Model output discussion 9th April onwards

[Frosty.]

Looking at the longer term GEFS 12z there are glimmers of hope here and there that we might see a pattern change to something more appropriate as we head towards the start of the meteorological summer?...fingers ️ ...cherries included..for sure, the mean improves long term!!!!!  

 

Edited April 28, 2021 by Jon Snow

[SqueakheartLW]

Couldn't fail to spot this outlier run within the 12z GFS which produces snow, yes snow in early May too and a lot of it too.

Member 29 is going for almost 28cm of snow in Scunthorpe between the 4th and 5th of May. I mean, just wow if that really came off.

500mb chart

Here's the 500mb chart which clearly shows up the culprit system for this

That is a southerly tracking low which is taking strong winds and with the above snow depth chart rain, sleet and snow with it. Just look at how far north that air has come from to interact with this low pressure

850mb chart

Here's the 850mb chart for the same time showing just how cold the uppers are for the time of year

Apart from the far SE of the UK the vast majority of the UK is under at least -5 uppers and the -10 uppers look to be threatening to move down towards the far N of the UK. No wonder it is showing a snow risk and that temperature contrast between Scunthorpe and SE UK is no doubt responsible for that predicted 28cm of snow

2m Temp chart

That is some very low 2m temps for early May and although it can't be clearly seen here the 2m temp for Scunthorpe at this time is only 1.8C. This is some major outlier in the ensembles but what if it was correct and the others come into line with it. Are we going to see one last bite of winter before we finally warm things up. Considering how cold April was at times then we can't rule something like this out.

[ANYWEATHER]

Charts like this are very rare in early May...wish I could check up tonight on historical data  but have no time to  do so.....but the cold continues ...I I would not be surprised for snow to appear even in southern Britain...in the following days....!

[ANYWEATHER]

PS these are Winter charts....

[damianslaw]

In the reliable - if you like northern blocking you'll rejoice in the current model output. Significant northern blocking in stall, long drawn northerly airstream and pure arctic air = very cold uppers for the time of year, much of the north locked in sub 528 dam air for much of the next 7 days.  Its a notably cold outlook.

A change to a cold cyclonic pattern next week, southern parts may see temps a bit closer to the early May average but under cloud, wind and rain - it won't feel particularly pleasant.

Very disappointing outlook for the start of May.

Edited April 28, 2021 by damianslaw

[Frosty.]

Here’s a few charts that got my attention on the Gfs 0z operational despite the low res timeframe!!!...the duality of spring in a nutshell!!...summer heat not far to the south (31c 88f) across parts of France ...   doing battle with the polar / arctic airmass further north.....this is but one of many reasons why I love the weather sooo much!!! ⛈  

Edited April 29, 2021 by Jon Snow

[PiscesStar]

2 minutes ago, Jon Snow said:

Here’s a few charts that got my attention on the Gfs 0z operational despite the low res timeframe!!!...the duality of spring in a nutshell!!...summer heat not far to the south doing battle with the polar / arctic airmass further north.....this is but one of many reasons why I love the weather sooo much!!! ⛈  

May I just say a huge thank you for your posts I love em 

[PiscesStar]

The insanity continues Folks as as the GFS latest output keeps northern blocking Throughout the run.  Also, like a crazed cleaner, Notice how the gfs sweeps the warmth and high pressure to the Eastern corner of Europe as fast as it tries to establish itself... Oh dear!! 

Edited April 29, 2021 by Snowfish2

[minus10]

2 hours ago, Snowfish2 said:

The insanity continues Folks as as the GFS latest output keeps northern blocking Throughout the run.  Also, like a crazed cleaner, Notice how the gfs sweeps the warmth and high pressure to the Eastern corner of Europe as fast as it tries to establish itself... Oh dear!! 

Yes.. its like the warm air keeps knocking on the door but it will not be let in..

[damianslaw]

3 hours ago, Snowfish2 said:

The insanity continues Folks as as the GFS latest output keeps northern blocking Throughout the run.  Also, like a crazed cleaner, Notice how the gfs sweeps the warmth and high pressure to the Eastern corner of Europe as fast as it tries to establish itself... Oh dear!! 

Northern blocking often a feature of May, sometimes we sit on the cold side of the polar front throughout, with consequential northerly and chilly easterly airstream, sometimes the highly amplified flow pushes the Atlantic front far to the SW and we draw in a warmer continental feed, more of a west based NAO scenario. Currently it looks more east based, which means cold.

