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

[Frosty.]

The GEFS 12z control run shows a lot of warm and bright weather in the week ahead, especially further south, you can add  2 or 3 celsius to these 12pm temps to get the max,, so mid 70's F for the southern half of england and wales until the end of next week with sunny spells and light winds, very good for the last full week in september, a trend to cooler and more unsettled weather across northern uk but it's only a shortlived cool blip for the south by next sunday and early the following week before it warms up again for a while. The further south you, it looks like above average temps and a fair amount of sun but some cloudy weather too, not unbroken sun but more than acceptable for this stage of autumn.

Edited September 21, 2013 by Frosty.

[Man With Beard]

Slipping under the radar a bit - I imagine date records will be under threat tomorrow in places to the east of high ground; 24C has been reached today so on tomorrow's chart (below) I'd expect 25C will be achieved, possibly in places like Newcastle and Aberdeen, could 80F be reached even?

 

Mid-term and enough agreement that we will be on the warmer side until at least T120, so I expect 23C to be reached every day for the next 5 days, the possibility of warmth staying all week remains - cloud amounts tbc but may be less problematic if the winds lose a westerly component which is quite likely after tomorrow

 

 

[Summer Sun]

t216 sees a deep low moving in pushing the cool uppers away

 

[Summer Sun]

Unsettled but not overly cold to start October, blocking also developing to our north east

 

[Frosty.]

The GEFS 12z mean shows a warm and settled start to next week with a mix of clouds and sunny periods but then beyond midweek, the high pressure that we start with gradually drains away as pressure falls from the southwest with the uk coming under the influence of a large slow moving shallow trough so the weather breaking down later with more unsettled conditions and when that happens, the temperatures slide back towards average in the south and a little below average for northern britain, next weekend would be cyclonic with sunshine and showers and longer spells of rain but then the trough fills and pressure begins to rise somewhat across the southeast with a trend to drier and brighter weather with temps around average but feeling pleasant in the sunshine, the north & west of the uk would be more unsettled and cooler with low pressure in control, further into october suggests temperatures in the mid teens celsius for the south and east, between 9-13c across more northern areas with the PFJ edging further south eventually.

Edited September 21, 2013 by Frosty.

[Summer Sun]

NAO slowly moving upwards again as we move into October so its quite possible that after an unsettled end to September and start to October things could improve around 2 weekends time (5th / 6th)

 

[Frosty.]

It's a very interesting Ecm 12z operational run tonight, it stays warm all week further south with generally fine weather with sunny spells, trending more unsettled across the northwest of the uk but fine further south & east, but then by the end of the week, a major breakdown arrives from the west as a slow moving trough pushes east into the uk, I can see where the met office get their mention of thundery rain from as the warmer uppers (T850hPa) is slowly replaced by cooler atlantic air, in that process the atmosphere would be a bit lively so there is a good chance of heavy and thundery rain next weekend with local flooding a risk if the rain pours down for many hours following a dry week, the ecm then really becomes very autumnal with vigorous lows pushing northeast and just shortlived weak ridging separating us from the next low, and the PFJ comes much further south so the uk ends up just about on the cold side of the jet by the end of the month with wet and windy spells and temperatures struggling to reach average.

[Summer Sun]

Latest from Gibby

 

All models show a mild and moist SW flow covering the UK currently with a warm front clearing NE out of Northern Scotland tonight. All areas are prone to extensive cloud cover overnight lowering to modestly high hills with drizzle in places. Tomorrow will see Eastern areas, mostly those in the lee of high ground to the West and South such as parts of Eastern Scotland, East Wales, parts of the Midlands and SE England later. Western hills and coasts will continue to endure the low grey stratus cloud throughout with little chance of brightness here. Through Monday and Tuesday the brightness may extend to other areas for a time with temperatures well above average. By midweek winds of change are shown by the output but it does look as though dramatic changes are unlikely to occur quickly.

