Model Output Discussion - 15th April Onwards

[Summer Sun]

Best make the most of the weekend I think

Come Monday its back to low pressure

And that set's up the pattern for much of the week, plenty of high pressure building in the East and North East of Europe

Edited May 9, 2012 by Gavin D

[ANYWEATHER]

Even early next week @T+144 gfs and ecm disagree...

[MP-R]

Is it not worth mentioning just how high air pressure is being forecast for Saturday, 1040mb just to the west of the British Isles. Is that unusual for this late in the year?

[Robbie Garrett]

That`s Summer written off then Robbie-oh dear!

Seriously though let`s not put too much faith in the CFS outputs..We have enough trouble with reliability within 5-15days where we try to forecast using the 4 times daily models and the NCEP 500hPa upper air charts.

Even these vary in their outputs and if you read the comments by the forecasters on the site they often have only low or medium confidence in them.

Granted the medium term outlook out to 10 days or so is mainly unsettled and cool but let`s keep an open mind beyond that.

Can't really say if that's Summer written off, because perfectly honest I wouldn't be surprised to see an unsettled few months, or a longer period having seen one of the fairly longest settled period in ages, enough so that it's caused a drought that's apparently worse than 1976. Everyone should have soaked the Sun up why they can, and should expect that the climate we live in is an Island climate on a latitude that can get weather cold enough that it can snow, and warm enough that it's unbearable being next to Europe.

Let's wait and see, but from many experiences the CFS did well this winter, has done very well for April and so far has had May spot on.

[bluearmy]

ecm op in its fi begins to retrogress everything with the trough lifting out a little as heights build to our east. if we are indeed to see a sceuro height rise lead us out of the nw european trough, this is not a bad run.

[Snowy Easterly]

GFS 12z

Settled weekend for England and wales, it then turns unsettle and cooler than average for the time of year into next week, high pressure is shown to build once more from the 20th

http://www.jp2webdes...o.uk/ds/gfs.htm

GFS 12z

Settled weekend for England and wales, it then turns unsettle and cooler than average for the time of year into next week, high pressure is shown to build once more from the 20th

http://www.jp2webdes...o.uk/ds/gfs.htm

The amount of times you have said high pressure building is ridiculous, ignore FI when high pressure is showing

the GFS is as bad as it gets, frosts will damage crops.

Edited May 9, 2012 by Snowy Easterly

[coldwinter]

Could there be some intense thundery showers tommorow in the yorks/lincs area? Check the soundings as they are pretty outstanding: maybe up to >900 CAPE. Looks interesting anyway. http://rasp.inn.leedsmet.ac.uk/RASPtable.html

Ryan.

[Robbie Garrett]

I think Robbie that solar cycles can determine things slightly more than CFS predictions and it was obvious that solar activity was lower in April than in March so that is probably why. Checked the MJO yesterday and it appears it is either going into phase 5 or 6, to me that teleconnects to a mid atlantic ridge, like GP said in the technical section that the MJO would be the wild card in how the summer behaves. Also I agree with the Met Office about the winds coming from the west or north west as well.

Winds from the west/northwest generally mean Atlantic onslaught. (i.e that's is the direction of the north Atlantic) that would also signify a North Atlantic ridge. If you read his posts, you'd have seen that he said ' the prospects for July and August have nudged towards unsettled if things stay as they are.'

There is a chance of some good settled weather in June, but when is anyone's guess. But being honest now, you can probably well forget May. Summer starts in June, so we will have to see what happens. Fantasy Island keeps showing a ridge developing, over the UK but it has been doing that for the last month and a run is about 2 weeks, so I see no signs of that either yet.

There is all these hints and clues, and charts and graphs, but nothing is set in stone... and that includes the CFS.

[Milhouse]

What is noticable throughout the model runs tonight though, is regardless of it being high pressure or low pressure in FI, there is very little warmth being shown. Therefore if high pressure towards the end of the month does verify ( as shown in GFS FI ) then there is a good chance it could be a dry but cool flow, with temps only hitting average in most places.

Regarding the lack of warmth this weekend:

The high will not have come from a favourable position to deliver any warmth. Nor will it hang around long enough to bring up some warmth from the continent. At the moment, the weekends high is sat out in the Atlantic with a lot of cool air filtering south on the eastern side of it. That is what eventually makes its way over to us and, in the absence of any warm front, temperatures will not be as high as the charts would suggest. Ideally you want a low coming round the top of the high with the warm front ushering in the warmer air.

