Model Output Discussions 12z 03/05/2016

[wishingforsnow]

Yes I suspect things won't be clear cut until the middle of next week. 50/50 at the moment. Hopefully we won't be on the wrong side of the 'so close yet so far scenario.'

[Singularity]

...or we could see the trough cut-off quickly, leaving it to fade away without doing much more than slightly destabilising the atmosphere over the UK.

The 12z det. runs so far (GEM, UKMO, GFS in order of enthusiasm) have moved toward this markedly, due to stronger jet south of Greenland days 4-6, which essentially means it's more inclined to head on east rather than dive south and continue to arc around the base of the trough west of Europe.

GFS refuses to cut the life-support for the trough until the weekend, but GEM and UKMO perform the operation sooner. In both of these solutions, the trough is all but gone by day 6:

 

Note too the high pressure NE of the UK and disrupted Atlantic trough. With a bit of amplification upstream, GEM allows the high to merge with a ridge from the southwest by day 9:

I daresay UKMO could pull off the same trick, given how similar it is to GEM at +144. In fact it looks a bit more amplified in the Atlantic.

Due to the Euro trough lingering longer, GFS takes until day 11 to achieve anything of such nature - and even then it's rather tenuous. Even so, it's interesting to see the emergence of this potential route to a fine spell of summer weather in June such as the Met Office have been hinting at for quite some time now.

One does have to assume, though, that the trend to a stronger jet S of Greenland days 4-6 does not reverse over the next 24 hours!

[knocker]

With the upper trough to the SW set to decline quite rapidly towards the end of the 6-10 period there would appear to be fair chance that the surface low will decline in influence over the BH weekend as well. The north should be okay in any case. So maybe some fine and quite warm weather Sunday/Monday but it all boils down to the detail regarding the surface low and how much convective activity is around down south stll. Post the weekend the GEFS anomalies have the HP in charge.

Helps if I post the correct chart.

Edited May 20, 2016 by knocker

[Singularity]

ECM really stretches things to get the polar jet right across to Europe and 'lever' the trough up through the UK during the weekend. Seems a rather unlucky outcome - but if anything that makes it more likely in this country 

Still all manner of possibilities for the BH weekend but it does look like we'll do well to avoid seeing at least a few showers on Sat/Sun. Monday is up for grabs perhaps. Early June is carrying some very promising signals - much as the final week of May once was. The fine weather has been delayed but that hopefully does not mean it's a red herring!

[wishingforsnow]

The High Pressure influence and fine summer weather has already been delayed from the last week of May unfortunately, but the models right now are throwing around all sorts of different scenarios for Bank Holiday weekend - now we are seeing some outputs showing a trough to the SW being dragged down, or the polar jet being levelled up. In these sort of situations where the models cannot firm up on an outcome, I tend to think what will happen is a halfway house situation so hot weather mixed in with occasional low pressure influence. And afterwards, June is looking good 

Edited May 20, 2016 by wishingforsnow

[I remember Atlantic 252]

1 hour ago, wishingforsnow said:

The High Pressure influence and fine summer weather has already been delayed from the last week of May unfortunately, but the models right now are throwing around all sorts of different scenarios for Bank Holiday weekend - now we are seeing some outputs showing a trough to the SW being dragged down, or the polar jet being levelled up. In these sort of situations where the models cannot firm up on an outcome, I tend to think what will happen is a halfway house situation so hot weather mixed in with occasional low pressure influence. And afterwards, June is looking good 

ECM suggests good start for Whit week! but bound to be gone in morning

[knocker]

There is a pretty good symmetry between the ecm and NOAA anomalies this evening which still leaves the BH difficult to call regarding detail but obviously this far out that would always be the case, But if we can firm up the upper air pattern it might be a tad easier to resolve later.

Anyway in the 6-10 range both have the trough just to the west and HP ridging to the east and then west north of the UK. The problem is that the end of this period is the BH weekend and about the time that the trough starts retrogressing and HP builds in the vacinity of the UK and is in situ by Tues/Weds and remains there until the end of the run.

