Model Output Discussion - 17th Oct Onwards

[Frosty.]

So I guess one of the questions in need of an answer is will we see a blocking scandi high forming beyond the next week or so or will we continue with the generally mild and unsettled spell through to november? In my opinion we currently have a higher chance of a change of airmasses from tropical maritime to a cooler north atlantic or even eventually to a Pm airflow by later the following week, perhaps separated by a ridge next weekend bringing the first widespread frost of the season.

Edited October 19, 2013 by Frosty.

[bluearmy]

Naefs week 2 still strong on that growing high anomoly, close to our east.

[AWD]

GFS 0z FI wants to bring the "day after tomorrow" to the UK;

Big outlier within it's ensemble suite though;

Does go to demonstrate the uselessness of the far reaches GFS FI stuff though.

[Frosty.]

The GEFS 00Z mean shows the very mild and unsettled spell continuing for most of the week ahead but then briefly turning cooler and brighter from the north with sunshine and showers due to a shallow trough but lighter winds and this is followed by a weak ridge later in the weekend with sunny spells by day but cold nights with the first widespread frost  of the season, away from the far south and especially for northern rural areas, however, it soon turns more unsettled and milder again with low pressure returning to the northwest of the uk and pressure remaining high to the south of the BI. Later, pressure begins to rise from the south, forcing the PFJ northwards with the southern half of the uk becoming more benign with sunny spells by day and foggy nights with a touch of frost, the unsettled atlantic weather persists across n.ireland & scotland throughout the end of october and early november according to this run.

Edited October 20, 2013 by Frosty.

[Frosty.]

A rather chilly and very unsettled end to the Ecm 00z op run, high pressure tries to gain a foothold across the southeast but is soon brushed aside, indeed, the high pressure across the near continent is banished much further southeast with cooler and unsettled weather spreading well into mainland europe too.

 

In summary, mild and very unsettled for most of the week ahead, then briefly becoming fine with lighter winds across the southeast corner but remaining unsettled further north & west with cooler air spreading southeastwards, then rather chilly and unsettled into the following week and becoming cold enough for snow across northern hills / mountains.

Edited October 20, 2013 by Frosty.

[Mark Neal.]

GFS 0z FI wants to bring the "day after tomorrow" to the UK;

image.jpg

Big outlier within it's ensemble suite though;

image.jpg

Does go to demonstrate the uselessness of the far reaches GFS FI stuff though.

 

I know it doesn't get much backing, but the GEM has been going off on a similar route mostly towards the end of its run on giving us a big storm to come our way. Obviously being way out in FI shouldn't be taken 'too' much notice off, one to watch anyway? 

[bobbydog]

GFS FI hinting at building HP over russia.

 

 

 

a small glimpse of the light at the end of the tunnel maybe?.........

 

here's a good example of comparing runs (00z to 00z) to look for trends-

 

 

24 hours later, there's that russian HP again.......

[Summer Sun]

Latest from Gibby

 

The General Situation. Low pressure close to SW Ireland dominates the UK weather currently with bands of showery rain crossing NE on occasion mixed with drier and brighter spells in between. It will be very mild for nearly all of the Uk except the far North where temperatures hold closer to average. Tomorrow sees a new Low centre swing North to the West of Ireland pushing troughs quickly North over Britain and then a cold front much slower East on Tuesday. The West will become very wet tomorrow with less rain and some brightness in the East where it could become exceptionally warm (20C) in places tomorrow afternoon. Through Tuesday the cold front will bring a band of heavy rain East across the East too followed by a mix of sunshine and squally thundery showers in places through Wednesday. It will remain mild too but with a blustery SW wind and rather cooler weather still  in the duller far North. On Thursday a drier interlude overnight will be replaced by another depression moving NE over Britain carrying another spell of strong winds and rain in a gusty SW wind across the South. Through Friday and the start of next weekend clearer and cooler air is shown by most models to cross SE through most areas with winds turning NW briefly as a brief ridge approaches from the West.

