Model Output Discussion - September Onwards

[snowlover2009]

I think any mild spell, if it comes after the blip next week, will be are average, sort of October mild spell, maybe something similar to end October 2009, maybe a tad less mild, as that was quite big mild spell for the time of year, wasn't it? This spell at the moment is an historic event, so any hope of another rinse and repeat will leave people disappointed, maybe low 20s possible in odd favoured spots in the south, if we get another major ridge, but I can't see it. The current pattern apparently is caused by an amplification of the jet, which produces intermittent ridges and troughs and giving north to south or south to north air movements ( known as meridional flow) as opposed to the regular west to east flow. Where these ridges and troughs are situatated dictate what type of airstream one is in. Either record breaking warmth (like now) or cold released from the poles (forecast). So the recent cold runs from gfs in FI and the colder ensembles on the models, maybe onto something. Could be an interesting month weather wise.

Edited September 30, 2011 by snowlover2009
It's common courtesy to acknowledge someone when quoting them

[Liam J]

A very unsettled ECM 12z run with LP systems racing across the North of the uk bringing cool wet and windy weather much more typical for the time of year, although areas further south and east may hold onto to less unsettled conditions at times.

[summer blizzard]

Looks to me as if the morning runs were likely outliers with both ECWMF and GFS12z runs ending the warm spell at day 6 although they do keep the Azores High close afterward.

[Frosty.]

The Ecm is really struggling today, the 12z bears no relation to the 00z and it seems the scandi trough is the main reason because the models still don't quite know what impact it will have, as for the ecm 12z, it looks like turning into an unsettled run with low..ridge..low etc etc whereas the Gfs 12z is a week of two halves with a reasonable first half with temps lower but still comfortably into the low 70's as the 850's still look warm but cooler across northern britain with some rain and showers with stronger W'ly winds, a vigorous depression rushing in off the atlantic next wednesday will bring an unsettled few days nationwide but then the gfs wants to settle things down again and we again import warm winds from southern europe but there is a sting in the tail of the gfs 12z with a shock Northerly and then some rather wintry synoptics late in FI but it's so far ahead and not worth taking seriously.

[Gibby]

A little late tonight and no report in the morning as too busy but should be OK for the 12zs

.

GFS tonight shows the current hot spell in the South ending on Monday as the current pressure pattern changes to High pressure to the South with a developing Westerly flow in association with Low pressure to the North. A cold front crosses on Monday lowering temperatures and again on Thursday with some rain in places as it passes, chiefly in the North. Behind the fronts pressure rises with a High pressure area slipping eastwards over the UK bringing dry and bright weather with some cool misty nights with local frost. After a few more dry, pleasant days in association with the high pressure shifting towards Scandinavia. Towards the end of the run pressure builds in the Mid Atlantic with further High pressure over Greenland pulling a very cold Northerly flow down across the UK with some wintry showers over Northern and Eastern areas with more general cold and unsettled conditions at the expiry of the run.

UKMO tonight also shows the cooler weather arriving early next week with a fresh westerly wind picking up and much more cloud bringing temperatures down to levels nearer the early October average. With regard to rainfall, amounts will be small for most areas but a little more appreciable in the North.

ECM also looks much more seasonal tonight. Following the other models cooler air spreads over the South late Monday/Tuesday with all areas becoming breezy and changeable though the remainder of next week. After the innitial cooling of the weather a further drop in temperature takes place over Thursday as a cold front crosses east with some rain. Behind it NW winds bring cool and breezy conditions with occasional rain to all areas at times as the run ends.

Tonight sees unity between the models in as much as our late summery spell ends on Monday. Thereafter a period of Westerly or Northwesterly winds looks likely with progressively cooler conditions towards the end of next week. High pressure looks like being to the SW though far enough away to allow at least a little rain in the south at times.

[Frosty.]

What a beautiful chart after all this heat, that would bring snow to most of scotland and frosty nights to all areas, and then continuing on the cold side with a threat of further northerly outbreaks later in the month..shame it's so far out.

[J10]

I think perceptions of summers tend to be biased towards the latter part of the summer. This year's summer is now routinely described as "dreadful", and I might just about agree with that if we were talking about August, but in truth rainfall and sunshine were both close to average for most of us during June and July.

100% agree, especially with the first sentence.

Back to the models and the inevitable end to this warm spell is now very much on the cards, but it does like like staying warm and sunny over S and E parts for much of the weekend.

