Model Output Discussion - September Onwards

[J10]

It is sometimes difficult to resist replying to others when they go off topic.

Back to the models, looking very autumnal at the moment, with a mobile westerly flow with only the briefest of transient ridges giving some drier weather at times, even this concentrated for southern areas.

[MP-R]

Am I one of the only ones on here who would prefer a less settled, more changeable outlook? The models certainly paint that picure with a wet few days followed by a dry few days and then a repeat. Certainly not a washout but not a dry spell either. The GFS shows some sort of anticyclone out in FI but as it keeps being pushed further and further back, I wouldn't count on that.

[Gibby]

Good evening.

We almost have unaniminity between the models tonight. In brief the models show a fine day tomorrow as a cell of high pressure moves gently east over the UK with fine bright and reasonably warm feeling conditions. On Friday a trough moves in from the West with low pressure developing on its Northern edge which drifts slowly ESE over the North through the weekend and out into the North sea as a filling feature by Monday.

The Models then show winds backing SW as Low pressure near Iceland becomes the driving force to the weather keeping things rather damp at times in the North while the South sees a slow rise of pressure meaning dry conditions by midweek. There will however be a trailing front near to the South which could manitain cloud cover for a while but this should dissipate as GFS and ECM show High pressure moving in close to Wst and SW Britain later next week.

GFS goes on to show a strong Anticyclone close to the UK in FI with dry, bright, luke warm conditions by day but the chance of the first widespread overnight mist and fog patches where skies clear.

In Summary then a pattern change looks on the way. The Atlantic ocean near to the UK becomes much quieter as deep Atlantic Lows are steered towards Greenland aiding the pressure build near to the UK with its attendant settled weather. However, caution is needed as we are talking 5 or 6 days out still and in any event improvements in the far North will be slow.

[damianslaw]

Outlook - typical September fare in the main, changeable with a shortlived cooler settled spell, followed by a wetter/showery and quite cool spell for the weekend, followed by milder but still wet/showery conditions early next week, with hints of something much drier and quite mild for the south later next week, this possibly extending further north in time but conversely becoming cooler especially at night.

Very little to get excited about, note the few posts on this thread in recent days - I do find Sept very tedious for model watching, I say this every year.

[mushymanrob]

Am I one of the only ones on here who would prefer a less settled, more changeable outlook? The models certainly paint that picure with a wet few days followed by a dry few days and then a repeat. Certainly not a washout but not a dry spell either. The GFS shows some sort of anticyclone out in FI but as it keeps being pushed further and further back, I wouldn't count on that.

yeah i like a more traditional autumn, or should i say one that i imagine is traditional.. a mobile westerly regime, late sun/heat frustrates me.

... and thats pretty much what we have had this month, and are likely to have for the foreseeable future.

[Gibby]

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

GFS this morning shows todays fine weather moving away tonight as Low pressure and troughs move in from the West tomorrow. A band of rain moves east through tomorrow although the SE may stay dry until very late in the day. Behind the troughs comes a mix of sunshine and showers with blustery west then northwest winds as Low pressure moves ESE from Scotland into the North Sea. Next week sees a large Atlantic depression near Iceland taking charge with a broad Westerly flow over the UK. The North would see a continuation of unsettled and windy weather with rain frequently while the South sees less rain and longer drier spells. High pressure briefly takes control of the weather in the South late next week as a ridge moves East. Then as it moves away east winds back south for a while and a couple of troughs bring rain for all as they move east over the UK Through FI things stay unsettled in the North throughout but High pressure builds slowly from the South with dry and bright weather by the end of the run extending slowly North.

UKMO today also supports a deterioration in the weather tomorrow as Low pressure takes over from the NW lasting through the weekend as it moves ESE into the North Sea by Monday. In the early days of next week winds back West or Southwest with a NW/SE split developing with a continuation of rain at times for the NW while the South and East see longer drier spells close to continental high pressure though a cold frontal trough is approaching the West by 144hrs.

The Fax Charts show a series of troughs crossing the UK tomorrow and early Saturday followed by a showery West to Northwest airflow. As we move into next week a warm front crosses most areas with rain with a cold front into the Northwest soon afterwards in a westerly flow.

ECM today shows the same sequence of events over the weekend with rain then showers for all in a breezy West/Northwest flow. As we move into next week the deep Atlantic Low present near Iceland then pushes troughs over the UK from the west with further rain. By midweek this depression lies NW of Scotland with a strong west flow and showers or longer periods of rain for most, least in the SE. As the Low moves away a rise of pressure takes place late next week as a slack airflow is setup over the UK for a while. With weak troughs around some rain or showers are possible but the South and East is shown to become dry and quite warm by 240hrs as High pressure settles just to the SE.