 

GFS then shows Low pressure gradually taking shape somewhere near the North of the UK with rain at times developing from later in the week with temperatures falling back somewhat. Thereafter through to the end of the run changeable conditions develop with High pressure parked to the North of the British Isles for much of the time. With the Jet flow to the South Low pressure is pushed across the Atlantic towards the UK bringing rain at times across the UK in temperatures close to normal and maybe a shade below at times in the North.

 

UKMO shows Low pressure developing across Northern Britain at Day 6 with increasingly unsettled weather with rain at times and cooler temperatures.

 

GEM shows a complex situation of developing Low pressure close to the West of the UK with rain breaking out in many places before the end of the week. through the weekend and start of the following week the weather winds up quite a bit with the potential of gales and heavy rain for many for a time.

 

NAVGEM shows deepening Low pressure moving East across Northern Britain late in the run with rain and strong winds spreading across many areas next weekend, most prolific in the North.

 

ECM shows complex Low pressure down to the SW mixing with a new centre to the NW with the whole setup moving bodily NE over the UK next weekend with rain for all, some of which could well be heavy and thundery for a time. By the end of the run Low pressure sits over the UK with rain and showers for all in fresh to strong winds and temperatures no better than average.  

 

The GFS Ensembles shows much of week 1 being relatively warm and dry though with a cooling trend through the second half of the week. The second half of the output shows the risk of rain increasing with Low pressure in close proximity with temperatures much closer the seasonal average for all.

 

The Jet Stream shows the flow just to the North of Scotland currently with it's position maintained for several more days whilst weakening in situ. Later the flow such as it is sinks steadily South ending up South of the UK towards the end of next week and through Week 2 though there is not much unity on any particular outcome at that range.

 

In Summary tonight the trend is well set for a gradual but notable return to more Autumnal conditions later next week and more especially over the weekend and beyond. Pressure and temperatures are both expected to fall steadily over the second half of the coming week with the warmth of the first few days ebbing into cloudier conditions with some rain almost anywhere before the weekend. It then looks like Autumn turns the screw somewhat with the potential for some proper wet and windy Autumn weather as deep Low pressure areas cross the UK as pressure looks like staying High over the Arctic and the Jet flow having moved well South by then.

 

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

[ribster]

Looks like the wheels come off as early as Tuesday on the GFS. So we've gone from 20 summery days (haven't seen one yet due to cloud), to looking forward to snow on the hilltops! 

[Gaz1985]

High pressure in control into Monday

 

 

With good temperatures

 

 

Tuesday still looking warm for most away from the far north 

 

[ribster]

High pressure in control into Monday

 

 

With good temperatures

 

 

Tuesday still looking warm for most away from the far north 

 

You seem to have missed weds, thurs, fri...

[Captain Shortwave]

You seem to have missed weds, thurs, fri...

Wouldn't be any snow anywhere on those charts either, not even for the hermit on the highest peaks of Scotland. Well up to the weekend at least. 

Even the latest GFS would have temperatures in the south in the high teens/low 20s

To plume or not to plume, that is the question.... for the end of the week. GFS 12Z/ECM say yes, latest GFS and UKMO say no.

To be honest anything past Monday still isn't really sorted to be honest as slight changes could mean the difference between a flow from Iberia and a flow from a polar source.

[Dancerwithwings]

You seem to have missed weds, thurs, fri...

[ribster]

Captain and Dancer you've both missed the point... Or perhaps you haven't :-D

[mushymanrob]

well its looking abit clearer this morning. summers last stand is here and will give us a few very nice days (in fact more then most of us had all last summer (12) ) before from wednesday onward theres a gradual deterioration with the south hanging onto anything summery the longest. its set to become unsettled by the end of the week, returning us all into 'normal, average' conditions which look set to stay.

 

so make the most of the sun/warmth, we are unlikely to see temps as high again this side of may 2014 ( and even then thats not guaranteed).

