Model Output Discussions 12z 01/09/2016

[Man With Beard]

Signs for the last week of September remain a little half-hearted but certainly many options for another Azores push through NW Europe next weekend

  

the angle particularly of the ECM could lead to another rather warm period - the GEFS shows many warm variations

I suppose the curve-ball might be low heights over eastern Europe getting nearer than expected

though this is a big outlier on the ensemble set. Odds more favouring the warmer direction

 

 

 

[legritter]

IF we can believe the GFS towards the end of its run Batten down the hatches  The Atlantic kicks in and throws Dart boards in our direction .

ECM keeps us fairly dry and with some fairly good temperatures any one taking a late break could do well .

Hoping the Azores high takes a break this winter but thats another story , take care all 

[Cheshire Freeze]

1 hour ago, Matthew Wilson said:

Found this interesting from the CFS for December. The first chart was December 2015 forecasted September 2015 and is pretty accurate with high pressure to the south pumping up warm air. Now the second chart is for December 2016 and notice all the Northern blocking in red. A complete reverse forecast for this year

 

The CFS model has been showing December blocking for a while now and is backed up by the Glosea. I have found if the seasonal models converge on a +NAO then it's nearly always nailed on. It is encouraging we have some consensus towards a HLB in the seasonal modelling thus far.

[Summer Sun]

This morning ECM has a southwesterly or westerly flow throughout its run some deep lows could affect the UK on a couple of occasions but it no conveyor belt so far

Temperature around or maybe a touch above average throughout

 

Edited September 18, 2016 by Summer Sun

[phil nw.]

No real change so far for the coming week from the 12z runs. The UK again showing in a south westerly flow between low pressure towards the north west and the Azores high ridging across towards southern areas.

A few charts to illustrate

Day 3 from the UKMO and day 5 from the GFS

the frontal systems quite active to the nw and weakening somewhat as they come se.

A couple of rainfall and pressure images -just snapshots-Tues and Fri as GFS sees things currently

Temperatures look close to normal overall,as ever warmest in the se where high teens.possibly 20c could well be reached most days.

A pretty normal late September pattern by the looks with quite benign weather for many away from the far north west.

[legritter]

Tonights charts certainly  carry on with quiet conditions and temp above normal ,perhaps becoming more unsettled later this month if gfs is on the ball ,so still plenty of grass cutting to come  take care all .

[phil nw.]

Whilst it's a bit quiet in the thread i thought for Winter lovers it is of some interest to view the latest GFS Op.run NH view to see the first signs of the building Arctic cold modeled over N.Siberia as we progress through to month end.

2 images at the 850hPa level- first at T24hrs and then at T240hrs showing the gradual spread south of sub-zero temperatures over there.

this area, apart from Greenland, is usually the area to see the first lying snow of the approaching Winter.

A look at the temperatures expected at the surface over the next 2 weeks

 

so in a few days the region will go below zero-day and night as the cold settles in.

Early days and just for fun really but we can see already the effects of the sun going below the horizon in the high Arctic as the upper air cools rapidly and the Polar Vortex starts to expand as we go pass the equinox.

[mb018538]

Morning output is still continuing along the same theme today - GFS is keen for an Azores high reload and a bit more warmth by day 9/10. Fairly benign really, better in the SE.

[summer blizzard]

As per the above GFS delivers a modestly warm end to September.

GEM has a bit more excitement..

[I remember Atlantic 252]

1 hour ago, summer blizzard said:

As per the above GFS delivers a modestly warm end to September.

GEM has a bit more excitement..

think you mean GFS has more excitement

[Yarmy]

The GEM ends with a significant dartboard depression blasting through the UK:

 

This is the result of a tropical storm forming on Friday hundreds of miles off the eastern seaboard, before it hitches a lift on the jet and arrives in the British Isles.

 

The UKMO also has this feature and looks like it might carry on to a similar outcome:

 

The ECM makes less of it:

 

...and the GFS doesn't have it at all:

 

GEFS don't seem interested either, but something to keep an eye on maybe.

 

 

 

 

[mb018538]

ECM also follows the GFS suit in bringing some very warm air across the UK again by the end of the run (850s up around 15c again!) though less settled as the ridge doesn't build in as much. I guess much will depend on how the TD interacts once more, but either way I don't think it will be desperately unsettled. GEM looks well wide of the mark to me, as amazing as that low looks!

