Model Output Discussion - 15th April Onwards

[AWD]

GFS 12z not as settled as its morning 0z run, although parts of the South could get away with a drier start to the week as a rather deep Depression runs through Scotland on Sunday night/Monday.

Pressure does then drop in the South with Low Pressure coming up from Biscay. Thundery weather for the South and South West perhaps?

Then as we enter FI, it is a rather widespread unsettled outlook tonight from the GFS, with another rather Deep Depression in FI ( although I doubt it will come to fruition ).

UKMO also has a very stormy period of weather to start the working week for Scotland and Northern England with very windy and wet weather here. Further south, although still breezy, it should be drier to start the week.

Also notice on the T144 chart, there is also Low Pressure working its way up into the Biscay area, similar to the GFS, which will provide something wetter for the South midweek, perhaps Thundery?

All in all, generally unsettled and cool sums up the output tonight, with the South seeing the best of any dry and brighter weather about.

[Snowy Easterly]

lets hope the GEM is on to something, the UKMO is awful with that horrible northerly for next week, i bet the GEM downgrades and jumps on board with UKMO

[johnholmes]

I suggest those predicted a decent weekend make the most of it as the outlook over the 7-15 day period is for not much change from what we have had (endured for some) over the past week or three!

Nothing on the 500mb anomaly charts or indeed the MJO actual, nor its forecast suggest much change ( a bit too close to the origin in its orbit for me to have a great deal of faith in this), so maybe others more learned in the longer term might like to say what they think.

For me, other than the odd day here and there the UK looks locked into the wavelength for some time to come, most of May probably.

I will put check No 10 into the thread tomorrow sometime but to me its another good guidance over the 7-10 day period from the 3.

Edited May 10, 2012 by johnholmes

[Summer Sun]

High pressure will give england and wales and settled weekend and Scotland a decent saturday

A deep LP system then crosses scotland on Monday

The rest of the week remains unsettled though the far south may see the odd settled day with high pressure edging up from Europe at times

Edited May 10, 2012 by Gavin D

[Robbie Garrett]

CFS consistent in making things warmer early June. Week ending 16th May, 11*C Temperatures cooler at 9*C max but little rain, so I take it high pressure in control here. Nearing end of may, things slightly drier again. Temperatures up to 16*C max mean in the CET zone. Looking a little wet, but not much as we get into early June, but temperatures in the CET zone creeping up to 18*C, best of the weather likely in the south west with max mean of 19*C. Things starting to warm up with a max of 20*C in the CET zone. Not as wet as recent times. But looks to turn cooler and wet nearer the end of June.

Early July, looking fairly dry and temperatures likely topping 21-22*C as a mean max in the CET zone. Turning quite wet again, late July. August potentially, being an absolutely bonkers washout. Especially for the northern half of the UK and western areas. September looking the best of the weather with temperatures widspread across the south 20-21*C, with most of the rain towards the Ireland and Scotland.

The CFS has been pretty keen on a washout, for late July since about early April (this now seems to be around the August period)

From a long term perspective, the key points/signals remain.

1. Late May high pressure looking to regain control, and a slight warming up, in time for Summer.
   
2. A fairly decent June, with a cooler ending possibly fairly wet.
   
3. A fairly decent start to July with the best of the Summer weather to be had then.
   
4. Late July/August looks set to be a monsoon.
   
5. However as we get nearer to Autumn, September is looking pretty good.
   

Edited May 10, 2012 by Robbie Garrett

[damianslaw]

The very unsettled changeable weather continues into the foreseeable future.

Models are all in agreement of another deep low pressure influencing things early next week barrelling in from the north with a dig of very cold polar air on its western flanks - for the north another bout of unseasonably cold air with snow on high ground and a tempestuous north wind - hardly late spring weather!

Further into next week, GFS and ECM are suggesting heights will lower over Biscay as the mid atlantic heights advect way out west. Its not a good sign as it suggests a possible very wet spell later next week with fronts moving northwards into southern england..

Mmm I'm really struggling to provide any crumb of comfort for those wanting a settled dry warm spell... this May has potential to end up as one of the most unsettled northerly dominated Mays' in a long time and for the north at least a jolly cold one.. there is still plenty of time for a major change in fortunes as we approach the latter part of the month, but the background signals make the odds very slim.

[Milhouse]

The Azores high is making better inroads in our direction than it has done for quite some time. I see that as an encouraging sign.

April saw persistant low pressure over Europe meaning that the UK was always stuck in a northerly airstream. Now there is a greater tendency for high pressure to ridge into Europe, which is a good sign for prospects for the UK. Its at least a step in the right direction.

[bluearmy]

just to say that the differences, run to run, in the reliable models (ecm, gem ukno, gfs) in the day 6/8 timeframe is very noticeable. noaa cpc have had low confidence for several days now. longer range ens still show a 'getting better' period as we approach the last week may. in the meantime, cool and changeable if not unsettled sums it up.

