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

[shotski]

4 minutes ago, abbie123 said:

Ten days till Christmas gfs ecm gem all to to Progressive with blowing the block away to east changes to come next few days my gut feeling . Everyone has there own opinions.

Let's hope so, could do with some good fortune. Is it not also conceivable that we could end up with a mid Atlantic ridge come Xmas day ?

[knocker]

5 minutes ago, Frosty. said:

Shows how poor winter is when I'm happy to see a chilly westerly zonal flow. Yippee, Ecm 12z rocks!

It wouldn't be the only thing that rocks if that verified!!

[Frosty.]

Just now, knocker said:

It wouldn't be the only thing that rocks if that verified!!

Indeed, batten down the hatches but still the experts not going with a full blown unsettled spell with continental heights still influencing the S / E.

[nick sussex]

Putting aside the later differences there are disagreements within T120hrs between the big 3. This looks like a relatively minor difference given the grand scheme of things but its a good pointer as to where the energy after that time might go. The ECM as previously mentioned is a bit sharper with that low compared to the GFS. You can see that here:

ECM                                                               GFS

 

For newbies its an easy quick way of having an idea of the movement of that trough energy whether it  will be just heading mainly east or whether some of it heads se. So the sharper the angle the more goes se. Theres not as much at stake here because we're not talking of an undercut unless theres some major model drama but something to keep an eye on in tonights GFS 18hrs run.

 

 

[Man With Beard]

16 minutes ago, knocker said:

It wouldn't be the only thing that rocks if that verified!!

Camborne would be a great place for a view of the stars if that happens ... because your roof won't be there any more!!

All the ops have a storm heading for some part of the UK next weekend - with heights to the east taking a vacation, I think we're stuck with this one

         

[Frosty.]

1 hour ago, Snow Grain said:

I must say I am pleased with my forecasting methods as I did forecast this warm December way back in November

Hats off to you in that case.

[BLAST FROM THE PAST]

Got to say ECM is of interest here. It is showing some potent weather come Xmas time.  Now JH like for like run method thenn12z is of real watch period guys.  

I see that Matt Hugo tweeted re most if not all Dec LRFs have been derailed.  I agree to a certain degree but we still have half of Dec left.  I agree though that the mid lat slug..... I hadn't read in any LRF with that in it.

I actually think we need to keep watching Xmas time....could be some very severe weather around and with a wintry offering too

Snowgrain......warm December?  With 16 days still to go?

BFTP 

 

 

Edited December 15, 2016 by BLAST FROM THE PAST

[nick sussex]

Looking at the longer range ECM ensembles well both the op and control run bring some snow to De Bilt on the 23/24 December. The temps in this set up suggest that for parts of the UK you could knock off a few degrees and De Bilt has maxes over there of around 5c for the 23/24/25.

http://www.weerplaza.nl/15daagseverwachting/?r=midden&type=eps_pluim

Although we're looking at similar patterns across all the major models  the uncertainty is really how much colder air can get into the mix, the ECM because of its better early trend has a much better chance of at least delivering some snow as the jet angle is more favourable.

Because we're not dealing with colder uppers any snow is more likely to be over higher ground but you couldn't rule out a surprise elsewhere. However at this range the exact trough set up and how far se this might get is likely to change and the GFS is much less interested and we have to factor that in.

So for the timebeing its best to not  raise expectations until the models converge on a solution and lets hope that its the colder one!

 

Edited December 15, 2016 by nick sussex

[knocker]

The two main questions that are at the moment unresolved concern the Xmas period and if, or when, the pattern change post Xmas occurs and in what form will it take. Well the second remains unanswered but I suspect the answer to the first is firming up.

The 6-10 anomalies this evening are still struggling somewhat with the structure of the Arctic.Canadian.Greenland vortex and by extension the Atlantic trough associated with the Greenland lobe. The ecm has it a tad more intense with a more inclined negative tilt whilst at the same it has pushed the centre of the HP much further east but realigning the ridge with a negative tilt into eastern. Scandinavia thus making it more amplified than the other two. Also the evolution towards day ten is to move everything east so the trough really dominates and it's difficult to see, under this scenario, how all of the UK can avoid some wet and windy weather over this period with the distinct possibility of severe gales in the west and north.

NOAA and the GEFs are not quite so progressive with the  trough as the ecm,  and with the HP still centred around the Baltic States, they retain an westerly upper flow which is quite slack over the south of the UK so the slim possibility remains for the south east to remain dry whilst the systems spawned by the trough track north east.

In the 10-15 period there is no agreement although there is a theme if we leave NOAA out of the equation as it keeps the trough to the north west but is quite a long time frame. The GEFS has quite a strong signal for some retrogression with the weaker Atlantic trough realigning in the western Atlantic with positive anomalies in north west Europe and the Azores ridging into the UK. The EPS doesn't exactly copy this but it certainly has made significant steps in that direction by the end of the run

Edited December 15, 2016 by knocker

[Paul]

Can we keep it to the models please - there are lots of other threads to discuss this december, the winter overall, the cet etc. 

