Model Output Discussion - What does April have in store?

[knocker]

One thing that is noticeable Tues/Weds is as the low pressure edges NE the surface wind over the North Sea will back on shore again effecting north eastern coastal regions before a mixed bag on weds as the trough and cold front edge north. The storm potential is greatest during this period one would think

Edited April 21, 2019 by knocker

[Frosty.]

The Ecm 12z for the next few days is more of the same beautiful sunshine with temperatures into the low to mid 20's celsius but wednesday is the transition and it could end with a bang

[Methuselah]

The GEFS 12Z  ensemble is -- for what it's worth -- suggestive of an early May warm-up; the Op, however, now sits at the warmer side:

Edited April 21, 2019 by Ed Stone

[Frosty.]

8 minutes ago, Ed Stone said:

The GEFS 12Z is -- for what it's worth -- suggestive of an early May warm-up; the Op, however, now sits at the warmer side:

Yes Ed the GEFS 12z mean ended better with the azores high ridging in..I think I'm right in saying it's the best GEFS mean so far today, the 18z may be even better.

Edited April 21, 2019 by Frosty.

[Frosty.]

Colder air coming down from the north..milder / warmer air coming up from the south..yes it's definitely spring..just checking though since it currently feels like summer!

[MATTWOLVES 3]

1 hour ago, 049balt said:

Where can I get long range/seasonal charts?

You can view the CFS charts on meteociel.. I think it goes out about a month.

[MATTWOLVES 3]

Some signs by day 10 on the ECM of a change back to warmer conditions and perhaps more settled, with hopefully a pressure rise from the South. Not bothered posting the earlier frames, because no1.. They have already been posted, and no2.... They are crap... Well if you like a showery set up, you will be in your element... Hopefully for not to long. Just had a gander at the CFS and it's looking very high pressure into may... So fingers crossed. 

[Frosty.]

2 minutes ago, Mattwolves said:

Just had a gander at the CFS and it's looking very high pressure into may... So fingers crossed. 

 

I guess the CFS has to be right sometime..may would be a good time to start!

[Singularity]

Hmm - signs of the Nino forcing putting up more of a fight than had been modelled by GFS and UKMO, but ECM having none of it until D10. That last one's developed a strange habit of depicting what I least want to see in the past few months - I've been frowning at ECM charts 9 times for every 1 time at a GFS or UKMO one! 2+ years ago it was often the other way around - how times have changed.

 

What we see here is the retrograding trough tendency that forms part of the typical Nino-type response to falling AAM against a +AAM (i.e. Nino state) background. In the winter months we sometimes see this represented by -NAO patterns transitioning from east-based to west-based. The sequence this coming week is similar, but with the HLB focused further north than is typical of a -NAO setup. More room for Euro ridges from that - and this too is typical when there's a Nino background.

ECM seems to be overriding this trough retrograde (and sluggish N. Atlantic westerlies) via the MJO P2-3 forcing. Yet it's MJO projection is at lower amplitude than GFS'. So I'm not sure how much the unfortunate outcome for the UK actually comes down to that. While the HLB development from the Pacific side is very likely to be MJO-related (with some help from the polar vortex having warmed-out), the greater westerly flow from the N. Atlantic across the UK may come down to model dynamics. Whether it's an erroneous bias, remains to be seen.

[Frosty.]

Looking at tonight's Ecm 12z ensemble mean, yes it's going to turn much more unsettled and cooler later in the week ahead but there are hints that by day 10 the surface conditions will improve with weak heights close to the south and a generally slack pressure pattern, less troughy but still a risk of showers together with plenty of pleasant dry and sunny spells too..in the meantime, still 2 more days of summery very warm and sunny weather despite some increase in high cirrus cloud from the south and some saharan dust and even wednesday still looks warm and quite humid but midweek is the breakdown and for some it could be thundery.

Edited April 21, 2019 by Frosty.

