Model Output Discussion - September Onwards

[Frosty.]

The models are really firming up now on an early autumn heatwave affecting much of the uk from the second half of next week with temps hitting 27c 81f in the southeast by this time next week and a general 22-25c for most areas. The Ecm 00z would offer something a little cooler with the airflow tending to be more from eastern europe instead of southern europe but it could just be a blip as the general consensus is for winds to be more from a southeasterly direction from southern most europe. It looks like the anticyclonic spell will last well into october but the 850's will probably become lower by week 2 of october with more chance of frost and fog by then. The Gfs 06z shows the first cold blast sweeping southeast through scandinavia at the end of FI and the other startling feature is how blocked the atlantic becomes in FI with no low pressure to be seen.

[johnholmes]

replying to post 322

where on earth do the Met O say 'colder'?

Why oh why can folk not quote what is actually said,

the phrase is this..- 'although it may not be as warm as the previous week with some cooler days possible'.

[Milhouse]

Agreed, i wouldnt have though the met o would be using the word cold just yet, especially at that range. Far more likely that they will use terms like average, below average etc. Obviously it will turn cooler though as after maxes of 25c the only way is down.

[Frosty.]

replying to post 322

where on earth do the Met O say 'colder'?

Why oh why can folk not quote what is actually said,

the phrase is this..- 'although it may not be as warm as the previous week with some cooler days possible'.

I don't think the heatwave will be sustainable beyond the end of next week and temps will probably begin to slide downwards towards average by the second week of october, common sense tells us this and not just what the meto think..also,the gfs 06z has a cold plunge at the end of FI which could be much closer to the uk if there is sufficient high pressure retrograde so there are a few things to keep an eye on as we head towards mid october.

[No Balls Like Snow Balls]

replying to post 322

where on earth do the Met O say 'colder'?

Why oh why can folk not quote what is actually said,

the phrase is this..- 'although it may not be as warm as the previous week with some cooler days possible'.

I was actually refering to the meto update of yesterday and the day before and the day before that. Toys can go back in pram now thank you.

[Frosty.]

I was actually refering to the meto update of yesterday and the day before and the day before that. Toys can go back in pram now thank you.

And maybe tomorrow they will be saying it again..the gfs has been hinting at a cold snap on some recent runs at the T+300 range with a possible Northerly plunge so it could be a very interesting few weeks ahead with a heatwave followed by a much colder spell around mid october or alternatively the heatwave will just subside into a settled but cooler more typical october spell with ground frosts and mist/fog giving way to pleasant sunny afternoons/evenings before turning more unsettled around mid october.

[johnholmes]

I was actually refering to the meto update of yesterday and the day before and the day before that. Toys can go back in pram now thank you.

no toys out of any pram from me just a request for accuracy.

I may well have missed the word cold so please refer me to the specific forecast on the 2 threads Stewart runs most days for the 6-15 and 16-30 day outlooks.

I'll readily apologise if I'm wrong.

Meanwhile the synoptic models do now seem to believe the 500mb anomaly charts that hinted at this upper air pattern about 7 days ago and have been consistent ever since. The overall idea of it cooling down after some quite high temperatures for late September/early October seem pretty sensible to me as the high tends to edge (upper and surface) further west possibly north west. Its exact position obviously will define how much lower the temperatures will be.

Edited September 23, 2011 by johnholmes

[No Balls Like Snow Balls]

no toys out of any pram from me just a request for accuracy.

I may well have missed the word cold so please refer me to the specific forecast on the 2 threads Stewart runs most days for the 6-15 and 16-30 day outlooks.

I'll readily apologise if I'm wrong.

Meanwhile the synoptic models do now seem to believe the 500mb anomaly charts that hinted at this upper air pattern about 7 days ago and have been consistent ever since. The overall idea of it cooling down after some quite high temperatures for late September/early October seem pretty sensible to me as the high tends to edge (upper and surface) further west possibly north west. Its exact position obviously will define how much lower the temperatures will be.

