Model Output Discussion 01/09/17

[knocker]

1 minute ago, draztik said:

around Mid-September?

Yup around there.

[Summer Sun]

The proper unsettled spell of Autumn could be on the way next weekend and into the following week

Some high rain totals are possible for the west over the next 10 days anything like that and river flooding would be very possible

 

 

Edited September 3, 2017 by Summer Sun

[Frosty.]

It looks increasingly like a very autumnal spell of unsettled / disturbed weather will hit the uk towards the end of next week with vigorous depressions bringing strong winds and bands of sometimes heavy rain interspersed with brighter but showery conditions but then the Gfs 6z operational shows a gradual improvement during week 2 as high pressure builds in from the south / southwest introducing benign warm and dry sunny weather across especially the southern half of the uk as we approach mid month. As others have already said, mid september could be a generally much nicer period..I certainly hope so!

Edited September 3, 2017 by Frosty.

[Summer Sun]

The GFS ens shows pressure begging to rise from the south during week 2 after what could be a very unsettled start I say could as all this is still a way off yet and anything could happen in the coming days with the potential low

Edited September 3, 2017 by Summer Sun

[Summer Sun]

GFS 12z (left) has the centre of the low further north than the 00z (right) next Sunday

[knocker]

The gfs going for explosive cyclogenesis that would be accompanied by heavy rain and severe gales.

 

[sparky1972]

hi guys, love to hear that things will be turning more Autumnal very soon, but i just hope it can wait till late sunday, im in a tent on the south downs for Goodwood Revival from thurs morning till late sunday, lol, will keep tabs on here regarding the potential for high winds that i have seen on some forecasts

[Summer Sun]

GEM hasn't got the low next weekend as deep as previous runs

00z

12z

[Frosty.]

To sum up the week ahead..in a nutshell it's a broadly westerly atlantic flow with bands of rain interspersed with sunshine and showers with average temps, feeling cool in the wind and rain and warmer in the sunny spells but towards the end of the week ahead it looks like becoming very disturbed according to the Gfs 12z with vigorous depression (s) heavy rain and strong to gale force winds, perhaps severe gales for some..it's being mentioned on tv and the met office are firming up on it being a truly very autumnal period next weekend into the start of the following week..it will soon be time to batten down the hatches for the first time this autumn.. there's potentially plenty of action packed weather ahead for the weather enthusiasts which we all are aren't we?.

Edited September 3, 2017 by Frosty.

[Guest]

19 minutes ago, Frosty. said:

To sum up the week ahead..in a nutshell it's a broadly westerly atlantic flow with bands of rain interspersed with sunshine and showers with average temps, feeling cool in the wind and rain and warmer in the sunny spells but towards the end of the week ahead it looks like becoming very disturbed according to the Gfs 12z with vigorous depression (s) heavy rain and strong to gale force winds, perhaps severe gales for some..it's being mentioned on tv and the met office are firming up on it being a truly very autumnal period next weekend into the start of the following week..it will soon be time to batten down the hatches for the first time this autumn.. there's potentially plenty of action packed weather ahead for the weather enthusiasts which we all are aren't we?.

Don't know why but part of me wants a stormy wet 'n' wild autumn. Perhaps because last year was so benign and dry. Certainly next weekend kicking off the new season in style, I wonder if this will be a recurring theme during the coming months?

[Frosty.]

21 minutes ago, Steel City Skies said:

Don't know why but part of me wants a stormy wet 'n' wild autumn. Perhaps because last year was so benign and dry. Certainly next weekend kicking off the new season in style, I wonder if this will be a recurring theme during the coming months?

It's potentially a weather enthusiasts dream come true next weekend if the met office are right unless you're in a tent (sparky1972)..fingers crossed for you that your area misses the worst of it!

Not sure it will have any bearing on the rest of autumn but we are probably due some wet 'n' wild periods although I've heard there is potential for some warmer settled spells, at least across the southern half of the uk during the second half of september.

