Model Output Discussion 1200 hrs 30/09/14

[ANYWEATHER]

The gfs is still contented with a european high east of the uk for next week at t+168 ..the ecm is having none of it.......?

[Newberryone]

Looks like todays forecast from the UKMO has firmed up on a more settled end of Oct into early Nov with temperatures generally above average during the day. So I would assume winds with a southerly component for a time.

C

While I agree it's all about spotting trends early on, but realistically way outside the reliable time frame to carry any real clout.Nothing's set in stone right now and it's not unknown from times past for UKMO to revise their long range forecast.  Besides, Frosty's ( ) likely to become a manic depressive should this be the eventual outcome.  

[ANYWEATHER]

While I agree it's all about spotting trends early on, but realistically way outside the reliable time frame to carry any real clout.Nothing's set in stone right now and it's not unknown from times past for UKMO to revise their long range forecast.  Besides, Frosty's ( ) likely to become a manic depressive should this be the eventual outcome.

Metoffice generally go with ecm, although ecm is more unsettled than gfs...

[damianslaw]

Those speculating about late October prospects, bear in mind late October is on average one of the most disturbed parts of the year.. rarely do we see lengthy settled weather, however, 2009 and 2010 produced a lengthy dry settled period leading into the latter part of the month.

 

Back to the here and now, the deep low looks like filling in situ as it moves gradually NE blocked by heights to the NE. Into next week a slack set up, frost and fog likely before a pronounced trough looks like developing to our west and all eyes then on where the jet decides to position itself, if it sticks to its current path then we could easily end up with a similar situation to this week, if it goes north this would allow a ridge from the SW to anchor towards us.

 

Its certainly an interesting synoptical set up, a far cry from the southwesterly/ westerly mush that can dominate October with a raging Polar Vortex and jet. Its a set up conducive to early cold pooling to our east, which could result in a chilly unsettled November with a NW-SE tracking jet, think 1996.. getting ahead of myself here.

[knocker]

The anomalies tonight at day 10. NOAA and ECM are not dissimilar with a weak HP orientated roughly west-east south of the UK.and a weakish trough eastern Canada. The GFS has a stronger trough and a ridge west of the UK. On the surface this translates to a slack low pressure area over the Atlantic for the ECM and an Atlantic west.east split for the GFS with low pressure to the east and HP to the east. With the jet still fairly weak this is a fairly static pattern and certainly not one in which to place high confidence.

Edited October 8, 2014 by knocker

[Polar Maritime]

Some pretty cold synoptic's showing this morning by the GFS out in the run, With the blocking pattern re-establishing drawing some cold N/N/E winds. Maybe even some Snow for lowland Scotland... The Models have been very skippy over the past few days, Let's see where we go from here. Damian mentioned last night of a cold pool setting up in the East, Good call.

 

 

Edited October 9, 2014 by Polar Maritime

[knocker]

My question is how much influence has the recent typhoon activity impacted upstream on our weather pattern of late that has been rather static?

 

Ryan Maue posted this on Twitter

 

Introduce a typhoon into extratropical latitudes -- u can take a zonal jet and in 5-days get a lot of waves

 

https://twitter.com/hashtag/Rossby?src=hash

Edited October 9, 2014 by knocker

[knocker]

A spot of warmth for Tunbridge Wells - 26C?

 

[Summer Sun]

ECM drags up some warm air during the second half of next week as winds switch round to a south westerly

 

 

The further south and east you are the drier it should be if you get any sunshine it would feel quite pleasant given the warm direction of the wind

 

[Gibby]

HERE IS MY LATEST TEXT ANALYSIS FROM THE OUTPUTS OF THE WEATHER COMPUTER PREDICTION MODELS FOR TWO WEEKS FROM 8AM TODAY THURSDAY OCTOBER 9TH 2014.

 

NEXT UPDATE FRIDAY OCTOBER 10TH 08:00

 

THE CURRENT GENERAL SITUATION. A showery SW flow covers the UK as Low pressure fills and drifts North across Northern Britain.

