Model Output Discussion - Spring Has Sprung

[WYorksWeather]

For the shorter range, worth looking at UKV for the next few days on temperatures. Temperatures for Wednesday through Sunday afternoons below at 850hPa and then at the surface.

In short, a growing tendency to bring increasingly warm air in at 850hPa. Notable increases in predicted temperatures compared even to yesterday's output - getting 10-11C at 850hPa by Sunday and temperatures quite widely into the mid-20s.

Day by day, UK maxima are projected by the model from at 20C, 22C, 23C, 25C and by Sunday 27C, and again if usual slight underestimation were to apply maybe 28C somewhere on Sunday?

Worth remarking actually how warm this is for so early in the year. For a bit of context the earliest 30C ever achieved is on the 12th May, so we're only a couple of degrees off all time records for the time of year. It would only take a very slight upgrade to put 30C on the table for Sunday.

What a turn around from late last week, when there was talk of temperatures being limited to low 20s only. On Saturday and Sunday those temperatures should be reached by 9am if UKV is right!

 

[Scorcher]

 WYorksWeather Really impressive to see such high temperatures widely across the country over the weekend. It's not too often we reach 25C before the 2nd half of May here.

[WYorksWeather]

 Scorcher Definitely not a common occurrence historically, no. But without going off topic it just happens so easily these days. I mean we don't even have a spectacular setup - soils are quite wet, there's still expected to be a bit of wispy cloud around, SSTs are still relatively cold though warmer than average, and the sun is still a fair way from peak strength.

Of course by Sunday it will be equivalent to the very end of July, so not that weak any more, but still a factor especially when combined with the others above.

 

[damianslaw]

 WYorksWeather We seem to be in a situation where we are starting from a base state 2 degrees above the mean average for the time of year, meaning rather average synoptics can give appreciable warmth. 

[LetItSnow!]

2 hours ago, WYorksWeather said:

What a turn around from late last week, when there was talk of temperatures being limited to low 20s only

To be fair, I do remember seeing a couple days ago the first idea of a warmer pulse of air and commenting on it, though at that time it was on the 10th, now it's probably around the 12th.

Taking my usual look at the GFS (left) and ECM (right), they show a general agreement until the 13th. High pressure naturally relaxing back eastward and drawing up a very warm south-easterly flow, though with weakening pressure a risk of things going BANG and maybe more general thundery rain.

How they individually handle weakening pressure by the 16th is different though. The GFS is keen to send the low into Europe and build a ridge in, possibly dry and warm weather after a thundery break. The ECM is much different and forms a major low pressure system which would risk further deluges and a wet May.

Both ensembles show signs of at least weak pressure over the country by Thursday the 16th. At the moment it seems this is the signal so by day 10 it could remain quite thundery with some torrential downpours and longer spells of rain around. Either way though it's all looking warmer than average. Even if something like the ECM came off it would probably return warmer than average means due to mild nights.

Things can change though. We've seen before a run pick something up and then be right so don't discount a more settled look, but to me I think unsettled, and possibly thundery, is a relatively safe look for mid-month.

[Daniel*]

3 hours ago, WYorksWeather said:

growing tendency to bring increasingly warm air in at 850hPa

I’d exercise caution I have noticed UKV sometimes gets carried away, general models supporting 9-10C 850hPa temps further SE not exceptional. I can’t see 30C being a possibility with the air mass, typically minimum for 30C it needs to be 12C, I recall in summer 2018 this was enough at times, but there were drought conditions, soils were very dry and of course we were not as early in year. Not just locally but what makes is even more unlikely to our near south, France also has very saturated soils, which is not usual for the time of year. I’d say we probably will be limited to 27-28C which of course is still very warm.

[northwestsnow]

00z EC..

A truly awful chart.

Better make the most of the next 4 days as things look like going downhill dramatically thereafter.

UK trough .

 

[Bats32]

 northwestsnow Just came on to say that, all models look like they're showing it for next week. Very poor outlook this morning. UkMG ....  

[clark3r]

 northwestsnow after few days break the relentless rain may be on the way back! I hope this pattern can break for the summer 

[Scorcher]

Big overreaction from some this morning. The positioning of the low is still changing from run to run so no point jumping to conclusions yet.

Only yesterday it was being shown as further to our south west which would allow warmth to continue albeit much more unsettled.

