Model Output Discussion - 15th April Onwards

[Alex]

It seems to me that most runs recently seem to be very varied which indicates a pattern change? the period of change really starts from next week with some slightly warmer air getting into the mix!

[SP1986]

I'm not sure i buy into this easterly trend, I think it'll have a tendency to back away eastwards. What this means, in my opinions is that whereas the southeast may catch some milder weather, for most to the north and west, a continuation of the wet and cold weather we have become used to.. and I think this could last a long time. I don't really buy into the settled spell that is being produced on some outputs; and I am already seeing the tendency for the easterly to be pushed eastwards very quickly, allowing a cooler Atlantic regime to settle in.

You will have a job convincing me that the country is heading for a period of warmth from the east/southeast, because I just can't see it personally.

Plenty of rain on the way though judging by the plethora of low pressures that are due to affect our shores; and it will feel very chilly indeed in the rain. Tomorrow may well even fail to exceed 5C in some areas where the rain falls, which for late April is as cold as it gets in the day.

[Cloud 10]

Some very lively weather to come in the UK over the next few days with a fairly deep depression

crossing the country giving some heavy rain to many areas,

Spot the low pressure!

The weekend could be interesting with a big temperature contrast between the UK and the near continent

which would lead to some large rainfall totals if GFS is to be believed.

[phil nw.]

I'm not sure i buy into this easterly trend, I think it'll have a tendency to back away eastwards. What this means, in my opinions is that whereas the southeast may catch some milder weather, for most to the north and west, a continuation of the wet and cold weather we have become used to.. and I think this could last a long time. I don't really buy into the settled spell that is being produced on some outputs; and I am already seeing the tendency for the easterly to be pushed eastwards very quickly, allowing a cooler Atlantic regime to settle in.

You will have a job convincing me that the country is heading for a period of warmth from the east/southeast, because I just can't see it personally.

Plenty of rain on the way though judging by the plethora of low pressures that are due to affect our shores; and it will feel very chilly indeed in the rain. Tomorrow may well even fail to exceed 5C in some areas where the rain falls, which for late April is as cold as it gets in the day.

A slack Easterly is being modelled by GFS and UKMO around T120-144hrs for a short period as our trough finally splits with pressure rising further to the north.

However it does indeed seem to be a transient affair according to 12z GFS as a more familiar pattern evolves with the Azores high trying to nose in promising something more settled-at least further south.

Low pressure still around to the north however.

A variety of solutions has been offered in recent outputs as we enter a new month but it does appear that something of a change to somewhat fairer weather is likely with some warmer days as the polar maritime air starts to mix out with the demise of the stubborn upper trough.

Edited April 24, 2012 by phil n.warks.

[Summer Sun]

ECM is looking better into next week, we have finally lost the LP systems after another and high pressure will be building strongly to our east

All in all a much better outlook tonight with high pressure becoming more of a feature as next week progresses

Edited April 24, 2012 by Gavin D

[Frank Trough]

I'm not sure i buy into this easterly trend, I think it'll have a tendency to back away eastwards. What this means, in my opinions is that whereas the southeast may catch some milder weather, for most to the north and west, a continuation of the wet and cold weather we have become used to.. and I think this could last a long time. I don't really buy into the settled spell that is being produced on some outputs; and I am already seeing the tendency for the easterly to be pushed eastwards very quickly, allowing a cooler Atlantic regime to settle in.

You will have a job convincing me that the country is heading for a period of warmth from the east/southeast, because I just can't see it personally.

Plenty of rain on the way though judging by the plethora of low pressures that are due to affect our shores; and it will feel very chilly indeed in the rain. Tomorrow may well even fail to exceed 5C in some areas where the rain falls, which for late April is as cold as it gets in the day.

The ECM buys into the easterly in a big way this evening. I have been watching May 3rd since it first arrived at t+ 384 on the GFS and it was consistently showing a flow from the east/southeast (i could have predicted that when i booked the day off a month ago because that's not the direction i want!).

As you say though, the GFS has somewhat dropped the idea having picked up on it in its outer reaches. We'll see - that's two ECMs in a row that back an easterly flow developing next week.

whatever happens i do think we'll see temperatures recover -most options on the table tonight lend themselves to that. this fits nicely with the Met office outlook today.

i think the trend has moved toward a change in the last 48 hours.

[Scorcher]

The ECM buys into the easterly in a big way this evening. I have been watching May 3rd since it first arrived at t+ 384 on the GFS and it was consistently showing a flow from the east/southeast (i could have predicted that when i booked the day off a month ago because that's not the direction i want!).

As you say though, the GFS has somewhat dropped the idea having picked up on it in its outer reaches. We'll see - that's two ECMs in a row that back an easterly flow developing next week.

whatever happens i do think we'll see temperatures recover -most options on the table tonight lend themselves to that. this fits nicely with the Met office outlook today.

i think the trend has moved toward a change in the last 48 hours.

