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

[BARRY]

3 minutes ago, bluearmy said:

The eps post day 10 flatten the pattern a bit more than the 00z suite did. However, there is some encouragement at day 10 in respect of the op and the control is on the same page (but suppressed a bit further south). Will be a frigid run for de bilt. The scandi ridge stays in place till day 13/14 and slowly pulls away day 14/15. 

the eps are basically MLB sinking south to become euro/s uk high 

It's that day 10 again 

[bluearmy]

1 minute ago, BARRY said:

It's that day 10 again 

The op has snow across the country from day 7 ?

[SMU]

24 minutes ago, Dancerwithwings said:

Steve is this the Anom spread chart that Ive highlighted in your post ?

Yes & the reason theres high spread there is one cluster will have low pressure over NW scotland V the other cluster having a wedge of high pressure there...

[Stuie]

4 minutes ago, Steve Murr said:

Yes & the reason theres high spread there is one cluster will have low pressure over NW scotland V the other cluster having a wedge of high pressure there...

Steve, Am I right in saying that chart is showing HP settling over/NW of the UK? (what we are after)

[SMU]

13 minutes ago, Stuie W said:

Steve, Am I right in saying that chart is showing HP settling over/NW of the UK? (what we are after)

No mate it shows where theres higher ensemble divergence - so the higher you are up the scale the more scatter there is in the suite- as expected that area has high uncertainty...

[knocker]

Although the anomalies this evening are on the same page still there are differences that will make some difference to the detailed day to day evolution. Firstly just to point out what will not show up on these is the brief amplification in the western Atlantic around T144 which initiates the trough plunging SE over the UK and a spell of wintry weather.which is pretty much nailed on.

Upstream the Alaskan ridge continues it's retrogression and weakening into the Arctic but the Canadian vortex is in some disarray particularly with it's connection eastwards to the  Scandinavian trough. At the moment the trough is to the NE of the UK and so with the Azores HP playing a much more minor role, albeit still positive anomalies in the Atlantic, the upper flow is tending towards zonality across the Atlantic with the jet not as strong but more inclined west-east. The EPS is the exception to this with more ridging close to the UK. Thus a lighter upper flow and systems may well be inclined to effect the north more than perhaps is indicated by the other two. Either way temps a fair bit below average mid period recovering to just below. The det. runs can sort the detail Note. NOAA still high confidence with both periods.

They are roughly singing from the same sheet in the 10-15 period albeit with some differences. The Alaskan ridge has gone and the vortex is more around Alaska with the trough to the east now more inclined to be orientated SE into the Atlantic but there some disagreement on the precise detail which of course is to be expected. As there is with the ridging adjacent to the UK with NOAA and the EPS going for it and GEFS not so keen. So taking a punt on NOAA and the EPS being nearer the mark, a lightish SW upper flow with temps slowly recovering to near normal

[Nick F]

Only useful free charts from the ECMWF website are the ensemble mean and spread charts, the one below for day 10 for 500 hPa shows the heightened uncertainty over the far north Atlantic including where the ridge builds NE (right panel purple colours), similar area to meteociel chart posted, the largest area of uncertainty/ deviation in the whole of the N Hemisphere. 

 

Edited January 6, 2017 by Nick F

[bluearmy]

The latest gfsp is out (06z) and its interesting in that it follows the ECM from the 12z run without the late on amplification which delivers a few days of v cold with snowfall opportunities across the country. Probably a more realistic middle ground solution between the normal  GFS and the amplified ECM for the 7/10 day period. 

[Frosty.]

Anyway, nice to see a more upbeat mood this evening with some snow likely to occur in parts of the uk later next week including areas which haven't seen a single flake yet, which is most of the uk! Hopefully we will see upgrades in the days ahead and a large blocking scandi high through mid / late Jan would be lovely jubbly.

Come on Ecm!

Edited January 6, 2017 by phil nw.
Off topic comments removed

[Stuie]

15 minutes ago, Steve Murr said:

No mate it shows where theres higher ensemble divergence - so the higher you are up the scale the more scatter there is in the suite- as expected that area has high uncertainty...

That`s actually a great chart mate. Thanks for the explanation.

[Zakos]

Wow, what an anomaly at 168.Finally seeing the Euro High being replaced with low pressure perhaps?

We currently have a small area of low pressure over SE Europe.