 

MODELS-2 WEEK HEADLINE  Changeable weather with rain at times and strong winds too later but with some dry and bright weather for some next week especially in the East.

 

THE JET STREAM ENSEMBLE FORECAST The Jet Stream in this morning's GFS Ensemble run show the flow maintained close to Southern Britain for the next three to four days. It then weakens and splits with the main arm remaining close to the South of the UK with a weak northern arm to the North briefly weakening. Later in the run the pattern simplifies to a main West to East flow across Southern Britain.

 

GFS The GFS operational today shows the current UK based low pressure filling slowly and drifting North. It now looks like another Low moves NE towards Southern Britain at the weekend with more rain at times and it will become rather cool in the North. Then as this moves away pressure recovers and a couple of milder and brighter days are shown with mist and fog at night before the Atlantic is shown to ratchet up a few gears again with deep Low pressure crossing to the North and bringing rain and gales to all areas before colder and showery weather develops later on a marked cold North wind with some snow showers on Scottish mountains and frosts widespread at night towards the end of the run.

 

THE GFS ENSEMBLES. The GFS Ensembles look distinctly unsettled this morning following the operational up until the early part of next week. It then brings a deep Atlantic Low slowly in towards the UK with another batch of wind, rain and showers not dissimilar to the setup we have currently. This then becomes reinforced by further Low pressure from the West at the end of the run and with colder air entrained around a major Low to the North by the end of the run gales and heavy showers would be the order of the day for all with temperatures somewhat below average by then.

 

UKMO UKMO this morning shows pressure only very slowly rising at the weekend and start to next week with a trough remaining close to Southern Britain in particular maintaining the threat of some rain at times well into next week. Northern parts look like becoming rather direr if rather chilly by night with some mist and fog also a risk at night for many as winds will become generally light Easterly.

 

THE FAX CHARTS  The general thrust of the Fax Charts this morning focuses on a slow and gentle rise of pressure and a slackening of winds across the UK over the weekend and start to next week. There will be a lot of dry weather around but a lot of cloud at times too along with some night time fogs to clear. Some rain is also possible mostly in a showery form and more towards the South by Tuesday.

 

GEM The GEM operational today also shows Low pressure moving up perilously close to SE Britain early next week with some rain for many Southern districts. At the same time pressure builds to the North and NE and once the Low has passed a ridge builds strongly down across the UK with dry conditions with mist and fog at night and some warm days in the SE. The strengthening South-easterly winds on it's Western flank will bring cloud and some rain towards the far SW later.

 

NAVGEM NAVGEM also brings a new Low pressure up from the South towards Southern England early next week bringing more wind and rain here. it is shown to stay somewhat more settled in the North as pressure builds somewhat and this better weather then extends South to all areas towards the end of the run as Low pressure is held well to the west and a slack high pressure develops close to the East.

 

ECM The ECM operational today brings new Low pressure up towards Southern Britain early next week with several more days of wind, rain and showers while the North stays at least somewhat drier with higher pressure to the North. Later next week the model brings Atlantic Low pressure into play and with pressure rising over the near Continent the weather warms up considerably under SW winds. However, fronts will be pushing slowly in from the West with some heavy rain and strong winds where the warm air meets the polar frontal zone somewhere across the UK.

 

NOTABLE TREND CHANGES FROM PREVIOUS RUNS The trend has shifted away from a UK wide improvement towards a more modified version probably lasting only a few days and more towards the East.

 

MY THOUGHTS  A very complex synoptic pattern is shown to develop across the UK in the coming weeks as the desire for High pressure to rise from the SE and deliver some mild and pleasant weather is confronted by rather less desire for pressure to fall to the North of the UK next week. The result is a standoff involving a delay in improvements by slack pressure gradients across the UK and a new Low moving up from the South to affect principally Southern areas early next week with a renewed batch of rain and showers. Once this has passed there is a window of opportunity for high pressure to the SE to link with the ridge to the North and with the UK likely to lie on the Western flank of this a warming Southerly or SW flow is likely to develop from the middle of next week. After this the long term models remain mixed but it all hinges on how much progress and what angle of attack a deep Low pressure in the Atlantic has in making inroads into the UK later. Most of the longer term output does show it making at least some progress and setting up another windy and wet spell at the end of the run and if the door fully opens as GFS shows today then some very wet and windy weather is likely with colder air entrained too. It's all very complex this morning and will not be resolved until we see how the spanner in the works Low pressure early next week behaves with it's engagement of other pressure systems around the UK. So I think we can summarise by saying changeable conditions are likely over the next two weeks with rain and wind at times for all areas but with some drier and brighter periods too when it might feel quite mild.

