Model output discussion - winter proper underway

[Summer Sun]

UKMO extended starting to get more unsettled for Christmas Eve maybe some snow in the north just a shame we don't have the 850's

[Frosty.]

From a cold perspective, the 12z model output looks as good as the England cricket team in australia..shockingly bad..putting it mildly.

[ANYWEATHER]

Evening All ! Hope you have had a great weekend , Im really glad that the jet stream has gone north this week as it allows Christmas activities to go forward with out and problems from the weather well apart from some fog for some..... The jet stream really kicks in by around Christmas day bring wet and windy weather cold enough for snow over higher ground so a White Christmas for some although not many , after that the jet stream fires up to bring us some stormy weather between Christmas and new year

[phil nw.]

29 minutes ago, Singularity said:

The mean is longer reaching near 3 SDs from zero (the circle is 1 SD) for any model, with GEFS having reduced the amplification a lot in a single day and ECM to a lesser extent. The stronger the MJO activity in phases 6-8, the more amplification to the Pacific pattern is likely, and so the more poleward the ridge from there is likely to go in the 6-14 day range, and as a result, the better our prospects for amplification in useful places later in time.

Hopefully an over-correction... by 4 pm tomorrow the next update will be telling.

Just musing S but i wonder if nwp is seeing the MJO signal weakening because of the cooling C.Pacific.As this area of convection heads east into the cooler waters convection is being dampened down.

This was the last graph available

I am no expert but from what i have read the most active area of  tropical convection resides around the marine continents further west where the warmer waters are in a typical Nina pattern.

As you say the next update will be interesting.

Edited December 17, 2017 by phil nw.

[knocker]

Quote

https://twitter.com/DanLeonard_wx/status/942466272012496896?s=17

Someting I should have noticed in my earler post on the ecm det output as this does very much affect the ensuing evolution in the Atlantic

 

[bluearmy]

7 minutes ago, knocker said:

Someting I should have noticed in my earler post on the ecm det output as this does very much affect the ensuing evolution in the Atlantic

 

but it's an op at day 8.5/9 knocker ....... not worth the effort imo. Just an illustration of the uncertainty as evidenced in the day 10 spreads I posted earlier 

[knocker]

4 minutes ago, bluearmy said:

but it's an op at day 8.5/9 knocker ....... not worth the effort imo. Just an illustration of the uncertainty as evidenced in the day 10 spreads I posted earlier 

I fully appreciate that ba but I merely thought it worth illustrating why a small adjustment of the upstream pattern can cause major differences downstream. Anyway it makes a change from all the abundance of theorising on what the models are picking up which really isnt worth the effort imo

[feb1991blizzard]

Yet another run with a huge 492's worth of PV slap bang to the North West, the fat lady gargling her throat for January,

[blizzard81]

The models seem intent on ramping up that pv. It almost seems like a foregone conclusion now. The question remains - for how long? Ha ha, in tendem there Feb. 

Edited December 17, 2017 by blizzard81

[swfc]

Was kind of hoping for a weakening in the pv and building of heights to the north and east on the 18z. Mmm pretty rank to be honest

[feb1991blizzard]

Instead of runners around the base of the trough, its 950mb troughs around the base of the PV!

[bluearmy]

A better gfs fi for coldies with the vortex drifting west 

six clusters on the eps post day 10 (not surprising really )

better end to the day for coldies  

[feb1991blizzard]

Having said that its a better run - theres elongation and disruption and energy going SE albeit too Far east.

[Tim Bland]

Most of the uk has snow for New Year and the Vortex looks very disorganised in FI. 

 

[Catacol]

With the arctic set to see temperature anomalies so high that temps may rise above freezing as a result of a huge alaskan ridge around Xmas time.... and consequent downstream cold flooding into the US I would expect to see NWP modelling struggling to produce any coherence at present. The alaskan high is the big player here - being fed by MJO phase 7

On/off forecasts of typhoon activity to the east of the Philippines may also impact on the pattern, feeding the high further. Struck by the extreme nature of these events - extreme seems to be becoming closer to the norm in our climate change world. Is loss of arctic sea ice on the north pacific side also significant?