[Captain Shortwave]

Still not much agreement at T144 and hence the weekend is still pretty unknown

GFS

 

UKMO

 

GEM

 

ECM

The ECM is interesting this morning, the Atlantic is struggling to get in as a Scandi high forms

Synoptically with winter in a few months this is nice to see

Edited September 22, 2013 by Captain shortwave

[Frosty.]

The fax charts show the south holding on to some residual warmth until later in the week but the high pressure leaks away so it would slowly, eventually become more unsettled, the far north of the uk becomes much cooler and brighter as a cold front drifts south on tuesday bringing a band of light rain, as the front pushes further south into the warmer airmass it develops a wave feature which peps up the front with heavy rain a risk for the northeast by the middle of the week,. In the meantime, becoming warm with clouds becoming more broken, especially to the east of high ground where temperatures today could reach 23-24c, tomorrow could be even warmer with 25c for favoured spots and on tuesday the south /se could reach 26c 79f but then it looks like a gradual deterioration will occur for all areas with temperatures drifting down towards average in the south and cooler further north where winds briefly swing around to a N'ly or NEly for midweek.

Edited September 22, 2013 by Frosty.

[Summer Sun]

Here is the latest from Gibby

 

Good morning. Here is today's and this week's extended look at the midnight outputs of GFS, UKMO, GEM, NAVGEM and ECM for today Sunday September 22nd 2013.

 

The General Situation. A broad and warm SW flow covers the UK on the NW flank of High pressure close to South Eastern Britain. With the air very moist in it's lowest levels a lot of low cloud, mist and hill fog affects many upland areas of the UK and will continue to do so for a while to come. Well inland and in the East the cloud should break with some warm sunshine over the coming few days with temperatures well above average. Towards the middle of the week pressure is shown by all models to begin to fall with details in weather conditions at the surface very hard to pin down currently as slack pressure develops over the UK. This should mean temperatures slowly falling away to average with areas of cloud drifting South over the North as well as up from the SW. This will bring some outbreaks of rain almost anywhere by the latter days of the week as pressure continues to fall. By the weekend most output shows Low pressure forming somewhere near the North or West of the UK with rain moving NE in strengthening South or SW winds in average temperatures.

 

The GFS operational this morning shows slack conditions persisting well into next weekend with no one pressure system High r Low having overall control over the UK weather. As such there will still be a lot of dry weather around with just patchy outbreaks of rain in what would most likely cloudy and misty conditions. It's not until well into the following week when conditions deteriorate more markedly as Atlantic low pressure more meaningfully crosses the UK with windier and wet conditions for all towards the end of the run in average temperatures.

 

UKMO today shows a cocktail of weak troughs over the UK next weekend having either fed down from the North or up from the SW. As a result there will be patchy rain spread about over the UK with almost anywhere at risk of some showery outbreaks from cloudy skies. By the end of the run it does look like a more organised area of rain will form over the North as Low pressure develops there.

 

GEM is also slow to deliver Low pressure in any meaningful sense to the British Isles this morning with the benign pattern of rather cloudy weather late in the week with patchy rain lasting into the weekend. Banks of Low pressure are queing up in the Atlantic and they make there move early next week with marked and substantial areas of rain moving bodily East and NE through the British Isles then with some heavy rain for all along with strengthening winds from the SW innitially but turning NE from the North by Day 10 as substantially colder air arrives from the North.

 

NAVGEM today shows Low pressure gradually becoming more dominant over the British isles next weekend as systems move NE across the UK. At the same time a deep Low forms West of the UK and looks set to swing NE over the UK early next week with rain and strong winds likely for all then in temperatures close to average in mostly overcast conditions.