Edited September 3, 2017 by Frosty.

[knocker]

The ecm diverges strongly from the gfs by Saturday 12z. Instead of a rapidly deepening low over N. Ireland and explosive cyclogenesis it has drifted the main low into the northern North Sea and has the developing disturbance in the south west quadrant of the main circulation (south west of southern Ireland) tracking south east into France where it has become a nasty little low by early Sunday. Over the next 24 hours it rushes east into Poland and the UK comes under a cool northerly airflow and a large area of low pressure centred to the east.

[Summer Sun]

ECM doesn't have the low as deep as some models have over the past few days it does put us in a cooler northerly flow though

Temps, I would think ranging from the lower teens in the north to the upper teens in the south

[Frosty.]

Shame its not winter, those Ecm 12z charts later in the run would mean wintry showers and snow with an unsettled broadly northerly flow setting in. 

Edited September 3, 2017 by Frosty.

[phil nw.]

As already been pointed out by other members, a very unsettled looking weekend to come- based on current modelling.

Details will likely change somewhat wrt tack/development of this low but all main runs show a fairly deep one situated close to Scotland by the coming weekend.

The UKMO and ECM charts

A more detailed look with the GFS charts for next Saturday which appears to be the stormier of the 3 developing a secondary centre south of the main low and runs it across Scotland,tightening the isobars further.

Note the strong jet streak at appox 200mph from the sharp temperature contrasts aloft.The first real cold air coming south from the Greenland shelf meeting the sub-tropical air of the south Atlantic. 

We are likely to see deeper lows than this as the season progresses i dare say but even so this would be notable for so early in September.The first Autumn storm with strong winds,possible gale force gusts and heavy rain moving through the UK.

 

Edited September 3, 2017 by phil nw.
corrected text

[Dancerwithwings]

1 hour ago, Frosty. said:

To sum up the week ahead..in a nutshell it's a broadly westerly atlantic flow with bands of rain interspersed with sunshine and showers with average temps, feeling cool in the wind and rain and warmer in the sunny spells but towards the end of the week ahead it looks like becoming very disturbed according to the Gfs 12z with vigorous depression (s) heavy rain and strong to gale force winds, perhaps severe gales for some..it's being mentioned on tv and the met office are firming up on it being a truly very autumnal period next weekend into the start of the following week..it will soon be time to batten down the hatches for the first time this autumn.. there's potentially plenty of action packed weather ahead for the weather enthusiasts which we all are aren't we?.

What a difference 10 days ago or so in what the models were hoping for the first week in September

Still wouldn't mind seeing this in ten days though.....Autumn can wait for now

Edited September 3, 2017 by Dancerwithwings

[ANYWEATHER]

Hello Folks! Due to an unusually cold Artiic  and very active Hurricane season ,this September will see a strong jet making a bee line for the uk , and  this weekend looks interesting as regards development for some deep low pressure systems ...certainly not unusual at this time of year given the "Disorganized ripple effect" the other side of the pond but devil will be in the detail regarding this

[damianslaw]

1 hour ago, ANYWEATHER said:

Hello Folks! Due to an unusually cold Artiic  and very active Hurricane season ,this September will see a strong jet making a bee line for the uk , and  this weekend looks interesting as regards development for some deep low pressure systems ...certainly not unusual at this time of year given the "Disorganized ripple effect" the other side of the pond but devil will be in the detail regarding this

Yes we appear to be starting this autumn on a very different note to many recent ones, with a much more active atlantic and cooler arctic, which is likely to result in much stronger low pressure systems with more advanced temp gradients, hence a potentially much stormier season than of late. Last autumn was so benign it barely got going. The early September high pressure spell is dead this year.

Next week looks very unsettled with a strong atlantic flow, then a possible deep low pressure system next weekend bringing early gales and some quite chilly air, it will feel more like late October.