[Gael_Force]

4 minutes ago, mb018538 said:

ECM also follows the GFS suit in bringing some very warm air across the UK again by the end of the run (850s up around 15c again!) though less settled as the ridge doesn't build in as much. I guess much will depend on how the TD interacts once more, but either way I don't think it will be desperately unsettled. GEM looks well wide of the mark to me, as amazing as that low looks!

There were charts like that for Gaston and it just fizzled out, maybe Karl will do same.

[mb018538]

Chart for the 240 ECM for those interested:

[Man With Beard]

2 hours ago, mb018538 said:

Chart for the 240 ECM for those interested:

These charts are coming up again and again for the end of the month. Perhaps humidity rather than heat will be the theme unless the high pushes further north. However the Atlantic is looking a lot more active now - albeit on a SW-NE axis so still a warmish pattern the further south and east one is - so I think high pressure is going to have its work cut out to get established right through the country.

I would also add a very alternative cluster is showing up on the GEFS ensembles, which shows low pressure barrelling through Scandinavia between T240 and T288 - the GFS 06Z is on the same page as this:

and of course the ECM op hinted that this might be its next step after D10, too:

So possibly some warmer days to end September but could it then be all change for October, with pressure finally rising towards Iceland and a much cooler W to NW being permitted?

Edited September 19, 2016 by Man With Beard

[Paul]

This weeks syntopic guidance blog from Matt is online now:

Synoptic Guidance - The Week Ahead - 19th September

[johnholmes]

Keep it going Matt, nicely presented for experienced and less so is how I see your postings-thanks

It could be even more read come the 'silly season'-which we all know is getting closer.

[Summer Sun]

Pretty much a west or southwesterly flow throughout tonight's ECM the odd low gets close enough to bring some windier and wetter spells (Sunday could be the day to watch out for) but most pass to the north or west with temperatures around or a bit above average

[Newberryone]

Must say tonight's Ecm is looking very amplified and increasingly benign, even possibly for parts of Scotland and N Ireland, as we go through next week owing to that huge swathe of high pressure down over Southern Europe which seemingly refuses to do a hike.  Can only hope at this early stage that this feature will not become a major player during the upcoming season. 

[mb018538]

Morning campers

Much the same (again) today. All depends on how the high builds over the UK as to how nice it may or may not end up. GFS builds it in:




Still there at 312, turning fairly warm too:



 

[mb018538]

ECM has much more in the way of low pressure interaction - thus preventing the high from becoming as dominant as the GFS run. I guess as we move nearer the time these difference will be ironed out!

[Faronstream]

Looks like the high pressure finally after 3 weeks of control is giving up (?) and the power of Atlantic is coming back, Both ECMWF, GFS and GEM agree on this. Below normal temperature for the first week of October also

[mb018538]

21 minutes ago, Faronstream said:

Looks like the high pressure finally after 3 weeks of control is giving up (?) and the power of Atlantic is coming back, Both ECMWF, GFS and GEM agree on this. Below normal temperature for the first week of October also

I'm not too sure about that - high pressure is still controlling things in that low pressure are taking a NE track away from the UK rather than ploughing through. There is plenty of energy there, just not totally in our direction at the moment.

[legritter]

16 hours ago, johnholmes said:

Keep it going Matt, nicely presented for experienced and less so is how I see your postings-thanks

It could be even more read come the 'silly season'-which we all know is getting closer.

Its great to have interesting postings on a forum which is the best and interesting around ,And yes the silly season will soon be upon us  ,wish we had this Forum 30/40 years ago  i could have saved money on Met office Fax charts being posted ,mind you still that uncertainty at five days out ,currently things i think becoming more mobile as October approaches ,its great to be able to look in more as family commitments have now improved with elderly relatives ,looking forward to the silly season ,cheers all .

[Newberryone]

17 minutes ago, Faronstream said:

Looks like the high pressure finally after 3 weeks of control is giving up (?) and the power of Atlantic is coming back, Both ECMWF, GFS and GEM agree on this. Below normal temperature for the first week of October also

While in the short to medium term, yes things do look like becoming more autumnal with low pressure gaining the upper hand, especially so for more northwestern parts, I would have thought the opposite then again being the case as we near Oct with yet again high pressure taking up residence over the low countries. So admittedly while 24 hrs can be classed as a long ways off in terms of meteorology, let alone a week from now, I wouldn't care to hedge too many bets right now on your assertion of The High Pressure finally losing control.

PS very wise to have placed a question mark with that statement, as you did