Edited May 9, 2012 by Milhouse

[Thundery wintry showers]

I would agree with the above re. warmth, but with the caveat that if the airmass behind the warm front is moist then we tend to get a cloudy high to begin with, and the warmth ends up emphasised through the night-time minima. Usually though if the high extends across the country cutting off the supply of tropical maritime air, the strong sun during late spring and summer will kill off the stratocumulus sheet within a couple of days. A good example of this happened with the high pressure area at the start of June 2011- the 1st was a dry but mainly cloudy day for most of us, the 2nd had more broken cloud, and by the 3rd most places had clear skies. Of course if we don't get much moisture following the warm front (which tends to be the case if it's pushing up from the south rather than heading straight in off the Atlantic) then a warm, possibly hot, sunny spell awaits right from the beginning- I think the exceptional heatwave of late June 1976 commenced this way.

Millhouse is right regarding the lack of warmth associated with Saturday's high, with cold Arctic air becoming embedded in its circulation. If we could get a more established anticyclone centred close to the British Isles the result would probably be abundant sunshine, warm days and chilly nights after a cool start to the anticyclonic spell, but the brief ridge shown by the models isn't going to be sustained enough to allow daytime temperatures to rise significantly. Saturday does look like being a dry and bright day, but I continue to feel that mid-morning convection flattening out into stratocumulus may turn out to be an issue for many of us.

[samadamsuk]

Morning all.

Looking horrific model wise as usual!

Maybe the polar air that is streaming down into our semi-permameent trough might loose a bit of it's cold source in the next 10 days http://www.met.sjsu.edu/weather/models/gfsp/thick-ani.html - seems like the weather's doing all it can at the moment to keep us in it's flow -

Cheers, Sam

[William of Walworth]

Outing myself here :

Am I to write off the weekend off the weekend of Fri 18/Sat 19/Sun 20 then? (a 'mini holiday' for us -- but in Derbyshire of all places!)

I agree that current output is very far from encouraging, but as frustratingly ever, prospects seem to fluctuate a fair bit from run to run -- hardly ever ATM in any kind of HP influenced direction, sure, but the real variations seem to be not just between cold air/less cold air, but in likely rainfall amounts too.

So I'm finding it pretty tough -- tougher than usual -- to answer questions coming at me from 'fellow Derbyshire bound people' about how it's all going to pan out next weekend. I'm being very cautious for now ... best I can hope for perhaps is not too much of a washout?

Can I make a more general plea too? That ESPECIALLY when current output is so disheartening for summer lovers (as now), additional comments that pretty much write off the whole of May, most of June and even the rest of the summer are kept at a premium please?

I know you added caveats and that your comments were aimed at informed interpretation, Robbie, but yes 'writing off' is what your posts looked close to doing! Which is a longer term forecaster's sin in my book.

Bad news I can take on the chin, the current anti-summer outpuut is there for all to see, but we all know reliable forecasts after about 10 days (max) are always very hard to nail down.

High Pressure/more HP influenced conditions can occasionally (very occasionally!) develop from seemingly nowhere , troughs can retreat further than expected too. Who's to say that won't happen again? (I doubt any earlier than before very late May though, and most likely not even then on current readings ... but there is such a thing as too much pessimism/realism!)

Edited May 10, 2012 by William of Walworth

[samadamsuk]

Always the problem though - is the owness on the poster not to write his/her thoughts if they are for a negative long term outlook, or for the reader to not take the negativity onboard if they think that a large chunk of time has been dismissed without good reason... I go with the latter, no disrespect to the above post.

[William of Walworth]

My point was broader than just my own sensitivities on this (although yes I do have em!).

I genuinely do think that longer term, season-long forecasts are something that are absolutely fraught with danger for any forecaster, however informed and professional. And there's sound meterological reasons for caution, in our part of the North Atlantic especially

Perhaps all I really request is that even when prospects right up to the medium term genuinely do look unsummery, and with good evidence, just that we have more caveats, less longer term writing of! Less 'no possibility of any improvement ever' style doom n gloom ..

