Hi everyone. Here is my report on the midnight outputs from GFS, UKMO, GEM, NAVGEM and ECM for today Friday September 20th 2013.

All models show a very confused and mixed pattern beyond the start of next week with a variety of different outcomes on offer this morning. In the short term the weather will be straightforward enough with a fine day today with sunny spells under a ridge of High pressure. A weak warm front tracks NE across the UK tomorrow injecting milder Atlantic air across the UK with more cloud, hill fog and light rain and drizzle to the north and West before the weather brightens again from Sunday with some warm or very warm sunny periods developing in the South. Then things begin to diversify between the models as we progress through next week.

GFS shows lowering temperatures creeping down from the North later next week along with falling pressure with an eventual Low pressure belt developing from the Azores, across Southern England all the way to a deep centre over Russia. The result would be to increase the risk of rain over the UK with potentially rather cold conditions developing over the North as a NE flow develops. This Autumnal feel continues as pressure patterns reset to Low pressure developing over the UK vigorously and meaning rain and gales in rather cold conditions for all at the end of the run.

UKMO today has Low pressure slipping South towards Norway with another centre well to the SW while Southern Britain clings on to High pressure with fine and dry weather maintained for most at this stage with mist and fog issues at night a probability while the days stay bright and warm but less so in the North.

GEM shows colder air gradually sinking South across the UK next week as high pressure leaks away to the SE. Some rain or showers could well affect the North later next week in a cool NW flow while Southern areas come under attack from the SW later as Low pressure troughs edge in from the SW as part of a deep parent Low well out in the Atlantic Ocean.

NAVGEM is very much more relaxed in it's output today offering some influence from the Low to the SW early next week when some rain may occur in the far SW for a time as High pressure declines SE. However, later in the week the Low fills and High pressure is shown to build back up over the UK maintaining fine and dry conditions for all of the UK once residual cloud and any rain leaves the SW in relatively mild conditions.

ECM shows a period of slack winds and pressure for a time next week as our weekend High declines. Thereafter a new High forms close to the NW in much colder air which infiltrates down over the UK beyond midweek. Towards the end of the run milder Atlantic winds battle the cooler Autumnal air lying over much of Northern Europe with the North and East staying largely cool and bright while the SW become at risk from some heavy rainfall from slow moving troughs in a cool ESE wind.

The GFS Ensembles paint a strongly cooling trend this morning with uppers falling below average for a while following the warm interlude of the next few days. After a settled start the weather is shown to turn more changeable from most members with considerable spread at a quite an early stage of the output so much indecision is still likely with some stark changes run to run over the next few days likely.

The Jet Stream shows the flow being pushed north of the UK over the next few days before high pressure over the Arctic pushes it slowly back South over the UK and potentially to the South later next week, a pattern that we have seen so often over recent Autumn and Winter seasons, a trend that looks like it could be replicated again at the start of this season.

In Summary today there is a real cocktail of options on offer between the models and the ensemble members within each model. The next 4-5 days should be OK with benign and settled weather likely with some warm sunshine to be found, especially over the South. However, from early next week things become very complex as the surge of cold air over Northern Europe is shown to be considerable on some output. It is the interaction of this along with warm Atlantic air added to the fact that pressure is high over the Arctic that could set up some interesting synoptics over the next couple of days and I wouldn't be surprised to see a major and intense depression shown somewhere soon if these two opposing air masses are allowed to interact. As it is currently a gently cooling trend is shown with the risk of rain increasing from later next week as Low pressure gradually squeezes the life out of any UK High pressure later next week but will the rain come from the cold air to the North or warm air to the SW is anyone's guess this morning. Very interesting synoptics nonetheless.

Thank you Martin..

Just waiting for October changes now.

Me too , looking forward to some decent fog , real Autumnal nights

Morning Martin. Thanks for the summary. I am extremely busy at the moment meaning that I cannot study the output as I would normally wish to do. These reports keep me up to date with the current situation.

Interesting outlook as you say..a very similar synoptic pattern set itself up in October 2003 as a very cold surge of air from the north established after a period of settled high pressure.

