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

[phil nw.]

Not a very seasonal look before Christmas either with a cloudy and rather gloomy weekend to come.

Mild,damp and cloudy air moving in which gets trapped within the slack circulation of the now poorly positioned high -now a south westerly drift,not a continental one as modeled earlier in the week-seems like an age now..

so the frost risk has virtually disappeared under the gloom.

We do see a shake up though as we head into next week as mobility in the pattern heads south east into the UK

Quite a vigorous looking jet streak to the west and the possibility of a deep low close to the north developing.

[Matthew.]

Still not sure if the Low will influence as much as many propose. Here's the ECM from this morning:

 

 

 

I'm sure this evenings run will clear things up a little.

[Geordiesnow]

2 minutes ago, oasis said:

Though some may disagree, if the russian high can cling on a little bit, warm 850s can get pushed into the arctic, then that can be a trigger for the wave 2 action, as mentioned by GP in strat thread. Hopefully such wave 2 action could push back against the downward propagation of insanely high zonal winds. Also of note Anthony Masiello on twitter mentioned that we're in a - EPO state? Which apparently couples well with wave 2 action when it comes to impacts. Seeing the insane push of "green" 850s into the arctic could lead to colder impacts down the line. 

Not when you got a rampant Northern arm of the jet, you need any blocked set up well over Scandi which of course then send all the WAA towards Svalbard and the Arctic and cold air will flood down on the Eastern side of any block. The angle of the Russian high is just in the worse possible position for coldies and it serves no use at all. Its this pattern which is one factor why sea ice in Barants/Kara struggles to grow in some winter seasons and its a pattern I really hate too see because you just think where on earth is the significant cold air going to come from?

Having a blob of PV over Western Russia is much rarer nowadays and whilst its there, you always got a chance of that PV heading westwards as per that 1 ECM run, but now its looks like it will finally get blasted away by the Northern arm of the jet and if that does happen then its going to be a while before anything significantly cold will head our way.

[Summer Sun]

The GEM ens goes for an unsettled festive period but not to the extreme of GFS and the GEM Op

And to highlight the differences between the GFS Op and the Control unsettled but not to the extreme of the Op

Control                                                       Op

 

Edited December 15, 2016 by Summer Sun

[legritter]

The good old zonal train as crept in by the looks of things ,tonights ECM might put some meat on the bones regarding any potential deep low systems ,but with a large block further east i think models will struggle somewhat . so a week from now it could be batten down the hatches or just cloudy and mild , looking interesting on how this turns out ,many twists and turns to come , never boring on here but frustrating at times ,that low on gfs at the end is a real dartboard low 930 mb ,the GFS is certainly computing something so expect some wild runs soon . cheers gang .

[Singularity]

The thing about having that block to the east is that if any one of those potential deep lows misses the boat i.e. doesn't position in the right place relative to the jet stream for such efficient development, the outcome of the battle could change considerably. Quite a few ensemble members are exploring this option, resulting in 24th-26th hanging in the balance between settled and unsettled (best chance settled in SE... nothing new there if you've been keeping up to date with the Met Office outlooks).

[Summer Sun]

GFS P (06z) looks to have the best run so far with the Xmas eve low pulling away during the day to leave a somewhat calmer 25th and 26th

[A Frayed Knot]

[IDO]

At T300 the GFS op looks to be progressive compared to the mean: 

 Control: 

But early days to be confident after D11 IMO.

Some more seasonal uppers after D7 for a few days on this run: 

Though rather uninspiring in that modified PM flow. The CET hit 2c above average yesterday so hard to see anything but a very mild December for many on the final reckoning?

 

 

[Nouska]

25 minutes ago, oasis said:

Though some may disagree, if the russian high can cling on a little bit, warm 850s can get pushed into the arctic, then that can be a trigger for the wave 2 action, as mentioned by GP in strat thread. Hopefully such wave 2 action could push back against the downward propagation of insanely high zonal winds. Also of note Anthony Masiello on twitter mentioned that we're in a - EPO state? Which apparently couples well with wave 2 action when it comes to impacts. Seeing the insane push of "green" 850s into the arctic could lead to colder impacts down the line. 

Edit: The more directly that warm air can go into the arctic, the less the siberian cold pool will be pushed back - I think.

For anybody not sure what a negative EPO ridge is, an illustration.

https://www.theweathernetwork.com/news/articles/epo-what-you-need-to-know/43796/0

Similar to the PNA pattern but more focus on the EPAC rather than CONUS.

Add a strong wave2 from Eurasia and the vortex is squeezed down over us - in theory.

In practice - a good example December 2010.

[booferking]

Atleast matt is being honest with his tweets on twitter something has went wrong with the forecast predicted over the last few weeks.  And yes this weather has been boring the block to east has delivered diddly squat not even a frost for weeks i will hold my arms open wide for a change from the West we might even see transient snow..

[Bristawl Si]

1 hour ago, mountain shadow said:

I have absolutely no idea what that means.

My immediate thought as well. I'm convinced that the more 'intense' and/or cryptic posts are deliberately written to confuse, so people just 'go with the flow' and think someone is a genius.

