Hi everyone. Here's my take on the midnight outputs for today Tuesday August 20th 2013.

All models remain in tune with one another up to the weekend before differences emerge. All areas lie under quite slack conditions with High pressure over Southern and Eastern Britain. Here it will be largely dry with sunny spells and quite warm with light winds. Towards the NW a depression os moving in towards Scotland, weakening as it does but sufficiently strong to bring a spell of wet weather across Scotland and Northern Ireland later today and tonight before a weakening cold front slips South and East over other Northern and Western areas tomorrow with perhaps some showers in places. The South and East should stay dry and bright and become very warm later in the week and some of this could extend Northwards for a time before a cold front edges in from the West on Friday bringing outbreaks of rain East across the UK, first to the West on Friday and areas further East on Saturday.

GFS then swings an active trough across the UK on Saturday and Sunday with rain or showers for many as well as lowering temperatures. In it's wake a unstable NW flow develops backing Westerly as further troughs make their way across the UK next week with further rain at times, heaviest in the North. Later in the run the trend for a North/South split to develop is shown, the South seeing a lot of dry and potentially warm weather as a ridge from the Azores extends over the south at times while the North keeps Westerly winds and rain at times.

The GFS Ensembles look very underwhelming this morning with a sustained period of average temperatures, changeable weather meaning rain at times the order of the day for all areas. The operational was on the warmer side of the suite at times.

The Jet Stream shows the flow never far from the UK over the next few weeks, in general coming down over the UK from the NW at varying degrees of strength.

UKMO for Bank Holiday Monday has a weak NW flow over the UK with High pressure out to the SW. A lot of dry weather would be most likely but with a NW flow and maritime air a lot of cloud would likely be present though not much rain if any in temperatures close to average.

GEM is rather poor this morning with a deep Low to the North of the UK early next week digging down into Europe too leaving the UK in a very unstable and cool NNW flow with thundery showers or outreaks of rain off and on next week with just brief drier spells.

NAVGEM too looks quite unsettled next week as Low pressure developing to the North of the UK carries the changeabe weekend forwards into a changeable week too with rain at times, heaviest in the north but not exclusively so.

ECM starts next week off with rather changeable weather with showers at times for most before a North/South split develops with the North seeing further rain at times while the South close to a ridge, (this morning shown in the English channel) stays mostly dry and bright and possibly warm.

In Summary the model rollercoaster continues this morning. The pendulum has swung back towards more changeable conditions next week again today with GFS, GEM, NAVGEM and to a much lesser degree ECM all showing unsettled weather next week in whole or part for much of the UK. The GFS Ensembles are from inspiring with regard to warm and fine weather today as well so all in all it's a case of preparing ourselves for a period of Atlantic based weather from either a Westerly or North-westerly dominated flow with the chance of rain at times and temperatures close to average. The olive branch this morning comes from ECM and GFS operational in it's latter stages when Southern areas become influenced by a ridge from the Azores. The only consolation we have is that the models are still unsure of events of this weekend so we can expect outputs further out to change constantly until the weekend pattern is resolved.

Thanks Martin..

We will keep an eye on the reports for all changes..

Happy with it as I am working on Saturday during the unwelcome rain so at least mega car boot sales on Monday looking excellent day with low 20's and sunny spells as pressure rising. 

LOL.

It looks like there'll be a trough at some point but the details are sketchy still, as you say.

In the winter we'd be moaning about short-waves messing up the pattern.  No different at any time of year, is it?

OK, that's it - off to umpire a cricket match in the sunshine..

The models can't even nail a weather pattern a week out, yet some people on twitter and Facebook are wetting themselves when a LRF model predicts a blocked January  

Originally Posted by: nsrobins 

Some people I know on Facebook just like wetting themsleves - period

Matty you know as well as any that we're entering the silly season where every LRF, MRF, MILF, crystal ball, astrological sign, cloud writing, rant, rave, tweet, twat and tabloid paper is pawed and scrutinised to the nth degree for signs of sleet on Chritmas Eve.
All part of the fabric of this forum and I wouldn't swap it for anything (apart from a job with Weather Commerce perhaps)  

Originally Posted by: Matty H 

And Matty looking for pink blobs come November!

I see a number of "forecasters" on Facebook promising a hot weekend with sunshine. How anyone can forecast with confidence and accuracy the prospects for the weekend at this stage with the models being all over the place is beyond me (especially to promise hot sunshine!).

I'm refusing to go into detail myself and have just said mixed with details uncertain. Doesn't stop people asking for specifics though

Also getting irritated by people on Facebook talking of a heat wave. Its a warm spell (away from the north and west), not a heat wave!!!!

Does this just afflict women? And only once a month?

If you will use needless Americanisms such "period", you kind of set yourself up for that. 

How about 'Some people just like wetting themselves - full stop.
Actually, that sounds dangerous.

Last major BBQ party of the year on Saturday and I am expecting a warm and humid day here with the chance of a thundery shower later.

Not even a warm spell, really. Only one day (Thursday) has maxima above 25C, then for the "scorching" bank holiday weekend we have maxima of 21C, 21C, 22C even in the warmest areas...