[Milhouse]

Changeable or mixed best sums up the weather for the next 7 days. All areas will see rain at times with Scotland seeing the highest rainfall totals. All areas will see some decent drier interludes, the best of these the further south you go. Temperatures will remain at or below average with the top temperatures likely to occur on Sunday in the SE. Northern Britain will often be cooler thanks to northery winds.

[PubliusEnigma]

The very unsettled changeable weather continues into the foreseeable future.

Models are all in agreement of another deep low pressure influencing things early next week barrelling in from the north with a dig of very cold polar air on its western flanks - for the north another bout of unseasonably cold air with snow on high ground and a tempestuous north wind - hardly late spring weather!

Further into next week, GFS and ECM are suggesting heights will lower over Biscay as the mid atlantic heights advect way out west. Its not a good sign as it suggests a possible very wet spell later next week with fronts moving northwards into southern england..

Mmm I'm really struggling to provide any crumb of comfort for those wanting a settled dry warm spell... this May has potential to end up as one of the most unsettled northerly dominated Mays' in a long time and for the north at least a jolly cold one.. there is still plenty of time for a major change in fortunes as we approach the latter part of the month, but the background signals make the odds very slim.

An excellent analysis. There has been some questions raised about the longer term synoptics.. How things can change, how the longer term prognosis might be wrong etc.. however the charts out to FI, the teleconnections, MJO phasing etc.. and to a lesser extent global patterns, all paint a picture of more of the same, in fact as May progresses its looking as though it will become colder than at present with higher rainfall totals. Im glad you've picked up on on the danger signals of Low pressure encroaching from Biscay. some see this as a thundery prospect with warmth embedded. however thats a fine line to call. more often than not as was the case for the last couple of weekends. Plumes of warmth and thundery activity spreads NNE over france into benelux with the UK becoming stuck under the wrap around of moderate or heavy rain, with a surface easterly off the north sea making for very miserable conditions in the south and east. temps of 10oC or lower by day, and endless grey skies and rain. Not only as you mention is May looking to be one of the coolest in a while dominated by winds from a northerly quadrant. Id say we are in line for one of the dullest May's in a very long long time. I don't think we've recorded more than 8 hours sunshine here so far in May, which would in fact be poor for the month of December, let alone May.

No real sign of a pattern change for June.

[conor123]

Well there's certainly a trend for Southern areas for a more settled week next week with Sundays front fizzling out as it heads south then high pressure rebuilding from the South West.

[PubliusEnigma]

Well there's certainly a trend for Southern areas for a more settled week next week with Sundays front fizzling out as it heads south then high pressure rebuilding from the South West.

Dry warm and sunny settled ?

[Cheese Rice]

I'm not too fussed if May ends on a cold note. I think most of us have come accustomed to it.

Would rather wait till summer if it only means a week or so of warmth.

Although May is looking cool I wouldn't say it was anything out of the ordinary. Swings in roundabouts.

[samadamsuk]

18Z gfs looks a bit more promissing with warmer thundery air coming along next wednesday/thursday courtesy of a trough/cut off low pumping up a rifde infront of it before getting absorbed - we'll probably end up with another deluge though the closer we get to the time - longer term though and there does seem to be signs that we'll loose the exreme polar feed that we've had for weeks, so maybe a chance for HP to build up from the south moving into the end of may -

The patio's pressure washed, the BBQ's built - I'm all ready. Just need the sun now!!!

[Milhouse]

18Z gfs looks a bit more promissing with warmer thundery air coming along next wednesday/thursday courtesy of a trough/cut off low pumping up a rifde infront of it before getting absorbed - we'll probably end up with another deluge though the closer we get to the time - longer term though and there does seem to be signs that we'll loose the exreme polar feed that we've had for weeks, so maybe a chance for HP to build up from the south moving into the end of may -

The patio's pressure washed, the BBQ's built - I'm all ready. Just need the sun now!!!

I dont observe every GFS run but the 18z in FI is the first time i've seen a proper spell of very warm weather with some heat being pumped up from the south. The temperature charts indicate a max of 24c in the south but you could add a couple more degrees onto that with much of the country under 10c 850 hpa temps.

Some rather impressive CAPE values showing up too

Edited May 10, 2012 by Milhouse

[shedhead]

Blimey it's quiet in here this morning, which is a bit of a surprise given the rather more encouraging outlooks emerging across the model suite. OK, not exactly dry, hot and sunny through the mid month period, but certainly a lot more in the way of fine, settled weather around for the south in particular, with the monsoonal conditions of recent weeks finally giving way. The jury remains out as to where we go for the final third of May, but I think the slow, steady trend towards better weather should continue, as well as move north.

Edited May 11, 2012 by shedhead

[Thundery wintry showers]

A dry day tomorrow bar the odd isolated shower but the current outputs don't change my view that it won't be particularly warm (11 to 15C, compared with an average of 17 or 18C in London for mid-May) and the afternoon may be fairly cloudy inland as convective cloud flattens into stratocumulus under the high. Tomorrow will nonetheless be your best bet for outdoor activities in most regions as by Sunday wet and windy weather will be piling in off the Atlantic- East Anglia and the SE may hold onto drier brighter weather though.