[summer blizzard]

Two interesting things to crop up on the GFS6z..

 

The first is that the GFS completely removes the cool air at day 8..

 

 

The second is that deep FI gives us our first evidence that the sun is getting too weak to warm the high as a light inversion tries to develop.

 

 

Just two months ago you'd have been looking at low to mid twenties from that.

[IDO]

Such a volatile output at the moment with GFS in FI switching between possibilities with seemingly no trend developing. The 06z brings us a HP dominated FI, The Atlantic trough next week fills and then runs across the north of the UK bringing a wet couple of days:

 

D8:   D9: 

 

By D10 heights are moving in and mostly HP for the rest of the run:

 

D10:   D15: 

 

Yet the control has the core low in the Atlantic trough remaining deep and introduces unsettled weather from D10 to D16:

 

  

 

The GEFS are not a lot of help: 

 

Though a rise in pressure from D5-10 looks nailed now. The JMA update from yesterday for week 2 suggests that pressure will stay high:

 

 Week 3-4 is not conclusive but does not suggest a rampant Atlantic zonal washout: 

 

The MJO from GFS looks like going high amplitude phase 1 for mid-Oct onwards: 

 

And the relevant composite is: 

 

So this ties in with the JMA of week 2, a pressure rise over Scandi-Euro bringing calmer seas to the UK. However throw in the possible mid-latitude disruption when the Pacific Typhoon (strongest of this year) hits the jet in the next 3-4 days and depending how it interacts this could strengthen the MJO signal. At D13 the trough to our west was the wave from the interaction of the tropical storm:

 

 

Lots of wether things going on, so difficult to see how it will play out, although the MJO signal is quite strong from GFS, so HP may be the call from mid month.

 

 

[Milhouse]

Very warm air pumping up from the south on the ECM 0z

 

Edited October 9, 2014 by Milhouse

[Man With Beard]

Very warm air pumping up from the south on the ECM 0z

...and very cold air pumping from the Arctic Circle into Scandi - though I hardly expect this chart to verify in its exact form, I see across the models the likelihood, after T168, of warm air moving through W Europe and at the same time cold air moving from the NE. From the chart, you couldn't rule out a block developing to our north, eventually allowing the low in the Atlantic slipping to its south and sucking the colder air our way. So perhaps a 20% chance of 25C on your chart, but a 10% chance of snow into the NE a few days later. Which of course means a 70% chance of something much more average

[SMU]

Almost a Winters Chart there-

 

http://modeles.meteociel.fr/modeles/gfs/runs/2014100912/gfs-0-120.png?12

 

Very unusual chart there for October with the polar vortex dropping into Western Russia.

Snow also moving into Scandi.

 

A steady drop off in temps for the UK - this depicted well on the Theta charts from this

 

http://modeles.meteociel.fr/modeles/gfs/runs/2014100912/gfs-6-6.png?12 the +46c line in Southern Norway.

 

7 days later

http://modeles.meteociel.fr/modeles/gfs/runs/2014100912/gfs-6-168.png?12 the 10c moving south - indicating a 36 degree drop in theta.

 

The UK moving down from 30 to around 18-20.

netting out maxima from around 8-15c across the piste.

 

Frost at Night in the north.

 

S

[Captain Shortwave]

Still looks like the warm air will win out though, this mornings ECM mean even had 850s of +10C approaching the south coast. The operational approaching the mid-teens with temperatures in the low/mid twenties.

Anyway the GFS and GEM building heights north of the UK which then collapse just east of the UK with a ridge building ahead of the deepening Atlantic trough.