[ANYWEATHER]

 Scorcher I think models are now firming up on next week ,yes with the caveat of some changes in the synoptics still to assertained,  but make the most of this week , different ball game totally next week....

[Catbrainz]

Overall trajectory of the pattern seems that with pressure rising over northern UK the low is pushed south towards Iberia/Biscay and being weakened but I will reserve solid judgment until the weekend as cut off lows can be unpredictable 

[Howie]

I truly hope the deluge doesn't return

[danm]

Not great charts for early next week this morning, the through becomes centred over the UK which will keep it cool and wet. However, only yesterday it was showing the trough to the SW of the UK so more runs needed. 

The GFS gives some encouragement. It also shows a UK based trough early next week, but it quite quickly fills and sinks to the SW so that we get this by Thursday and Friday:

[Alderc 2.0]

Disappointing output this morning, once that pattern gets in you can’t expect it to clear out for at least a week.

[Alderc 2.0]

 danm agreed although it’s a pretty clear signal, can’t see this turning around quickly. 
 

[ChannelThunder]

Yep, the high relinquishes its grip on Sunday and it's back to square one. I'll certainly be making the most of the rest of this week. Thankfully I get good WiFi on the patio so I can work out there when I've not got meetings! Being south facing, it gets pretty toasty in the sun 

[danm]

 Alderc 2.0 the sea level pressure chart you posted does show it recovering fairly quickly. Not back to wall to wall sunshine but something more settled, with a trough to our SW which should give a mix of warm sunny spells and perhaps some thundery showers. Probably drier over Scotland in that set up. 

[Scorcher]

 Alderc 2.0 No mention of the fact that the op is very much on the lower end of the ensembles for early next week?

In terms of pressure anyway. If it ends up being further south west as was shown yesterday evening, it will make all the difference. There is still scope for that to happen.

In any case it's not back to square one as someone has suggested in here- it's not exactly an Atlantic onslaught. We could well still have E/SE winds next week which is unlikely to mean constant rain for the west side of the country at least.

[Downburst]

Certainly a cool down, with a complex to model double low on the latest ECM next week. Obviously will change, but the picture is a little worse than I expected for next week. Likely more rain West of Ireland and SW England and Cornwall, but pretty much everywhere to get some rain with average 10 to 30 mm over next 10 days. Can the hedges break all records in growth, please not.

I don't know what to make of this weather, hard to see on the 46 day what is going to happen, latest ECM showing a flabby High out west, but the mean is low pressure out west.  I don't think it's looking very settled over next 4 or 5 weeks, but then again it might be pleasant nevertheless in the lived experience. The very long range seasonal suggests the summer to get better as it goes on, so can we at last have a great August and September, not one or the other. 

Final part of Summer, please tell me that's a northerly Jet and we get frequent ridging, but it's not showing any positive pressure to the south of that lower to the north.

[Scorcher]

 Downburst Given the ECM was showing widespread rain and showers for parts of England for today only a few days ago, I don't think we should be trusting those precipitation charts for next week.

[Howie]

Is it me or is the 06z run glitching on wetterzentrale

[Rain All Night]

21 hours ago, Rain All Night said:

0z ensemble means, out to Wed 22 May (day 15)

It seems the small trough is destined to fill over or just to the south of the UK next week, but the following weekend remains up for grabs. 

0z deterministic runs, on Tue 14 May (day 7)

It seems the low is going underneath us to the southwest initially, which might buy some more time under the settled weather conditions for those further northeast?

I did find one dissenter...

0z ensemble means, out to Thu 23 May (day 15)

There remains no meaningful signal beyond Friday 17th May, so everything remains on the table for the following weekend.

0z deterministic runs, on Wed 15 May (day 7)

There's no denying it, this is unfortunate. At least we've got this week, including a fabulous-looking Friday and Saturday, and the hope that better days could return again from Saturday 18th May onwards.

 

[WYorksWeather]

 Daniel* I totally agree, which is why I said it would require a further upgrade - just making the point that if we see 27C in the modelling it wouldn't take much of a tweak. As it happens the model has moved slightly the other way this morning - max for Sunday is down to 26C.

 

[Downburst]

 Scorcher Agreed on the totals, but the general trend is lower pressure which means rain more likely, but it's a tricky one to model so plenty of time to change the detail.