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

[radiohead]

12Z ECM. Some strong winds heading for western Scotland.

[Sky Full]

7 minutes ago, ArHu3 said:

I was meaning to do this, compare ensemble with current setup but I can't find old ensembles on meteociel, do you have a link or were you just so prescient to save images?

Sorry, ArHu3, no link.  I just wanted to compare 10 day forecasts with reality and so saved the image from the 9th December.  I imagine this exercise would show varying degrees of success depending on the time of year but I didnt think the GFS did too badly on this occasion.  It might be different in another 10 days given the way the jetstream is getting more determined to target Western Europe.

[Summer Sun]

Scotland and maybe northern England taking the brunt of the winds on Christmas eve

[West is Best]

9 minutes ago, radiohead said:

12Z ECM. Some strong winds heading for western Scotland.

Yep. ECM finally coming on board. Ouch, this looks rough.

[The PIT]

Good job I didn't bet on white xmas. Should have bet on T shirts and Shorts. 12 oz GFS shows a very mild 11C to 12C for us in the afternoon. The real story is the wind a lot of the country seeing 55mph gusts upwards from the off and only dropping away in the evening. This could well spoil a few xmas days for some.  Sadly no sign of anything really cold on the GFS.

[Summer Sun]

Very windy Xmas day

[fergieweather]

1 hour ago, swfc said:

 

hows  things shaping up atm ian???

Well, very low confidence...!! As expected.

We will see whether ECMWF Monthly this evening keeps banging the blocked drum, or switches and offers the much more mixed signals of GloSea5 (slowly progressive, some blocking, but ensembles unconvincing re ultimate outcome). Dominant signal for remainder of winter (albeit as previously discussed, a divergence in ECMWF & GloSea5 output) is for broadly +ve avg temps (some colder phases possible); +ve NAO (mostly, with possible exception part of Jan) and SPV remaining stronger now. Broad GloSea5 pattern ultimately favours high pressure to S of UK, helping perhaps to keep things drier overall but there's equal probabilistic weighting on +ve/-ve PPN anomalies. December Contingency Planners doc offers further context.

[radiohead]

The Xmas Day storm threat looks reduced on the 12Z ECM. Windy for the very far north of Scotland but doesn't look as severe as previously...

Edited December 19, 2016 by radiohead

[Geordiesnow]

2 minutes ago, Summer Sun said:

Scotland and maybe northern England taking the brunt of the winds on Christmas eve

Reckon the central belt could see severe gales from this set up but its a run by run basis on this now, this evenings ECM looks more or less the same regarding the track of this low but where the strongest gusts will be and just how deep this low will get is still far from certain.

Be interesting what it will show for the Christmas period regarding the potentially 2nd deep low.

[radiohead]

2 minutes ago, Summer Sun said:

Very windy Xmas day

Those winds are at 850mb.

[Summer Sun]

60 to 80mph gusts widely on tonight's ECM exposed high ground and the northern Isles could easily top 100mph

[Stuie]

3 minutes ago, fergieweather said:

Well, very low confidence...!! As expected.

We will see whether ECMWF Monthly this evening keeps banging the blocked drum, or switches and offers the much more mixed signals of GloSea5 (slowly progressive, some blocking, but ensembles unconvincing re ultimate outcome). Dominant signal for remainder of winter (albeit as previously discussed, a divergence in ECMWF & GloSea5 output) is for broadly +ve avg temps (some colder phases possible); +ve NAO (mostly, with possible exception part of Jan) and SPV remaining stronger now. Broad GloSea5 pattern ultimately favours high pressure to S of UK, helping perhaps to keep things drier overall but there's equal probabilistic weighting on +ve/-ve PPN anomalies. December Contingency Planners doc offers further context.

Not sure that is what the masses wanted to hear Ian! Thanks for that though.

[phil nw.]

The 3 main models starting to come to a similar outlook at T120hrs

A deep low whipping across just to the north of Scotland on Friday.Isobars squeezed together with the AH pushing into France so gales/Strong winds affecting many of us.

[booferking]

5 minutes ago, fergieweather said:

Well, very low confidence...!! As expected.

