Model Output Discussion - September Onwards

[Backtrack]

GEM also refuses the high pressure entry to the UK and at 240 hours out, it is as good as the ECWMF.

It may get warmer this weekend however there is no guarantee it will be dry or sunny.

GFS just needs to shift the high pressure Westwards by a couple hundred miles, and with it being so far out it's likely to move. Whether that is towards us is to be seen :lol:

Then again, with it been so far out it could disappear all together.

[Radiating Dendrite]

Would love that ECM chart in the middle of winter!

At that time frame the positioning of a high is always going to be different between the models. Reading between the line all we can say is that high pressure may form to our East, possibly allowing a southerly flow and some warmer uppers (10+).

Edited September 20, 2011 by Radiating Dendrite

[Frosty.]

The Ecm is refusing to drop the idea of a hot/humid spell next week with temps of 25c and higher in the southeast but the gfs 06z is again more reluctant and maintains the unsettled pattern across nw britain throughout, also a hint on the 6z of an early october brief cold snap for the north and pressure does look generally higher in FI but the 6z still shows depressions tracking across the north with the main high pressure further south. The latest meto is not suggesting hot southerly winds from spain/africa but it does indicate that pressure will generally rise and there will be some warm sunny days but with chilly nights and increasing frost risk with mist/fog. In the reliable timeframe it's very much looking like a nw / se split with the south & east of england becoming warmer and drier later this week and weekend with plenty of sunshine but the north & west remaining unsettled as lows continue to track towards nw scotland although probably with less frequency as time goes on.

[Gibby]

Good evening. From a very wet SW England tonight here's a look at the 12zs from GFS, UKMO and ECM.

GFS this evening shows the cold front currently moving slowly SE over Southern Britain clearing away from the SE tomorrow with a brisk westerly flow and showers in Northern and Western areas. By Thursday strong winds and rain move into Northern Britain, gradually spreading SE through the UK but weakening as it goes. By the weekend another front crosses east through the UK with some rain for all for a while. As we move through next week warmer air will extend North and East over the UK but with modification to be rather cloudy as fronts continue to run close to the west and North with rain at times while areas further south would see a lot of dry weather but a lot of cloud too before a spell of wind and rain runs east through the UK at the end of next week. In the far reaches of FI a new high develops this time from the Azores and brings light winds for all with bright and dry weather too though without the southerly feed of previous runs less warm by day and possibly chilly, misty nights.

UKMO is showing the same pattern it has for several days now with the current cold front over the South clearing away tomorrow leaving a breezy westerly flow with showers for the North and West. Things become wet and windy on Thursday in the NW while the South remains mostly dry and breezy. With time over the next 48hrs winds back SW with warmer conditions extending North and East with another front crossing East on Saturday with some rain for all. Following this the weather becomes quite pleasant on Sunday and Monday while the NW becomes wet and windy yet again.

ECM tonight shows a similar picture to its recent output with the main event being that temperatures are likely to rise as we move into next week. The weather remains pretty changeable with rain and wind in abundance for the NW while the south and east see much drier and some times brighter weather. Tonight though shows an extra incidence of rain for the south than previously with Monday joining Saturday when some rain could fall even in the SE. Following that and on to the end of the run High pressure crosses east through the UK and on out into Scandinavia setting up a very warm southerly flow by the end of next week with the chance of some very high temperatures and some thundery showers in the SW by next Friday.

There has been some slight modifications to the late summer spell originally progged for next week. Things are still shown to get warmer, significantly so from ECM whereas GFS after giving the UK a warm south or SW flow for a while replaces the European High with an Azores model moving into the UK following a brief spell of rain and wind sustaining dry weather but not necessarily producing the high temperatures that a continuation of the European High would. In a nutshell tonight there is still fragility shown in the nature of what type of weather we will get under the warm weather next week. It doesn't always follow that warm southerly winds mean an Indian summer type heatwave in Autumn.

[damianslaw]

BBC seem confident in the suggested pattern change being shown by ECM this eve verifying next week. But it is no means a dead cert next week will turn out to be dry and settled and warm - subtle variations in the positioning of heights will make a significant difference- GFS would bring a shot of warm uppers but followed by cooler uppers with some colder nights, ECM promises a very warm spell but one which could very quickly switch to cold as lower heights from the sw are forced to undercut these heights. Warm southerlies can often quickly transfer into cold northerlies...

[snowlover2009]

The ecm is cracking, will it be a sunny high? I have my doubts, I do find it interesting though. The orientation of the high would bring bitter cold to the UK. If the ecm verifies, it will be a pretty warm end to september for the time of year and by the end of the first week of october, it could quite possibly end up being the opposite, by that i mean very cool air pushing in afterwards. The northern blocking which cfs and net weather are suggesting looks to be setting in after the warm spell, if these charts are to go by. One final round of summer and that is probably going to be as good as it gets till next spring.

[MP-R]

What we would give to get this in summer! :

Alas it is autumn but nice to look at anyway. Current GFS run is a remarkably warm one but increasingly wet further west in the realiable timeframe.