[summer blizzard]

The Ecm is really struggling today, the 12z bears no relation to the 00z and it seems the scandi trough is the main reason because the models still don't quite know what impact it will have, as for the ecm 12z, it looks like turning into an unsettled run with low..ridge..low etc etc whereas the Gfs 12z is a week of two halves with a reasonable first half with temps lower but still comfortably into the low 70's as the 850's still look warm but cooler across northern britain with some rain and showers with stronger W'ly winds, a vigorous depression rushing in off the atlantic next wednesday will bring an unsettled few days nationwide but then the gfs wants to settle things down again and we again import warm winds from southern europe but there is a sting in the tail of the gfs 12z with a shock Northerly and then some rather wintry synoptics late in FI but it's so far ahead and not worth taking seriously.

I suspect that the reason for the sudden confusion is the recurving Hurricane Ophelia which has seen rapid development unlike the moderate development forecast (it strengthened by 50mph in 24 hours to become a major category 3 hurricane). This is obviously going to put more energy into the Jet Stream than previous modeling expected.

[johnholmes]

very true re the effect any hurricane may have. No model for weather of more than 10 days away has yet been created that adequately factors in that far ahead the possible effects.

We just have been very lucky, away from NW areas of the UK, that one did not upset the pattern of the current hot and sunny spell.

[mountain shadow]

A shock to the system in about a week of the overnight models are to be trusted, a colder northerly plunge with below average temps and the first snow for the higher peaks.

As an aside, where is my Netweather weather warning for rain this afternoon?, the Met Office have given me one.

[Frosty.]

The models are starting to look a lot more unsettled for most of the next few weeks compared to yesterday when high pressure had the upper hand, the week ahead will see three depressions crossing the uk, the first will only really affect the north but the front will make it to southeast england by tuesday night or wednesday with rain for southeast england midweek, the second depression will arrive during wednesday to nw scotland and the third will arrive next friday, it look like next weekend will be a lot cooler and windier with rain and showers..the further outlook appears mixed with rapid changes in airmass and short lived ridges rushing east being chased by depressions as we get further into october. The current hot spell will begin to fragment tomorrow but will hang on for dear life until monday evening across the far southeast but with more cloud spreading down across england and more breeze. Tomorrow there looks like being a lot of rain across the lake district, durham and northumberland into southern scotland.

[Strider]

Model agreement and continuity still looks very poor to me. GFS esembles are all over the place post 5th Oct. I don't think any conclusions can be drawn about the weather post 5th

[gottolovethisweather]

Hi Gavin D and others.

I'm no expert but I suspect even the MetO supercomputers can't be sure what the weather will be like in 15 days time.

FI is on the whole, usually placed within the range of 5 to 10 day's ahead, so I do feel (not a personal attack here, Gavin ) looking forward at a 15 to 30 days timescale is PURE AND SIMPLE MADNESS. Surely just plain ole statistical flaws, butterfly effects, sudden weather impacts, chaos theory and all manner of other effects will take their toll here.

Anyway, enough ranting and if your prediction of a settled start to October comes off then I'll be happy and especially well done for continously saying it would happen if it does so.

Extra special thanks to the likes of Gibby for keeping the thread going through the desperate summer period.

Kind Regards

gottolovethisweather

Well, I shouldn't really reply to my own posting but I feel I need to admit to something here, "me and my big mouth" springs to mind. Supercomputers can and do correctly interpret the weather, even at t+15 day (360 hours!) range. Gavin D did get it right! Expected chaos theory effects etc., call them what you like, on occasion, do not have a dramatic effect on future climatic conditions.

Anyway, that's off my chest, what of the future? A gradual cool down to near normal temperatures after early next week. Unsettled, particularly further north and west, driest and warmest in the southeast. Pretty average stuff it seems.

Cheers all.

gottolovethisweather

Edited October 1, 2011 by gottolovethisweather

[Thundery wintry showers]

There is a stark contrast between different sides of the NW-SE divide at present, and it looks like here in Cleadon the frontal system will just manage to hold off enough to allow another hot, sunny and (for October) record-breaking day here. Further south across England and Wales things remain set for some records to tumble, but Scotland is already much cooler and cloudier. Tomorrow the main rain belt is set to sink SE so northern England will have a cloudy damp day, but the southern half of England will end up almost as hot as today. On Monday the divide will become a little extreme with the rain fizzling out across northern areas and the south becoming a little less hot.

The mid to latter part of the week will see a rather more "normal" early-October pattern, and for Tuesday those fronts will finally clear out of the way of northern areas leaving a brighter showery day. There are strong signals for a persistent Scandinavian trough, but as long as pressure remains high over Europe we are unlikely to see many northerlies this side of the 10th October and temperatures are thus likely to stay a little above the long-term average. I am expecting colder weather to start to establish towards midmonth.

[Frosty.]

