Model Output Discussion 26/10 2012 >

[Chris D]

Let's hope it hasn't started to pick up on a new trend. Now I know it's the 18z and deep FI thus shouldn't be taken too seriously but I've seen this kind of thing happen on numerous occasions before.

Yeh, but at least the NAO appears to be on our side, although the AO looks a bit iffy. Longer term, I mean.

But really pure guesswork at this stage, at least for the next 2-4 weeks or so.

If I'm brutally honest though, November doesn't look that great as a whole to me atm.

I think everyone is too busy focusing on the snow thats currently falling outside their window

And yes, I've heard the reports of snow. And to say I'm well jel is an understatement.

But then again, it's October. So meh.

And I'm in the south.

Edited October 27, 2012 by Chris D

[ICETAB]

The GFS is disapointing for cold lovers this morning, everything looks further west around the 2nd/3rd of November and that prevents the colder air filtering over us. UKMO looks allot colder for the same timeframe with snow on higher ground possible.

[chionomaniac]

The GFS has the following low predicted to head NE as shown -

I am just not convinced by this.....

[legritter]

The GFS is disapointing for cold lovers this morning, everything looks further west around the 2nd/3rd of November and that prevents the colder air filtering over us. UKMO looks allot colder for the same timeframe with snow on higher ground possible.

Such a big change past 144 hrs that im convinced that anyoutcome is possible .it will probably be a big difference again today .all modells i think will struggle with pressure patterns because of the cold synoptics now setting up over the arctic areas ,Icetab you mention UK Met office information for Nov 2/3RD compared to GFS ,what type of information is that ,just curiouse ,SHIVER ME TIMBERS just been outside [fag] cant remember it this arctic fresh in october its like a knife ,next lot of updating on its way .

[Gibby]

Good morning. Here is the report of the 00zs from GFS, UKMO and ECM.

All models show a cold Northerly flow blowing sown over the UK currently. With most places under sparkling clear skies a cold and frosty start will be experienced for many while Northern and Eastern coastal counties see wintry showers giving a covering of snow in places. Through the day the winds back Westerly, cutting off the cold feed with cloud and rain with hill snow reaching the NW later. Tonight will see this cloud and rain move SE to all areas giving a cold feeling Sunday with cloud and rain at times for all. By Monday clearer weather will move SE to affect all areas later with a dry if rather cold day likely with just a few showers near windward coasts. By Tuesday a dry start will give way to increasing cloud as a Westerly wind increases and cloud and rain moves in from the NW through the day. By Wednesday all models show a large and deep depression close to Northern Britain with a cool and blustery South-West or West wind with rain or wintry showers covering all parts as troughs move in from the West.

GFS then moves forward with Thursday showing a frontal trough moving steadily East carrying rain with showers following. Low pressure then influences the weather for some considerable time moving gently East, North of Scotland with rain or showers, heavy and wintry at times, especially over Northern hills. Then through FI the weather stays rather cold and changeable for a while before a gradual change to High pressure pushes ridges in from the West with the cold weather gradually transferringg less cold air in with a SW flow taking hold by the end of the run.

The GFS Ensembles show a rather cold couple of weeks for Southern Britain as uppers are shown to stay on the cold side of average for much of the 00z run. Further north uppers become much closer to average after the next day or so. There will be plenty of rain about through the period, lessening somewhat later in the run in the South.

The Jet Flow continues to flow SE over the UK for the coming days before settling to a position just to the South of us in a week or so time.

UKMO for midnight on Friday shows Low pressure close to NE Scotland with a cold and showery NW flow over all of Britain. Rain or showers falling as snow on Northern hills will affect all of Britain through the day.

ECM also shows a showery NW flow midweek before backing winds to the West with further rain at times thereafter. It would be cold enough for snow on Northern hills and mountains. Later in its run ECM the weather is shown to remain as unsettled and windy as ever as further fronts and Westerly winds keep things quite volatile over Britain. There could well be some snow over Northern hills though throughout the run.

In Summary the pattern remains broadly similar as was shown yesterday today. Low pressure will be centred near Northern Britain later next week with rain and showers, wintry on hills affecting all areas. Later in the GFS run a quieter spell does develop in FI but things could equally remain unsettled. There are no signs of any major wintry outbreak over the period with wintry weather restricted to the hills and mountains of Northern Britain only with just limited frost and fog.