[Purga]

Oh well, I suppose May is looking to start cold and wet as a change from cold and dry!

plus ça change, plus c'est la même chose

[mb018538]

3 hours ago, Snowfish2 said:

The insanity continues Folks as as the GFS latest output keeps northern blocking Throughout the run.  Also, like a crazed cleaner, Notice how the gfs sweeps the warmth and high pressure to the Eastern corner of Europe as fast as it tries to establish itself... Oh dear!! 

Not sure I agree there....

Day 4 - Greenland high                         


Day 10 - Starting to break down





Day 13 - gone


Day 16 - Completely gone



The N Hem profile always looks a bit weaker once the PV disappears for the summer anyway, but that last chart shows pretty low heights for mid May.

 

[Methuselah]

Out to T+231, and the GFS 06Z is starting to look worryingly similar to both 1983 and 1996 . . . not that the following summers were at all bad, mind?

     

It's just that, what with lockdown coming to an end, the last thing we need now is a long, drawn-out wait for summer?

[Methuselah]

Day 10, and is this the final fling from el norte? Hope springs eternal!

     

[Allseasons-Si]

Could this be the first plume of 2021 with maybe some fireworks in the channel,...i hope so cos i am sick of this non descript Spring cool weather ...

gfs 06z 276,...come on.

Edited April 29, 2021 by Allseasons-si

[Methuselah]

          

[mb018538]

11 minutes ago, Allseasons-si said:

Could this be the first plume of 2021 with maybe some fireworks in the channel,...i hope so cos i am sick of this non descript Spring cool weather ...

gfs 06z 276,...come on.

20c 850 air over Spain and France in early May is quite exceptional.
 

Probably in part due to the fact that North Africa has been baking hot and way above average for a while now. Any plumes headed our way could have extra oomph to them this year (though recent years have hardly failed to deliver on the heat front anyway!) 

[Guest]

I hope I don't curse this but GFS appears to moving away from more northerlies in the 8-10period but its going to be pretty a unsettled spell instead. Any true warmth looks like being injected more into central Europe with us being more on the periphery and liable to rapid breakdowns, still its a start despite the pattern still being too for east. 

[Methuselah]

Definite 'potential' at T+384 (isn't there always?). But, at least things are at last looking up?

     

Unless, of course, the GFS operational run has merely switched form the cold end, to the warm end, of the spectrum?

[Tim Bland]

Ensembles suggest nothing exciting, but at least a return to something more average for the time of year and some much needed rain for the farmers & gardeners ..

[summer blizzard]

Euro this morning showing something perhaps of interest at day 9/10 or perhaps just very wet.

https://www.wetterzentrale.de/en/topkarten.php?map=1&model=ecm&var=2&time=216&run=0&lid=OP&h=0&mv=0&tr=24

[stodge]

Evening all

It seems there's an almost febrile desire for a change in the current pattern. London should be 17c but again we struggle in the low teens. 

I wonder if the May minimum temperature record will be under threat over the weekend.

Looking ahead, a selection of the T+240 charts:

So that's the 12Z from GFS OP, ECM, GEM, JMA and GFS Control.

If you can see a warm and settled outlook from there, you've got better eyesight than me. Varying degrees of unsettled with LP moving NE close to the British Isles.

The significant change from the current pattern isn't Greenland but Europe and heights now showing over southern and south-eastern Europe which would "suggest" milder air though again nothing exciting and the price of a small rise in temperature is a big rise in precipitation. If you have heights to the NW and the SE, the trough has to fit in the middle and that means north-western Europe as LP forms near the Azores and runs NE across Britain.

I have to say further into FI the hint is for renewed height rises to the north east over Scandinavia which I don't buy at this time but the continued amplified pattern leaves mid-Atlantic ridging on the cards which I suppose offers the prospect of ridging across the British Isles but again all conjecture at this time.

[Jordan S]

For those in the southeast apart from the chance of showers in the next few days, more significant rainfall will return later monday into early tuesday.

We've got the showers tomorrow, saturday and sunday for quite a lot of the uk, slow moving and some of them probably very heavy giving a significant amount of rain locally, sleet and snow likely at times in a few of these for high ground in the north, a small chance of one or two thunderstorms again but also a few places staying mostly dry with sunshine.

Low pressure moving eastwards on monday, you can see it seperating away from a large low over to the far west then developing quickly as it crosses the uk,the centre most likely will be a little further south than the Gfs is showing,  unseasonably windy with an active possibly in places squally weather front moving east on monday afternoon and monday night across England and Wales, the rain probably heavy at times and persistent in some areas with around 50mm likely for the north of England and south of Scotland. A possibility of snow falling on some high ground of southern or central Scotland, small accumulations could happen.