 

GFS then takes us through next weekend with further cloud and rain as a small Low is reluctant to clear East out of Southern areas with the North seeing a dry and brighter spell briefly. Then through the following week a few drier periods are likely in further warm Southerly breezes before a potentially stormy weather becomes shown late in the run as intense depressions cross the Atlantic over the heart of the UK with severe gales and heavy rain. Temperatures would fall to average levels and it would no doubt feel cold in the wind and rain.

 

UKMO this morning shows next weekend as still being unsettled with Saturday seeing rain clear SE behind a cold front with a much cooler and fresher feel likely. A drier interlude then looks likely before freshening Westerly winds bring cloud and rain back across the UK next Sunday.

 

GEM shows a more marked ridge next weekend bringing fine and cooler conditions to the South for a time next weekend. However, Low pressure to the North is shown to ensure improvements are muted and temporary as in the days that follow breezy West winds affect all again with a couple of cold fronts delivering a couple of spells of rain for all in temperatures much cooler and fresher than of late.

 

NAVGEM today concludes it's output with a strong SW flow chasing away a ridge of High pressure next weekend with a drying up Saturday followed by a return to strong winds and rain, especially in the North and West by the end of next Sunday.

 

ECM flattens any ridge next Saturday very quickly as the strong Atlantic Westerly flow following it overpowers the UK again with spells of rain and showers for all again as we move into next week. Low pressure is shown to cross the UK from the West and with a cooler Northern Atlantic source to such depressions it would be rather cooler and wet than that we have become accustomed too. Some gales would also be expected almost anywhere at times and in these it will feel chilly.

 

The GFS Ensembles today show an almost continuous period of Atlantic based Westerly winds with the current very mild conditions across much of Britain seeping away next weekend as fresher and cooler North Atlantic air spreads across all areas. However, it never looks like being cold over the coming few weeks with plenty of wind and rain at times for all with just brief drier interludes lasting less than a day looking more likely than not.

 

The Jet Stream this morning shows a confused pattern, especially later but in the short to medium term continues to pump NE across the UK having crossed the Atlantic on quite a Southern trajectory.

 

In Summary today it looks like a couple of weeks with Atlantic based winds driving the weather over the UK. In the first week with the trajectory of the depressions moving SW to NE across Western and Northern parts we can expect very mild weather to continue but through Week 2 it looks like that trajectory will shift to more of a West to East motion pulling colder North Atlantic air across the UK from next weekend bring temperatures back to average and making it feel cold in the strong Westerly flow. However, having said all that the air will never be frigid and there is little sign of any real cold, late Autumn weather anywhere with the incidence of frost and fog over the next few weeks kept to an absolute minimum or none at all for many. Sunshine amounts will be at a premium, experienced mostly during the showery days and gales can be expected on a number of occasions as always more so in the North and West.

 

http://www.norton-ra...is(2859336).htm

[Frosty.]

I really like the conclusion of the Ecm 00z op run this morning, it has a very seasonal flavour with a cool pool of unstable air covering the uk with sunshine and showers and cold enough at night for a slight frost where skies clear, colder uppers (T850 hPa) approaching the far north of the uk which could spread further south and turn the showers to sleet and snow across the higher hills across northern uk if the 528 dam line pushes a bit further south.

Edited October 20, 2013 by Frosty.

[Barry12]

The CFS has been trending towards a below average November, the GFS has shown in some of its recent outputs that it will get colder for November. Most importantly, the ECM has shown colder air arriving by the time we get to November, which could even turn rain to snow over the hills. So it's definitely not doom and gloom if you want cold weather.

[Snowman.]

here's a good example of comparing runs (00z to 00z) to look for trends-

 

 

24 hours later, there's that russian HP again.......

Ahhh bigger and much higher chance of a influence on the UK.

[Frosty.]

 

The Jet Stream this morning shows a confused pattern

http://www.norton-ra...is(2859336).htm

With a confused pattern, all bets are off..I would not rule out a more amplified pattern with the jet tilting more towards nw / se during the course of week 2 onwards with colder shots from the northwest as we get into early / mid november.