Hi,

Post 521, below yesterdays meteo update

UK Outlook for Thursday 6 Oct 2011 to Thursday 20 Oct 2011:

Temperatures are expected to fall back to nearer normal for the time of year across much of the UK by day, dropping below normal at night, especially across the Midlands and southeast, leading to an increased incidence of overnight frosts. The cooler conditions at night will be mitigated by day in some parts by sunnier than normal weather, with both the far south and far north of the country favoured to see above normal amounts of sunshine, with nearer normal sunshine hours elsewhere. Rainfall amounts are correspondingly likely to be a little below average in most areas, especially in the west.

Updated: 1209 on Thu 22 Sep 2011

To me going from night time temperatures of 14/15/16c to possibly below freezing is a lot colder. Yes fair play it says cooler not colder, but i think what we believe the meaning of colder/cooler to be should be left to our own personal interpretation. It's more of a case of being pedantic rather than asking for accuracy.

Thanks.

[Geordiesnow]

UKMO looks like the output that turns mouthwatering charts into something that could into something more bogstandard, by 120 hours the Atlantic is trying to make inroads and Northern Ireland, Western Scotland and perhaps NW England would see alot more cloud with perhaps some rain although the ECM and perhaps the GFS suggests the front may stay to the west.

Just a bit of a cautious message before people talking about lengthy heatwave but high pressure is more or less nailed on for Monday and Tuesday although there could be a bit cloud in Southern areas from a dying weather front on Monday although this should melt away as the day goes on I would of thought.

Interesting charts though nonetheless and the further South and East you are, the more room for error you got in terms of sunshine and warmth.

[J10]

Models continue to look very promising for next week. GFS looks very good right through next weekend, ECM looks good to T+168, but the jump to but the jump to t+192 looks a bit quick, (If anything ECM is warmer than the 00Hz run, but not as sustained). As others have said, UKMO not quite as good, but difficult to see how it would go past T+144.

However nothing ailing nailed on, it certainly looks as if is turning noticeably warmer next week, but how warm and extensive the sunshine is a completely different matter.

[Gibby]

A bit busy tonight so just a quickie from me.

The 12zs from the big three tonight continue on from the earlier runs with the weather likely to warm up considerably with high pressure out to the east steering winds from the south up across the UK after the weekend which in itself will be pleasant for many apart from some rain in the far west tomorrow and more widely late Sunday. Thereafter the weather would be dry for all with all models supporting a dry and fairly sunny week by day with temperatures between 7-10C above the daytime norm although where winds fall light overnight fog would readily form. In the long term pressure falls from next weekend with low pressure slipping slowly in from the west as High pressure recedes away drawing in lower temperatures and the chance of rain.

In a nutshell a warm settled week is up and coming. The run to run differences are thankfully well out in FI with unity between the models out to next weekend. UKMO continues to be slightly less favourable for the highest of the temperatures next week with an Atlantic influence in the windflow reserving the highest of the temperatures for the SE.

[Beasterly]

Looking like a possibly exceptionally warm last fews days to September/ start to October, the Midlands record under threat (27c in Coventry in 1985)?

Although Wednesday is currently FI, take a look at the forecasted temperature for Cambridge updated few minutes ago.

http://news.bbc.co.uk/weather/forecast/324

[bluearmy]

Hi,

Post 521, below yesterdays meteo update

UK Outlook for Thursday 6 Oct 2011 to Thursday 20 Oct 2011:

Temperatures are expected to fall back to nearer normal for the time of year across much of the UK by day, dropping below normal at night, especially across the Midlands and southeast, leading to an increased incidence of overnight frosts. The cooler conditions at night will be mitigated by day in some parts by sunnier than normal weather, with both the far south and far north of the country favoured to see above normal amounts of sunshine, with nearer normal sunshine hours elsewhere. Rainfall amounts are correspondingly likely to be a little below average in most areas, especially in the west.

Updated: 1209 on Thu 22 Sep 2011

To me going from night time temperatures of 14/15/16c to possibly below freezing is a lot colder. Yes fair play it says cooler not colder, but i think what we believe the meaning of colder/cooler to be should be left to our own personal interpretation. It's more of a case of being pedantic rather than asking for accuracy.

Thanks.

Jim, i'd always be nervous about quoting the meto 30 dayer beyond tuesday as it updates on a friday, (courtesy of the ecm 30 day run 12z on a thursday) and it often tends to look a bit outdated once we get past the weekend. to be fair, exeter have been rowing back from this 'cooler' october scenario since the fi ens model runs began to drop the idea over the weekend, having looked to offer a quite chilly outlook for early october late last week beyond the upcoming warmth.

