Model Output Discussion 06Z, 13 Sep. 2013 ---->

[bluearmy]

This does look like it will not be sustained warmth. Probably 3 or 4 warm days and back to average and poss cool as you head ne.

[mushymanrob]

I think people are being very optimistic suggesting this settled and very warm spell could last 1 or 2 weeks. Thats pretty much unheard of.

 

Im awaiting the charts showing the inevitable breakdown after around 4 or 5 days.

 

why not?... i believe there have been lengthy settled/warm spells in september, anticyclones dont know what month it is.

 

all indications are that this expected high will sit on us for some time, at least next week, even the anomaly charts (6-10 day)  are suggesting a prolonged anticyclonic dominated spell, so i think 'the inevitable breakdown after 4-5 days' is unlikely.

 

"settled and warm spells in late September and early October have historical links with cold and snowy winters"

 Do you have any stats to back this statement up with?

As far as I know there has been no proven correlation between the weather type in autumn and the forth coming winter.

 

Late September warmth being shown by the GFS,ECM,UKMO, most would welcome that.

 

1978...

 

no there is no correlation between warm spells in autumn and the nature of the winter ahead. it can be mild/partly mild/cold/partly cold no matter what autumn delivers.

 

but frosty was countering the suggestion that a mild spell in autumn could lead to a mild winter... so he was actually making the point you reitterated!

 

.... i must say.... IF the current charts become reality, and IF we had had these in july, then this summer for all would have been a corker, and not spoilt by northeasterly incursions with stratus off the north sea, which did spoil it for us.

[Scorcher]

This does look like it will not be sustained warmth. Probably 3 or 4 warm days and back to average and poss cool as you head ne.

 

Could be but where is the evidence for this? The GFS Op looks very good again this morning, would certainly be above average all week if that came off.

[bluearmy]

Could be but where is the evidence for this? The GFS Op looks very good again this morning, would certainly be above average all week if that came off.

 

 

 

the gefs/ens spreads in broad agreement on this (at the moment)

[Captain Shortwave]

ensemble-tt6-london.gif

 

the gefs/ens spreads in broad agreement on this (at the moment)

But only a couple of days ago those "warm" days were only predicted to be about 16/17C before they increased as they approached the shorter time frame. What's to say that the same won't happen again?

[Frosty.]

Now that's what i'm talking about... , ladies and gentlemen we have cross model agreement, a very warm and anticyclonic spell is incoming. Temperatures by the weekend will be hitting the low 20's celsius (low 70's F) and next week the temps continue to rise from the low 20's c towards mid 20's c and I would not be surprised if favoured spots reach towards the high 20's c, high pressure will build in and intensify and it won't be leaving us for a while once established..this is going to be fantastic.

[Tom Montalbano]

As predicted by others earlier in the thread, certainly looks like "Humberto" will be playing his part in delivering a glorious spell of weather from the weekend and onwards into next week, anybody having booked a late holiday in the UK, looks to have hit the jackpot.

Would expect temps to be well into the 20s C next week, in parts of the S and E, if these forecast charts are correct.

 

From my own Coldist pov, would love to see charts like this, as we enter further into Winter.

 

 

With some slightly negatively tilted WAA, I'd be getting excited at the prospect of a bitter easterly, further down the line. 

 

Tom.

Edited September 18, 2013 by TomBR7

[bluearmy]

But only a couple of days ago those "warm" days were only predicted to be about 16/17C before they increased as they approached the shorter time frame. What's to say that the same won't happen again?

As expected - ecm tends to understate maxes on those graphs more than a few days ahead. However, the drop in average maxes supported by nearly all the runs is unavoidable. not to say we wont see high teens for the latter pat of next week but currently the ens suite has the cooler uppers coming in form the east and pushing the warmer ones away west and south. Which will prove stronger to begin with - the troughing from our east or the west. If the latter, as per the 00z ecm op, we could see the suite trending back warmer for longer. As we stand, its the former. If the answer were clear, it wouldnt be worth watching!

[No Balls Like Snow Balls]

But only a couple of days ago those "warm" days were only predicted to be about 16/17C before they increased as they approached the shorter time frame. What's to say that the same won't happen again?

 

They have only warmed up a couple of degrees, ECM still doesn't get above 20c from 17c earlier in the week. Latest GFS ensembles also show a cool down for the same sort of time frame after a brief warm spell.

 

 

A brief warm spell has been showing in the GFS and ECM ensembles for days now. Not saying it can't change but it's just what they both show. Either way looks like HP would still be in charge but just would feel a lot cooler again.

[Yarmy]

Not much to add. ECM great from start to finish with the blocking high holding on over us throughout (hopefully it can squeeze out an extra couple of days when I'm at Centerparcs ) 

 

 

Cold uppers flooding into Siberia/Russia/Asia. Long may it continue.

[Captain Shortwave]

Not much to add. ECM great from start to finish with the blocking high holding on over us throughout (hopefully it can squeeze out an extra couple of days when I'm at Centerparcs ) 

 

 

Cold uppers flooding into Siberia/Russia/Asia. Long may it continue.