Completely agree, how much more evidence do people need that a change is coming?

[Gowon]

It looks like a period of a very wet spell of weather for the end of April and the start of May, which is good news for water levels.

There does seem to be a pattern change coming up, a change for warmer weather (finally) as we head into May but it's still looking unsettled to me, at least for early May, but it should feel warmer when it's not raining.

[damianslaw]

Rest of the month staying unsettled with the trough sitting over the country bringing plenty of rain and cool temperatures. A deep low pressure system will sit just to the south of the country this weekend threatening the delivery of further heavy rain to southern parts and a stiff cold east wind, whilst at the same time we see heights building to our north and northeast.

Differences between ECM and GFS this evening, the former is suggesting May will start off much more settled than the last 4 weeks, as heights build strongly to our NE sinking the trough away to our south and consequently the promise of dry sunny and warmer temps (though nothing particularly warm for the time of year). GFS keen to draw the azores high northwest slightly allowing a westerly feed to develop pushing those heights to our NE aside.

ECM does well in forecasting easterlies, and early May is often associated with easterlies, but whether this is the sign of a pronounced pattern change, or just a temporary change remains to be seen. Azores heights look like staying far to our SW which will allow the trough to attack and drop down from the NW very easily..

We might not even get the easterly if the troublesome trough lingers in situ, the low pressure could easily hang around and rotate which would mean a very different outlook for the start of May, with this in mind it is too early to call an easterly set up just yet, there is alot of weather to get through before the end of the month and lots of propensity for further changes.

[WhiteFox]

Indeed, a change may be afoot, but as mentioned by other posters it may not be a change to widespread settled weather with lots of sunshine. Indeed, as we often see in winter, relying on the positioning of a high to the east to deliver favourable synoptics (in this case warmer and sunnier weather) can often result in an unfavourable solution. In this case, if the high is too far north or east, the southern half of the UK is left in unsettled, albeit warmer, weather. So yes, it seems a pattern change is being hinted at, but it is a fair way off and the detail will change. Besides, it is highly unusual for any synoptic pattern to persist longer than a few weeks, so probability wise we should see an end to the deep Atlantic depressions at least for a time.

[Milhouse]

London Ensembles are showing a definite warming and drying out trend. There are more members touching 10c that 0c.

http://www.wetterzentrale.de/pics/MT8_London_ens.png

[davehsug]

The sort of easterly progged in the models is pretty standard fare for this time of year though? Maybe not recently, but many Mays of my experience have started with Easterlies. Not nice in the East but Western & Central areas start cool & cloudy & gradually brighten up leading to pleasant warm afternoons. I'm surprised that some don't see it as likely or even possible.

[Scorcher]

The sort of easterly progged in the models is pretty standard fare for this time of year though? Maybe not recently, but many Mays of my experience have started with Easterlies. Not nice in the East but Western & Central areas start cool & cloudy & gradually brighten up leading to pleasant warm afternoons. I'm surprised that some don't see it as likely or even possible.

Yes I remember similar synoptics in the first half May 2006 and western areas fared very well then with warm and sunny conditions. I was in Lancaster at the time and that area of North West England is very favoured in easterlies.

[SP1986]

Im not sure I buy the easterly still. FI seems a little over the top with the cold - actually monumentally over the top, no chance of that occurring, but I still think it'll be fairly cool. If we disregard past 120 hours as the unreliable timeframe, then nothing much has changed.

[Robbie Garrett]

I am actually still thinking this idea of warm May here we come is a pipe dream, just as much as I thought we would knock out Barcelona tonight. Small chance but can/has happened.

CFS looks decidedly unsettled from a long terms perspective, but once again I'd like to highlight the fact this could be from a stormy perspective. I'd put my money on low pressure running into a stubborn euro high, and making sure Summer is an unforgettable one, for many reasons.

The trough looks fairly consistent to set up shop to the west of the UK, at 180hrs and is fairly consistent across the board (CFS, GFS, ECMWF).... where it goes from here is probably where we need to wait for. IMHO, fairly warm may, humid, very thundery but some very good sunshine days. Temperatures probably slightly above average. Rainfall well above average if the storms can get going.

However just having around and there are 3 scenarios, the above being one of them, the 2nd being high pressure over the UK or nearby keeping things remotely average/below average but settled (boring if you ask me) and the 3rd being the trough staying put, or coming back after being moved away slightly. 3 relatively explainable solutions to your problem of May.

[conor123]

There seems to be a trend now for two areas of potentially thundery unsettled weather moving up from Europe bringing warmer air, one this weekend and then another next Monday/Tuesday.

Hopefully some sunnier weather will follow although the 18z thinks different.

