Model Output Discussion 14th May 2012 Onwards

[phil nw.]

This seems like a good time to kick off a new thread ready to talk about this afternoons outputs.

Will we get any stronger signs of some warmer and settled conditions as we go towards the end of May or do we have to continue to be patient?

Hopefully the 12z runs will give us some clearer signal which way things will go as we approach the tail end of Spring.

Edited May 14, 2012 by phil n.warks.

[phil nw.]

The 00z mean hts underline the uncertainty for next week.

wrt to the placement of the lower heights(blue shading) around the UK.

ECM looks more unsettled so let`s see if some agreement will come this evening between GFS and ECM.

As some other posters have indicated on the old thread there`s no clear signal for a dramatic change.

Perhaps a hint of improvment as the upper trough starts to warm out and maybe split but as those mean hts show no clear and agreed signal on the placement of this towards days 8-10.

[johnholmes]

perhaps I may be allowed to post my thoughts again from the previous thread?

The overall trend on the 500mb anomaly charts over the past 3-5 days has been at the same mixed but fairly consistent.

If that sounds a bit odd then hopefully this explanation will help.

What all 3 variations have shown is the shifting of the long term position of the upper trough in the UK vicinity. Its not gone but its overall position is being predicted to change. The overall concensus seems to be for some kind of upper trough possibly even an actual cut off low to develop in the western Iberia area. Coupled with this are the signs of 500mb heights rising somewhere north, most suggest NE, of the UK. This was first indicated by the NOAA output about 5 days ago and has been increased as time has gone by. NOAA still shows the upper trough but now as a less pronounced feature extending towards Iberia and with a slacker flow into the UK. Two out of the 3 suggest that 500mb flow to be south of west, and that over several days now rather than the north of west pattern for so long a feature of the UK weather.

Just how the actual 500mb pattern will be 7-10 days down the line is still not certain by any means but I would suggest the 'cold' upper trough pattern we have had will be probably replaced by a more anticyclonic set up at least for the last few days in May with the axis of the upper ridge probably to our NE. What the actual 500mb flow into the Uk is going to be is not clear. It may be south of east or south of west. Its direction and how near the upper ridge is will be important for the actual weather that occurs at the surface.

Looking at the flow over north America and its generally predicted to be relatively 'flat' compared to what it has shown for several weeks (or at least for the majority of that time). This MIGHT suggest that the pattern over the UK is going to be fairly changeable.

I would imagine, IF this post from me is anywhere near correct that the outlooks from UK Met MAY start to show some of these ideas over the next few days.

I hasten to add that post very early June I have no idea how the upper pattern will evolve.

Just looking at the MJO actual=close to the origin and between 7 and 6 and the forecast (again I'm not a great believer in its ability to predict 500mb patterns when its very close to the origin) its predicted to be 8/1. Most of these late May into early June show blocking of some kind but a minority show troughing roughly west-east across most of the Atlantic into southern Scandinavia.

So a more settled end to May into very early June but pretty uncertain beyond that with perhaps the higher probability favouring an unsettled flow off the Atlantic rather than from more northerly areas which would at least suggest higher temperature values?

[Robbie Garrett]

According to the latest CFS....

• Slight warm up as we enter June, with a dip mid month. Possibility of lows tracking to the south providing some quite thundery weather as hightligted already. Average-Above average rainfall likely in this case.
  
• 
  
• July still looking as the warmer month, with a mean max of 22*C in southern England, even 19*C in Scotland for one or two of the weeks. Rainfall below average for most parts, except the north/scotland.
  
• 4 weeks in August averaging 19*C as a mean max till September 1st, average-above average rainfall likely.
  

A run through June, show the 850hpa temperatures not going above 8-12*C for pretty much up till last week of June for most of the UK. A pattern change is likely to come through soon though, the likely one of that being warmer conditions... but rather unsettled.

[Summer Sun]

GFS is looking better tonight, with conditions looking warmer and settled at times and warmer and unsettled, changes appear to be coming and not before time

http://www.null/ds/gfs.htm

[AWD]

For the Reliable Timeframe, aside from and odd day or two here and there, the GFS is unsettled, although gradually becoming warmer.

During the next few days the south and west should enjoy some decent sunshine whilst the north and east will be prone to more showery conditions.

To end the working week and start the weekend it is looking unsettled everywhere, with rain for all of us at some point, heaviest in the South.

High Pressure starts to build north of the UK at the end of the weekend and into the following week, so becoming less unsettled for Scotland, but still unsettled for the South with more rain to come here.

