Model Output Discussion - What does April have in store?

[Mike Poole]

ECM 12z:

The cool early spell quickly taken over into the weekend by a dry settled spell with increasing warmth, before a low pressure system from the west brings an unsettled end possibly with some thunder as the heat breaks down.

[Frosty.]

I mentioned earlier about the improved longer term GEFS 12z..here are the charts.

[knocker]

A bit of a narrow squeak there Sidney

Edited April 29, 2019 by knocker

[knocker]

I hope nobody has booked a holiday weekend break in Italy

[knocker]

Looking at the EPS it has a lobe of the vortex plunging some very cold polar air down into Europe

[Frosty.]

It only took 6 months for the first Northerly to verify..ok it hasn't verified yet but it will!!!!

Edited April 29, 2019 by Frosty.

[damianslaw]

1 hour ago, Frosty. said:

It only took 6 months for the first Northerly to verify..ok it hasn't verified yet but it will!!!!

We are now at the time of year when northerlies reach their yearly annual peak - not saying we should expect them, but we should expect them to appear more at this time of year than at any other. Its still a few days off, and there is a chance the cold northerly shot might just miss us - but the models are quite bullish this evening of a potent straight northerly bringing low maxima and cold minima with threat of widespread air frost Friday night - nothing unusual for the time of year.

Longer term - any northerly incursion looks very shortlived with the ridge toppling in quickly hopefully bringing a warmer end to the long bank holiday weekend. Into next week, signs trough will come back again from the west, but with no real oomph to the atlantic this too could be quite shortlived, and I wouldn't be at all surprised to see anticyclonic conditions begin to dominate as we move through the middle part of the month. 

[MATTWOLVES 3]

Alot being spoke of the upcoming Nthly, it's still very much a blink and miss it event. It certainly packs a punch in Scotland for a while, before pressure rises and temps gradually lift into the bank holiday.... Not bad overall!!! The south shouldn't be to troubled by this Northerly, but Scotland may suffer for a short while. 

meanwhile its a bit nippy up  North!! 

Edited April 29, 2019 by Mattwolves

[SunnyDazee]

8 hours ago, Ed Stone said:

Crap! Crap!  

Crap!  Said Victor Meldrew!

Seriously starting to think May might be a cooler than average month now

[SunnyDazee]

4 hours ago, Mattwolves said:

Alot being spoke of the upcoming Nthly, it's still very much a blink and miss it event. It certainly packs a punch in Scotland for a while, before pressure rises and temps gradually lift into the bank holiday.... Not bad overall!!! The south shouldn't be to troubled by this Northerly, but Scotland may suffer for a short while. 

meanwhile its a bit nippy up  North!! 

I always wonder whether I’m classed as up north when weather forecasters talk about it. Do you think they mean up north as in Cumbria and Northumberland or the entirity to the midlands

Edited April 30, 2019 by SunnyDazee

[knocker]

Outlook - A mixed bag over the next few days but notable the pattern change introduces much colder air into Europe

The Atlantic 500mb and surface analysis for midnight and the UK 0400 UTC chart

A clear start to the day in many areas, albeit a fair amount of mist/fog around, but this should clear quite quickly giving a quite warm and sunny day. But the west not quite so lucky as a stray warm front has already introduced cloud and patchy rain here. This will tend to peter out as the weakening front tracks east but more rain from the cold front following behind will effect N. Ireland far far western areas by late afternoon

The front and rain will gradually move east through the night  but eastern areas will remain dry, albeit cloudier than last night

The showery rain will spread east across the country during Wednesday, clearing N. Ireland for a time but returning later, but the south east will stay dry with broken sunshine resulting in much warmer temps here

,

Overnight Weds and through Thursday the pattern changes mentioned at the beginning are taking place and an upper trough connected to the vortex lobe over northern Russia is sinking south over Scandinavia and thus we have a quite intense surface low over Finland with an associated cold front sinking south over Scotland which introduces much colder air. While all this is going on sunny intervals and showers the order of the day

The cold front continues to track south on Friday resulting in a cold showery day, wintry in the north

By Saturday the front is well clear into France and influence from the trough in the NE begins to ease as the subtropical high amplifies to the west and a high cell starts to drift across the UK. But still another cold day, after a frosty start, albeit the showers now concentrated down eastern coastal regions.