[Scandinavian High.]

By looking at this its quite cool for Christmas and wetter this is for London.

[I remember Atlantic 252]

Just now, abbie123 said:

By looking at this its quite cool for Christmas and wetter this is for London.

nothing cool on there, they are 850's, different if HP in charge possible inversion, but they scream mild and wet

[feb1991blizzard]

2 minutes ago, I remember Atlantic 252 said:

nothing cool on there, they are 850's, different if HP in charge possible inversion, but they scream mild and wet

They scream average temps to me.

[Zakos]

The members are scattered towards the end of the month

However, when you view only the next week or so, it looks like the AO is set to rise, one member almost reaching +6

Thereafter, all members show a sharp decline in AO

Im unsure what model(s) is used for this forecast, hopefully its on to something. 

 

[Pembroke Dangler]

4 minutes ago, Zakos said:

The members are scattered towards the end of the month

However, when you view only the next week or so, it looks like the AO is set to rise, one member almost reaching +6

Thereafter, all members show a sharp decline in AO

Im unsure what model(s) is used for this forecast, hopefully its on to something. 

 

Thats quite a drop towards months end and quite unanimous small crumbs and all that. The Beeb just posted there flag to the mast caveats included but not looking too festive pictures of umbrellas folding inside out around the big day itself but hey there's still over a week to go plenty of time for changes I still feel the high out east will have more of a say.

[nick sussex]

In the earlier timeframe the GFS 18hrs run at T120hrs has moved towards the ECM. Interesting its now disrupting the trough better, shortwave developing at the base near the UK.

Good grief major drama! Snow close by now with that pool of colder air working nw towards the UK. OMG!

Edited December 15, 2016 by nick sussex

[Snow Grain]

3 hours ago, booferking said:

It would be good to hear your outlook for Jan saying that you got the month of Dec right? Thanks

January is shaping up to start off unsettled with wet and windy weather.  It will turn colder, initially from the northwest, then from the east, which will bring severe frosts and snow.  The snow will effect eastern counties at first.  Areas of snow will spread in from the southwest at times.

[carinthian]

5 minutes ago, nick sussex said:

In the earlier timeframe the GFS 18hrs run at T120hrs has moved towards the ECM. Interesting its now disrupting the trough better, shortwave developing at the base near the UK.

That's one hell of a battle developing next week. The block to the east resisting and signs of holding back or even distrupting the Atlantic front and sending some energy SE into Western Europe. All very interesting, any warm sector getting squeezed .

 C

[-uksnow-]

And so the drama is dragged out further, 18z 'revenge of the block'. The question is, is this an over-reaction to a slight change in jet angle, or the tomorrows trend?

[Dennis]

1 minute ago, carinthian said:

That's one hell of a battle developing next week. The block to the east resisting and signs of holding back or even distrupting the Atlantic front and sending some energy SE into Western Europe. All very interesting, any warm sector getting squeezed .

 C

its nice to see it here

[Ali1977]

Just now, -uksnow- said:

And so the drama is dragged out further, 18z 'revenge of the block'. The question is, is this an over-reaction to a slight change in jet angle, or the tomorrows trend?

I think the METO would have mentioned it if this is how it will go - the Atlantic will win this one I'm afraid !! Might be a cooler fed Atlantic though, high ground in the Notth may do ok , and the Alps may start getting the white stuff for Xmas.

[Kentish Snowman in Yorks]

1 minute ago, -uksnow- said:

And so the drama is dragged out further, 18z 'revenge of the block'. The question is, is this an over-reaction to a slight change in jet angle, or the tomorrows trend?

Not far off an Easterly there?!

[snowice]

6 minutes ago, carinthian said:

That's one hell of a battle developing next week. The block to the east resisting and signs of holding back or even distrupting the Atlantic front and sending some energy SE into Western Europe. All very interesting, any warm sector getting squeezed .

 C

The block gets removed then its back hanging on for dear life, hard to know how next week is going to pan out interesting model times ahead

Edited December 15, 2016 by snowice

[nick sussex]

Close but we need to see the high to the east extend a ridge west over the top of the shortwave. The next low upstream is going to deepen now and rush east so the ridge needs to get west to force that more se or at least help disrupt some energy.

[carinthian]

2 minutes ago, carinthian said:

That's one hell of a battle developing next week. The block to the east resisting and signs of holding back or even distrupting the Atlantic front and sending some energy SE into Western Europe. All very interesting, any warm sector getting squeezed .

 C

Plenty of cold uppers around the British Isles at 165t, but looking at developments this evening , all for the best, I think not to look much further than 144t as changes are taking place in this time span. Feel much better this evening that GFS are switching away from full throttle zonal in the reliable time span.

 C