Cheers, Steve.

How quickly does the energy from ex-Humberto drive LP towards Scandinavia? That's the million pound question this morning.

GFS is the fastest of the models, in fact it's already racing ahead at just 72 hours range. This allows for an amplified ridge behind to drive chilly air towards the NE. A HP cell sliding SE saves us from more than a glancing blow, resulting in one notably fresher day before the TM air returns from the SW. It really walked the line though!

Second fastest is UKMO. The slower pace to day 4 prevents that amplified ridge from having much effect, with HP lingering across the UK and holding the warmer air in place - though not without some dilution as some cooler air filters in. Days 5-6 see the LP advancing east to Scandinavia, and this puts more pressure on our residual HP, introducing the chillier airmass to the eastern side of the UK while the western side stays warmer.

ECM is the slowest, preventing that amplified ridge until day 7, and even then it's quickly rolling east across the UK, meaning another glancing blow scenario... but then the HP builds N and NE, leading to an easterly that looks like it would bring some chilly air by the start of October.

These split-jet scenarios seem to be cropping up a lot this year. The models probably can't wait to see the back of 2013!

Hopefully winter will be finger & toe-numbing, rather than mind-numbing

A reminder - links to charts only please

Originally Posted by: Matty H 

 

Hi Matty. Is there any way in which a system could be implemented whereby pictures are cropped down to a smaller size upon posting or even attached as a thumbnail. I think pictures/charts serve to appeal visually to the reader and also serve to embelish what the poster has to say.

Originally Posted by: Maunder Minimum 

I understand it is a copyright issue, rather than a presentational one.

Originally Posted by: CreweCold 

Correct. We had a threatening email a few years back about charts being directly pasted onto TWO. Anyone that knows Brian knows he doesn't like threatening emails, so we implemented a rule of links only. You could read it in the forum code of conduct if it hasn't disappeared when Brian updated the forum header, but I'm sure he'll get around to it. Eventually

Originally Posted by: Matty H 

I can understand that, you don't want a civil lawsuit to have to deal with. However, isn't it true that copyright law allows posting of copyrighted content under fair use, for instance critism or comment. I think you can only really get into trouble if you start publishing copyrighted content verbaitm. It makes sense, because otherwise journalism couldn't really exist due to the copyright wall. 

I am going to really enjoy the next week. A last chance to get out and enjoy the weather before the mind-numbing filth of winter encroaches.

Originally Posted by: Matty H 

 

Hopefully winter will be finger & toe-numbing, rather than mind-numbing

 

Originally Posted by: Saint Snow 

I kind of hope so, purely so I can read the cold lovers whinging about how high their fuels bills are and how it's not fair

Cheers Doc

Originally Posted by: Matty H 

100% agree ,hopefully by 2020 will be living in Montreal or Minneapolis , real summers real winters . even in December the latter has 4x more sunshine than London  ....none of this dull,dank nonsence we get here . i think i/the missus & kids could handle that

Apolgies Matty...  Ive deleted it off.

Hi all,

Here's todays video update;

October Look-Ahead;

http://www.gavsweathervids.com

I'm thinking we may get a bit of a "battle" setting up during October.

Thanks Gav

Yes, legally you can insert images and use them (for non-profit, current event discussion) under fair dealing - the oft-quoted copyright thing is a red herring. I've had multiple run-ins over the years with those who don't understand that aspect of copyright law.

That said, there are more practical reasons why posting charts en masse is frowned on:

• They end up cluttering up the thread, adding nothing to the discussion


• They take bandwidth away from another host, which is bad netiquette


• People don't trim them, shrink them etc, thus wasting bandwidth and space on the page

IIRC it was the Met Office who moaned about it, knowing that rattling the sabre will normally make places comply. You'll note places such as Wetterzentrale make money off the same charts (by surrounding them with adverts) - they've been doing it for over a decade yet nothing's happened to them.