In Summary it looks like I gave the weather the kiss of death in my report last night as the models have backtracked once more on an evolution into more settled conditions in the short term in preference of a continuation for rather longer of the unsettled Atlantic based weather pattern. The problem lies with the Icelandic Low pressure early next week. It is shown to move closer towards Scotland this morning instead of moving away NE as originally planned hence spreading its attendant rain bearing troughs down over all areas and keeping high pressure South of the UK in the mid term. In the longer term there is hope offered by both ECM and GFS but its a long way out and can bear little reliability at the moment. However as it stands they do give the UK a rise of pressure of sorts towards the end of their runs though, meaning some drier and more pleasant conditions though we may have to wait rather longer than we were shown last night.

[Frosty.]

The latest models (00z) show unsettled weather tending to dominate the next 7 days or so but then the trend is for high pressure to slowly take control as shown on the Ecm 00z towards T+240 hours and further into FI on the Gfs 00z so that we could be looking at a fairly settled last week of september if the models are handling the upstream pattern correctly but a very unsettled weekend coming up with strong winds for many areas, monday should be better as a ridge pushes east but then followed by another atlantic low but the tendancy is for the track of subsequent lows to be further north and the atlantic does look like becoming quieter with high pressure taking control later.

[Iceaxecrampon]

Could get a bit sleety on the tops for the far north?

http://hw.nwstatic.c...150/h500slp.png

Is this the closest yet for the 528 DAM line?

Edited September 15, 2011 by Iceaxecrampon

[No Balls Like Snow Balls]

Well thank god October is now starting to appear on the GFS, we can now start looking for signs of proper autumn and early winter in the models.

Cold pooling appearing to the North of the UK is a sight to behold.

Edited September 15, 2011 by Jimblob

[Frosty.]

Could get a bit sleety on the tops for the far north?

http://hw.nwstatic.c...150/h500slp.png

Is this the closest yet for the 528 DAM line?

Maybe at munro level (3000 feet +) there could be some sleet but it's unlikely at this stage, the models don't look that wintry even on the highest ground but another month or 6 weeks is required for wintry interest on the mountains. A cool and unsettled weekend to come with strong to gale force winds and squally showers and longer spells of rain but less unsettled on monday before another atlantic depression steams in off the atlantic but I still believe the atlantic will become more benign in the extended period allowing high pressure to gain more of a foothold on the BI.

[Gibby]

Hi folks. Here's my take on the 12zs of the big three tonight and where they take us over the next 7-14 days.

GFS tonight shows Low pressure over the North moving ESE into the North Sea late in the weekend. A weekend of sunshine and showers look likely after a wet spell for Northern regions tomorrow. The showers would be heaviest in the North and West although all areas will see some. Late on Sunday the Low pressure fills and moves away into the North Sea preceding new Low pressure near Iceland bringing further rain for all at the beginning of next week. As the second half of the week passes Low pressure to the North continue to affect northern areas while the south becomes somewhat drier as high pressure nudges up from the South. This first surge of high pressure is short lived as a cold front brings rain east across the UK over the weekend. Into FI a repeat of the previous few days takes place with a further band of rain crossing east across the UK before High pressure surges up from the SW to give the UK a fine spell at the end of the run.

UKMO shows a very changeable outlook tonight with Low pressure taking overall control of the weather through its run. A centre near Scotland and on into the North Sea controls the weekend weather with rain and heavy showers in cool blustery winds for all before a new large Atlantic depression centred near Iceland dominates the weather in the first half of next week. The North would see continuing unsettled conditions with rain and wind at times while the South sees some rain on Monday with perhaps a drier interlude before a cold front brings the return of rain east over the South too again midweek.

ECM follows the UKMO route very closely tonight with the extended part of the run setting up a NW/SE split with Scotland, Northern Ireland, NW England and NW Wales seeing further rain at times while areas SE of those mentioned see longer drier spells with just short spells of rain in temperatures near or slightly above normal.

In Summary, patience is going to be needed if its sustained fine weather your after. The models show a very stubborn Atlantic at the moment with depressions gaining the upper hand of the synoptics near the UK for the most part. However, tentative pressure rises to the South of the UK are shown to get close enough to offer some drier and warmer conditions for short periods in the mid to longer term for Southern and especially SE areas.

[ZONE 51]

GFS Meteorogram for London_UnitedKingdom

London, UnitedKingdom, ( Lat: 51.48 Lon: -0.45 elevation: 24 m )

-

here is the link where you can create your own settings for a meteorogram for London

http://ready.arl.noaa.gov/READYcmet.php

[Gibby]

Good morning. As we dip further into Autumn will the weather look any different in two weeks time. Well here's my take on the 00zs for some answers.