We will see whether ECMWF Monthly this evening keeps banging the blocked drum, or switches and offers the much more mixed signals of GloSea5 (slowly progressive, some blocking, but ensembles unconvincing re ultimate outcome). Dominant signal for remainder of winter (albeit as previously discussed, a divergence in ECMWF & GloSea5 output) is for broadly +ve avg temps (some colder phases possible); +ve NAO (mostly, with possible exception part of Jan) and SPV remaining stronger now. Broad GloSea5 pattern ultimately favours high pressure to S of UK, helping perhaps to keep things drier overall but there's equal probabilistic weighting on +ve/-ve PPN anomalies. December Contingency Planners doc offers further context.

That sounds terrible high pressure to the south the slug is back just like last year.

[West is Best]

5 minutes ago, The PIT said:

Good job I didn't bet on white xmas. Should have bet on T shirts and Shorts. 

Well you'd best get your timing spot on or you'll be turning blue.

Day before and after ...

[Summer Sun]

GFS para 06z going for an unsettled Christmas day

Boxing day sees the high slowly edging up from the south

[West is Best]

2 minutes ago, booferking said:

That sounds terrible high pressure to the south the slug is back just like last year.

Agreed. The UKMO at T144 gives some signs of hope regarding it retrogressing westward and actually even the GFS at the end of the run shows it doing the same. It will be interesting to see if the UKMO has been the first to spot a trend. If so then it's game on.

[Summer Sun]

ECM is a lot calmer boxing day

[Geordiesnow]

Well the 2nd low on the ECM looked rather unremarkable on the ECM than it does on the GFS but the potential is still there for sure. Question will be regarding the first low will be just how deep it will get and its track, if pressure rises too much in the South and East, it could deflect the low and most parts of the UK won't see anything too out of the ordinary however if the Euro models are right then more large parts of the UK could see severe gales.

And its the same with the 2nd deep low, higher heights over Europe would lead the UK being deflected between Shetland and Iceland leaving a windy day but nothing too much out of the ordinary. Very interesting outlook imo and hoping at least one of these deep lows hit the UK with a punch.

Still much uncertainty how much polar air will tuck in behind these lows but the window of opportunity for wintriness is still on the cards for a few but certainly not most people.

[Cheshire Freeze]

1 minute ago, Summer Sun said:

ECM is a lot calmer boxing day

Will we ever get rid of heights to our S??  I'm reading Fergie's post and thinking maybe it's just one of those winters! No matter what happens output wise, that HP to our S emerges triumphant. 

[chris55]

3 minutes ago, Summer Sun said:

ECM is a lot calmer boxing day

Thats a crisp and frosty start to boxing day on the ECM for the majority of the UK with the exception of the northern half of Scotland. That'll do me.

[chris55]

1 minute ago, CreweCold said:

Will we ever get rid of heights to our S??  I'm reading Fergie's post and thinking maybe it's just one of those winters! No matter what happens output wise, that HP to our S emerges triumphant. 

I think the "very low confidence" bit of Ians post just highlights how futile LRF can be. Lets just wait and see what unfolds before coming to any firm judgements. 

[Summer Sun]

As you were really high pressure to the SE low pressure to the NW leaving the UK in a southwesterly flow

Pleasant enough in any sunshine but always the chance of stubborn fog where / if skies clear then frosts would return

Edited December 19, 2016 by Summer Sun

[Geordiesnow]

Just now, CreweCold said:

Will we ever get rid of heights to our S??  I'm reading Fergie's post and thinking maybe it's just one of those winters! No matter what happens output wise, that HP to our S emerges triumphant. 

Heights to the South are low at present hence the stormy weather in the med but despite the deep lows that could head our way, high pressure is not all that far away and those heights to the south could act as a spoiler as far as stormy weather is concerned.

Its the PV that is the real issue though and whilst there is signs thing may eventually get more amplified across America, any significant cold/blocking is now a long way off I'm afraid but as with the weather, you can't rule anything popping up more unexpectedly.

[West is Best]

2 minutes ago, CreweCold said:

Will we ever get rid of heights to our S??  I'm reading Fergie's post and thinking maybe it's just one of those winters! No matter what happens output wise, that HP to our S emerges triumphant. 

The Bartlett High

I don't trust the ECM at the moment. It has been so wayward. It's only finally picking up on the Christmas Eve low.