[WhiteFox]

The sort of easterly progged in the models is pretty standard fare for this time of year though? Maybe not recently, but many Mays of my experience have started with Easterlies. Not nice in the East but Western & Central areas start cool & cloudy & gradually brighten up leading to pleasant warm afternoons. I'm surprised that some don't see it as likely or even possible.

Of course it's possible as May is generally when the jetstream is least active (iirc, May is often the best month for dry weather in Scotland and Ireland). However, this April has been more active than any I can remember for a long time; the storm lashing my windows right now is something I'd expect in November, not late April. Often the most powerful storm signals the end of an Atlantic dominated spell, but the last few years have seen the Atlantic pretty active through the summer months so we shall see. Just as with an easterly in winter facing off with the Atlantic I'll be more convinced when we get within 4-5 days...

[SP1986]

The outlook is becoming more defined; to put it simply; for the south and east warm and sunny with some thundery showers for the south in the medium range. For the North and west, cold-very cold wet and dull. Could be some unusual differences in temperature from northwest to southeast (maybe as much as 15C), but that's the only remotely interesting thing I can pick up from my northern perspective.

[shedhead]

The outlook is becoming more defined; to put it simply; for the south and east warm and sunny with some thundery showers for the south in the medium range. For the North and west, cold-very cold wet and dull. Could be some unusual differences in temperature from northwest to southeast (maybe as much as 15C), but that's the only remotely interesting thing I can pick up from my northern perspective.

I must be looking at a completely different set of charts to you, or talking about very different timeframes, because in my opinion the north looks driest and the south looks wettest going forward.

[Summer Sun]

Looking much better as we enter May with high pressure starting to become more of a feature, with the north seeing the best of the weather first whilst the south see's the most rain, later on we all move into the HP set up

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

[SP1986]

I must be looking at a completely different set of charts to you, or talking about very different timeframes, because in my opinion the north looks driest and the south looks wettest going forward.

Given the near time frame is pretty much nailed, I'm trying to work out the medium time frame. Besides even if the north is drier, it will be much cooler than southeast anyway I suppose what i should have said is the north looks dry and cool-cold (for April), and the west looks wet, dull and cold in general (west referring to Wales and western England). South is likely to be showery (wet), and milder/warm.

[ANYWEATHER]

Looking much better as we enter May with high pressure starting to become more of a feature, with the north seeing the best of the weather first whilst the south see's the most rain, later on we all move into the HP set up

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

To be Quite honest Gavin, I really dont see any clear cut way back to High pressure for all of us! Gfs keeps it unsettled right through to day ten taking us into May, Ecm however at day ten, shows High pressure keeping the North more settled, however looking by that the South will still see some unsettled conditions...

Edited April 25, 2012 by ANYWEATHER

[Milhouse]

The ECM mean has all of the UK under pressure of 1015mb or greater from 144h onwards which does suggest the dminiance of settled conditions over much of the UK. However that does not rule out the presence of occasional spells of rain associated with the low which will be never too far away from the south coast.

Looking at 144h onwards its looking like a situation with very much favours western Britian with north west Scotland possibly seeing the best temperatures. Further east there will be quite a keen easterly blowing at times but it should still be warmer than the single figures being experienced at present. There will be an abundance of warm air to tap into over Europe.

Edited April 25, 2012 by Milhouse

[Thundery wintry showers]

Easterly types can bring very different types of weather in May- the key factors are the strength of high pressure to the north vs. low pressure to the south, the strength of the winds, and the amount of frontal activity. For widespread dry sunny weather a strong high to the north can be counterproductive, as it produces a strong easterly flow which brings stratus and dull dry conditions well inland from the North Sea. Instead the optimal setup has a relatively slack, but dominant, high to the north and slack easterly flow, preferably vectored from south of east. There were certainly notable warm, sunny spells with easterlies during mid to late May 1992 and also the first half of May 2008.

But the other "face" of easterlies was starkly demonstrated in mid to late May 2008, when the settled periods were characterised by numerous dull dry days in the east and south, and low pressure to the south periodically threw up active slow-moving rain belts. In Norwich the two halves of May 2008 were exceptional for their contrasting sunshine amounts- the first half had almost a whole May's worth of sunshine, but the monthly total was only 10-20% above the local average.

Looking at the synoptics showing on the GFS, ECMWF and UKMO I am getting a strong "late May 2008" vibe, with low pressure playing a large role to our south and periodically throwing up slow-moving fronts, so probably not the sort of "summery" weather that many are after, but it does look likely to turn somewhat warmer with all that warm air having accumulated in the near-continent. The models are still struggling to get a grip on the pattern, so there is scope for change, but I don't see a "dry sunny" type easterly as being a very likely option at this stage.

[Robbie Garrett]

If the end of the 06z GFS is to be believed, that's about as unsettled as a washing machine going around. Early May may deliver a Thundery start, GFS has been hinting at this for a while.

Edited April 25, 2012 by Robbie Garrett