GFS this morning looks decidedly unsettled for the whole of its run. Starting from today Low pressure feeds east off the Atlantic bringing rain to all but Southern England by tonight. Through the weekend Low pressure transfers slowly out into the North Sea but only to be joined by further fronts connected to a depression near Iceland in the Westerly flow. So a showery weekend with some heavy, blustery and possibly thundery showers mixed in with some brighter spells too in cooler temperatures. On Monday rain spreads east to keep the unsettled weather going and although things may become less wet in the south next week the North will see little abatement in the fast moving changeable theme as winds remain brisk and westerly for all. By next weekend things turn even more Autumnal as depressions run over the UK and deepen with periods of rain and perhaps gales too as Low pressure becomes slow moving and complex over and to the west of the UK. This potentially stormy weather persists through much of the rest of FI with Low pressure remaining in total control until the merest hint of drier weather pops up at T384hrs.

UKMO this morning runs a similar route in its 144hr run with Low pressure taking control through the weekend and on well into next week with heavy showers or rain at times, the heaviest of which will be in the North as we move further into next week.

The Fax Charts show a series of troughs crossing the UK tonight and early tomorrow followed by a squally west to Northwest, showery airflow with further occluded fronts enhancing showers at times. As we move into next week a warm frontal sector crosses the UK Monday with a cold front clearing SE Tuesday with a wave near Southern Britain bringing further rain here through the day.

ECM today also maintains the unsettled theme going though is more optimistic about conditions in the extreme south as high pressure is close by in the middle of next week. However from the charts as shown there would be a trailing cold front somewhere near Southern Britain later next week which despite pressure near 1020mbs could result in cloud and rain if waves form along it. In any event Low pressure returns with a vengeance next weekend as a deep Low winds itself up SW of Ireland pushing mild, wet and windy conditions NE over all parts at the end of the run.

In essence this morning the outputs remain pretty disturbed with the pick of the bunch being the Euro's as they show at least a very temporary and possible chink of drier conditions for the south towards the back end of next week. However, even ECM brings a powerful Atlantic storm close to the UK towards the end of next weekend to accompany GFS and giving the UK a very wet and possibly stormy spell thereafter. Temperatures would remain close to normal for the most part as one would expect in a westerly flow though if winds back SW or South some warmer air could be drawn up over Southern and particularly SE areas at times.

[MP-R]

I normally choose the 12Z as the most reliable run as it more often comes into fruition than the 'fantasy runs' as I call them. Nevertheless, the 00Z GFS shows a much more unsettled remainder of September with low pressure further south and quite often ending up just to the SW of the UK into FI which could bring some late thundery potential, perhaps a la 2006. I do like this run but anyone looking for consistent settled weather will have to make do with brief ridges between lows.

[Pennine Ten Foot Drifts]

Unsettled, cool, windy at times - certainly no 'mists and mellow fruitfulness' !!! When was the last time we had a decent spell of settled weather with a strong HP being the major influence ? April maybe ? Is the main culprit a jet displaced too far south, and if so why, and when's it going to migrate further north ??? (there's probably a whole thread's worth of discussion on that one !)

[Frosty.]

Oh dear, the Ecm has taken a turn for the worse since the 00z yesterday, it now looks fairly unsettled out to T+240 hours although a NW/SE split does develop for a while next week with most of the unsettled weather across nw britain and the southeast POSSIBLY having some fine weather due to high pressure across the near continent but low pressure is always either close to or over the uk in the next 10 days so a pretty disappointing outlook as far as the current output is concerned.

[Frosty.]

A very unsettled looking Gfs 06z with only brief ridges between a constant supply of atlantic depressions, signs towards the end of the run that the jet will buckle, allowing high pressure to set up just to the west of the BI but also a hint @ T+384 that there could be an early cold plunge during early october as the jet tilts nw / se. There is actually a mini cold plunge earlier as we have a brief blast of Northerly winds due to a depression to the northeast and a building atlantic high so some early frosts would result but i'm sure the next run will show something completely different as is the nature of the gfs.

[summer blizzard]

Certainly an unsettled output from all models though with a N/S split. One notable thing is that in regards to temperatures, all models show average to below average weather which should certainly knock the CET back and all of them also show a very subdued Azores High as we approach day 10 which may raise the scope for a cool and wet October unless we see some tropical influence.

[Summer Sun]

The Met Office are now confirming what i've said for a while, the first half at least of October will dominated by High pressure, despite their been cool conditions it will be mitigated by day by sunnier than normal weather, with the far south and far north possibly seeing well above normal amounts of sunshine. Correspondingly rainfall is likely to be below average in most areas, especially the in the west.