Impact of this still uncertain. ECM op sees some major atlantic low pressure development on the back of this pattern 168 - 240.. but looks odd and overly swift. Meantime signs of attempted height rises over Europe clear to see at 10d in the Euro ensembles

but so much still to be resolved in terms of the hemispheric impact of the alaskan high and subsequent timing of any response to MJO phase and amplification. Very complex period of synoptic resolution ongoing from now until Xmas - dont see cold returning prior to the big day now for anyone away from favoured northern regions - I think that ship has sailed.... but end of the month and into the New Year going to make for interesting viewing. Can MJO forcing get the Euro high into scandy? Or will the downstream impact of such a powerful alaskan ridge of uncertain latitude fire up the canadian trough to such a degree that the MJO signal is suppressed?

I've hung my hat on the former solution for a while.... but its finger nail chewing time now. Anyone got a rabbit's foot handy?

Edited December 17, 2017 by Catacol

[Man With Beard]

First time tonight that I see some genuine hope for the NE heights plan on the EC ensembles - though it's still a fairly loose "hope" on the model at this stage. The theory being, heights pump up to the east, jet drops south, heights over the top of the Atlantic trough, voila we're in the eastern flow. I think a couple of tonight's D10-D15 clusters show a little extra hope than before for this progression:

Still the minority option though

Edited December 18, 2017 by Man With Beard

[MildCarlilse]

A couple of questions...what is NWP,who is GP and when people refer to the EC,do they mean the ECM model? Also,what does ‘progged’ mean? I am sure these queries belong in the model thread as that’s where I continually come across these points.

[northwestsnow]

Terribly disappointing day for coldies -

Its hard to see an escape from a very zonal disturbed spell of weather for the UK- pretty unanimous now across GEFS/EC/GEM and ens guidance 

I worry just how much wind and rain is going to be hitting our shores between xmas and new year- in particular those in prone areas.

I feel we have had a bit of luck so far - the cold shots we have seen have been brought about by mid Atlantic ridging as opposed to genuine high latitude blocking.

It seems to me the only time we see Greenland highs(that actually verify) on NWP is june or july!!

Have to say tomorrow is the first day in quite a while i will be viewing the NWP without much optimism..

 

 

Edited December 18, 2017 by northwestsnow

[swfc]

Gfs 0z is a slight improvement imo

Later on pv displaced to the east and ridging from the south

Kind of like the run, not a lot but I like it!!!!!

[MR EXTREMES]

Nothing at all interesting tonight in regards to real winter wonderland.

All show an extremely stormy wet cool zonal onslaught.

With pulses of Azores ridges up and sending the odd bout of northwesterly flow.

soelevation key for white Christmas in the north and in Wales.

I'm really not seeing nothing at all.

Bit of a mess.

This morning even worse if cold snow what your looking for.

the models show the vortex is on steroids.

 

[Dennis]

Jetstream position 

[Chesil View]

5 hours ago, MildCarlilse said:

A couple of questions...what is NWP,who is GP and when people refer to the EC,do they mean the ECM model? Also,what does ‘progged’ mean? I am sure these queries belong in the model thread as that’s where I continually come across these points.

 Hi Mild Carlisle.

NWP means numerical weather programming ie the runs generated everyday by all the different forecasting organisations

yes Ec does mean ECM and GP stands for Glacier Point who is a professional wmeteorologist and one of our highly esteemed Teleconnections experts

hope this helps

[Dennis]

we see some change rapidly ...... ok still we have one week to go -christmas 

 

Edited December 18, 2017 by Dennis

[chris55]

Hmmmmm, ECM looking interesting at 168  a more blocked pattern potentially developing?

Edited December 18, 2017 by chris55

[Interitus]

11 hours ago, bluearmy said:

See the mslp and z500 and the corresponding thicknesses 

the vortex in canada with a smaller chunk in e Asia over kamkatchka 

 

  

You are adding a near surface temperature criteria but it doesn't negate the fact that using a traditional understanding there is a lobe of the tropospheric polar vortex over and to the north of the UK -

What is a polar vortex? - http://sites.krieger.jhu.edu/waugh/research/polarvortex/

Edited December 18, 2017 by Interitus