So surface wise, at the moment, best guess scenario would be a very slack area of not very low pressure slowly dissipating through Saturday to Monday so you could take a punt on showery outbreaks south of the Midlands before a pleasant Monday. That's if you are daft enough at this range but it's a working hypothesis.

[knocker]

A quick look at the rain prospects for today.

Back to the BH weekend and the evolution is still as indicated already but the GEFS isn't clearing the upper low that quickly ergo on this morning's evidence the influence of the surface low may well be felt for the whole weekend so although quite warm outbreaks of rain, maybe thundery are very possible in the southern half of the country. All still very much conjecture at this stage of course

[knocker]

Regarding the BH the ecm det. is also in no hurry to remove the upper trough consequently this morning's run is showing low pressure in close proximity for much of the holiday so previous vis weather will apply.

[mb018538]

Maybe we're starting to finally firm up on the evolution of things now. Looks like the trough will be close to the UK for the bank holiday weekend, though exact positions will determine what weather we end up with. Either way, there is warm air in the mix, so temps probably around or just above average, possibly hitting 23c or so in any clearer spells. Devil is certainly in the detail.

[knocker]

Looking at the EPS ens anomalies it is a similar story. It seems that instead of the trough declining in situ as the HP drifts SW it slowly moves SE which has the effet of keeping the surface low a little bit longer in the proximity of the southern and eastern half of Britain,

Edited May 21, 2016 by knocker

[wishingforsnow]

Basically confirms what I think will happen for BH weekend: a mix of sunshine interspersed with thundery showers with temperatures breaking 20c again.

[cheese]

Familiar pattern.. I really hope this type of thing isn't a sign of what's to come throughout summer.

[phil nw.]

No sign of things settling down just yet with shallow low pressure continuing to affect us through next week.

The UK/GFS/ECM outputs all show the showery trough situated just to the south west-a snapshot at day 4 of the surface features indicating bands of showers and rain moving up from the south and south west during the coming days.

It doesn't look a complete washout every day by any means with spells of warm sunshine likely to be around in between.

This weather type looks like continuing until the BH weekend looking at T180hrs on the GFS mean

Some signs now  of high pressure building across from Scandinavia by day 10 brining drier conditions further north whilst the area of lower pressure to the south west drifts east into the continent.

Perhaps a sign of more widespread settled conditions under an easterly regime in week 2 although the continental low with rain/showers still remaining uncomfortably close to the south.

Still an element of uncertainty of course that far out so future modeling on that needs watching.

 

Edit.Please ignore image below-can't get rid of it!

 

 

Edited May 21, 2016 by phil nw.

[Cloud 10]

Increasingly bizarre GWO forecast over the last few days which has now disappeared off the screen!

 

I'm sure this will have implications of some description.

 

 

 

[wishingforsnow]

4 hours ago, cheese said:

Familiar pattern.. I really hope this type of thing isn't a sign of what's to come throughout summer.

I think GFS are underplaying the temperatures slightly here. Low-mid 20s currently forecast for my location for Bank Holiday weekend. What we see here is a north south split but encouragingly, as the charts posted by @phil nw. illustrate, as we move into June it looks like the High Pressure over Europe will begin to have a stronger influence over the low 

[cheese]

23 minutes ago, wishingforsnow said:

I think GFS are underplaying the temperatures slightly here. Low-mid 20s currently forecast for my location for Bank Holiday weekend. What we see here is a north south split but encouragingly, as the charts posted by @phil nw. illustrate, as we move into June it looks like the High Pressure over Europe will begin to have a stronger influence over the low 

The forecast for here looks pretty dreadful for nearly June. I'm not impressed at all. Looks like the rest of Europe except Iceland  and Ireland will see significantly warmer weather than the UK over the next week. Hopefully things do improve in June. 

May is typically our sunniest month of the year - my nearest Met station gets 211 hours of sun on average - but it seems like May has/is becoming cloudier/cooler.