Gearing up for 1st Oct?  Or is it later down there?  We kick off 1st Oct, 1st winter for the new contract too.  Hopefully it snows and snows and snows 

 LLTNP 105m asl 

Riiight. Now ECM and UKMO have stopped taking energy NE altogether, leaving GFS and GEM to disagree and leave us all very confused.

Just imagine what this thread would be like in winter - a last minute correction to a possible snowfest from ECM, with UKMO less inclined but still showing biting easterlies while GFS sticks with taking energy NE.

As it is, the options are:

GFS: Very warm conditions out to Friday next week followed by an Atlantic trough and then a ridge from the SW racing NE

ECM: A mix of warmer and cooler days before a vicious Atlantic onslaught in a week's time.

UKMO: warm conditions gradually subsiding as the flow becomes more easterly by day 6. The Atlantic waits to the SW but doesn't look very enthusiastic about attacking within the next week or so.

GEM: warm conditions lost by Friday as strong LP develops to the NE and brings a chilly Arctic outbreak to the UK with sub-zero 850's across all but Devon and Cornwall on 30th September.

Seems ECM is the fastest to displace the warmer air later next week, followed by UKMO, then GEM, with GFS the slowest.

Good evening. Here is the report on the midday outputs issued by GFS, UKMO, GEM, NAVGEM and ECM for today Friday September 20th 2013.

All models show a warm front moving NE over the UK tonight and tomorrow bringing progressively moist and damp air across all regions over the next 24 hours. Amounts of cloud will  will become large with low cloud shrouding hilltops and moors of the West and North late tonight and tomorrow. Through the latter part of tomorrow and more especially on Sunday and Monday the weather will brighten in the East and South with some warm sunshine expected while amounts of cloud remain a big headache for the rest of the UK.

GFS shows changes being very slow as pressure gently becomes slack with the warmest of the uppers cooling through the week. Any rain is unlikely away from the North of Scotland as Low pressure passes close by. Later in the output tonight changeable conditions gradually develop but it is hardly shown as a rain fest with a lot of dry weather alternating with some showers or rain at times as Atlantic depressions pass over or North of the British Isles with temperatures closer to average.

UKMO tonight shows Low pressure to the SW gradually becoming more dominant as we move through the middle of next week with occasional rain on a cooler SE breeze gradually working it's way NE over the South and West of the UK with the drier but rather cooler conditions persisting over the North and East.

GEM shows a trend to somewhat more changeable conditions as next week progresses with cooler and eventually more changeable conditions developing across the UK with a cool NW flow for a time next weekend delivering a cool and showery spell, especially to the North and East. On balance though a fair amount of settled and dry conditions still looks likely.

NAVGEM shows High pressure leaking slowly away SE next week with cooler and eventually more unsettled weather with rain at times by next weekend.

ECM shows a decline in temperatures and a change to more unsettled weather by the end of next week as Low pressure winds up close to Ireland with fronts in association with it swinging North and East over most of the UK with rain then showers at times. The deep Low then moves slowly East across the UK and out into the North sea with a cool wrap around of strong winds and rain at times with the following days shaping up to maintain an unsettled spell as further Low pressure is approaching the West from the Atlantic by Day 10.

The GFS Ensembles tonight show a slow decline to average uppers by the end of the run. Throughout though the trend  though down holds conditions aloft above average levels for most of the run. There is tonight, as this morning a lot of spread from members from quite an early point of the run with a slow increase in the incidence of precipitation through the second half of the run.

The Jet Stream shows the flow moving North to be clear of the North Scottish coast over the next few days. It is then shown to ease back South over Scotland next week at the same time as weakening as a new arm exits the States on a more Southerly latitude though not particularly strongly.

In Summary tonight's output show's variation on a complex theme of High pressure declining slowly next week and allowing Low pressure in one guise or another to affect most of Britain by next weekend. Amounts of rain look small until late in the week with ECM leading the way in introducing a potent looking Low directly over the UK next weekend. UKMO also shows approaching Low pressure from the SW at the end of it's run with an inconclusive clue shown as to what might happen post 144hrs tonight. GFS and GEM have their own versions of a more slight change to unsettled conditions which when all put together shows the fine and warm spell may only last a few days before something more Autumnal again arrives later next week.