The winds very strong in many places especially for the time of year with gales on some coastal areas and hills. Gusts of 40-50mph for most inland but for some coastal areas and on hills 50-60mph is likely and a little more than that possible in the most exposed location.

The middle part of next week rather complex with areas of low pressure still likely to be on a southerly track.. the low from monday/tuesday brings colder air south with the potential for snow on higher ground in any systems coming in from the west/southwest for midweek.. more likely for central parts of England and Wales but otherwise more rain likely here and especially for the south..

Icon I think is probably closer to the outcome for the midweek period though the northern limit perhaps the Midlands and southwards.

Ecmwf even further south though..

 

 A low pressure system for later next week more likely to develop quite quickly bringing another potentially very wet spell and possibly very windy too at the moment more for the west and south of the uk, temperatures perhaps close to average next weekend in the south but it remains colder than average for the north though.. and the snow chance still likely to continue for Scotland.

Looking further ahead Into the following week probably remaining unsettled especially the first half rain at times, more likely for the south though longer drier spells a little more likely compared with next week and the weekend. The weather in the north likely remaining similar.  Temperatures average to slightly colder than average most likely aswell for all. A brief big increase in temperatures a possibility for the south and east. 

Edited April 29, 2021 by jordan smith

[minus10]

54 minutes ago, jordan smith said:

For those in the southeast apart from the chance of showers in the next few days, more significant rainfall will return later monday into early tuesday.

We've got the showers tomorrow, saturday and sunday for quite a lot of the uk, slow moving and some of them probably very heavy giving a significant amount of rain locally, sleet and snow likely at times in a few of these for high ground in the north, a small chance of one or two thunderstorms again but also a few places staying mostly dry with sunshine.

Low pressure moving eastwards on monday, you can see it seperating away from a large low over to the far west then developing quickly as it crosses the uk,the centre most likely will be a little further south than the Gfs is showing,  unseasonably windy with an active possibly in places squally weather front moving east on monday afternoon and monday night across England and Wales, the rain probably heavy at times and persistent in some areas with around 50mm likely for the north of England and south of Scotland. A possibility of snow falling on some high ground of southern or central Scotland, small accumulations could happen.

The winds very strong in many places especially for the time of year with gales on some coastal areas and hills. Gusts of 40-50mph for most inland but for some coastal areas and on hills 50-60mph is likely and a little more than that possible in the most exposed location.

The middle part of next week rather complex with areas of low pressure still likely to be on a southerly track.. the low from monday/tuesday brings colder air south with the potential for snow on higher ground in any systems coming in from the west/southwest for midweek.. more likely for central parts of England and Wales but otherwise more rain likely here and especially for the south..

Icon I think is probably closer to the outcome for the midweek period though the northern limit perhaps the Midlands and southwards.

Ecmwf even further south though..

 

 A low pressure system for later next week more likely to develop quite quickly bringing another potentially very wet spell and possibly very windy too at the moment more for the west and south of the uk, temperatures perhaps close to average next weekend in the south but it remains colder than average for the north though.. and the snow chance still likely to continue for Scotland.

Looking further ahead Into the following week probably remaining unsettled especially the first half rain at times, more likely for the south though longer drier spells a little more likely compared with next week and the weekend. The weather in the north likely remaining similar.  Temperatures average to slightly colder than average most likely aswell for all. A brief big increase in temperatures a possibility for the south and east. 

Great post Jordan, What it illustrates is that at long last things will be getting more mobile again with some much needed rain for most areas. Hopefully still some sun at times and after a cool start a rise in temps should occur. Certainly in the sun today it felt very pleasant if not warm with little wind. Not had any of the showers yet though. Maybe in next couple of days before more general rain on Monday...

[Frosty.]

The long term signal from the GEFS 12z mean is indicating less unsettled and somewhat warmer..yes warmer!...and when you look at these perturbations you will see what I mean...there’s the possibility of a pattern change to something approaching summer-like as we head towards  or during the mid May period onwards!...so yes, next week looks unsettled with some very welcome rain ? ️ following such an extremely dry April...I admit I’ve cherry picked some decent charts here, there’s still some crud ensemble members but sometimes these longer term mean signals become reality!!...night all..

 

Edited April 29, 2021 by Jon Snow