[chris55]

Things look bleak with regards to a colder more seasonal outlook into and around the xmas period, but you have to keep the faith, it is Christmas after all. And even if we get a more stormy phase, colder air from the north west can deliver. Christmas 2004 highlights how that pattern can result in the white stuff even down south.

Edited December 15, 2016 by chris55

[DOdo]

If we have Snow for Christmas it will probably be a from a Northwesterly component. Any hope of an Easterly at this early stage is gone for the momenT.

Edited December 15, 2016 by Polar Maritime

[Kentish Snowman in Yorks]

The amount of disrespectful argumentative rude and condescending posts in this thread over the last 24 hours have made it a largely unpleasant experience to read!

The model output hasn't done much to brighten the mood either!  

[oasis]

15 minutes ago, Nouska said:

For anybody not sure what a negative EPO ridge is, an illustration.

https://www.theweathernetwork.com/news/articles/epo-what-you-need-to-know/43796/0

Similar to the PNA pattern but more focus on the EPAC rather than CONUS.

Add a strong wave2 from Eurasia and the vortex is squeezed down over us - in theory.

In practice - a good example December 2010.

Very interesting. Thanks for that. So if the scandi heights can hold on... Plus what has been mentioned about possible MJO activity, and angular momentum, then I guess potentially interesting times. I  recall someone with a lot more knowledge than me - I think Tamara? - saying as well what happens if a spike is put into a vortex which has rapidly intensified in a short period of time. Something about the higher they go, the higher they fall perhaps. Here's hoping - from a cold perspective. Also those composites from Gp earlier. hmmm...

Edit: If angular momentum can just stay around neutral, that could help make things more interesting. As Singualrity has pointed out its not falling as quickly as predicted. I suppose the current models are conditioned on the fall in angualr momentum occuring as predicted. 

Edited December 15, 2016 by oasis

[Dennis]

11 minutes ago, Nouska said:

For anybody not sure what a negative EPO ridge is, an illustration.

https://www.theweathernetwork.com/news/articles/epo-what-you-need-to-know/43796/0

Similar to the PNA pattern but more focus on the EPAC rather than CONUS.

Add a strong wave2 from Eurasia and the vortex is squeezed down over us - in theory.

In practice - a good example December 2010.

 

[mb018538]

Looks truly hideous to me, and I'm on the side of those who have now consigned the rest of the month to the scrap heap. I think the number of colder outcomes will slowly reduce down as we get closer to Xmas....just need to start looking for the next kick in the pattern to remove this nasty zonal set up.

[Guest]

9 minutes ago, Kentish Snowman said:

The amount of disrespectful argumentative rude and condescending posts in this thread over the last 24 hours have made it a largely unpleasant experience to read!

The model output hasn't done much to brighten the mood either!  

very true almost 20 pages with little or no model content has made it a difficult place to be... yes the models are not showing what most of us want or hope for... the brilliant outlook from Autumn has failed to materialise and things look like going down hill further... does this mean that the rest of Winter is a bust?? certainly not... if things can change to bad output it can change quickly back again...

[NeilN]

As I'm still learning to read the models, does that mean it'll be cold and miserable? I mean surely average temperatures this Christmas would be better than last year's mildfest? 

[nick sussex]

A rather underwhelming GFS 12hrs run which wasn't a great start to the evening. The UKMO isn't that great down stream at T144hrs but  better upstream compared to the GFS.

NCEP were talking about uncertainties with shortwave track and amplitude this morning and its showing up on tonights outputs. We do need as much amplitude as possible upstream, not that theres much to begin with but certainly whatever we can muster.

[Man With Beard]

GEFS ... has finally given up the ghost with regards an easterly for next week. It was actually just a few hundred miles away. So hard to get an easterly to the UK! The theory is simple, the practice is more difficult!! It's having a stab at height rises to the NW at D15 now instead (a few members, not a majority), will the EC46 follow suit later...

But I do have some excellent news for the thread tonight ... @Mucka will be NOT be running through the streets naked. That's something to be thankful for  !!

 

Edited December 15, 2016 by Man With Beard

[chris55]

4 minutes ago, Man With Beard said:

GEFS ... has finally given up the ghost with regards an easterly for next week. It was actually just a few hundred miles away. So hard to get an easterly to the UK! The theory is simple, the practice is more difficult!!

But I do have some excellent news for the thread tonight ... @Mucka will be NOT be running through the streets naked. That's something to be thankful for  !!

 

Well that comment has done it now.....watch the models flip on a sixpence tomorrow haha, icy easterly incoming resulting in mucka's naked body all shrivelled ....cause of the cold!! Im looking forward to the pics.  

[Dennis]

well your hat could FLY 

[nick sussex]

The ECM the best of the big 3 at T120hrs, that's not saying much but its a bit sharper to the nw with the low pressure over Greenland and better than the GFS upstream.

Less energy should head east which might help down the line.

T144hrs still the best of the big 3, better high to the east and a better angle of attack from the troughing.

Edited December 15, 2016 by nick sussex