Early next week looks cool, bright and showery (certainly until Tuesday) with some snow possible to low levels in northern Scotland and on hills as far south as northern England, but also with rather more sunshine than most of us have been used to in recent weeks. A ridge of high pressure moving across the south on Wednesday/Thursday may promise a dry, sunny, warmer interlude over most of England and Wales but with Scotland and Ireland possibly prone to frontal systems moving across to the north of the high giving grey damp weather.

The extended outputs on the ECMWF ensembles suggest a cyclonic south-westerly type, which implies continuing changeable (whether it's bright and showery or often cloudy/wet with fronts is hard to determine) but also becoming rather warmer.

[shedhead]

A dry day tomorrow bar the odd isolated shower but the current outputs don't change my view that it won't be particularly warm (11 to 15C, compared with an average of 17 or 18C in London for mid-May) and the afternoon may be fairly cloudy inland as convective cloud flattens into stratocumulus under the high. Tomorrow will nonetheless be your best bet for outdoor activities in most regions as by Sunday wet and windy weather will be piling in off the Atlantic- East Anglia and the SE may hold onto drier brighter weather though.

Early next week looks cool, bright and showery (certainly until Tuesday) with some snow possible to low levels in northern Scotland and on hills as far south as northern England, but also with rather more sunshine than most of us have been used to in recent weeks. A ridge of high pressure moving across the south on Wednesday/Thursday may promise a dry, sunny, warmer interlude over most of England and Wales but with Scotland and Ireland possibly prone to frontal systems moving across to the north of the high giving grey damp weather.

The extended outputs on the ECMWF ensembles suggest a cyclonic south-westerly type, which implies continuing changeable (whether it's bright and showery or often cloudy/wet with fronts is hard to determine) but also becoming rather warmer.

Whilst I don't disagree with your overall assessment, I do feel you may be a little hasty in writing off Sunday for most at this stage. Scotland and N Ireland do look like succumbing to wind and rain, but I think England and Wales should remain predominantly dry through daylight hours at least. Yes cloud will increase, as will the breeze, but I think most places will remain at least bright, even sunny in the south and southeast.

[Ruzzi]

A tiny wee glimmer of a trend continuing in FI, Hopefully for once it will come to fruition. We need SUN!!

[Ian Ballinger]

Please let it pull off, I have been looking at pictures I took back in March, quite astonishing really the difference

[Summer Sun]

Before we can look forward to any warm weather there is the chance of some more damaging frosts for gardeners next week

Edited May 11, 2012 by Gavin D

[bluearmy]

latest 32 dayer is inconclusive.

ecm extended ans are now showing a trend to av temps in london for last week may. wide spread on rainfall shows the probable lack of grouping though.

http://www.meteo24.fr/fr/home/meteo-france-et-europe/passion-meteo/ensemble-de-previsions.html?eps=london

this is not a big surprise, given the 00z ecm ens mean which appears to be lifting the trough out into mid atlantic by day 10. JH made ref to this in the tech thread. blip or trendsetter ?

NAEFS is less bullish about the trough headed west. stays close enough that we dont receive the benefits of a decent looking sceuro ridge, judging by the spreads and mean.

http://www.meteociel.fr/modeles/naefs_cartes.php?ech=192&code=6&mode=0&map=&runpara=

[Robbie Garrett]

Just on my mobile, as working all weekend, but cfs highlights quite a warm June, with quite a good warm mean max.

http://www.weatherweb.net/cfs/cfses4londontemp.gif

Edited May 11, 2012 by Bottesford
Fixed link :)

[phil nw.]

Still low confidence being expressed in the 500hPa forecasts for the medium term by the American`s.

http://www.cpc.ncep....day/fxus06.html

refelected by the variations in recent model runs.

The trend for the nearer term though is to keep this cooler flow from the North/North West as another low moves across the north early next week.

After this another brief ridge before an unsettled picture to end the week with more low pressure modelled around the south as the upper trough digs in again..

So not really a settled outlook but at least there is the likelhood in this setup of some brighter and warmer days than we have been used to, under the brief periods of high pressure for this weekend and around midweek.

Edited May 11, 2012 by phil n.warks.

[AWD]

Well the GFS 12z as reverted back to quite an unsettled outlook bar a few days here and there.

The deep LP that arrives into the north late Sunday as been shunted a little further south now, with only the far south escaping dry into the new working week.

For midweek next week however it turns unsettled over all of the UK, with rain at times for all of us, interspresed with some sunny periods too.

Into next weekend, which starts unsettled widely, finishes with High Pressure ridging up from the South, drying things out here initally before becoming settled widely under High Pressure, which lasts into the start of the following week.

UKMO does have Sunday nights/Mondays LP system a little further north than the GFS, with the South Midlands southwards escaping with a predominetly dry day, but like the GFS, it does bring widespread unsettled conditions back by Tuesday.

Edited May 11, 2012 by Active Weather Dude