[UV-RAY]

With a confused pattern, all bets are off..I would not rule out a more amplified pattern with the jet tilting more towards nw / se during the course of week 2 onwards with colder shots from the northwest as we get into early / mid november.

Thats exactly how I see things panning out Frosty, the models seem to be toying with this idea right now.

[AWD]

Definitely support for a change in the Jet Stream trajectory and possible height rises somewhere to the east of the UK as we progress into November. Whether heights rise over Scandi, Eastern Europe or Russia remains open to debate and ultimately will affect the angle of the Jet Stream and associated air source over our part of the world.

A look at the GFS 0z Op first (normally i wouldn't take much notice of this model so far out, but it's evolution to the east of the UK does have support from other output) show heights building over Russia, far enough east to keep the UK rather unsettled to say the least;

Worth noting that the depth of the negative anomaly over the UK isn't supported by it's ensemble suite or other model output. This is shown purely to illustrate the support for a positive anomaly to our east somewhere. The GEFS for eastern/north Eastern Europe show support for a build in pressure too;

Just uncertainty at this stage of where exactly. This illustrated in the difference between the ECMWF & GFS 500mb anomaly output;

One has a weaker signal than the other, but both hint at positive anomalies to our east again. The NAEFS output shows a relatively stronger signal for this scenario;

The difference being however, are hints that the heights could be more Scandi based than Russian based on the NAEFS. Therefore being closer to the UK, this could affect us a little more and will almost certainly change the Jet Stream trajectory more considerably;

Possibly with any troughing further west of the UK compared to the GFS, thus something a little more less unsettled for some possibly?

The above scenarios also shown amongst the forecast MJO signal, with a slow transition into phase 1 well supported, if not a little on the weak side still;

Which would lead to a northern hemispheric pattern resembling something like this;

Which brings us back to something very similiar to the 0z GFS FI output of heights over Eastern Europe and Russia and troughing over or near to the UK. The difference being this would be unsettled and cool weather in a more westerly or possibly north westerly flow rather than the mild south westerly winds we are currently seeing.

So a pattern of heights somewhere to our east has reasonable support at this stage. It's just where exactly these heights set up that will ultimately dictate the weather conditions for Western Europe. A change into November away from the above average temperatures does look favourable though at this stage.

[Geordiesnow]

Unless your looking further afield, I don't see much change to the current pattern of the more normal PAO pattern of cold air bottled up in the polar regions and for mid latitudes to be much milder and the UK being under the influence of the Atlantic. Obviously if this occurred in winter then cold fans would be suffering right now but I'm content with what I'm seeing, some Atlantic based weather but very mild, nothing too unusual for October with the exception of the above average temperatures.

 

Some potent weather fronts are still showing so again, the main risk in the short to medium term will be localised flooding. Still waiting for another deep Autumnal low pressure system to occur though and there is no real signs of that as of yet. 

[Frosty.]

Gibby mentioned cooler north atlantic sourced air by week 2, I would go along with that and have said as much in the last few days, indeed, I would go further.. with the jet veering from the current sw/ne alignment to more of a direct w/e...it wouldn't take much to tilt it more wnw/ese or better still..nw/se and draw winds down from greenland through early to mid november, that is what I think will happen, the week ahead =  unsettled &mild / very mild, week 2 = unsettled & average trending cooler, week 3 + = unsettled, colder shots with wintry showers and night frosts.

[draztik]

Unsettled seems to be the buzz word atm, and looking at the last 2 runs from the GFS, coupled with the ECM ens and recent EC32, it would appear that this is the general setup for the foreseeable.

[Polar Maritime]

Gibby mentioned cooler north atlantic sourced air by week 2, I would go along with that and have said as much in the last few days, indeed, I would go further.. with the jet veering from the current sw/ne alignment to more of a direct w/e...it wouldn't take much to tilt it more wnw/ese or better still..nw/se and draw winds down from greenland through early to mid november, that is what I think will happen, the week ahead =  unsettled &mild / very mild, week 2 = unsettled & average trending cooler, week 3 + = unsettled, colder shots with wintry showers and night frosts.

