The hunt for cold - Model discussion (late November)

[northwestsnow]

2 minutes ago, bluearmy said:

Eps mean says uk centric ......... let’s see how varied the clusters are to see if the mean is a reasonable place days 10/15

the spread at day 10 shows just to our west up towards Iceland as being pretty solid for the upper ridge extension 

Sounds more promising than GEFS to me.. Dont want to see any high getting shunted into Europe.

[SLEETY]

1 hour ago, bluearmy said:

Anyone expecting to see height rises in the n Atlantic (Iceland west) in the 10/16 day period  - the GEFS say impossible with low Greenland anomolys 

that’s good then,because the gefs are pretty useless and flip flop all the time anyway.

[nick sussex]

If this was a simple low clears east ridge gets pushed ne ahead of the east USA low then the outlook would be a bit more certain .

The problem is the shallow low over the UK doesn’t move east as a whole but splits with energy heading sw and east .

So the limpet high to the south can’t escape north until that energy separates . As you’ll see from the ECM it pulls the high further nw but there’s not sufficient jet cut back to draw colder uppers in from the ne.

It’s still possible Christmas week will develop more interest at least in terms of some frostier conditions . 

Best wait and see how the models resolve the complicated low set up over the UK.

Edited December 17, 2018 by nick sussex

[Interitus]

8 hours ago, feb1991blizzard said:

Yes, was going to say that, however, we wont know the actual synoptics as we cant see the strat height profile but i have a fairly good idea of what might happen, thats just about as good as it gets for us, build up of searing cold on the continent while a Greeny delivers the goods, then a topple into scandi to advect the Jan1987 uppers westward at yes, you've guessed it, the coldest time of the year, 

That 18z FV3 was nothing particularly special - here is the zonal wind time series -

Minimum of 7.9 m/s at 29/12 06z

End of run 16.7 m/s at 1/1 18z

 

 

Edited December 17, 2018 by Interitus

[Summer Sun]

24 minutes ago, Seasonality said:

Thanks @Summer Sun, thats GFS output right?

It is indeed

[Interitus]

25 minutes ago, Interitus said:

That 18z FV3 was nothing particularly special

00z minimum 9.5 m/s -

end of run slightly less than 18z at 15.3  m/s, but vortex looking less like splitting -

[Met4Cast]

EPS towards Christmas has high pressure developing just to the West of the UK, extended EPS ridge it a little further Northwards towards the New Year period though I wouldn't exactly call it a HLB, more a mid/extending Northwards block. 

Certainly cooler and seasonal, but probably not the deep cold many want just yet

[carinthian]

On ‎16‎/‎12‎/‎2018 at 07:07, carinthian said:

And a happy Sub Tropical Christmas from ECM. Think you know you are in trouble ( cold lovers ) when all the models show the same milder picture at 144t. Can we rescue Christmas from turning down thermostats switch ?  Looking at the short term probably not, however, only 4 days ago we had NElys taking over. Maybe time for a switch again. I will next get an update from what our singular model is showing tomorrow morning and see whether it has come into line with the milder outputs now being shown by the big ones.  I think we will have to see where that high ends up by day 10 as this is possibly not resolved yet. Keep the faith ! ( Northern Cold )

C

Morning all, I have an update from over here. A complicated outlook with the post Christmas cold spell toned down a bit but not irretrievable. In the shorter term , Thursdays looks very windy for Southern England before the Low further North starts to fill. Just before Christmas the secondary Atlantic trough drifts into the British Isles and pivots across Central Britain and divides the colder air mass to the north and mild to the south. Thereafter, the outlook is not all of one mind as so to speak but the  model shows a build of pressure again to the NW with little zonal flow over the Christmas Period. So pressed for a prediction ( colder conditions in place by Christmas Day for much of the British Isles ) but where the high settles or moves to very much open to change. Hope this helps .

C

[legritter]

Good morning Gang .Just looking at the next 6/7 days on the ecm , and nothing wintry showing but rain ,some sunny days and Gales perhaps some wintry showers across the far north .But something is a foot ,I put my recycling out last night , plus a bag of old clothes for charity ,just checked on it and the bag was opened over night ,gone missing is an old scarf ,wool gloves ,several pairs of old socks ,the next door neighbour said there were several Squirrels out there at first light rummaging through my recycling and charity bag ,they even had their own carrier bags ,she let the Dogs out and they scarpered off towards the woods with all my stuff .Think the squirrels know what tonights ECM  will bring and The next updated Met office outlook will bring ,the Wood shed is full of Wrens and Vermin all busy making themselves cosy .well gang we still have 10/11 weeks of winter left thats about 154 ecm runs ,plus 300 or so GFS  etc etc ,so plenty of toys out of prams ,STELLA RUNS , being led up garden paths episodes ,Razor blade episodes ,and of course PROZAC  moments, ENJOY the ride .This forum is the best in the world ,if you are interested in weather, the holy Grail .cheers Gang STellas are on me .

 

 

 

[Met4Cast]

Latest GEFS are not at all pretty..

[Methuselah]

The GFS 06Z is not a pretty sight either...Like Katy Price, without her makeup - all the lines are where they shouldn't be!

Edited December 17, 2018 by Ed Stone

[swfc]

Does the last few pages of posts point to a change in the much touted colder ( blocked ) chances going threw jan??Zonal winds upticked ?