The Gfs 06z shows the very warm 850's lingering across southern england until thursday before briefly being blown away from the uk but soon warming up again through next weekend into the following week, furthern north across the uk an unsettled and cooler spell is just about nailed on but it could well be replaced by another anticyclonic spell soon after. Into FI indicates a fast moving fluid weather pattern with warm days and colder days with some polar maritime air, especially for the north but this run is so different to the gfs 00z that it's no more likely than the earlier run.

[Frosty.]

Crack open the champagne..the october 1st 1985 record high temp has been smashed..currently 30c 86f in gravesend and scope for it to go a notch higher! the models show southern england remaining warm or very warm until next thursday but several degrees down on today by mon/tues but still well above the seasonal average..turning cooler elsewhere and windy with rain and showers, at least for a few days before high pressure builds yet again?????

[rob48]

Well, I shouldn't really reply to my own posting but I feel I need to admit to something here, "me and my big mouth" springs to mind. Supercomputers can and do correctly interpret the weather, even at t+15 day (360 hours!) range. Gavin D did get it right! Expected chaos theory effects etc., call them what you like, on occasion, do not have a dramatic effect on future climatic conditions.

Anyway, that's off my chest, what of the future? A gradual cool down to near normal temperatures after early next week. Unsettled, particularly further north and west, driest and warmest in the southeast. Pretty average stuff it seems.

Cheers all.

gottolovethisweather

If you continually predict hot weather "next week" every week for five months, eventually you'll get one right.

Pity we didn't have this heat when he was forecasting it in July, rather than spoiling the week just gone.

[Summer Sun]

If you continually predict hot weather "next week" every week for five months, eventually you'll get one right.

Pity we didn't have this heat when he was forecasting it in July, rather than spoiling the week just gone.

About time FI got it right for once, it don't happen often,

A new record has been set and it's NOT Gravesend, it's..........

Cambridge at 30c

Edited October 1, 2011 by Gavin D

[summer blizzard]

There are threads for the temperature in different sections of the forum.

In regards to the models, GFS and GEM have us below average at day 5 and ECWMF at day 6. Afterward it does seem as if there is a clot of confusion with some runs maintaing a cool, wet pattern and others attempting to reset, possibly relating to whether Tropical Storm Phillipe recurves or not.

[Gibby]

Good evening folks.

GFS tonight shows Westerly winds developing over the UK by Monday with cooler air flooding in from off the Atlantic also bringing an increase of cloud too. Rain over Northern regions from a cold front tomorrow moves away east leaving all areas with similar weather. Through the week winds continue to freshen with a cold front crossing east late Wednesday into Thursday followed by a cool NW flow with showers for Northern and Eastern regions with snow on Scottish mountains. By the weekend and into FI high pressure drifts east to the South of the UK with a further surge of warm air for a while for Southern and Eastern Britain while the North and West continue to see more cloud and some rain. This extends South and East at times but total amounts of rain in the South look likely to be very small.

UKMO shows the same Westerly flow extending to all parts by Tuesday lowering temperatures steadily as the wind and increases of cloud extend fresher Atlantic origin air over the UK. Through the midweek period a fast moving cold front crosses SE over the UK dropping temperatures to normal or below with sunshine and showers following a short period of rain for most places, especially in the North and West. The end of the week sees High pressure to the SW with a rather cloudy Westerly airflow with temperatures back to the seasonal norm.

ECM tonight also shows the big cool down for England and Wales after tomorrow with rather cloudy and breezy westerly winds developing though a lot of dry weather still. Tomorrows rain in the North and West decays and moves away East tomorrow night. as the week progresses a cold front crosses Wednesday night with a short band of rain for all. Behind it winds turn into the NW and eventually the North bringing very chilly air South to all areas with showers in the North falling as snow over Scottish mountains later, this weather type continuing through next weekend. In any overnight clear skies frost would likely occur in all low lying areas nationwide late in the week an over the weekend. The run ends with Low pressure out to the east and High to the SW with an unstable and cool NW wind for most and the risk of some showers, chiefly for the east.

Tonight sees a real 'Pot Pourri' of offerings from the models. GFS takes us back into a further warm up after next week, though it is important to add that any such warm up would not reach the dizzy heights of the last few days. In the meantime the model shows significantly cooler conditions as we progress through next week with at least a little rain in most places at some point. The Euro's tonight show the cool down too but as far as ECM is concerned extend the period of cool NW then North winds behind the trough on Wednesday night. If their run verifies daytime temperature next Saturday over parts of Eastern England could be some 16-17C lower than this Saturday. However, the main message tonight is a transfer into more standard Autumn fayre as we move through next week.

[phil nw.]

12z run shows that the end is in sight of this remakable heat--even for the South.