[knocker]

Outlook -  A major pattern change will get underway over the next few days involving the vortex lobes over N. Russia and Canada, and associated troughs, in conjunction with the loss of the block to the north east of the UK as the European high ridges NW forming a cell over Greenland. Simultaneously the negatively tilted trough associated with the Canadian vortex facilitates low pressure becoming established in the Eastern Atlantic. Thus the UK weather becoming unsettle with temps returning to around average.

The NH 600mb profile and the Atlantic surface chart for midnight

Any rain still lingering around NW Scotland will soon clear leaving a warm and sunny day for just about everyone.A tad cooler along the coasts, particularly the north east. And some showers may pop up in the west Midlands and Wales this afternoon

tonight will be clear but convective activity may become more prevalent in the west for a time.

Tomorrow will be another warm and sunny day, possibly the odd shower in the south west. But the trough is taking closer order and the surface wind across the North Sea backs more onshore and thus again cooler in north eastern coastal regions.

Over Tuesday night and through Wednesday the trough continues to move north east and a belt of thundery outbreaks, coalescing into longer periods at times, will track north though the day and it will be much cooler than of late.

Over Thursday and Friday the trough becomes established in the eastern Atlantic resulting in a plethora of showers and much cooler conditions

[knocker]

And over the weekend the aforementioned pattern change is beginning to materialize so the unsettled theme continuesd

[knocker]

This morning's fax updates are pushing the trough/front through a tad quicker on weds with frontal rain tracking into the south west overnight

[Summer Sun]

As fires break out around the UK some much-needed rain is on the way this week and next 

[knocker]

Some convection across Brittany into Biscay?

Edited April 22, 2019 by knocker

[Polar Maritime]

Gales also expected by the end of the week into the weekend as Lows push in off the Atlantic. 

[Methuselah]

It looks as though, once the current fine spell comes to an end, by Wednesday, we'll enter a 'downward spiral' into a pattern increasingly determined by some kind of HL blocking, and with winds originating from more of a northerly quarter?

FV3:       

GFS Op:

The 00Z GEFS Ensemble isn't exactly a 'thing of beauty' either...But its stark difference to yesterday's 12Z does highlight the pitfalls involved, when comparing one run to another, perhaps...?

             

Edited April 22, 2019 by Ed Stone

[MATTWOLVES 3]

I did say careful what you wish for regarding rain, now we appear to be locking in to at least 10-14 days of garbage trust me the novelty will soon wear off! Cool, wet miserable and at times very windy.... Fantastic weather for ducks, and if it were October! I just hope and prey this doesn't lock in long term!  So most definitely enjoy the next 2 days... 

[Methuselah]

So here we are at Wednesday, and the trough has moved through, ushering-in a change to more unsettled, less-warm weather:

 

What happens next is (as the chopping and changing ensembles clearly show) uncertain...It could literally go any which way, longer term?

[MATTWOLVES 3]

Let's hope my good friend the CFS has got the pattern change back to high pressure correct! Been hinting at it for some time, it also shows the upcoming unsettled spell correct, so it's not so out on its own has some think. 

[Frosty.]

It looks like those of us who are loving this summery weather will soon be paying a high price for it but that's the swings and roundabouts of spring and model watching.

[Frosty.]

The Gfs 6z operational shows a brief window of drier, brighter and warmer weather for the s / se on sunday thanks to a ridge.

Edited April 22, 2019 by Frosty.

[Methuselah]

The all-important questions is: will Sunday's potential 'waft' give the SE half of Englandshire a warm and muggy day?

 

 

[knocker]

Following earlier comments on the pattern change the evolution from the EPS mean anomalies this morning is not unexpected and along the same lines.It ends in the later period with main vortex lobe/trough N. Russia > Scandinavia whilst upstream there is a ridge into Greenland with a negatively tilted trough south of it into the NW Atlantic This results in the upper flow diverging leading to a relatively weak westerly over the UK. Probably portending changeable but fairly benign weather with temps around average

[knocker]

A veil of cs has encroached here  in the last hour or so