[mushymanrob]

typical.... ideal summer synoptics arrive too late to be of any use

[Gibby]

Good morning. Here's my take on the morning output from GFS, UKMO, the Fax Charts and ECM.

GFS this morning continues the theme as before in generally keeping a breezy spell of weather for the next few days with some heavy rain for the NW today in association with a cold front. A weaker cold front is just exiting SE England so the damp weather here should depart soon to leave a bright and breezy day in the south. This looks like lasting tomorrow and Friday too with a steady warm up in temperatures from the South. Over the weekend and again on Monday troughs bring some rain east briefly to all parts with dry, bright and reasonably warm weather inbetween. Next week then develops into a warm and increasingly humid week with a lot of cloud, but little rain away from the NW and some brighter, perhaps sunnier moments for areas towards the SE. This all due to high pressure over Europe fending off Atlantic troughs from all but the far NW. Well into FI pressure remains high to the east and then NE with fine warm SE winds for most with the chance of some thundery rain in the SW at times.

UKMO also shows the same pattern with a lot of dry weather to be had for the South and East though with two potential rain events on Saturday and possibly again on Monday. Further North and West the weather remains changeable with periods of wind, rain and showers at frequent intervals. With time temperatures will be on the rise as warmer air feeds up from the South over most areas by next week.

The Fax Charts today show decaying fronts today and tomorrow near Southern Britain dissolve away by Friday while the NW sees active waving frontal troughs continue to deliver spells of heavy rain on occasions in strong SW winds. Over the weekend a slow moving cold front not dissimilar to yesterdays front meanders SE over Southern Britain delivering some rain for most at some stage on Saturday slow to clear.

ECM once more follows the pattern of the other two up to Monday of next week with rain events likely for the South on Saturday and Monday as cold fronts move NE or east over the UK. In between some dry bright weather would occur here while the North and West stay windy and wet at times. Through this coming weekend it becomes reasonably warm and humid as warm air is pulled North and East from Southern latitudes, a process that continues through next week although on this run the warmest air is held east of the UK with Low pressure close enough to Western Britain to keep things very unsettled in the NW with the chance of a more widespread spell of rain in other areas once more next Thursday/Friday.

In Summary pressure continues to be shown to be high over Europe next week. The question is will it be close enough to the UK to provide warm, settled weather. The jury still looks out from the models this morning with Low pressure shown annoyingly close to the west of the UK at times steering the warmest conditions to our near continental neighbours and delivering short spells of rain on occasions not just to the NW. My own gut feeling if these charts verify is that next week will be rather warm but with a lot of cloud and dry weather with rain possible on Monday and late Thursday/Friday and more generally in the SW (potentially thundery) later in FI as per GFS.

[Radiating Dendrite]

A warm start to October if the GFS is to be believed with temps into the low 20s in the south!

[johnholmes]

The indications for several days on the 500mb anomaly charts has been for an upper ridge with a surface ridge beneath it to develop over/east of the UK. This pattern seems to be gaining concensus amongst the major synoptic models.

To me it still suggests a NW-SE split with the less settled weather type more prevalent for W/NW Scotland, along with N Ireland. Most of England and Wales would come under the more settled type. Hardly a heatwave but pleasant enough for many of those areas with little breeze. At this time of year then mist and fog and quite cool nights but a pleasant enough spell looking more and more likely for the end of the month and into the first week of October.

Cloud amounts will be dependent for some on just where the surface high sets up.

[conor123]

typical.... ideal summer synoptics arrive too late to be of any use

And you can bet that they will come off aswell without any downgrades, the irony that the beginning of October could be warmer than any days in May, July or August here if the GFS came off.

Edited September 21, 2011 by conor123

[Thundery wintry showers]

Those of us who enjoy this kind of weather would be advised to make the most of it rather than lamenting about the time of year- surely the opportunity to experience it at all is better than nothing? If it verifies of course.

I have a feeling that this will end up as quite a "sunny" high if it stays far west and south enough. Too far east and we'll end up in an Atlantic regime with some slow moving fronts, and too far north and we'll pull in some cloud off the North Sea, but the ECM in particular looks favourable for a couple of warm, sunny days for the majority of the country midweek next week, with a southerly off the continent.

Before that, the weather will turn mostly dry and sunny tomorrow and Friday with the ridge of high pressure coming into the south, but the weekend will have rather more cloud, especially in western and northern regions with that moist south-westerly flow, and a band of light frontal rain. Sunday is looking the more likely of the two days to feature some sunshine in eastern and southern areas.

[mushymanrob]

Those of us who enjoy this kind of weather would be advised to make the most of it rather than lamenting about the time of year- surely the opportunity to experience it at all is better than nothing? If it verifies of course.

ill like it, im just lamenting the fact that a stunning 'summer' chart arrives now (if it does!)

[I remember Atlantic 252]

What we would give to get this in summer! :

Alas it is autumn but nice to look at anyway. Current GFS run is a remarkably warm one but increasingly wet further west in the realiable timeframe.