By 192 on the ECM, we have deep low heights over  all of Europe. If this chart verifies, the rest of Jan has much potential for further cold spells IMO.

 That cold pool over Europe wouldn't be going anywhere fast, especially considering the timidness of the atlantic weather systems this winter.

 

 

Edited January 6, 2017 by Zakos

[karlos1983]

Chalk and cheese between ecm op and it's mean, which will be even clearer when the ens are out later.

I will do a naked run from Poole to the Lake District if that comes off. And eat my hat at the same time 

[Purga]

4 minutes ago, karlos1983 said:

Chalk and cheese between ecm op and it's mean, which will be even clearer when the ens are out later.

I will do a naked run from Poole to the Lake District if that comes off. And eat my hat at the same time 

OK - then what would you do if the ECM Control run came off Karlos?

[shotski]

5 minutes ago, karlos1983 said:

Chalk and cheese between ecm op and it's mean, which will be even clearer when the ens are out later.

I will do a naked run from Poole to the Lake District if that comes off. And eat my hat at the same time 

I think they look quite similar seeing as one is only a mean of 51. Just MHO

[pegg24]

Just now, karlos1983 said:

Naked Cartwheels  

Plenty of building blocks to eat on the way as well lol. 

[karlos1983]

6 minutes ago, shotski said:

I think they look quite similar seeing as one is only a mean of 51. Just MHO

At face value maybe, but look at Europe, one has low heights the other does not. That's a big big deal. And makes a huge difference to what we would see. The op is just a run, the mean takes an average of its suite, so I'm not liking the odds of the op verifying, but then it is a D10 chart and it's winter 2016/17 so who in ones right mind would. 

Edited January 6, 2017 by karlos1983

[radiohead]

Noticeable difference already on the 18Z GFS compared to the 12Z that will have an impact on what happens here. Look north of Newfoundland.

[bradymk]

Completely off current modelling but thought i'd share this. 

This graph basically showing how ECM last month was over keen on blocking in the North Atlantic, particularly at longer ranges. A clear bias to wanting a -NAO particularly post day 10. 

[Rocheydub]

1 minute ago, bradythemole said:

Completely off current modelling but thought i'd share this. 

This graph basically showing how ECM last month was over keen on blocking in the North Atlantic, particularly at longer ranges. A clear bias to wanting a -NAO particularly post day 10. 

As long as I've been watching models, I was always of the opinion that ECM was prone to -NAO and -AO bias, and that the GFS was prone to +NAO and +AO bias beyond T120. When I started viewing here, I found most were of the same belief... Seems despite how far we've come in terms of NWP modeling, the same bias still exists. Used to be of opinion that UKMO was prone to -NAO and -AO bias too, but not to the extent as ECM. 

Can I ask where you got this verification chart from please?

[bluearmy]

5 minutes ago, bradythemole said:

Completely off current modelling but thought i'd share this. 

This graph basically showing how ECM last month was over keen on blocking in the North Atlantic, particularly at longer ranges. A clear bias to wanting a -NAO particularly post day 10. 

Do you have similar for GFS op in the opposite direction? 

[radiohead]

A rain to snow event as that low crosses on the 18Z GFS? Cold air gets in a bit quicker than the 12Z too.

[TEITS]

Just catching up with the excitement.

If members read my post this morning I did highlight the chances of an E,ly albeit a slim risk. So the 12Z ECM isn't surprising to me. However im back on the fence and will probably end up with piles at this rate.

18Z more amplified than the 12Z GFS.

[Nick F]

Flow more Nly than the 12z op next Friday - which is an improvement re: getting the best CAA. Though at the mercy of secondary lows not being picked up or badly modelled at that range that may hamper CAA.

[Captain Shortwave]

GFS day 7 and the ECM 12z

   

Well the GFS moves back to a better solution, it will be interesting to see what the GFS can come up with up to day 10.

Edit - Well well, it follows the ECM op pretty much exactly all the way to day 10 with snow showers transferring from western coasts to eastern coasts as the winds veer north easterly and remain cold enough for snow to low levels.

A good end to the day in my opinion.

 

Edited January 6, 2017 by Captain Shortwave

[Zakos]

Quite a shift from the 18z GFS at 180.

The model output is definitely trending towards the removal of the Euro High.  At the very least we would be prone to further pm blasts if this occurs.