It sure is, whilst the uppers tend to get mixed out over us, we do develop a south easterly wind which at this time of year is still a warm direction, especially with the temperatures rising across the near continent throughout the coming week. Good ensemble support too.

Day 10 still has high pressure right over the UK with a fairly deep trough in the atlantic

Even the ensemble mean shows where all the cold is

 

The BBC video about Humberto suggests the maximum temperature over the weekend will be around 23C, which is where the GFS is pitching. Wish their 5 day forecasts wouldn't contradict this though

Edited September 18, 2013 by Captain shortwave

[Tamara]

There is good support for a climb in temperatures from the weekend into next week and lasting, at least, to midweek. The ECM ensemble maps, overall, show consistently where the 'very warm' upper is, and it is not too far to our south.

 

Realistically, I don't think we should expect anything significantly very warm or hot to come from this overall - a definitive draw from southern europe would be required for this to happen later into September as we are getting, but that said, certainly plenty warm enough by day to give a welcome reminder of the season past

 

The script is much as stated yesterday, and I would agree with suggestions up the page that temperatures look like tailing off again thereafter and the question then becomes what effect the major players in the overall NH pattern have on our weather..again much as stated and explained yesterday and more particularly so well illustrated and described by snowking

Edited September 18, 2013 by Tamara Road

[Summer Sun]

Latest from Gibby

 

Good morning folks. Here is today's look through the midnight outputs of GFS, UKMO, GEM, NAVGEM and ECM for today Wednesday September 18th 2013.

 

All models continue to reflect the pattern as the past few outputs of changeable conditions with further Atlantic fronts bringing a further spell of wind and rain East across the UK tomorrow after a brief ridge brings a drier and brighter interlude today. It will be somewhat less cool. Through Friday and the weekend High pressure builds from the South with dry and increasingly bright and warm conditions affecting the South and East. After a bright day on Friday the North and West will be cloudier with some rain and drizzle as a warm front spreads warm and moist air across the upslopes of Northern and Western Britain.

 

GFS then shows a new High build in over the top of developing Low pressure well to the SW of Britain, extending across the UK and maintaining fine and relatively warm conditions across the UK with some cool and misty nights. By the second weekend things will slowly become more unsettled from the West as troughs associated with Atlantic Low pressure turns the Southerly drift into a stronger SW then West flow with rain at times for all for a time before fine and dry conditions return right at the end of the run as High pressure builds back once more from the South.

 

UKMO today closes its run with a High pressure belt across the UK with only the far SW seeing any sort of breeze from the SE. Fine and pleasant days would ensue with mist and fog problems night and morning.

 

GEM is probably the most interesting run this morning in that it shows High pressure over the UK with its parentage in the form of an intense High over Greenland. In addition a very deep Eastern European Low feeds a lot of very cold air over Russia and the North of Europe while in the Atlantic another deep deression has a lot of warm and moist air in it's circulation. If these ingredients came together they could make for a pretty potent and stormy spell of weather but as it is the UK lies in the void between the systems with quiet and benign conditions with mist and fog at times before some cloud and rain finally reaches the SW late in the run.

 

NAVGEM shows a large bubble of High pressure across the UK and Western Europe in the middle of next week with pleasantly warm and sedate conditions with sunshine by day and mist and fog at night. The far NW could be a little cloudier at times in something of an Atlantic drift.

 

ECM shows High pressure to the East next week with a warm Southerly drift across the UK with fine and warm conditions very likely with some sunshine especially across the South. The far west and NW may see cloudier skies later as a weak front brushes by to the West.

 

The GFS Ensembles today point to a warm and settled period to come before things slowly turn somewhat cooler and more chageable towards the end of the output.

 

The Jet Stream continues to be programmed to become pushed further North from the weekend where it remains for much of next week before indecision in output makes it's course difficult to call at this range this morning.

 

In Summary a fine and settled spell is still the most likely probability next week with some warm sunshine by day but with the chance of mist and fog problems night and morning. As always in the extended outlook period changes in the position of our High pressure are shown which could have fundamental effects on conditions in any one place but overall rainfall amounts will be small with only the far North and perhaps SW at risk later on. GEM throws up an interesting setup at the end of it's run which would deliver an early taste of Winter to parts of Russia and Northern Scandinavia with the UK ridge separating this from warm moist and rain laden air in the Atlantic which does make some inroads into the SW late. This is probably an outlier in isolation as it is not well supported from any other output I have seen so far this morning or at least not as extreme.

 

http://www.norton-radstockweather.co.uk/Model-Analysis%282859336%29.htm

Edited September 18, 2013 by Summer Sun

[NO LONGER POSTING]

Not so model related but a good idea of where Humberto is expected to go.. which will play a key part in what the models predict..

 

 

 

[Summer Sun]

After above average uppers next week they return to average taking us into October keeping temperatures pleasant

 

 

Once this high leaves we have a brief unsettled spell before a new high builds as we start October

 

http://www.null/ds/gfs.htm

 

Edited September 18, 2013 by Summer Sun

[Frosty.]

