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

[feb1991blizzard]

We did start to see a warming right at the top a few days ago in FI but never looked like it was going to sustain an attack on the vortex anyway, while we are on that subject, does anyone have the mountain torque charts please?

[Man With Beard]

Decent cold cluster again on ECM ensembles 2 Jan to 6 Jan - indeed, it is the dominant cluster by far. Maxes for London around 3/4C for those days, and colder at night.

A point on 850 means by the way. Bear in mind, say you have 3 ensemble runs and 2 of them give -5C whilst the other gives +10, the mean is 0C. But the odds are still 66.6% for the -5C cluster, rather than 50% for 0C. Worth remembering when you see an ensemble mean 850 that wouldn't support deeper cold at face value.

[mcweather]

Just thought  I'd check out the 18z before going to bed. Looks to me like. Santa,s already been. Happy Xmas everyone.

[Banbury]

Op very much an outlier but they might follow later

 

[Allseasons-Si]

Just now, Banbury said:

Op very much an outlier but they might follow later

 

I hope they follow cos that is in the realms of fl

10 mins to Christmas dayho ho ho

[bluearmy]

That's sounds a fair old spread post New Year's Day 

Looking through the members and there is a lack of direction apart from a propensity to amplify 

[Allseasons-Si]

1 minute ago, bluearmy said:

That's sounds a fair old spread post New Year's Day 

Looking through the members and there is a lack of direction apart from a propensity to amplify 

that's not a bad thing BA

[BlueHedgehog074]

May you all have a great Christmas and a Happy New Year.  

And may Santa keep bringing some nice chilly and/or wintry conditions for those that want it. It's nice to see various models showing some kind of mid-Atlantic ridge scenarios with their cold Northerlies and North-Westerlies, especially that from the 12Z ECMWF run! But should that pesky Vortex to our North-West gives us any trouble, there's someone who can take care of that darn thing...  

[blizzard81]

Gfs ensembles trending cold in my very simple unscientific evaluation. Great Christmas model watching. Merry Christmas to all on Netweather

[Allseasons-Si]

And............MERRY CHRISTMAS TO ALL

let the snowy times begin,we much deserve it after the last couple of years of dross,i raise a glass to you all

and our lass says that i can open my Christmas present now

Edited December 25, 2016 by Allseasons-si

[feb1991blizzard]

Just now, blizzard81 said:

Gfs ensembles trending cold in my very simple unscientific evaluation. Great Christmas model watching. Merry Christmas to all on Netweather

Generally yes although the last suite is hard to define in terms of improvement or downgrade on 12z.

[karlos1983]

Ok I lied, one more comment....

holy flipping festivities 

It really doesn't get much better than that 

Edited December 25, 2016 by karlos1983

[Day10]

My one and only post on the 'model discussion' forum, and one that I understand.. Merry Christmas to one and all... 

[Catacol]

55 minutes ago, feb1991blizzard said:

We did start to see a warming right at the top a few days ago in FI but never looked like it was going to sustain an attack on the vortex anyway, while we are on that subject, does anyone have the mountain torque charts please?

 

 

[tight isobar]

Merry modeling. .

Have a good en everyone. 

[feb1991blizzard]

Just now, Catacol said:

 

 

Thanks, hopefully towards the end of Jan, we will see a big uptick on the red line although I'm not holding my breath.

[Catacol]

14 minutes ago, feb1991blizzard said:

Thanks, hopefully towards the end of Jan, we will see a big uptick on the red line although I'm not holding my breath.

Yep - nothing very remarkable at the moment suggesting a major assault on the vortex. My gut feeling is that we arent going to see an SSW this season - and it may be that we dont see much of an assault on the strat at all. This would leave us looking for pacific forcing to allow high lat blocking in January... but I have to be honest: I'm not seeing it. The MJO has retreated today - it looks set to remain very low amplitude for a while yet, and not much showing on Ventrice's site suggesting anything other than a drop off of activity in the 2 week period:

There is some suggestion of a rise in frictional torques that will help prevent GLAAM from falling through the floor

but I dont see the forcing necessary to sustain significant amplitude in our region. In essence we have lost our ENSO disconnect, and the atmosphere is now reflecting a Nina base state, ironically just as the pacific itself begins to move to a neutral state. This was the worst case scenario postulated by Tamara a few weeks back.

I have not posted in detail since seeing these signals develop, largely because I am a snow lover myself and to see the signals for high lat blocking fade has not been a pretty sight - and not something to add to the Xmas cheer. But as I seem to be posting prior to finishing the stockings I'll throw my predictive hat into the ring and state, rather soberingly, that we have a wave train in the pacific that will promote the amplification we are seeing in the models right now... but we dont have the building blocks in place to sustain it. Therefore we might get lucky for short period with some cold, but I then think that through to mid Jan we will see the block flatten and anything from north or east become rather transitory. Good for the Scottish Ski Centres on a North West feed - not so good for snow starved southern England.

Fingers crossed for something more cheerful as we approach the second half of January - or for a lucky hit from the forecast amplification in the medium range. 

Edited December 25, 2016 by Catacol

[BLAST FROM THE PAST]

1 hour ago, bluearmy said:

Not as far as I can see

Then the set up is too early imo and garden path comes to mind

BFTP

[feb1991blizzard]

2 minutes ago, Catacol said:

Yep - nothing very remarkable at the moment suggesting a major assault on the vortex. My gut feeling is that we arent going to see an SSW this season - and it may be that we dont see much of an assault on the strat at all. This would leave us looking for pacific forcing to allow high lat blocking in January... but I have to be honest: I'm not seeing it. The MJO has retreated today - it looks set to remain very low amplitude for a while yet, and not much showing on Ventrice's site suggesting anything other than a drop off of activity in the 2 week period:

There is some suggestion of a rise in frictional torques that will help prevent GLAAM from falling through the floor

but I dont see the forcing necessary to sustain significant amplitude in our region. In essence we have lost our ENSO disconnect, and the atmosphere is now reflecting a Nina base state, ironically just as the pacific itself begins to move to a neutral state. This was the worst case scenario postulated by Tamara a few weeks back.