Edited December 17, 2018 by swfc

[Paul_1978]

4 minutes ago, Daniel Smith said:

Latest GEFS are not at all pretty..

They only go to 1st Jan though, and most of us are not expecting anything significant wintry until after that anyway? (Post-SSW territory).

[Singularity]

22 minutes ago, Daniel Smith said:

EPS towards Christmas has high pressure developing just to the West of the UK, extended EPS ridge it a little further Northwards towards the New Year period though I wouldn't exactly call it a HLB, more a mid/extending Northwards block. 

Certainly cooler and seasonal, but probably not the deep cold many want just yet

The most reasonable model signals I've seen so far today for the final week of this month.

Still room for a bit more adjustment NW of the ridge based on what I wrote about yesterday.

Meanwhile GFS/GEFS appear to be in chocolate fireguard mode.

[Met4Cast]

Just now, Singularity said:

The most reasonable model signals I've seen so far today for the final week of this month.

 Still room for a bit more adjustment NW of the ridge based on what I wrote about yesterday.

Meanwhile GFS/GEFS appear to be in chocolate fireguard mode.

You would expect the ECM/EPS to have a better handle on dealing with post SSW compared with the GFS too which is encouraging, I wouldn't trust the GFS zonal forecast too much yet, especially given what happened last week and how dramatically it backed away from the zonal signal it was showing. 

[Newberryone]

15 hours ago, tight isobar said:

Yeah..certainly..the raws..seem to be miss firing-on the upper layers...and spike responces at hand.

Even this 1 snap ecm 12z op..

Has to my eye underestimate..on the flow...and maybe moreso that tap in -injection of cold out east/north east..

Again im sticking....xmas the doors open...the party starts...

Confidence growing 4 me..

And the raw-datas..should begin 2 pull a line on the above mentioned!....

Within coming days.

 

Having viewed the rather underwhelming overnight runs it's at times like this that one has a tendency to look back on recent posts such as this for some form of solace. One can only hope there might be an equally positive follow up within the next 12 hours....or so! 

[Nick F]

Increasing signal from GEFS for high pressure to build towards the end of the month, perhaps a blocking high in vicinity of the UK, but perhaps not positioned far enough north, given low heights signalled in the arctic circle, to bring any noteworthy cold other than chilly days and frosty nights. 

London                                                      Aberdeen

Before then, low pressure system clearing east from UK start of next week could usher in a chilly NWly flow by the end of Christmas Eve so a chilly start to Christmas day, with perhaps a slight frost inland. After that it looks like a ridge may build in earnest from the south, but for now doesn't look to build far enough north. 

I think a low chance that most of us will see any cold and wintry weather this side of New Year,so not much to get excited about before January, but with the EPS yesterday starting to dabble with a SPV split in early January and the GEFS mean going for -10 m/s zonal wind  and all members below 0 m/s - there is still much for cold and snow lover to look forward to in January and February.

 

[Interitus]

1 minute ago, Nick F said:

I think a low chance that most of us will see any cold and wintry weather this side of New Year,so not much to get excited about before January, but with the EPS yesterday starting to dabble with a SPV split in early January and the GEFS mean going for -10 m/s zonal wind  and all members below 0 m/s - there is still much for cold and snow lover to look forward to in January and February.

 

26 GFS runs since and including the first to feature a reversed zonal wind - 8 runs reverse, 18 don't, only 1 reversal in last 7 runs - something's got to give.

[Nick F]

1 minute ago, Interitus said:

26 GFS runs since and including the first to feature a reversed zonal wind - 8 runs reverse, 18 don't, only 1 reversal in last 7 runs - something's got to give.

I take it you are growing increasingly pessimistic of a SSW in the New Year then?

[Methuselah]

The eventual demise of that long-lived Atlantic low has always been a potential fly-in-the-ointment, I feel: each run has a different 'solution': 

Nooooo! Not one of those.

Edited December 17, 2018 by Ed Stone

[Interitus]

2 minutes ago, Nick F said:

I take it you are growing increasingly pessimistic of a SSW in the New Year then?

Conditions seem right but it could go either way, or if there is one it could be marginal so as not to have much of an impact. Then depending on how it affects the waveguides it could be well into February before there is another shot.

[mountain shadow]

Meanwhile, back in the troposphere, we see a continued and growing signal for the return of the trop PV to exactly where we don't want it....

[frosty ground]

 

Well that's a pretty nondescript set of ensemble Pretty much all the snow chances have gone and any interest for the next 15 days might be the occasional frost

[Midlander]

I don’t know how true this is but I had heard that pressure rises in the mid latitudes may be the first response to a Stratospheric warming so would it be plausible to expect some milder weather or at least mild upper air temps before hopefully something colder.

[Nick F]

2 minutes ago, Interitus said:

Conditions seem right but it could go either way, or if there is one it could be marginal so as not to have much of an impact. Then depending on how it affects the waveguides it could be well into February before there is another shot.

Thanks for the reply, I have been thinking that the GFS maybe a bit too progressive in slowing and eventually reversing the zonal winds, as other models have yet to show such consistency with such a strong reversal. So still reasons to be optimistic but caution required for now I guess. In the meantime, trop lead for the next few weeks at least, hopefully the MJO cycle goes back into the colder phases in the New Year in a coherent amplitude potentially, which will help us out before any possible strat-trop coupling should the SPV displace/weaken in the New Year.