Looking further ahead, we could see a more settled quiet spell as we approach mid month, with ridge development to our west anchoring itself across the country, but I suspect it will be shortlived with further atlantic gusto behind it - this could be the theme of the autumn, very unsettled wet stormy cool weather interspersed with shortlived quieter settled conditions, at least through Sept and October. November I feel could be a bit more different.

[knocker]

Last night's anomalies merely confirm the probability of a very unsettled and cool period of weather over the weekend and into next week There are differences in the pattern  though which may be important when it comes to the determination of detail by the det runs. This was apparent last evening vis the gfs and ecm for example. The differences being the strength and orientation of the trough (upper low) over the UK, associated with the Canadian lobe and low pressure in the Greenland/Iceland area and the Azores pushing north in mid Atlantic.The ecm is more pushy with the Azores and thus the upper flow veers towards the north west which will effect the direction of travel of systems arriving from the west. It will be interesting to see if this morning's runs get to grips with this. Either way it's not looking good for a few days.

So any bright spots this week? Rather cloudy today with outbreaks of rain and s drizzle in most areas but tomorrow and Wednesday are not looking too bad once the front is out of the way tomorrow.

Thursday starts off okay but by 18z the next Atlantic low has ariived between Iceland and Scotland with associated fronts already impacting the north west. Over the next 24 hours these track south east and by then the low is just east of Thurso 990mb with the UK in a cool, showery, NW airstream.

The low continues to track ESE veering the surface wind northerly over the UK and little lows develop within the circulation one of which tracks SE into France and brings some inclement weather to southern Europe. This is a nod in the direction of last night's ecm and needless to say totally different to the gfs run  The northerlies prevail but becoming quite slack as the low disappears east but again the picture quickly transforms as the next quite intense low arrives on Tuesday bring more wind and rain. At least the jet has eased a little

Just to note this morning's GEFS 6-10 anomaly has shifted towards the ecm

Edited September 4, 2017 by knocker

[knocker]

Still significant differences between the gfs and ecm that start quite early in the run. The latter develops a low east of Greenland and by T144 has it swinging SE west of Ireland. From here the track becomes easterly as it develops and nips across southern England to be over Great Yarmouth 24 hours later. Thus a very wet day over England and Wales as Sunday progresses. The weekend remains a work in progress for detail

[mb018538]

Looks like full steam straight into Autumn (not that we weren't there already with the terrible second half of summer). Could be some heavy rain and gales on the way - great if you find that sort of weather fascinating, I suppose.

[Summer Sun]

No great surprise to see the ECM Op overdoing the low around Sunday or Monday again on the London ens

The mean has pressure at a low of around 993mb whilst the Op gets down to around 978mb

Further east towards the north Norfolk area the Op gets down to around 970mb whilst the mean remains around 990mb

 

 

[SteveB]

1 hour ago, mb018538 said:

Looks like full steam straight into Autumn (not that we weren't there already with the terrible second half of summer). Could be some heavy rain and gales on the way - great if you find that sort of weather fascinating, I suppose.

Problem is of course, we good easily see that kind of weather right the way through to March next year.

 

[stodge]

Afternoon all

The problem for western Europe is storms like Irma not doing what we'd like - missing land, re-curving into the Atlantic and pushing the Azores HP up over us and giving us a benign settled spell.

Instead, Irma fizzles in North America and slows the progression of LP out of that region encouraging mid-Atlantic ridging and the trough to sink SE over the British Isles.

GFS 06Z OP at T+216:

Not exactly what we want to see.

[Cheshire Freeze]

3 hours ago, stodge said:

Afternoon all

The problem for western Europe is storms like Irma not doing what we'd like - missing land, re-curving into the Atlantic and pushing the Azores HP up over us and giving us a benign settled spell.

Instead, Irma fizzles in North America and slows the progression of LP out of that region encouraging mid-Atlantic ridging and the trough to sink SE over the British Isles.

GFS 06Z OP at T+216:

Not exactly what we want to see.

Actually, N Atlantic blocking as shown above is exactly what I want to see. There is a historic correlation between this blocking in September and N blocking during winter.