[Liam J]

Although Wednesday is currently FI, take a look at the forecasted temperature for Cambridge updated few minutes ago.

http://news.bbc.co.uk/weather/forecast/324

The highest UK temp for September (1906) is 35.6c in South Yorkshire. The highest ever October (1985) temp record is 29.4 in Cambridgeshire.

I don't think we will top those values but there is potential.

http://www.metoffice.gov.uk/climate/uk/extremes/monthly_temperature_country.html

[damianslaw]

After weeks and weeks of unsettled conditions - alas a pattern change. Quite an unusual synoptical output, the atlantic looks exceptionally sluggish - not something you associate with late sept/early octand could well be a sign that the remainder of the autumn will see much settled weather thanks to little energy in the jet, but we will have to wait and see whether this is the start of a pronounced pattern change or just a blip.

In terms of temps, everything will depend on cloud amounts, far too early to be saying 80f is nailed on. Yes there is a chance but only under sustained sunny skies. 75f a more safer bet for favoured SE parts, with low 20's elsewhere, and high teens for the far north of scotland.

Longer term - a very quiet atlantic will help aid retrogression of heights northwestwards - turning a very warm spell into a possibly quite cool one, with likelihood of frost and fog increasing markedly. The charts remind me of Oct 1995 that was a very 'blocked' warm month with much southerly airflow. Would like to know what the NAO/AO forecasts are for October, the synoptical output would suggest negative in both cases at least to start.

ECM tends to do much better than GFS under euro high scenarios, so my eyes will be on ECM model in the coming days, the tropical storm season looks to have stuttered after quite a lively start.

[Frosty.]

The Ecm 12z has thrown a spanner in the longevity of the very warm settled spell by ending it in around 8 days time although much of next week still looks very warm and sunny with S'ly to SE'ly winds although the far north of the uk will have some rain and strong winds next monday, it's a rapidly improving picture from tuesday onwards. The Gfs 12z holds the settled spell for a few days longer but then is eroded by depressions approaching nw scotland and there is even a threat of the the first cold snap making it as far south as scotland in early october but southern britain holds on to higher pressure but with temps returning to normal as the very warm 850's are drained away as we lose the supply of warm winds from southern europe.

[Milhouse]

Although Wednesday is currently FI, take a look at the forecasted temperature for Cambridge updated few minutes ago.

http://news.bbc.co.u...er/forecast/324

Seriously impressive! 27c forecast for Lincoln too, 6c higher than Tuesday which shows how quickly the warmth is set to build.

Edited September 23, 2011 by Milhouse

[summer blizzard]

A few developments have occured today which cast some light on the road ahead.

Firstly, ECWMF now has the warm spell over for all by day 10 with the GFS agreeing at day 12. Both just push the high east as the Jet Stream strengthens but this senario needs to be watched.

Secondly, while the ECWMF senario would yeild 27/28 as a maximum from the 27th-2nd, GFS has the centre of the high over eastern England which despite a very warm airmass would allow minima to fall which in turn prevents maxima getting as high.

All in all, very warm but not record breaking and an output which needs to be monitored.

[Thundery wintry showers]

Quite a few posts note UKMO as "less good", but I think with the flow being almost from due south, rather than a south-westerly, most places would still end up sunny and warm. Indeed, I think that the UKMO setup, with high pressure further east, could well be conducive to higher temperatures than the ECM/GFS, as we'd have a stronger input of airmasses from a long way south and with a bit of breeze temperatures wouldn't fall away as readily overnight. The main issue with the UKMO is the smaller "margin for error", in the sense that if the setup got much further east we'd be more likely to see widespread cloud.

Here's the chart for the 8th October 1995 (a day when large areas of the country had clear blue skies all day)- note how close by the Atlantic lows were:

http://www.wetterzen...00119951008.gif

So as far as I can see the three models are still agreed on some very warm and probably sunny weather for most of the country, but perhaps uncertain for Ireland and western Scotland which will be more subsceptible to fronts/cloud if the UKMO verifies.