[IDO]

The 12z yesterday was like many of GFS's colder op runs, a cold outlier and no surprise it has been blown away; in this case hundreds of miles west! The second shot of cold now dissipates west of the UK and the LP system's centre is also less incumbent in our area:

http://cdn.nwstatic.co.uk/gfsimages/gfs.20121027/00/153/h850t850eu.png

As the total rainfall shows (next eight days) the east/south UK escapes any substantive rainfall:

http://www.weatherweb.net/tvweather/gfsopuktotpcp192.gif

Also the wind direction is more favourable so most will have a milder air flow (SW) so not feeling so cool even with the cool uppers. All in all this run is rather mundane autumnal output.

In FI, from about T228 HP edges in, hinting at a more zonal pattern, with the Jet back on the UK's Northern flank:

http://cdn.nwstatic.co.uk/gfsimages/gfs.20121027/00/384/hgt300.png

The GEF ENS show the OP run having high confidence with the other members:

http://cdn.nwstatic.co.uk/ensimages/ens.20121027/00/t850London.png

so all in all a more realistic run, not inspired by the colder op runs of late.

[NorthernRab]

The GFS has the following low predicted to head NE as shown -

I am just not convinced by this.....

It's quite counter-intuitive, it's track just isn't convincing to the eye really.

[Buzz]

The GFS has the following low predicted to head NE as shown -

I am just not convinced by this.....

Could you explain why please?

Edited October 27, 2012 by Osbourne One-Nil
A smiley doesn't make it less of a smartarse comment.

[chionomaniac]

The low stalls, then is held in position, before moving NE then the model seems to go into default mode - increase the PV.

All to do with the differing energy projections.

And it doesn't fit in with the November MJO phase 3 pattern.

[Isolated Frost]

The low stalls, then is held in position, before moving NE then the model seems to go into default mode - increase the PV.

All to do with the differing energy projections.

And it doesn't fit in with the November MJO phase 3 pattern.

Yes indeed- had a look at the MJO plot, and then the 00z and thought, well, one of these aint going to happen- and I'd be inclined to trust the rather more stable and less erratic MJO plots for now. Cold zonality looks the game now, but GP's hint of a N Pacific LP and +ve heights to the NE are showing shoots of hope. Another note has to be the PV being pretty weak without a notably warm stratosphere.

[AWD]

Looking at the GFS 0z Ensembles there are a group of members that go for a brief warm up around the 2nd/3rd November, clearly leaving the main cluster briefly.

http://www.meteociel.fr/cartes_obs/gens_display.php?ext=1&x=510&y=4

[Frosty.]

The recent Ecm 00z (12z) ens mean is showing a return of arctic winds towards T+240 hours as the main trough eventually gets away to the northeast and allows N'ly winds to sweep down with a ridge in the atlantic, speaking of the atlantic, both the gfs and ecm ens mean show a strong ridge extending southwest between greenland and canada which completely blocks the western side of the atlantic and cuts off the normal route of depressions as they would normally head towards the uk, the ecm mean is much more promising in terms of another cold shot in the 7-10 days range, the gfs becomes rather flatter as high pressure builds to the southwest of the uk with eventually a less unsettled pattern for the south but the north continues to be dominated by low pressure and rather cool with winds tending to be north of west. The week ahead looks like becoming very unsettled and windy with low pressure over the uk. temps will be below average as the air originated in the arctic but was then strongly diluted by the long sea track around the low and then up and across the uk but still cold enough for snow on the higher hills in northern britain, then the air becoming more polar in nature with the showers turning more wintry and increasing frost risk if the ecm mean comes close to verification.EDIT..The Ecm was from 12z last night and not 00z, my apologies

Edited October 27, 2012 by Frosty039

[SnowObsessor90]

I've noticed a tendancy from the GFS over the last few runs for the PV to stengthen by quite a fair bit, no wonder it's so quiet in here, does anyone think it could be onto something?

[A Winter's Tale]

Good afternoon all. After a spectacular and eventful Friday, the picture for the rest of Saturday is for the showers in eastern/south eastern parts of England to continue through the afternoon and early evening but they will fade away. In the north west of Scotland cloud cover should push further south and east and rain across the hebridean islands and the north west highlands - falling as snow on the mountains - and this should should move southwards and eastwards. Rain should arrive in northern Ireland too later today and cloud cover should inrease across northern England. However, across much of Wales and England there should be fantastic clear skies. Tonight however should be a largely overcast one with heavy and persistent and rain in the north west and precipitation scattered elsewhere. Minimum temperatures should be 2 to 7C - it could be cold enough for a brief frost in parts of the south east.