 

 

Edited April 30, 2019 by knocker

[Fourty Point Three Degrees]

Latest GFS suggests this weekend and into next week will be a battle between HP out west and LP out East with the UK stuck in between receiving a chilly Arctic feed for several days. Night time temps hovering around freezing and daytimes struggling to get above 10C. Could be damaging to gardens. Going to be rather confusing for nature as well as most wild life have just woke up from hibernation and will be thinking its Winter.

[knocker]

But in fact, according to the gfs the trough does not entirely lose it's influence over the rest of the holiday and showers continue down the eastern region on Sunday with some frontal rain moving down from the north east on Monday. Most of the country remains sunny but not particularly warm.

And the reason the trough to the north east staying influential is because the gfs has dropped the vortex lobe south over Scandinavia. There is still a lot of uncertainty vis the beginning of nest week so much caution is advisable.

Edited April 30, 2019 by knocker

[knocker]

After a cold but relatively dry Saturday, temps below average and showers down the east coast the ecm has Sunday a calm, sunny but not overly warm day with temps below normal but by Monday the ridge is under pressure as another trough drops south into Norway with the associated front tracking south west over Scotland. The movement of the front continues through Tuesday and the patchy rain moves with it but the key point here is that it introduces much colder air into the north eastern half of the country. It is but a glancing blow (hopefully) as cold air floods south over Europe into North Africa

 

Edited April 30, 2019 by knocker

[mb018538]

Cracking Greenland and Arctic high on show here.....d'oh!!

 

 

Edited April 30, 2019 by mb018538

[knocker]

Not a good trend with the EPS this morning with a highly amplified Europe and  a trough becoming established in the west with some (just about) cross polar flow. And the trough in the western Atlantic has more traction below the Greenland ridge resulting in the subtropical high being under pressure from two directions, The surface analysis tricky but temps below average. A not surprising scenario given the det, output

Edited April 30, 2019 by knocker

[Summer Sun]

It could even be cold enough for some snow over higher ground in the north by Friday

The chance of snow continues through the weekend albeit increasingly restricted to Scotland

[Methuselah]

The likelihood of a distinctly cool first half May appears to be growing:

GFS: 

Para: 

Ensembles agree: 

[BlueHedgehog074]

1 hour ago, Summer Sun said:

It could even be cold enough for some snow over higher ground in the north by Friday

The chance of snow continues through the weekend albeit increasingly restricted to Scotland

Hey... wait a minute!  Commenting on wintry weather in the models, eh?? This can’t be the real Summer Sun; you must be Summer Snow in disguise!

[knocker]

deleted

Edited April 30, 2019 by knocker

[Methuselah]

What's three-days' long and starts with a meh?

 

[MATTWOLVES 3]

8 hours ago, SunnyDazee said:

I always wonder whether I’m classed as up north when weather forecasters talk about it. Do you think they mean up north as in Cumbria and Northumberland or the entirity to the midlands

Quite an area for disagreement, usually when they state Northern and Central areas, its a reference to Scotland and the central swathe of the UK, (ie) Northern England, and to say Central, Southern parts would include larger parts of the Midlands, Southwards! I suppose you could put the North Midlands on the boundary to the more central section of the uk. Just looking at the GFS 6z out to day 8, still looking pretty ridgey, temps nothing special, probaly around average, so a rather uncertain start to May. Perhaps it will be the mid or final 3rd before we see an upturn in the more settled and warmer conditions. 

[Methuselah]

Northerly incoming at Day 10!

Anywho, the end is better than the beginning...Even then, every cloud has a silver lining: something's needed, if today's persistent dross is to be blown away!

Edited April 30, 2019 by Ed Stone

[Frosty.]

Longer term the GEFS 6z mean looks much better with high pressure from the azores to scandinavia and the PFJ well to the north.

[Methuselah]

All's well that ends well:

Not that things could have gotten worse!