Into FI and things do become settled and warmer for a while. High Pressure builds strongly in the Mid Atlantic, and ideally would be better around 200 miles further East to get the best benefits from it, as it is currently modelled though, we are on the Eastern edge of any better weather. ( 1040Mb pressure in the Atlantic, Lol )!!

The last couple of frames show unsettled conditions returning widely again.

UKMO in good agreement with GFS out to T144, with a wet end to the week, followed by High Pressure building to the North of Scotland.

GEM also similiar to the GFS and UKMO, and interestingly has the strong High Pressure building in the Mid Atlantic towards the end of next week. Again though we are right on the Eastern Edge of it, and ideally would like it pushed a couple of hundred miles further east for the real benefits.

So all in all, a half decent couple of days to come for the south now, whilst the north and east stay a little more showery and rather cool. A wet end to the week for all of us before pressure starts building for the north settling things down here a bit, staying unsettled and wet for the south into next week though, with more rain here, but warmer.

Signs of some warmer and settled weather again in FI, but at this stage it is touch and go as to how settled and how warm, depending on how close the High Pressure in the Atlantic can build to us. Current model output have us right on the East of it, not seeing the real benefit, and probably a lot in the way of cloud. Plenty of time for change on this matter though, so for now one to watch certainly.

Edited May 14, 2012 by Active Weather Dude

[William of Walworth]

I'm far from optimistic on the latest runs posted above about avoiding a wet weekend coming up (we 'll be in S Derbyshire). All I can do is monitor and cross fingers ....

[AWD]

I know it FI, but this goes to show the many options on the table as we enter the final week of May!

Even this weekend there are differences!

The ECM a more unsettled run everywhere than the GFS with little sign of anything settled in its entire run.

Edited May 14, 2012 by Active Weather Dude

[PubliusEnigma]

I know it FI, but this goes to show the many options on the table as we enter the final week of May!

Latest MET O forecast now says below average temps in the south, and above average rain for another month

at least out until 10th June ( almost mid summer)

http://www.bbc.co.uk/weather/2635167

[Thundery wintry showers]

There appears to be agreement on an easterly flow during the coming weekend, low pressure to the south and high pressure to the north, though GFS makes more of the high to the north than ECMWF/UKMO.

Under such a setup western Scotland and Northern Ireland would most likely end up dry, sunny and fairly warm, but cloudy damp weather would be likely in central and southern regions (due to low pressure and slow-moving fronts) and the north-east (due to the long airmass track over the North Sea).

The settled weather showing in the GFS FI has high pressure situated in the wrong place for warmth or sunshine, except in parts of north-western Britain (western Scotland and Northern Ireland again perhaps the most favoured). The ECMWF run hints at a warmer southerly type becoming established after T+168, but I won't necessarily consider this as a likely outcome unless we pick up some ensemble support for that evolution.

Not much change since I last checked the model outputs re. this coming week- sunshine and showers tomorrow (most showery in the east, not many showers towards the SW), and the possibility of sleet/snow even to low levels in parts of Scotland, though restricted to hills to the south of the Scottish border. After that, a quiet day on Wednesday with sunny intervals and just isolated showers, and then fronts spreading cloud and rain in by Friday. Tuesday and Wednesday nights look likely to be frosty so gardeners take care.

[PubliusEnigma]

There appears to be agreement on an easterly flow during the coming weekend, low pressure to the south and high pressure to the north, though GFS makes more of the high to the north than ECMWF/UKMO.

Under such a setup western Scotland and Northern Ireland would most likely end up dry, sunny and fairly warm, but cloudy damp weather would be likely in central and southern regions (due to low pressure and slow-moving fronts) and the north-east (due to the long airmass track over the North Sea).

The settled weather showing in the GFS FI has high pressure situated in the wrong place for warmth or sunshine, except in parts of north-western Britain (western Scotland and Northern Ireland again perhaps the most favoured). The ECMWF run hints at a warmer southerly type becoming established after T+168, but I won't necessarily consider this as a likely outcome unless we pick up some ensemble support for that evolution.

Not much change since I last checked the model outputs re. this coming week- sunshine and showers tomorrow (most showery in the east, not many showers towards the SW) and then a quiet day on Wednesday with sunny intervals and just isolated showers, and then fronts spreading cloud and rain in by Friday.