?????????????????? chart seems fairly average to me

[Isolated Frost]

?????????????????? chart seems fairly average to me

It updates automatically - I think he had yesterday's 18Z run chart. Indeed today's 12Z chart for the 4th of October would probably give humid, cloudy skies to most areas with some rain in the west and sun in the south-east.

[Gibby]

Good evening.

GFS tonight shows a few more days of normal temperatures with some rain at times in the North and West. After a weak cold front crosses the UK on Saturday with some rain in places, chiefly in the west the weather clears again for Sunday before another glancing blow for the west and North as a small but active Low spreads rain across those areas with a weakening band crossing East over England and Wales on Monday. Thereafter things warm up considerably with temperatures well above normal in a southerly breeze. It will be dry and bright in many eastern areas while the far west would likely see more cloud and maybe a little rain as troughs lie North-South to the west. By Friday a more concerted attempt at bringing rain into the UK occurs as slack low pressures bring some rain and showers in from the SW in still relatively mild air. Further out in FI the weather looks more unsettled as the Atlantic strengthens again bringing wind and rain at times for many though conditions might still not be that bad in the far south.

UKMO shows a steady warm up in the weather over the next 5 or 6 days. Low pressure to the North will continue to bring unsettled weather there for a while with two weak fronts crossing east over areas further south and east on Saturday and Monday bringing some light rain in places for a while. By Tuesday pressure builds from the SE with warm southerly winds and some sunny spells lifting temperatures strongly over most of Britain by midweek.

ECM finally mirrors the UKMO output with next week becoming warm and breezy with some sunny spells in the east while the west stays more cloudy. By Friday winds strengthen further as pressure is High to the NE and Low to the SW with some very wet weather entering SW Britain and up into West Wales and Northern Ireland later. The run ends with the block to the NE holding firm as the rain in the west dissipates through next Saturday while the east stays fine and warm throughout.

A major warm up looks likely next week with some warm air even extending up into the North at times. The weather looks like becoming rather breezy which should help break any cloud cover up so some welcome warm sunshine for many with temperatures comfortably in the 70's for Southern and Eastern areas. Later in the week things look more complex as Low pressure to the west tries to attack the high pressure block out east. Whether it succeeds or not is too far out to worry about for now as if ECM is to be believed the block fends off any Low pressure to maintain fine weather next weekend though as the high re-orientates itself it cuts off the southerly feed somewhat so temperatures look like they may well be on the slide in the days that follow 240hrs.

[J10]

I quite like the potential of the plume for next week, after all it comes after I had long given up hope of any summery weather. If it doesn't come off, that will be a major surprise.

[ANYWEATHER]

Some feeble attemps from the models to bring an "INDIAN" summer to the uk but i do think this wont happen. It looks almost a certainty that pressure will build over to the East and NorthEast of the Uk,,,, but will it hold the Atlantic at Bay? Both Models say no in the later stages, although at least next week we are looking and at "CAUTION" some temperatures "IF"the models are correct will reach the 70,s especially in the East. If the High is further West than predicted , very warm conditions will pirsue[ Akin To An indian Summer] but what is likely to happen is the High will slip further East and allow the Atlantic to give us some Murcky conditions. Im not quite sure how long this synoptic pattern will last for but Ive got a Feeling we are in for a "Stormy" October.....!

[conor123]

The charts still all indicating some kind of plume next week, in fact the GFS has widespread 22-24c which would mean 26c was possible in some areas.

[snow_mad_09]

Too late for a tan ?

[summer blizzard]

http://www.wetterzentrale.de/pics/MT8_London_ens.png

Ensembles are pretty poor for cold weather fans.

[scotty_boy_winter]

Good, winter chat isn't relevant as of yet

http://www.wetterzentrale.de/pics/MT8_London_ens.png

Ensembles are pretty poor for cold weather fans.

[Iceberg]

As has been mentioned by several people the upcoming warm spell is really rather good for the time of year a week of 20+C temps if you live in the south with temps maybe reaching the mid 25's constitutes both an Indian summer and an Autumn heat wave for me. This is supported by Ensemble and good cross model agreement. The only real divergence occurs over the breakdown of the high to the SE. Added with the complication of any possible plume instability.

I am off to Paris next week for 5 days and temps will be comfortable summer values of 22-25C, which is a real bugger as I've just brought new fleeces, jeans, boots coats etc for the family.

It will certainly shoot up the CET.

[Snowmad79]

The GFS this morning seems to continue its "better late than never" summer theme for next week with temps progged to be in low to mid 20's even in the north with Scotland registering temps of 20c. What else is quite nice to see is that GFS is showing this to last a week atleast with night time temps some days remaing around 15-18 degrees counrtry wide and as for any return to an atlantic regime, that is now considered as being way out in FI.

However, one thing I've learnt is that the GFS can over cook temps and 20c can quite easily turn out to be a cool 15c. That said, high pressure influence backing westward over the UK is most certainly within the reliable time frame, so what will this mornings ECM have to say about LP influence? because it was favouring the development of a new LP core to dig in toward the UK from the west and assert itself putting a spanner in the works of any chance of a sustained spell of decent weather lasting more than just a couple of days.