Nights across the Midlands and southeast could be see temperatures dropping well below normal with frequent frosts.

Perfect conditions, frost's at night for some next month but very little rain, with high pressure in charge, and plenty of Sunny day's.

[gottolovethisweather]

The Met Office are now confirming what i've said for a while, the first half at least of October will dominated by High pressure, despite their been cool conditions it will be mitigated by day by sunnier than normal weather, with the far south and far north possibly seeing well above normal amounts of sunshine. Correspondingly rainfall is likely to be below average in most areas, especially the in the west.

Nights across the Midlands and southeast could be see temperatures dropping well below normal with frequent frosts.

Perfect conditions, frost's at night for some next month but very little rain, with high pressure in charge, and plenty of Sunny day's.

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.

Okay, of course we need Model Discussion and I'm possibly not helping add it to much here. However, I would say "unsettled, often windy with some drier interludes" and "temperatures near to or slightly below average at times" sums it up for most folk, out to FI.

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. Of course, others will shoot me down in flames and I'm a big man so can and will take the wrath!

I just feel these posts like, the like of which I talk about above, will put off the lurkers and also stop others from posting.

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

Edited September 16, 2011 by gottolovethisweather

[Liam J]

The Met Office are now confirming what i've said for a while, the first half at least of October will dominated by High pressure, despite their been cool conditions it will be mitigated by day by sunnier than normal weather, with the far south and far north possibly seeing well above normal amounts of sunshine. Correspondingly rainfall is likely to be below average in most areas, especially the in the west.

Nights across the Midlands and southeast could be see temperatures dropping well below normal with frequent frosts.

Perfect conditions, frost's at night for some next month but very little rain, with high pressure in charge, and plenty of Sunny day's.

the models show a mainly unsettled spell of weather for the short to medium term with the odd ridge thrown in here and there, anything out in FI should be taken with a large pinch of salt. The Meto's long range forecast tends to reflect what the models show at that range so there long range forecasts can and do change just like FI in the models. Look at the short - medium range in the outputs and any sudden big pattern change in the long range output should be treated as suspect, unless of course there is a good support from various data sources and a trend maybe emerging for long range prospects.

We are in quite an unsettled period at present with changeable conditions with a mobile atlantic in charge, this can be quite a difficult pattern to shift IMO and I wouldn't be surpised for this to continue into October, with short periods of less unsettled weather in the mix.

[Summer Sun]

the models show a mainly unsettled spell of weather for the short to medium term with the odd ridge thrown in here and there, anything out in FI should be taken with a large pinch of salt. The Meto's long range forecast tends to reflect what the models show at that range so there long range forecasts can and do change just like FI in the models. Look at the short - medium range in the outputs and any sudden big pattern change in the long range output should be treated as suspect, unless of course there is a good support from various data sources and a trend maybe emerging for long range prospects.

We are in quite an unsettled period at present with changeable conditions with a mobile atlantic in charge, this can be quite a difficult pattern to shift IMO and I wouldn't be surpised for this to continue into October, with short periods of less unsettled weather in the mix.

I've quoted this from another forum, make what you will of it

Morning all...

Not done this for a week or two, but i've had a look at the ECMWF 32 day charts this morning and interestingly there is a potentially marked change in the weather on the way. There is a clear signal for unsettled conditions to continue for the next 7 days or so, but the final week of September is signalling a great big whopping high pressure and positive pressure anom across the UK, so the end of September may well become far more settled than of late. This weakens early October, but the final 4th week covering the middle of October once again signals high pressure.

In summary I'd expect an update to place more emphasis on drier than average conditions over the next month as we end September and move into October with perhaps temperatures near or just slightly below average. Overall it looks as though some fine and settled conditions may well materialise and a wet, wild and windy end of September/early October looks highly unlikely, which for me is a good signal for winter and longer term..

[johnholmes]

I've quoted this from another forum, make what you will of it

has anyone any idea who on another web site quoted from the ECMWF T+32 day outlook please?

thanks

[Summer Sun]

has anyone any idea who on another web site quoted from the ECMWF T+32 day outlook please?

thanks

http://www.theweatheroutlook.com/twocommunity/default.aspx?g=posts&m=201667#post201667#post201667 - Post 38

[johnholmes]

Matthew Hugo BSc(Hons), FRMetS

Meteorologist

Weather Commerce Ltd

On Twitter @MattHugo81

ha

Mr Hugo, did he not used to do forecasts for, best not give the name on here?

I wonder how he manages to get hold of the T+768 hour once a week ouput. Its normally guarded by both ECMWF and UK Met as closely as Fort Knox!