It is very much dependant on the position of a longitudal trough which may develop over northern Spain and France. As this pumps thunderstorms NNE

up over France, Luxembourg, and Belgium the developing low, drags the decaying remnants and deep cloud around the low. A surface flow of the north sea means we end up with grey skies, persistent light to moderate rain, and a nagging north easterly wind in the south.. This would be a dreadful outcome if realised for any wanting milder weather..

[Bottesford]

Can we stick to the models in this thread please and keep your enlightened theories about supposed change in our climate to a forum with a rather similar name...

[A Winter's Tale]

In the meantime, we've got a cool period with northerly winds and perhaps some areas may see a frost. Not ideal for crops and farmers and for myself and Gavin included, but again, it's fascinating to see a May with so many cool and frosty days which aren't out of place and we can still get the type of days we want out of it - but patience will be required if we want to see more of this. And the end of this month and beyond could see the change that we may want so I suppose we should keep an eye on trends and developments in the models and watch them get nearer the reliable time-frames. I would think that a notable period of high pressure, sunshine and very hot temperatures could happen this summer - perhaps not, knowing the random and unpredictable nature of weather - and that will be interesting and enjoyable before another change comes along and be interesting and in some shape or form enjoyable too. That's what makes the Great British Weather and I wish you Gavin, the Daily Mail and others will come along and join this train.

[Costa Del Fal]

Anyway, back to the models, this week for the southern half of the UK isnt too bad looking. Friday and Saturday look quite grim however but until then some good sunny spells and a few showers especially tomorrow maybe thundery but no real washouts and very chilly days like we saw a couple of weeks back. Needless to say, under any rain it wont feel too great. But Id say for much of England and Wales this week, the outlook could and has been worse. Its just some warm temperatures we are really lacking.

Edited May 14, 2012 by reef

[damianslaw]

Lots of uncertainty as we head through the second part of the month. Reliable timeframe remaining very dissapointingly cool and unsettled for the time of year, and yet again a far from ideal weekend looks on the cards .. we are getting towards the time of year when weekends become very precious for us in the north, when you really do want good weather - by mid July its usually down hill.. (I'm being honest here, the school holiday period is notoriously unsettled here in the NW...).

Signs of the trough splitting but heights do look like staying low to the south, so whilst the end of the month may see a warm up, it does look like staying unsettled unfortunately.

[Bottesford]

Once again - stick to the MODELS please and cease the bickering! Any more OT posts will get deleted ok.

[reef]

The sheer amount of off topic garbage in here tonight is ridiculous. This is not the thread for long-term forecasts, predictions or guesses, its for the discussion of what the models are showing.

To echo the above, any more will be removed and the offenders responsible possibly going with it.

[PubliusEnigma]

As an interesting experiment, based on T120 for the Bracknell Fax. What weather would you expect to experience in say Reading, Berks this Saturday, if this chart were to verify. ?

[TonyH]

Humid brightening to possible thundery showers.

[Timmytour]

I have a feeling that the models will be pointing increasingly towards a warm dry settled spell towards the end of the month and into June.

The Daily Express on tuesday have headlined that the cold wet weather will last for a month. This is normally the conduit for change!!! :-)

[conor123]

Seems to be a growing trend for Scotland, Northern Ireland and Northern England to settle down by Sunday with high pressure linking from the Azores up through Scotland and into Scandi whilst low pressure stays over or near to Southern areas dragging in showery rain and strong easterly winds.

[Buzzit]

The GFS ensembles have been slowly pointing to a warmer outlook come the end of May / start of June.

Run by run the ensembles have been showing higher heights over London, which is a good sign.

Tonights 18z at the extreme of FI looks very encouraging for warmth in my opinion.

I say change is a blowin in the wind.

Wasn't April and May 'supposed to be wet' (which has happened) and then warm up from start of June (sounds right to me)

[Scorcher]

GFS 00z is showing higher temperatures for the weekend than previously for the south- looks like from the Lake District southwards temperatures will be higher than during the week while remaining unsettled. ECM seems to want to delay a warm-up until next week when it introduces warmer uppers.

Edited May 15, 2012 by Scorcher

[Summer Sun]

Changes are finally showing now GFS has high pressure building across the North from the 21st it then covers all the country by the 25th

http://www.null/ds/gfs.htm

[TonyH]

A milder weekend being indicated now, with the low expected closer to SW England than SE England, so that GFS is now progging 12 to 14c for my region instead of the 7c when I did my guide 2 days ago.

EDIT: As noted above by Scorcher.

Edited May 15, 2012 by TonyH