Sunday is setting up to be a wet and cloudy day for almost everywhere and some persistent rain moving south east throughout the day. Maximum temperatures could be 8 to 11C. Later in the day, as the rain moves further south, some clear breaks could develop over northern Scotland. Sunday night should be largely overcast with most of the rain across southern areas. Minimum temperatures of 4 to 8C.

However, Monday at the moment is looking like a much better day with plenty of sunshine across most northern areas; the southern third and some eastern areas may be more overcast with some rain. Maximum temperatures at around 8 to 12C. During Monday night, some light rain to the north of Scotland may push the clear skies further south with much of England, Wales and Ireland under starry skies. Some cloud cover may hang onto the very south of England. Minimum temperatres of 4 to 6C.

Tuesday looks like a day where the southern and the eastern areas enjoy the sunshine whilst in Northern Ireland, western Scotland and north western England there'll be a threat of showers and some persistent rain across north western Scotland. Maximum temperatures could be 9 to 10C. Tuesday night could be a largely cloudy one for the British Isles and a very wet one arcoss northern and western areas with some particulary heavy rain across parts of Ireland and western Scotland. A milder night with lows of 6 to 8C.

Wednesday at the moment is looking mostly cloudy with some heavy rain across south western areas and some heavy persistent rain near the seas to the north and west of Ireland and Scotland. Maximum temperatures of 9 to 11C. Wednesday night again seems likely to be largely cloudy with plenty of precipitation around, particulary in the surrounding seas and across the southern and eastern areas of England and Wales. Lows of 4 to 8C.

The outlook for the next few days is an unsettled one with plenty of precipitation around and some windy conditions at times. Monday and Tuesday however are likely to be the best days for sunshine. Beyond Wednesday, a depression situated close to the north west of Scotland will keep things unsettled but the positioning and track of the low is vital in determining what sort of weather we'll see and where, aswell as it's duration and what could follow next.

[legritter]

I've noticed a tendancy from the GFS over the last few runs for the PV to stengthen by quite a fair bit, no wonder it's so quiet in here, does anyone think it could be onto something?

It could be but i think all modells will churn out a realmix of possible outcomes ,we have some very lively and interesting weather going on in the northern hemisphere at the moment .plus some early seriouse cold for the time of year setting up in variouse parts of the arctic . i still think high pressure will set up eventually to our v far north so things in UK could get very interesting past next thursday .and indeed the PV could produce some seriouse weather IF it sets up in tandum a sort off battle ,i dont mean battle ground snow event but a much more large scale event .but now till thurs looking typical autumn ,past this ,Stay tuned .

[Isolated Frost]

No comments? Vortex displacement leads to the infamous svalbard high riding on top of that dipping trough- also of note the extremely zonal outlook o/ NE US.. 216= big waa o/ e greenland and low pressure moving se'wards from it.

Big signal from the latest run for a northerly- alternating with a easterly come mid-november ? time will certainly tell- aleutian low to play a big role i think- the longwave pattern certainly is up for grabs.. expect plenty of interesting solutions in the up and coming runs

[liam300]

Please explain why not, Liam. Thanks

Sorry i copied an incorrect image.

[Robbie Garrett]

No comments? Vortex displacement leads to the infamous svalbard high riding on top of that dipping trough- also of note the extremely zonal outlook o/ NE US.. 216= big waa o/ e greenland and low pressure moving se'wards from it.

Big signal from the latest run for a northerly- alternating with a easterly come mid-november ? time will certainly tell- aleutian low to play a big role i think- the longwave pattern certainly is up for grabs.. expect plenty of interesting solutions in the up and coming runs

It's what I was thinking might happen, I suspect that Scandinavian block may move over and or join forces with a Greenland block, with a cold northerly come December. It's what the CFS was showing a few weeks back.

[Isolated Frost]

Noticed how the GFS 06z is very dissimilar to the ECM 00z when it comes to the N-Hemi pattern- less amplification and more meridional flow o/ ne usa as the subtropical ridge ridges n'ward into louisiana, tennessee, and a more amplified north pacific low, leading to a stronger pv and -ve heights o/ ne europe..

end product still a northerly as the waa up greenland leads to a eastward leaning ridge; and the trough doesn't have the subtropical support to rise towards svalbard

[Isolated Frost]

It's what I was thinking might happen, I suspect that Scandinavian block may move over and or join forces with a Greenland block, with a cold northerly come December. It's what the CFS was showing a few weeks back.

tbf it's a long way away, and the chances of a cold northerly come 'december', roughly 35 days away, or +900 in model terms, is nigh on impossible to predict with any agree of certainty- pressure anomalies however are, and the upstream pattern will have to be watched.

and a side note, the cfs shows basically every possibility there is eventually.. a broken clock is right two times a day

[Panayiotis]

Reload in over a weeks time been showing this for quite some time (but i know its early FI)

Then UK warms up, but look east cold is heading in the direction where we want it!