The Ecm 00z ensemble mean is SENSATIONAL..I think this is the best looking ens mean so far in the build up to this very warm anticyclonic spell. High pressure books in for what looks like a 2 weeks + holiday in the uk.....BOOM

[snowmadchrisuk]

The 6z doesn't look very good temp wise ( I haven't seen any other runs this week) Back to mid teens by Tuesday . Is it the next week looks good then downgrades situation that we seem to have had for at least the last 3 weeks ? Still will be nice to see some autumn sunshine down here in the SW .

 

Edited September 18, 2013 by snowmadchrisuk

[Summer Sun]

The 6z doesn't look very good temp wise ( I haven't seen any other runs this week) Back to mid teens by Tuesday . Is it the next week looks good then downgrades situation that we seem to have had for at least the last 3 weeks ? Still will be nice to see some autumn sunshine down here in the SW .

 

 

Better on Monday, Wednesday and Thursday though

 

 

Tuesday is still very respectable especially in the south with temps in the high teens to low 20's

 

[Summer Sun]

To follow on from my post the 00z for Tuesday had temperatures widely into the mid 20's

 

 

Current run (06z)

 

 

Monday is roughly the same on both the runs (00z and 06z)

 

This afternoon's 12z will be interesting to see which run it follows 00z or 06z for Tuesday

Edited September 18, 2013 by Summer Sun

[johnholmes]

The reason for the drop in values SS is down to after effects from ex Humberto.

Sunday and Monday we have highish Td values as the high is over the continent. As ex Humberto pulls away then a high cell forms in its wake and pulls lower dewpoint (cooler air) in off the central Atlantic rather than the air coming from more southerly parts.

[Frosty.]

I think part of the reason for the cooler blip on the 6z is the forcing that takes place as the 2 anticyclones merge into 1, the atlantic high slowly becomes absorbed into our original anticyclone and in that process, cooler oceanic air briefly feeds around the top of the atlantic high and filters down across the uk behind a very weak cold front but it is really just a reboot of the whole anticyclonic pattern which soon goes from strength to strength with warmer uppers again feeding up across the uk, just as they do through this weekend where we get an initial burst of Tropical Maritime warmth sweeping up from the southwest enabling temps to soar into the low 70's F, 21-23c across a large area, there is no guarantee that there will even be a cooler blip, it's only the Gfs 06z showing that so pinch of salt at this range, high pressure is going to dominate the next 10 days at least, perhaps the next few weeks with generally above average temps, sometimes very warm for the time of year and even locally hot in favoured spots, mid 20's celsius is definately achievable, perhaps high 20's c for some, there will be lots of sunshine followed by clear nights where temps will drop low enough for some mist or fog in places, and on the 6z, a weak cold front would be sliding down across the uk early next week but dissolving as it drifts through the high pressure with no more than a band of fragmenting cloud. The outlook is about as good as you could get for late september, on this run, our anticyclone eventually gets squeezed by a trough to the east and an atlantic low but there are no signs of the atlantic cranking up .

Edited September 18, 2013 by Frosty.

[AWD]

I take anything past T144 with a pinch of salt, regardless of what it is showing or how much support it has.

I've seen things change dramatically many times before at a relatively short timeframe so for now I'm going to enjoy the pleasent weekend and start to next week.

The potential is certainly there for a prolonged spell of settled weather with some respectable temperature at times, but equally to balance that out, I can see one or two ways, beyond T144, where things could change if some pressure patterns change slightly. The Met Office update hints at something similiar for northern areas as we leave September and start October, with the possibility of this change extending southwards too.

Anyways, I'm rambling now. A warm and settled period of weather is approaching us now with a very useable weekend to come. How long it lasts through next week I don't know, for me, it's too early to call yet!

[Captain Shortwave]

I would say that high pressure being in control until the end of next week is probably the most likely solution. Given the current tropically forced pattern developing over us and later on over in the US, in fact the eastern states look likely to have a final blast of summer in a weeks time with 18C uppers reaching eastern Canada. This pattern looks developing into a deep Atlantic trough stuck between our ridge and the one over the States. 

I think a breakdown will happen eventually and probably from the south west. Perhaps our high will start heading towards the pole in time too.

Edited September 18, 2013 by Captain shortwave

[AWD]

I would say that high pressure being in control until the end of next week is probably the most likely solution. Given the current tropically forced pattern developing over us and later on over in the US, in fact the eastern states look likely to have a final blast of summer in a weeks time with 18C uppers reaching eastern Canada. This pattern looks developing into a deep Atlantic trough stuck between our ridge and the one over the States. I think a breakdown will happen eventually and probably from the south west. Perhaps our high will start heading towards the pole in time too.

Something not too disimiliar from this then CS;Tentitive hints there of something similiar to what you just described. A lot of positive pressure anomalies present there!

[Stormyking]

GFS and ECM, still looking very good for high pressure and warmth for at least a good week , slight signs of GFS going for a breakdown aswe go into FI, but thats FI so it could still change  

 

This should be really nice