T72hrs show a much cooler flow from the West establishing as low pressure moves across towards Scandi and the High recedes over the continent.

http://www.wetterzen...ics/Rukm721.gif

http://www.wetterzen...cs/Rtavn722.png

http://www.wetterzen...ics/Recm722.gif

Monday looks to be the last really warm day down here and thereafter. all of the UK. joins those from further North in experiencing temperatures much nearer to the October average.

Edited October 1, 2011 by phil n.warks.

[Frosty.]

Major disagreement tonight between the gfs & ecm 12z op runs...the gfs run reminded me of what a good summer would look like with prolonged warm anticyclonic weather dominating and it seems the gfs run does not want to let summer go but the ecm does, the main problem for both models is with the anticyclone to the southwest of the uk at the end of next week, the ecm keeps it at arms length and has a lot more faith in the scandi trough being a major player by the end of next week whereas the gfs shunts it out of the way with another high which again brings a very warm spell although not as hot as currently..so there are a few problems to iron out and hopefully both models will be in agreement either tomorrow or monday. As for today, it's nice to see a 26 year old record smashed and funnily enough, it may be a degree hotter in the southeast tomorrow but then it's a downward trend, 27c in the southeast on monday but probably the low 20's by tuesday and the T850's take a nosedive by thursday but then where do we go? another very warm settled spell or something much more average.

[Weather Boy]

Well the 0z seems (judging from earlier postings) to be fairly consistent with previous runs, in showing a brief windy and unsettled spells mid to late in the week, followed by a significant re-build of pressure from the south, eventually warming up again with temps of 20-23 at a guess. However, the ECM and indeed the UKMO are far more reserved about such a move and tend towards a continuation of the unsettled weather, rather than the blip that the GFS shows. It will be interesting to see which one backs down. You'd imagine that, following comments on the ECM's performance lately that the GFS will win the day, but time will tell.

[Frosty.]

The Gfs 00z looks almost identical to the 12z yesterday, it's like a stuck record and shows a return of very warm anticyclonic weather after a brief cooler blip. It will cool down everywhere in the next few days but the degree of change is still uncertain. The ecm and gfs are in just as much disagreement as they were last night, the ecm 00z has a more significant cool plunge whereas the gfs is more of a glancing blow before high pressure builds back into the uk. The ecm keeps the azores high in the azores although it does bring high pressure towards day 10 but with a much cooler airmass over the uk with frost and fog rather than the gfs with it's warm clear nights and very warm sunny days.

[Gibby]

Good morning folks. Here's todays look at the 00zs.

GFS this morning shows a slow cool down over the next few days as winds become westerly drawing in cooler and more cloudy Atlantic air with time. Later in the week a cold front crosses east with a little rain for all followed by cool and showery NW winds. Night times would become chilly with the chance of frost in low lying areas overnight and snow showers on the top of the mountains of Scotlands.. Over next week and beyond the charts are characterized by High pressure close to the South with Westerly winds further North. In weather terms this would mean precious little rain at all for the South and temperatures could rise above normal again at times while the North is more unsettled and breezy with some rain but never a wash out even here.

The GFS Ensembles put the operational above right on top of the pack from the 9th to the 13th while most members prefer to keep the temperatures close to the seasonal average while maintaining lower than average rain in the South.

UKMO brings the slow drop in temperature too for the South in the next few days while the very wet weather in the North becomes less extensive over the next 48hrs. By midweek a cold front sweeps east bringing any remaining above average temperatures in the SE back down to the seasonal norm at the same time as bringing a band of rain eastwards. Behind the front winds would turn NW and be quite strong for a while bringing rather cool conditions and showers to most areas, heaviest in the North. A ridge of High pressure approaches Western Britain by Saturday.

The Fax Charts show weak and decaying cold fronts crossing Southern areas over the next 48hrs gently lowering temperatures and displacing the continental air mass with fresher Atlantic air. A front is shown crossing midweek with cool and fresh and somewhat showery NW flow behind.

ECM continues to show a more sustained breakdown later in the week following the cold front Wednesday/Thursday. Instead it shows the cool and showery NW flow late in the week giving way to further frontal activity and eventual Low pressure moving down off the Northern North Atlantic. So rain at times would develop for all from the weekend with temperatures near to or maybe somewhat below normal especially in the North and NE. Very late in the run High pressure drifts in off the Atlantic behind the Low and could offer a cool, frosty and foggy spell should it verify.

All the models continue to offer a variety of options for the period later this week and beyond. GFS, not for the first time wants to keep things settled and dry and still on the warm side at times in the South while ECM wants to make things much more Autumnal late next week and through the weekend with some rain for all before a cool High pressure developing behind would bring us our first widespread hoar frost and fog by midweek following. We have to wait for future outputs to see which model backs down to the others way of thinking or whether a different resolution develops.