Having said that the 06Z GFS looks more reasonable for next week with HP ridging across the southern half of the UK quite nicely next week.

http://www.wetterzentrale.de/pics/Rtavn2041.png

Nothing too warm but 22-23C by day by midweek in the south. Perhaps a bit fresh down in the SW where I'm going to be but hopefully some sunshine on the Cornish coast 

Hi all,

Here's today video update;

A Cool And Changeable End To August;

http://www.gavsweathervids.com

Not a disaster, but cooler and more unsettled from the weekend - Summer maybe starting to ebb away...

BBC as usual put temps very low on Thursday at 24C against the 29C on 06z runs as they are talking differently than what the models put down.  Downgrade on the rain spikes as they are flatlining toward the weekend so give it another few days we may end up back orginally being a warm settled BH.

21c , 20c and 22c are the forecasted temps for MBY

as long as it is dry that is good enough for me

Anything from Friday onwards has about the highest level of uncertainty possible, as it could be anything from a washout to a few showers on the breeze or even still mostly settled on Saturday and/or Monday (latter day more likely to be that way).

The jet stream seems to be getting all energetic, but in a fitful manner that is really giving the models some trouble. With a relatively strong PV in place, a rather flat and benign westerly pattern could be a frequent visitor during the coming few weeks. Obviously if anything gives the jet an extra boost, such as an ex-tropical feature, then something more interesting could evolve.

UKMO 12z OP looks a hell of a lot better for the weekend than the 0z.

http://www.wetterzentrale.de/pics/Rukm1201.gif

Yes and the GFS 12Z is also pretty good. A bit more unsettled at the weekend perhaps than the UKMO but HP soon rules the roost 

http://www.wetterzentrale.de/pics/Rtavn1681.png

No sign of the northerly plunge that had been threatened.

http://www.wetterzentrale.de/pics/Rtavn2401.png

HP in charge right out to September 

http://www.wetterzentrale.de/pics/Rtavn2881.png 

http://www.wetterzentrale.de/pics/Rtavn1024.png

http://www.wetterzentrale.de/pics/Rtavn10217.png

Saturday looks unsettled

http://www.wetterzentrale.de/pics/Rtavn1264.png

http://www.wetterzentrale.de/pics/Rtavn12617.png

Sunday might be ok, if showery in nature

http://www.wetterzentrale.de/pics/Rtavn1504.png

http://www.wetterzentrale.de/pics/Rtavn15017.png

Monday looks the best day of the three

i give in !

never seen split trough energy so poorly modelled from run to run within the same model.

Hi everyone. Here is the evening version of the midday outputs from the big 5 weather forecast modules for today Tuesday August 20th 2013.

All models show a depression moving NE close to NW Scotland with rain spilling NE across Northern and Western parts of Scotland and Northern Ireland through the night and tomorrow before dying out steadily by Thursday. England and Wales lie under a ridge of high pressure with quiet and benign conditions over the coming few days though with an increasing risk of showers. A push of warm air on a Southerly breeze moves up across principally the SE on Friday at the same time as a weakening frontal zone moves East across the UK with outbreaks of rain or showers, some heavy in places. This showery pattern looks like continuing on into the first half of the weekend too.

GFS then shows the second half of the weekend on an improving note especially in the North as a ridge spreads slowly SE across the UK over the first half of the week with fine and dry weather for most. Through a large part of the extended run the weather maintains this pattern with High pressure lying across the UK with fine, dry, sunny and reasonably warm weather continuing for most until a change looks possible right at the end.

The GFS Ensembles show a spell of average temperatures both at 850 levels and on the surface as a period of West or NW winds look likely from early next week as High pressure remains dominant to the SW and rain bearing Lows cross east to the north of Scotland.

The Jet Stream does indicate a shift in the flow to the North of the UK for much of the period although it's axis ridged over the Atlantic means a flow from the NW moves down over the UK at times.

UKMO shows a weak area of pressure across the UK in almost'col' type conditions indicative of a sunshine and shower scenario with light winds and average temperatures.

GEM tonight holds High pressure down to the SW with successive ridges interrupting spells of showery weather in a rather cool NW flow for most of the time.

NAVGEM shows an area of slack pressure across Southern Britain with sunny spells and the odd shower. A more direct Westerly flow blowing across the North is shown which could bring fronts across at times with a little rain. Temperatures indicate near to average levels are the most likely.

ECM tonight shows a showery weekend in a NW flow behind the exiting weekend trough. then through next week the weather stays changeable but with a lot of dry weather as well with occasional bursts of rain or showers in near to average temperatures for late August.

In Summary the pattern remains somewhat confused with the favourite option being one of NW winds with High pressure down to the SW from next week on. The uncertainty falls on how big a role High pressure down to the SW is going to play on the UK weather with varying degrees of this shown tonight ranging from a continuing feed of showers from Low pressure close to the East or a full blown ridge across the UK from the SW.

Cheers Martin - Talk about confusion on the model forecasts.

Recently i've been amazed at the models' ability to precision predict a MCS at several days out - what is it with this little trough that is causing so much difficulty?

Further dowgrades on the Saturday LP being shunted further north so that keeping us in mid 20's every day except Monday here when the winds change northerly as the HP ridges in then warm up again for late August and early September.  September would be another good month possible again.  Overly settled here with few isolated showers on Saturday instead of wash out day as previous runs shown.