I have not posted in detail since seeing these signals develop, largely because I am a snow lover myself and to see the signals for high lat blocking fade has not been a pretty sight - and not something to add to the Xmas cheer. But as I seem to be posting prior to finishing the stockings I'll throw my predictive hat into the ring and state, rather soberingly, that we have a wave train in the pacific that will promote the amplification we are seeing in the models right now... but we dont have the building blocks in place to sustain it. Therefore we might get lucky for short period with some cold, but I then think that through to mid Jan we will see the block flatten and anything from north of east become rather transitory. Good for the Scottish Ski Centres - not so good for snow starved southern England.

Fingers crossed for something more cheerful as we approach the second half of January - or for a lucky hit from the forecast amplification in the medium range. 

Cant see sustained HLB myself this season, the best we can hope for realistically is a Dec 8 1990 setup and BTW that is perfectly feasible in about 2-3 weeks time but obviously huge odds against due to the precision position and timing of the sinking trough of course, are there any favourable analogue years where the vortex has been this strong both at trop and strat level at this time of year and a very potent cold spell has occurred before the end of February without any significant strat warming event happening? (can be any enso / qbo, / PDO etc combination included)

[Mucka]

Much better effort from GFS though not as good as last nights ECM (Synoptic wise. May be a good FI though)

but very disappointing UKMO.

Place your bets on ECM,.

 

GFS cold but largely dry day 9/10 but if the pattern upstream remains amplified we could hit the jackpot eventually as with other output.

Nice to see cold uppers in day 8/9 range but we generally need high pressure further West or further North to get the instability that would bring snow.

Edited December 25, 2016 by Mucka

[SnOwFeSt]

An early xmas present from the 00z. Things scream with potential from the new year with a shredded vortex and a number of interesting routes to cold being played out.

[Duane S.]

Happy Christmas everyone from the middle of the Indian Ocean.

Some great model output over the past 24 hrs I see, It would be great to see the upcoming ECM00z continue the trend.

it would indeed be ironic if we can pull something out of the (cold) bag despite less favourable background signals. That is exactly how it works sometimes though. When only a double six will do, we go and roll it!

 

[knocker]

Today and tomorrow

Today England and Wales cloudy with patchy drizzle, breezy,  and exceptionally Perhaps the December max of 15.6C will be broken. Ni. Ireland and Scotland also cloudy but as the front tracks SE some wintry showers will develop but mainly effecting the high ground. Becoming increasingly wind, particularly in the far north with gusts in the 80mph region. The front will continue it's travels SE bringing cooler weather to all with showers but a another brief belt of strong winds will effect the far north, Orkney and Shetlands tomorrow as the main low tracks E/SE

The GEFS anomalies this morning are much the same as yesterdays 12Z so once again it's a matter of looking at the fluidity of the phasing of the bouts of amplification and the interaction of the warm/cold air.

The first change occurs immediately after Boxing Day with the surge of high pressure over the UK and the usual trough deconstruction mid Atlantic and a cut off upper low ejected to track SE towards the NW African coast. This will leave the UK under the influence of the HP for three days until it sinks SE and fronts can encroach to the north west. So dry with temps around average.

The fronts seen  on the chart above traverse the country NW/SE over the weekend as a small upper trough runs around the high pressure to phase in with the aforementioned upper low to the SW. This initiates a brief burst of cooler conditions as the surface wind veers northerly with wintry showers being the order of the day

From here once again more amplification but again the interesting scenario mentioned in previous posts. Still a huge amount of energy being emitted upstream. Some being diverted SE reinforcing the cut off upper low to the SW but the vital ingredient is energy tracking east around the HP and phasing in with the active trough to the east which which then slips south bringing a small Arctic surge to the UK as it in turn phases in with the trough to the south west

So in a nutshell dry and fairly pleasant until the weekend then two or three days of cooler unsettled weather before giving way to more high pressure influence but  with temps now possible a little below average. After that it's hello Atlantic on a 180Kt westerly jet But, dear oh dear, I'm forgetting myself, the deep realms of FI must only be mentioned if brutal cold is involved.

Edited December 25, 2016 by knocker

[The Beast From The East]

HAPPY CHRISTMAS to all my fellow snow chaser friends and everyone els on this fantastic Weather Forum. 

ECM.... PLease give us a nice Christmas presant to wake up to. 

[Captain Shortwave]

Well wouldn't you believe it, maybe the GFS has pulled the old Grinch routine here and has rediscovered the true Christmas spirit.

     

Still no snow-fest but at least we would get some snow showers and some hard frosts under that high. 850s down to -12C pushing in from the north initially and then from the east. Lets see how the ECM handles things, at day 6 it has a much more significant area of low heights sinking towards the Azores.

Edit - ECM for comparison

      

Not too bad, it would be interesting to see how things go from here. The GFS oddly has the weaker high and a stronger jet coming out of north America but this simply topples the high favourably for us to pull in some cold air from the east. The ECM blows that high up and it tends to sit there just to our west. A full blown cross polar ridge would be the dream with cold air coming from a long way north, but second prize would probably be the high trying to topple toward Scandinavia with cold air piling west from Eastern Europe.

 

Edited December 25, 2016 by Captain Shortwave
Me fail English, that's umpossible....