Edited May 21, 2016 by cheese

[Geordiesnow]

Kinda typical outputs for this time of year with an easterly flow soon developing and look like persisting in some capacity for the foreseeable future. 

Wednesday does look like it could be the coolest/dullest/wettest day of the week but a lot of uncertainty regarding the details, the shallow trough could well be in a different position by Wednesday comes around which of course will certainly affect the weather on the day itself. 

Certainly potential to scoop up some warmth but I don't as of yet see much in the way of a dry settled spell, can't complain as we recently just had one and at the moment, heights over Greenland are low which could bode well for the summer. 

[wishingforsnow]

29 minutes ago, Geordiesnow said:

Kinda typical outputs for this time of year with an easterly flow soon developing and look like persisting in some capacity for the foreseeable future. 

Wednesday does look like it could be the coolest/dullest/wettest day of the week but a lot of uncertainty regarding the details, the shallow trough could well be in a different position by Wednesday comes around which of course will certainly affect the weather on the day itself. 

Certainly potential to scoop up some warmth but I don't as of yet see much in the way of a dry settled spell, can't complain as we recently just had one and at the moment, heights over Greenland are low which could bode well for the summer. 

Yes, nothing overly dry, hot or settled for the next week but the signs of high pressure influence as we enter next month have been bullishly forecasted over the past week or so. Perhaps it is delayed by the greater low pressure influence during the last week of May but currently there is a good chance of something better to follow as the HP becomes more influential. Low heights over Greenland and Easterlies should also be good for greater influence of continental warmth this summer compared to last year.

[knocker]

A brief resume of this morning's GFS run for the next ten days. By midweek the low pressure that has been well signaled for some days is in situ west of Iberia. From here until Sunday this, along with the high pressure to the north east will strongly influence the UK synoptics. Because of the nature of the latter, instability creeping north from France detail, even at this range, is impossible to nail down so this just represents this morning's snapshot.

Friday looks the most likely day for thundery outbreaks almost anywhere but particularly in the south as a small unstable area of low pressure moves north over France.and into the North Sea. The affects of this will linger into Saturday but by Sunday, with tha main area of low pressure moving east the Azores HP is edging inn and is the main influence by Monday.

This, if it actually verified, wouldn't be a bad scenario for the BH with temps above average and becoming drier as the weekend progresses.

Looking at the anomaly there still must be some doubt on the timing of the LP moving east but it will be quite warm.

Edited May 22, 2016 by knocker

[knocker]

The ecm has an interesting take on proceedings post BH. It develops an upper low from the main trough to the SE which moves north into the NE, This spawns a surface low which swings west over the UK bringing some very inclement weather indeed.

Edited May 22, 2016 by knocker

[knocker]

Looking at the EPS 10-15 anomaly this morning the first week in June still looking fine with HP and temps a little above normal.

[Summer Sun]

Hello summer!

If the cloud isn't as thick as shown temps would rocket

Edited May 22, 2016 by Summer Sun

[reef]

4 hours ago, Summer Sun said:

Hello summer!

If the cloud isn't as thick as shown temps would rocket

There's a front stuck over the east of the UK and a keen easterly breeze so it would be disappointingly cool and cloudy for most with that. Western areas would possibly reach the low 20s in any sunshine though.

The current charts remind me of that easterly spell at the start of June 2007. Hopefully that's where any similarities end!

[Cheshire Freeze]

18 minutes ago, reef said:

There's a front stuck over the east of the UK and a keen easterly breeze so it would be disappointingly cool and cloudy for most with that. Western areas would possibly reach the low 20s in any sunshine though.

The current charts remind me of that easterly spell at the start of June 2007. Hopefully that's where any similarities end!

The thing that is most striking to me within the current output (have mostly been checking the GFS though it must be said) is the expanse of higher than average heights to our N. With sufficient latitude of these heights, the jet will be encouraged to the S of the blocking and on current viewing into the extended outlook, it looks as though this may be straight through or just S of the UK.

Whenever you see LP wandering up to the UK from the S or SW in summer, it has the potential to be very wet.