Edited October 27, 2012 by panayiotis

[MR EXTREMES]

just looked at the uk met fax ukmo and gfs all agree the greenland high pressure to stick around backing east ready for november some really nasty weather predicted.

all this withing the realiable timeframe infact it could well turn out below average temp wise and above average rainfall.

it really is turning out very intresting and its very possible mid november could be the turning point for our winter

[Adam lufc]

Deserted and empty on here. Poor poor models giving us big standard autumnal weather. The PV will descend soon so there's nothing unusual about that.

[phil nw.]

Deserted and empty on here. Poor poor models giving us big standard autumnal weather. The PV will descend soon so there's nothing unusual about that.

It does look like the next 10days or so will see a more Autumnal Atlantic pattern with the UK and NW Europe stuck under an upper trough not going anywhere fast.

http://www.meteociel...0&map=1

Those northern heights now on the wane as the vortex continues to cool with lower pressure extending down across the UK from the north west.

We can see those blues(low pressure)extending across the polar latitudes at T144hrs.GFS12z- similar to other models.

The jet stream, still pushed well south, will leave us in a rather cold polar cyclonic setup with rain or showers through the period and quite windy at times.

[Gibby]

Good evening. Here is my report on the 12zs from the output of GFS, UKMO and ECM.

All models are fairly agreed on the pattern of events between now and the latter part of next week. The current Northerly flow which still affects the SE will give way over the coming hours as winds back West in response to a low pressure moving SE close to Northern Britain. Milder air will infiltrate the UK over the next 12 hours with temperatures less low tomorrow. However, cloud and rain already over North-Western areas will move SE across Britain to reach all but the far SE by dawn. later tomorrow a cold front will move steadily SE to clear Southern Britain later on Monday. Further rain would move SE with it clearing to sunny spells and scattered showers for many later Monday. Tuesday looks a reasonable day at the moment as a ridge moves across Britain. Later in the day the NW would become windy and wet as further Low pressure deepens and moves down towards the NW. Through Wednesday rain will spread across all of Britain with strong winds for many as well. On Thursday clearer weather with squally showers will replace the rain eastwards to all areas with some heavy showers with hail and thunder, plus sleet and snow on Northern hills.

GFS then keeps Low pressure close by and with a cold feed around the western flank as it moves to the East of Britain all areas will feel cold and windy with further showers, wintry on hills into the weekend. Through FI tonight the weather perks up with pressure trending to build from the South tilting winds back more towards the West with time, lifting temperatures and reducing rainfall amounts, especially in the South as FI moves towards it's conclusion.

The GFS Ensembles show the mean for the run not exceeding the long term average temperature for the whole run in the South. The operational down here trended above the average for the pack in the second half becoming something of a mild outlier at the end. In the North a fairly average group is shown with no major cold or warm peaks of sustinance. Rainfall amounts would be commonplace with the South seeing some heavy rain at times.

The Jet Stream is currently blowing in two arms across the Atlantic, one moving SE over the UK while the other flows way South over Southern Europe. Over the next few days the main thrust of the flow is to the South of Britain where both flows join in a week or so close to Southern Britain.

UKMO for noon on Friday shows a deep Low pressure centre just to the North of Scotland with a rather cold and strong NW flow blowing down over the UK. there would be squally showers for all , heaviest in the North and West with hail and thunder locally. It would be cold enough for sleet and snow over Northern hills.

ECM tonight shows next weeks Low well established by midweek centreing as a complex system over the UK by Thursday with a large blocking High South from Greenland over the mid Atlantic. There would be copious amounts of rain and showers over all areas in strong and cyclonic winds sleet and snow over hills and mountains of the North. It would be somewhat on the cold side for all. Late in its run the Low pressure is still in control of the weather over the UK with a continuation of rather cold and unsettled weather with rain at times and snow over Northern hills. Winds will decrease somewhat though as the run closes.

In Summary tonight the pattern looks increasingly unsettled and at times wet as we move deeper into next week. With all models supporting a slow moving and deep Low centre in the vicinity of the UK through the second half of next week with rain and showers in fresh and rather cold winds, sufficient for occasional snowfall over Northern hills and mountains. GFS does show an improvement through FI but the operational is not that well supported in it's drier scenario for the South. ECM shifts the Low pressure trough to the East of the UK with the prospect of a day or too of quieter but chilly Autumn weather in the days that follow day 10.