Model Output Discussion - The final stretch to Christmas

[Matty M]

Some big changes over Canada on this run, with much better warm air advection over Greenland.

 

Would not be surprised to see the OP support the parallel run,.

 

Edit..

------------- Or not!

Edited December 22, 2014 by Matty M

[frosty ground]

Some big changes over Canada on this run, with much better warm air advection over Greenland.

 

Would not be surprised to see the OP support the parallel run,.

GFS(p) Going the other way With lower heights and pressure over Greenland......  :smiliz23:

I would suggest your initial assessment as being wrong with both the GFS and the (P) now going along the same lines......

Edited December 22, 2014 by frosty ground

[swfc]

The 12z op looks a downgrade of sorts ie pressure rise towards Greenland.Pretty much collapses after the northerly,GFS-p has dropped its mad run and looks like the op from earlier???Christ how long will this go on!

[Captain Shortwave]

Day 5 charts (to be updated)

GFS

Slightly better northerly developing behind this low compared to the 06z

 

Parallel

Wedge of heights to our north west, the northerly should be quicker here (other elements up for debate). Very different to the previous run.

 

UKMO

Deep low dropping south east down the north sea, rain and strong winds though nothing particularly drastic.

BTW clear route to a Scandi high shown here so expect an interesting day 6 chart.

Edited December 22, 2014 by Captain shortwave

[Dr. Astro]

GFS(p) Going the other way With lower heights and pressure over Greenland......  :smiliz23:

I would suggest your initial assessment as being wrong with both the GFS and the (P) now going along the same lines......

 

Edit - wrong data.

Edited December 22, 2014 by Dr. Astro

[johnholmes]

Why oh why cannot folk not be satisfied with what looks fairly certain in the nearer term, turning colder, frost for many, a lucky few in the north especially and with height may even see something white falling in the Xmas period? Rather wintry type weather expected, looking at the charts, in the wake of the low pressure system over the weekend. It 'could' be cold enough into the following week for more folk to see white falling from the sky.

Lighten up for gawds sake, it is only the weather and it regularly makes fools of most of us on here, and at times, those with professional experience and far more data available than we have.

 

Happy Christmas everyone-try and be nice to one another and SMILE.

 

I hope this has not overstepped the mark admin - mods, the link to GFS etc via Net Wx is given below, folk have a look at it, use Extra if you have access, see how close or not the respective models were and are now as the 12z output rolls out-great fun.

http://www.netweather.tv/index.cgi?action=charts-and-data

Edited December 22, 2014 by johnholmes

[Cloud 10]

Still a slight question mark over saturday's weather.

 

gfs p 06z..  gfs p 12z..

[frosty ground]

Edit - wrong data.

That's the 06z run..... i am talking about the 12z run that is still coming out.....

[Barry12]

Widespread snow possible at day 6 on the GFS P

 

 

:smiliz19:

[Matty M]

And the GFS OP gives us the worst possible return for our hand..

 

[frosty ground]

http://www.meteociel.fr/ukmo/runs/2014122212/UN120-21.GIF

Compact feature on the UKM 120 chart

[swfc]

Tbh It finally looks like gfs-op and gfs -p have got the same idea on the 12z imo.If ecm looks akin to this then I think a quick northerly then a high over the uk looks on the cards.Im generally wrong but hey ho!!!

Edited December 22, 2014 by swfc

[Mark Bayley]

Better agreement between the operational and the parallel. Sadly the 6z was never going to happen. It seems a brief but potent northerly before new year (with wintriness for some). Thereafter uncertainty continues, although settled, but probably cold conditions, to prevail into and through new year. As stated earlier, i do not believe that any strengthening of the PV will last long, for reasons outlined earlier and by many other members. I'm afraid it is a waiting game in our hunt for snowier charts (but charts that will come)!

[Nick F]

Quite a lot of uncertainty with regards to the timing of deepening and track of the low arriving to the NW at the end of the week. The low, which moves NE from the mid-N Atlantic on Thursday engages with a sharpening shortwave trough dropping SE from Greenland/Iceland area Friday into Saturday.  00z ECMWF has the low deepens earlier than 06/12z GFS, with the low dropping SSE across mainland UK, centre reaching the south coast 00z Sunday. Whereas 06/12z GFS deepens the low later and tracks the low SE across the North Sea then on towards Denmark.  00z ECM ensemble postage stamps had a wide range of positions of the low by t+120 (00z Sat 27th), most were deep with the low but varied with position – most had the low NW of the UK, some in the North Sea and some west of Ireland.