I think johnholmes's approach for eg (TWS too) is a good one on this -- JH doesn't shy from emphaising the unsettled even quite far ahead, when the evidence he sees supports that, but he also emphasises caution too and quite rightly ...

Edited May 10, 2012 by William of Walworth

[AWD]

I dont think the models are all that bad for the South than what they have been showing the last few days. There seems to be more of an influence to our weather from HP to the south of the UK, brining in a north/south divide. GFS and UKMO show this quite nicely.

Unsettled North, less Unsettled south

UKMO similar, with quite settled weather for thee South really.

GEM also similar to the GFS

The ECM on its own really in brining widespread unsettled weather to the UK next week

So ECM brings us all back to square one with widespread rain and showers next week. GFS, GEM and UKMO all bring a greater influence of HP to the south, giving a lot more settled weather the further south you are, although not totally immune from some rain. The north however, remain windy and unsettled on all runs!

[shedhead]

Good post AWD... was just prepping some charts to say much the same, but I think you've posted more than enough there to prove the point that HP should slowly become rather more dominant from the south as the 2nd half of May unfolds. The lack of warmth remains the main concern for me though (I don't mind the rain so much) and it makes it even more annoying to see much of the near continent bathed in it yet again, 24c as a min last night in Biarritz SW France for instance!

Edited May 10, 2012 by shedhead

[William of Walworth]

Interesting posts AWD, those are less out-and-out 'unsettled everywhere' outputs than before, for sure. But of course all is still subject to daily change. A lot will depend on where the North/South dividing line finds itself. Summer-preferrers or wet/windy Spring-avoiders can only hope for a Northwards retreat of that line, but I'm still none too optimistic on that so far.

Good post AWD... was just prepping some charts to say much the same, but I think you've posted more than enough there to prove the point that HP should slowly become rather more dominant from the south as the 2nd half of May unfolds. The lack of warmth remains the main concern for me though (I don't mind the rain so much) and it makes it even more annoying to see much of the near continent bathed in it yet again, 24c as a min last night in Biarritz SW France for instance!

I'm the other way about! All this recent rain has been getting to me. But each to their own etc ....

Edited May 10, 2012 by William of Walworth

[Jack Wales]

I agree with Robbie Garrett as the signals for this summer are most unfavourable for settled and warm synoptics. This is not negativity but sound forecasting underpinned by the current and projected teleconnections.

Despite the current ENSO neutral state, the northern hemisphere atmospheric profile remains reflective of the embedded ENSO –‘ve pattern which has plagued us over recent summers. In our neck of the woods this is reflected in the mid atlantic ridging and the NW to SE jet flow currently being forecast.

To me summer is already shaping up to be another wash out as I believe the transition to weak El Nino will arrive to late to break the current atmospheric base state, at best I believe we will have a settled end to August and a possible Indian summer.

As for the rest of summer, any hopes of a late shift towards a more average / settled conditions will rest with the Pacific and a possible increase in angular momentum. If (and it’s a big if) this can shift the MJO into phase 7/8, this could teleconnect to a negative AO which in turn will help switch the atlantic jet into a more SW to NE flow, well to the north of the UK. Interestingly, this pattern would also be supported by the current Atlantic SST profile (which is very different to 2011)……however I believe this is a long shot.

Finally, although seasonal forecasting remains very much an emerging science, I think it is wrong to dismiss the signals simply because they do not show what we want. In my limited experience I don’t believe we will see a return to more settled summers until a sustained El Nino pattern is re-established. I’m beginning to realise that during the period 1989 to 2006 we were spoilt with several good summers, it seems that many seem to expect sustained warm/dry spells in Jun-Aug when realistically we may not see 1995, 2003 or 2006 type summers again for another 50 years. Admittedly I know little about long term weather cycles but it does seem that we have shifted into a different phase since 2006, not just for summer but all seasons.

[DTHFCJ]

That Sir was a quality post..(Jack Wales)

Edited May 10, 2012 by BALE1

[Thundery wintry showers]

I doubt that El Nino will be much of a "saviour"- I remember the El Nino events of 1998 and 2002 and the dominance of westerly winds and Atlantic frontal systems during those two summers, particularly June and July in both cases.