[Iceni]

A few developments have occured today which cast some light on the road ahead.

Firstly, ECWMF now has the warm spell over for all by day 10 with the GFS agreeing at day 12. Both just push the high east as the Jet Stream strengthens but this senario needs to be watched.

Secondly, while the ECWMF senario would yeild 27/28 as a maximum from the 27th-2nd, GFS has the centre of the high over eastern England which despite a very warm airmass would allow minima to fall which in turn prevents maxima getting as high.

All in all, very warm but not record breaking and an output which needs to be monitored.

I remember September 18th 1998 being an absolute scorcher — it was my parents' 50th wedding anniversary and we had tables on the lawn for all the guests. I'd put a bottle of red wine on each one but had to bring them all inside again as they were spoiling in the noon sunshine. Today wasn't nearly as hot as that.

[Thundery wintry showers]

The 18th September 1998 was the first day of what turned out to be quite a notable hot dry sunny interlude for many parts of the country. The setup was quite similar but with high pressure positioned further west than any of the three main models are currently showing:

http://www.wetterzen...00119980920.gif

I don't remember that spell too fondly as from the 24th-30th easterly winds brought inceasant stratus to many North Sea areas. However, high pressure was rather further north as well as west on that occasion so I think a spell of easterlies is far less likely to arise into early October from the current progs.

[Thundery wintry showers]

This morning's runs have introduced more of a westerly component to the southerly flow, as well as the GFS/ECM drifting more towards yesterday's UKMO, so for much of Scotland, Ireland and the western side of England and Wales, sunshine and dryness are looking less certain than on yesterday's runs. Central and eastern England are still looking set to be very warm and sunny though, and with a stronger south to south-westerly flow, the GFS shows even higher temperatures late in the week than any of yesterday's runs. .24-25C maxes are shown across a large area on Thursday, and that's before correcting for GFS's tendency to underdo maxima, so some date records may end up under threat.

[Gibby]

Good morning. Here's a look at the 00zs from my perspective.

GFS shows a warm and indeed an increasingly warm southerly flow setting itself up currently. In the short term this is in the form of a southwesterly flow with a lot of cloud and even some rain for western and Northern parts today and again perhaps more extensively later tomorrow. It's from Monday when things warm up more noticeably, a trend that continues on through the week as winds slowly back South to Southeast bringing progressively clearer continental air North over the UK. In weather terms from Monday the SE in particular would see plenty of warm sunshine which extends further North and West through the week replacing any stubborn cloud cover. Then over the weekend the weather breaks down from the west as low pressure nudges the high away east. However, this phase is shown as temporary as after a few days of rain and wind at times an Azores ridge brings a return to drier and warmer conditions once more by the end of the run.

UKMO this morning is a little disappointing in as much as it keeps winds more from a SW quarter for the most part which would serve to bring in more cloud off the adjacent Atlantic for most away from the SE keeping temperatures lower and the best of the real warmth in the SE with most other areas seeing warmer than average temperatures but a lot of cloud.

The Fax Charts show a plume of warm air moving North over the UK in the midweek period with sunny spells and high temperatures for most after the weak troughs of the weekend finally dissipate.

ECM shows less of a SW feed than UKMO so it would extend the sunny skies NW to affect all areas from midweek. As the weekend approaches a new Atlantic cell of high pressure absorbs our European model to leave a centre close to the UK by the end of the run, so although temperatures would slide off a bit with more chance of foggy nights the weather remains set fair with sunny spells and very pleasant conditions for early October.

In summary things still look very good for next week with a dry week virtually everywhere after Monday. What's less clear is the amount of sunshine and what height of temperature the UK is likely to enjoy. As far as GFS and ECM is concerned temperatures will reach the low to mid 70's fahrenheit with ease by midweek with plenty of sunshine for all to enjoy in a south or southeast flow. UKMO on the other hand remains bullish about keeping the high further to our SE maintaining a south to Southwest flow which would serve to bring in more cloud cover off the near Atlantic which could prove stubborn to break up in western and Northern regions, keeping the high temperatures and most sunshine reserved for the east and SE.

[Methuselah]

Thanks for the summary, Gibby...

[Stuart]

Thanks Gibby I likeing reading them Summary