GEM

 

Scandi block or Euro block? could be the question which will be repeated throughout the coming months. 

Edited October 9, 2014 by Captain shortwave

[MR EXTREMES]

so we have our first undercut low pressure system at t192 on the gfs and look where the heights are heading.

like steve mentioned with the pv being booted from its favoured spot its not happy so happy holidays to the pv.

 

 http://modeles.meteociel.fr/modeles/gfs/runs/2014100912/gfs-0-192.png?12

 

and the ecm 192 also trys the heights into greenland to although this is this mornings ecm run.

http://www.meteociel.fr/modeles/ecmwf/runs/2014100900/ECM1-192.GIF?09-12

 

now for the gem at 192

its close but no cigar but its close.

http://modeles.meteociel.fr/modeles/gem/runs/2014100912/gem-0-192.png?12

 

ukmo at 144 lovely dartboard low once again nothing really worrying in terms of vortex 

http://www.meteociel.fr/ukmo/runs/2014100912/UW144-21.GIF?09-18

 

its certainly looking different this year but we have some october warmth to come to.

[Geordiesnow]

Finding the models interesting in respect how much less of a player that low is becoming despite the BBC's prediction of when rather than IF when it will hit the UK, it may still do so but the block is certainly keeping it at bay atm. 

 

The more likely potential is the shallow low coming up from the South with chilly NE'ly winds on the top side of the low so Eastern areas next week could be quite chilly, cloudy and wet whereas Western areas may see sunshine and quite chilly nights. 

 

It goes too show how volitile medium range forecasting can be and one too keep a note on as we go through the winter period. 

[SMU]

Whilst the ECM tonight isn't to bad for the UK, the overall backdrop remains much the same ( In respect to the OPI)

with a markedly weak & fairly fractured PV

 

http://www.meteociel.fr/modeles/ecmwf/runs/2014100912/ECH1-216.GIF?09-0

 

In terms of 'vortex heights' you are really looking sub 508 DAM, & if you look on the chart you see 1 main location over Central Russia that has these heights & a tiny patch over the pole.

Head to South Greenland / Northern Iceland & over to baffin & the persistence of the 540 line is good news if you want the status quo to continue.

 

Importantly we want this to continue into November....

 

S
 

[ANYWEATHER]

The gfs and ecm  disagree strongly at the hours of T+~168 

[nick sussex]

The gfs and ecm  disagree strongly at the hours of T+~168 

It's amazing the difference caused by the phasing of shortwave energy and the Atlantic troughing. The GFS/UKMO clear that energy away which leaves the trough further west.

 

The ECM trough gets pulled ne as it phases with the shortwave. The GFS is the most interesting in terms of cold potential especially if it had some trough disruption.

[John Cox]

Whilst the ECM tonight isn't to bad for the UK, the overall backdrop remains much the same ( In respect to the OPI)

with a markedly weak & fairly fractured PV

 

http://www.meteociel.fr/modeles/ecmwf/runs/2014100912/ECH1-216.GIF?09-0

 

In terms of 'vortex heights' you are really looking sub 508 DAM, & if you look on the chart you see 1 main location over Central Russia that has these heights & a tiny patch over the pole.

Head to South Greenland / Northern Iceland & over to baffin & the persistence of the 540 line is good news if you want the status quo to continue.

 

Importantly we want this to continue into November....

 

S

 

Good to see you on the forum so early in the Autumn/Winter season.

 

I hope this is a good omen for a cold one

Edited October 9, 2014 by John Cox

[SMU]

Indeed ^ ^ I think the ECM has thrown a wobbler tonight- GFS + UKMO Blend looks reasonable.

[Nick L]

ECM longer range ensembles showing high pressure anchored over Europe for the next couple of weeks. Beyond that, although suggesting a cool down, it's only back to more average conditions.

[damianslaw]

Looking at the Jetstream forecast it does look like next week will see a slack set up with atlantic trough action never fully getting in on the act allowing for stronger heights to dominate - frost and fog could be a strong feature.