Next week's weather is open to question, but despite initial appearances it doesn't look likely to follow a pattern of "settled in the south, unsettled in the north". The model outputs are agreed on a spell of wet and windy weather moving south-eastwards late Sunday/early Monday, though with uncertainty on how quickly the system moves. GFS has most places wet and windy by Sunday evening whereas the ECM suggests that Monday will be the wet day. Tuesday looks set to be cold, bright and showery across the country, the showers heaviest in the east, with some snow possible to low levels in northern Scotland.

The subsequent ridge of high pressure is where the outputs deviate- UKMO at T+144 implies quite a significant ridge promising some dry sunny weather, whereas GFS and ECMWF have the ridge just running along the south allowing Atlantic fronts to head in from the north-west, promising cloudy conditions and some light rain. The ECMWF ensemble mean paints a cool showery picture with the ridge of high pressure non-existent around midweek keeping us in a north-westerly type.

It doesn't look likely, however, that we'll be getting the sort of grey skies and persistent moderate-heavy rain that have often characterised recent weeks.

[Cheese Rice]

What a dire GFS, some very chilly (for the time of year) weather likely. A northerly bringing night times frosts and widespread wintry showers to Northern England/Scotland with snow over higher ground for a time. Certainly an if only this was winter pattern prevailing. The only consolation been we should see some sunshine although its likely to feel decidedly chilly in the nagging N/Nwesterly winds.

Edited May 10, 2012 by Cheese Rice

[Evening thunder]

I was wondering what are these signals for this summer that some are saying are most unfavorable? Just wondering because I've seen a few people saying this and a couple recently being very pessimistic about summer (too pessimistic IMO) but never actually posting about the signals and backing them up with charts etc.

I know we shouldn't dismiss signals because they don't show what we want, but no one's actually showed me any signals that don't show what I want, just saying they think this that and the other but no evidence to say why.. I even saw one person saying the other day 'could March be the warmest month of the year' With March having a CET of 8.3C, I don't know what they were expecting, Yellowstone to erupt?

I've also seen a few charts posted that suggest a better summer like the CFS version 2 going for warmer than average conditions for Jun/Jul/Aug recently.

I don't really know why because the weather is like this now, that it would continue like this for the rest of the summer? as it can and does change. Also remember Net Weather's summer forecast for last year, which shows this and that we can't accurately forecast seasons all the time as there are far too many variables/teleconnections which can and do change.

It seems a bit silly to suggest we won't see another 2003/2006 like summer for the next 50 years? how can any one tell that? they've been more frequent than that in the past. I'd expect there's a good chance the synoptic could randomly line up to give a good summer, even in an overall trend of more Atlantic dominated/wetter summers.

[Alex]

I was wondering what are these signals for this summer that some are saying are most unfavorable? Just wondering because I've seen a few people saying this and a couple recently being very pessimistic about summer (too pessimistic IMO) but never actually posting about the signals and backing them up with charts etc.

I know we shouldn't dismiss signals because they don't show what we want, but no one's actually showed me any signals that don't show what I want, just saying they think this that and the other but no evidence to say why.. I even saw one person saying the other day 'could March be the warmest month of the year' With March having a CET of 8.3C, I don't know what they were expecting, Yellowstone to erupt?

I've also seen a few charts posted that suggest a better summer like the CFS version 2 going for warmer than average conditions for Jun/Jul/Aug recently.

I don't really know why because the weather is like this now, that it would continue like this for the rest of the summer? as it can and does change. Also remember Net Weather's summer forecast for last year, which shows this and that we can't accurately forecast seasons all the time as there are far too many variables/teleconnections which can and do change.

It seems a bit silly to suggest we won't see another 2003/2006 like summer for the next 50 years? how can any one tell that? they've been more frequent than that in the past. I'd expect there's a good chance the synoptic could randomly line up to give a good summer, even in an overall trend of more Atlantic dominated/wetter summers.

Good post, take a look at the 70s most of the summers were dire but two stuck out - 75 & 76, I don't think anyone can rule anything out yet. As Jack Wales says if angular momentum increases and we get into an MJO phase 6-7-8 something synoptically similar to this April apart from the mid Atlantic ridge then we should be ok, what's to say this won't happen ESP with the MJO heading for phase 6?

[The PIT]

Some stormy looking weather for Scotland looking at the latest GFS over the weekend moving ino the north of england during late Sunday. More Snow on the cards for the Scottish mountains as well.

[Paul]

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