 

Aye Frosty., it's looking like next week should be the last of the mild/v mild weather that we have had to endure over the past few weeks, to a much more seasonal pattern for Autumn, Which is what the models have been hinting for a number of days now, and with growing support. 

Edited October 20, 2013 by Polar Maritime

[phil nw.]

We are certainly now into a typical mobile Atlantic pattern -very much on par for mid-Autumn.

The ever cooling PV lowering heights to our north and a lot of mid-latitude blocking giving the +ve NAO/AO set up which will likely see us into November.

 

http://www.meteociel.fr/modeles/ecmwf/runs/2013102000/EDH1-144.GIF?20-12

http://www.meteociel.fr/modeles/ecmwf/runs/2013102000/EDH1-240.GIF?20-12

 

The jet never far way from the UK will keep things changeable with bands of rain or showers on many days but with temperatures around or above average.

 

The real cold out of reach for now with the pattern looking very zonal but really Winter is some time away yet so this outlook is nothing unusual for now.

Edited October 20, 2013 by phil nw.

[damianslaw]

When the atlantic is ruling the roost, its always important to look at the projected position of the jetstream to identify the likely position of the longwave trough.

 

Currently the jet is aligned directly over the country in a static position but also in quite a southerly position, hence the very unsettled conditions and low heights to our west with no chance of ridge development and therefore no chance for the longwave trough to align itself away from its SW-NE trajectory hence no temperature changes.

 

However, there are signals of a more buckled jet as we move towards the end of the month which importantly would allow ridge development to build near and over the country with the longwave trough forced further to the west/northwest and the azores high forced to ridge NW rather than NE which in turn would allow heights to build somewhere to our east. The outcome would probably be a more NW-SE aligned trough and consequently much cooler conditions but not necessarily settled conditions.

 

GFS has hinted at such a development as we move into November.

 

As well as looking at model output, keep an eye on the jetstream forecasts, where there is uncertainty is often means a pattern change is imminent., ust like when the models go into scatter mode.

[Frosty.]

I have picked this out of all the 6z output as the GEFS 06Z control run is what I consider to be the most likely pattern from T+168 hours onwards, and also taking on board what the latest met office update said which was for it to start feeling colder across the north beyond the next 7-10 days ahead with a continuation of the unsettled, sometimes windy spell following a brief window of fine weather next weekend as a ridge pushes east across at least the southern half of the uk which is followed by temperatures gradually sliding back to nearer the seasonal average and the jet gradually tilting to more of a wnw / ese alignment with the PFJ slowly digging a little further south. Beyond T+384 the met office are saying southern uk, on balance, have a fair chance of calmer weather at times relative to the north with fog and frost but further north it continues windier and more unsettled, on balance.

Edited October 20, 2013 by Frosty.

[MR EXTREMES]

so the azores conveyor continues I think the chances of things settling into November or anything cooler in November is starting to recede with each models run.

[draztik]

Gem 12z continues with the unsettled theme tonight, with a notable low just north of northern Ireland @ t192

[karlos1983]

so the azores conveyor continues I think the chances of things settling into November or anything cooler in November is starting to recede with each models run.

 

Wow, that's some statement, the end of November is some 40 days away, I don't know of a weather model on the planet that can get to grips with +144, never mind 40 days away.

[gottolovethisweather]

so the azores conveyor continues I think the chances of things settling into November or anything cooler in November is starting to recede with each models run.

 

Mr model rollercoaster, you have posted some good analysis in the past and I know that from personal contact with you, but this post adds nothing to the Model Output discussion part of this thread, so please think again when posting and the same goes for everyone. On your question re: November, I have an open mind as to how things might develop towards the end of this month and I composed a post in the CSE & SW thread yesterday suggesting some thoughts. Not a lot has changed in the meanwhile IMHO but the model output over the coming days may help guide us towards an early trend. November is certainly a long way off yet and is pretty much beyond the realms of FI in terms of what the current models are capable of predicting. In the meanwhile, the overwhelming headline is WET, WET, WET, but "at least it will be mild".

Edited October 20, 2013 by gottolovethisweather