 

ECM also shows Low pressure strengthening close to the West and SW late this coming week and more especially over the weekend. After a cloudy end to the week with patchy outbreaks of rain the weather looks like turning decidedly wet and windy before the start of next week as troughs cross the UK from the SW with a strong and chilly SE flow shown affecting the North by midweek next week. the heaviest rain looks like affecting the South and West though all areas are at

risk from some in temperatures close to average overall.

 

The GFS Ensembles point towards a more changeable pattern developing over the UK from the 27th in the South and before in the North. In the interim period the warm uppers currently felt will dissolve away back towards the seasonal average by the end of the week, a level at which they are generally maintained thereafter. Some members indicate some quite wet periods through Week 2 when 10mm plus could fall on some days both North and South of the UK.

 

The Jet Stream driving this pattern shift is complex this morning with the general consensus being that the flow weakens to the North of the UK later this week to relocate at a more Southerly point across the Atlantic where it is then steered NE across the UK, probably close to Southern England from next weekend.

 

In Summary this morning the models are again struggling to deal with complex synoptics as Autumn 2013 digs it's heals in. With pressure fairly high over the Arctic with time the Jet Stream is forced South opening the door to the engagement of cool Autumnal air well formed to the north of the UK with the tropical maritime air out to the SW of the UK. The potential for some quite potent depressions and areas of attendant heavy rainfall is very real by next weekend but in the short term things look like remaining quite benign if rather cloudy with patchy rain late in the week. After a period of warm temperatures early in the week temperatures will fall back to levels we would normally expect at this time of year by the end of the week. As we look deeper into the following week it looks like a classic October setup could develop with deep low pressure areas tracking across the Atlantic and ending up near or over the UK with heavy rain and potential gales at times. There is some hesitancy in taking these depressions right across to exit East of the UK though and if things happen as shown it could feel quite warm and humid in the SE at times. However, if a GEM type route is taken cold northerlies could blow down over the UK in the wake of the depressions and bring some very cool air down from the North with wintry showers over Northern hills. So taking everything into account there is something for everyone in todays extended report with a lot of scope for changes as the day to day detail looks impossible to account for at the moment beyond the general trend.

 

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

Edited September 22, 2013 by Summer Sun

[Frosty.]

A warmer Ecm 00z overall compared to last night's 12z, the main difference being the trough later in the week is held back to the southwest which enables warmer, humid continental air to drift north across the uk and reinforce the warmth which never leaves the southern half of the uk in the week ahead, this run is also significantly warmer for the north than last night, only the very far north flirting with cooler air at times, it looks like eventually becoming more unsettled across all areas with heavy rain and a risk of thunder but also some warm sunshine at times, the warmest and sunniest weather looks like being during the next few days but with cloudier spells, then some slight relaxation in the warmth but feeling rather humid so it could actually feel warmer and then another pulse of warmth pushing north later in the week along with an increasing risk of thundery showers or more persistent heavy rain spreading from the south & west.

[Tamara]

There are variations on what is essentially the same theme this morning and it has been interesting to see how the models have been resolving the conflict between the opposing ferrel and polar converging cells - with the UK, as often is the case, the potential crossroads in the middle. The EPS members actually give very good agreement to the SW originated breakdown as a quite slow process later this week

 

It was mentioned the other day about how progressive the models can be with these signals and with that in mind then the majority of this week will be quite reasonable and quite warm for the time of year before showery rain arrives, to some lesser or greater extent.

 

Thereafter indicates the arrival of the much signalled unsettled phase, but, at least as of this point in time, the chances remain that we could cyclically return to more settled conditions again as we get into October. The blocking signal to the NE continues to look interesting into the further outlook too - so hopefully that will mean increased snow cover over the Siberian side of the arctic where the greatest (and increasing) cold pooling is set to be to take us into the start of October

 

[Frosty.]

