, with a blue band of -ve anomalies from SE of New Foundland all the way east  into southern and central Europe beneath +ve HGHT anomaly over Iceland.

Edited December 29, 2016 by Nick F

[Glacier Point]

Well that's 3 from 4 last eps means to show a broadly similar pattern for Europe with +ve height anomalies stretching from Greenland to Svalbard and Euro trough with low heights across the central part of the North Atlantic. Broadly in line with considered signals for gwo and mjo forcing.

That pattern with a pool of cold air already in place, and 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)

[northwestsnow]

Not suprised by this Nick.

The ecm 192 mean was enough to suggest things still looking good.GEFS look cold to me too...

[carinthian]

Major cold spell coming for Europe if that set up comes off. Could eventually see a link with the Arctic high and Atlantic block and then an easterly possible as indicated by the GFS in post 240h. At this stage all dependant where the Euro trough is centred and where the cold high relocates. Good charts this morning for cold weather fans. Its getting there, slowly but surely.

C

[MR EXTREMES]

6 minutes ago, radiohead said:

0Z ECM Day 10 mean looks very similar to the 12Z. Ridge slightly further east.

to be honest this has really been the theme shown by the models across the board.

vortex plus nina plus a strong west qbo really is winning the battle so far this although not a unsettled winter by far.

still cold at the surface.

i do however notice the ecm has very strong flaw of modelling heights in the atlantic and greenland starting with excitement sometimes for couple of days but then slowly drops it completely.

although gfs does this with low pressure to be fair the best charts to watch are the fax if long range is starting to get on ya nerves.

the mjo still very muted to but to be fair were very close to some real wintry excitement but i see from the models today heights dominating our weather with cold northerly in a decent time frame then atleast another 7 to days of crisp frosty cool sunny days.

there really is no note worthy outcome although the first northerly will bring wintry weather briefly for parts of the uk.

southern england not likely to see any flakes unless on the downs or heighest hills bit further north could get a covering in places.