No replies since my report last night! With the prospect of interesting synoptics possibly spawning some more interesting weather in a week or so time let me guide you through how I see things panning out today.

All models show a moist and warm SW flow across the UK with a weak warm front moving NE across most areas. Some brightness may develop in the lee of High ground to the West and SW such as the East of Scotland and East Wales with some warm sunshine possible. Then through the following days some more warm sunshine will develop as drier air gradually feeds over some Southern and Eastern areas while the North and West stay more cloudy and damp.

GFS then shows a slow decline in pressure through next week though any major rain bearing events are not shown by GFS operational run this morning this side of next weekend. However, it will become slowly cooler and stay quite cloudy with some showery rain in places by the end of the week. Then in the second half of the run the engagement of warm and cool air masses either side of the UK takes place spawning a deep Low pressure area which crosses the UK with rain and strong winds towards the end of the run when temperatures fall near to or a little below average.

UKMO today shows the UK in a void of pressure in among a multi centre bank of Low pressure which stretches between Russia, parts of Europe through the Atlantic and even out to Newfoundland. There is no major system at the Day 6 chart which affects the UK directly but the promise of cooler weather will be what is felt the most through next week rather than any major rain event.

GEM shows what does happen when colder Autumnal air from the Arctic engages the warmer Atlantic air out to the SW which as the early week High pressure dissolves away opens the door for this engagement to give rise to a deep Autumnal Low to spin across the UK towards next weekend and the week that follows with cool weather and rain and gales likely for all for a time.

NAVGEM is much more sedate towards changes next week with a gentler introduction to cooler weather from the North with rain limited to more Northern areas where a chilly North or NW wind will develop.

ECM shows a GEM and GFS type scenario as colder air from the North engages the milder air to the South with a deep and vigorous Low sweeping East across England at the start of the week after next with rain and gales sweeping East to all.

The GFS Ensembles show strong support for cooler conditions next week. It takes a long tome for though for conditions to become more unsettled with rainfall reserved for late in the run for many. The operational run was very much a cool outlier for the second half of the run with a more average level of temperature the more likely outcome.

The Jet Stream shows the flow migrating north away from the UK into next week before the flow weakens and edges South thereafter. Late in the output a new arm is shown exiting the States across the Atlantic on a course South of 50 deg North which could take it South of the UK in the second part of the run.

In Summary I yesterday talked about what could happen if the very cool air to the North of the UK next week engaged with the warm air still to the South of Britain. Today we have charts that show that very thing happening as GEM, ECM  and GFS all whisk up a deep Autumnal Low with gales and heavy rain in a week or so time. Other models appear to be sitting on the fence waiting for something noteworthy to happen and as a result show just benign conditions for much of next week with the only constant shown between all the models being the certainty that things will turn somewhat cooler as we move deeper into next week. Perhaps the weekend runs to come will begin to make things rather clearer on where the weather is trending later next week and onward.

Thank you Martin.

The  changes  are  happening...Slowly.

Later next week has the potential to be very stormy with such air masses close by to each other.

http://www.wetterzentrale.de/pics/Recm2401.gif

An unsettled start to October looks on the cards

The signals are increasingly pointing towards October being one crazy month...

After all, it looks to kick off with high latitude blocking and the Atlantic tracking well south of normal. Not only that, but the arrangement looks likely to bring chilly polar continental air across from the NE and have that running into warm or very warm tropical maritime air. That's a recipe for explosive developments as Duane rightly pointed out earlier

Before then, the models are suddenly in agreement on almost no energy going NE from the remnants of Humberto, meaning that a broad trough locates to our west while higher heights build above it and also extending well east from there, potentially right into Scandinavia for a time at least.

We find ourselves very much on the warm side of the jet stream for much of next week, though we do need to watch for any troughs developing to our NE and throwing some chilly air our way after what looks to be a particularly warm Monday-Wednesday period (less so Wednesday on ECM).