The ECM 00z ensemble mean shows the weather continuing on the warm side all week, especially across the southern half of england & wales, although the warmth does ebb away slowly compared to early in the week, temperatures would continue to be above the seasonal average until the following week, the general synopsis is we start the week under anticyclonic conditions but as we go through the week the high pressure will be leaking away although a weak ridge pushes southwestwards across the far northeast with cooler air filtering south behind a weak cold front and at the same time, a large trough will be edging in from the southwest approaches and gradually taking over by next weekend onwards but with winds generally from a SEly point, we would continue to draw in warm and humid air from the near continent into the  circulation of that trough, as the trough moves further into the uk, the warm and humid air would be slowly mixed out by more of an atlantic influence but with winds veering towards a sw'ly quarter, temperatures would remain decent for early october. So in summary, starting settled and warm, locally very warm, and then slowly trending more and more unsettled with a mixture of sunny periods, heavy showers and more persistent heavy rain  with a risk of thunder and remaining on the warm side of average across much of the uk, rather humid too, at least for the southern half of the BI until the following week..according to this run, which actually looks very similar to the Ecm 00z op which was also warm.

[phil nw.]

Not a straightforward setup for the coming week with a number of cut off lows modeled in the Atlantic reflecting the weak and disjointed Atlantic jet.

If we view the NH pattern we can see the bulk of the Polar Vortex and stronger jet is located over the Pacific side leaving gaps for some Height anomalies to our north

 

 

so a fairly quiet week to come with little rain about even though pressure will fall away gradually.

 

 

i think for many of us this last part of September will continue quite dry and warm in spite of some weak frontal systems nearby at times.The Atlantic yet to stir into full Autumnal gear,it will come come soon enough as the PV develops through October i am sure.

 

[Frosty.]

The GFS 06z operational run starts and ends anticyclonic..the week ahead is showing a rather warm and humid spell with variable amounts of cloud and sunshine although there should be an increase in sunshine during the coming few days with less overcast conditions overall, so london should be brighter by tomorrow onwards for example, as I said, a warm week with temperatures in the low 20's celsius and a moist humid sw'ly airflow slowly backing more southerly to se'ly as time goes on, the only areas missing the warmth will be the very far north where cooler air will filter down from the north behind a weak cold front and it also looks like most of the rain in the coming week will be across the northern half of scotland due to slow moving fronts which occasionally intensify as more moisture is injected into the flow at times but for the majority of the uk it's a very good last full week of september with above average temperatures, sunny spells and rather cloudy or misty warm muggy nights with temps no lower than the low to mid teens celsius. By next weekend it will probably be turning more unsettled as a trough edges up from the south/sw but a weak ridge building across the far northeast should eventually turn those areas drier and brighter by the weekend but for many, eventually a trough dominated pattern becoming established with temperatures slowly returning to average and slightly below in the most persistently wet areas, winds also increasing so a more autumnal feel after the week ahead, quite a locked in unsettled looking pattern for a time with high pressure in the atlantic and high pressure further east over europe but a slow moving trough in situ, however, eventually that trough fills and the atlantic high ridges into the uk with a more settled spell later in the run but a cooler high with a risk of overnight ground frosts and thick fog patches.

Edited September 22, 2013 by Frosty.

[Captain Shortwave]

Looks like the south will remain warm for the whole of this week, shown by both the GFS and UKMO runs, though I have to admit it's a little frustrating that we are dealing with scraps (20-23C for most of the week but higher tomorrow and Tuesday), meanwhile France looks like becoming hot with temperatures approaching 30C, case of so close but yet so far. But still decent for the Midlands southwards. The set up looks very messy, with the UK under a slack flow between the South and East for the majority of the week with some rain or showers from time to time with an area in Northern England/Southern Scotland being the line between the two air masses and probably having a rather damp and grey week at times.

[Summer Sun]

UKMO continues to keep pressure lower for the end of the week but with no deep lows in sight a lot of places should continue to see sunshine at some point

 

 

The south never really cools down much this week with temperatures back into the low 20's by Friday

 

 

 

 

Even into next week temperature remain high for a lot of us