 

Given the potential rapid deepening of the low, with GFS showing severe northerly gales around UK coasts and storm force northerly gales down the North Sea (with potential storm surge towards the Netherlands/UK North Seas coasts) this could be a notable storm. Not to mention the cold air being pulled south, which could bring the risk of snow to northern and eastern areas next weekend according to GFS, though this risk dependent on track of the low.

 

Beyond next weekend in the run up to New Year, there has been a lot of flip-flopping from model guidance over recent days, well, more than is usual. So confidence is quite low, even as early as Saturday, given uncertainty of the low deepening near the UK.  We've seem 00z ECMWF deterministic and EPS mean showing amplification of the flow upstream over the N Atlantic once the weekend’s deep low clears E or SE, with high pressure building in early next week across northern and western Europe. 06z and 12z GFS ops also build in HP across the UK by early next week, though the ridging more transient before giving way to more cyclonic conditions from the west by the end of the week.

 

A lot hinges on whether the potential strengthening of the arctic vortex over Greenland/Baffin/northern Canada indicated next week actually lowers heights again close to the NW and N of the UK as per GFS, or whether the vortex can dig deep enough upstream to maintain the ridging across northern Europe – perhaps even leading to height rises over Scandinavia, as the 00z EPS mean at t+240 hinted at. The pattern over the northern hemisphere upstream is not particularly favourable for the latter, given the transient or lack of ridging over Alaska which fails to build heights north into the arctic to have an impact on the Polar Vortex and amplify the flow downstream too. But, there's potential IMO for height rises to our NE, if the strengthening arctic vortex over Greenland doesn't push too far south and east into the Atlantic. Certainly don't think height rises to our NW (other than transient) is on the cards yet, until we see a proper pattern change.

Edited December 22, 2014 by Nick F

[karlos1983]

[Allseasons-Si]

Ukmo @ 120 hrs

 

 

could be an easterly from here,interesting model watching to say the least.

Edited December 22, 2014 by Allseasons-si

[Downpour]

Christmas Saturday and Christmas Sunday continue to represent the most weather interest from the GFS and its naughty sister the GFSp (which yet again finds a colder solution). 

 

Take you pick for that weekend. GFSop finds a way to a mild-fest later in its run but so far away not worth worrying about. 

 

Still think 26/27 is the watershed date to keep an eye on. 

[inghams85]

Better agreement between the operational and the parallel. Sadly the 6z was never going to happen. It seems a brief but potent northerly before new year (with wintriness for some). Thereafter uncertainty continues, although settled, but probably cold conditions, to prevail into and through new year. As stated earlier, i do not believe that any strengthening of the PV will last long, for reasons outlined earlier and by many other members. I'm afraid it is a waiting game in our hunt for snowier charts (but charts that will come)!

Im at work so cant post charts but yesterdays 12z's were worse. Heights to the North West were nowhere near as robust. Baby steps to synoptics shown 4 or 5 days ago. At T-96 i expect the chart for this day to look very good indeed!

[karlos1983]

can somebody please press the go button on the UKMO+144 

[Cloud 10]

Ukmo @ 120 hrs

 

UW120-21.GIF

 

Yes,that does look rather odd with a deep "football" LP with not much else going on around it.

[frosty ground]

can somebody please press the go button on the UKMO+144 

Is that because it's not out yet?

[karlos1983]

Is that because it's not out yet?

 

Just light humour fg

 

Good job I'm all grown up and don't take things to heart

Edited December 22, 2014 by karlos1983

[A.J]

keep it friendly please......................thanks

[Barry12]

Apart from the inital Northerly that could bring snow to lower levels on Sunday on the GFS P, both models are very boring indeed

[IDO]

Again can we trust the amplified GFS P; last three runs, Scandi high, Greenland High, now a cold UK high?

 

 

My thoughts are well known but I suspect the GFS op is too flat. The problem with this run is that the Alaskan High is stronger, earlier and it squeezes the flow and the Canadian PV wipes out any heights over Greenland. This happens on GFS P and Op as well as UKMO. The 06z mean did this exact thing:

 

 

Looks like the op will collapse the Alaskan ridge after D9: