Model Output Discussion - heading into April

[Methuselah]

Good morning, peeps...the GFS 00Z looks ooookay: High pressure in command!

    

    

    

    

    

And, for once, the GFS op isn't a cold outlier...Anywho, the mean's fine with me!

    

And, when will it rain? When will some of those Solar min-related extra condensation nuclei do their stuff!

[mb018538]

Looking like mid next week won’t be quite as hot as yesterday, but maybe 25-26c again which is decent enough for anyone. Still some debate on the direction of travel after midweek, but until then it’s looking decent for many. 

[Scorcher]

I've got to be honest, as someone in the north west of England, I'm slightly underwhelmed by the output this morning.

Yes high pressure is extensive, but will it be in the right place to actually deliver warmth and sunshine?

I think we've seen the issues this week with high pressure not being quite far enough north to produce widespread sunshine across the whole UK.

It was even cloudy for most of Tuesday here, despite us being only 50 miles or so from clear sky.

Yesterday was superb, but any time there is a westerly influence it can be a struggle here with cloud.

The GFS run is not great for us next week. I imagine people in the SE will be very pleased with it though. 

[mountain shadow]

3 minutes ago, Scorcher said:

I've got to be honest, as someone in the north west of England, I'm slightly underwhelmed by the output this morning.

Yes high pressure is extensive, but will it be in the right place to actually deliver warmth and sunshine?

I think we've seen the issues this week with high pressure not being quite far enough north to produce widespread sunshine across the whole UK.

At least there is no sign of any persistently bad weather.

At the end of the day, we do live in the worst part of the islands for calm and dry weather due to our proximity to the big blue.

 

[Scorcher]

2 minutes ago, mountain shadow said:

At least there is no sign of any persistently bad weather.

At the end of the day, we do live in the worst part of the islands for calm and dry weather due to our proximity to the big blue.

 

You're right, it could be a whole lot worse. I think after a glorious day of sunshine and 26C here yesterday though, it's natural to think of what you could have had more of.

Being inland here though, when the setup is right, we are often reasonably close to the SE in terms of temps (we weren't far behind yesterday).

[Leo97t]

This does almost feel like may-tune 2018 shifted a month back - the extent of high pressure shown by icon/gem/ecm only comparable to July 2018. Still worried about why the gfs is so keen to break it down and is refusing to correct although perhaps a very gradual improvement on yesterdays run this morning

[carinthian]

58 minutes ago, Scorcher said:

You're right, it could be a whole lot worse. I think after a glorious day of sunshine and 26C here yesterday though, it's natural to think of what you could have had more of.

Being inland here though, when the setup is right, we are often reasonably close to the SE in terms of temps (we weren't far behind yesterday).

Yes, I noticed that temp in Manchester and North Yorkshire as well. Was about 2 or 3 c warmer than Sussex where an onshore wind developed and tempered the temperatures a fair bit inland. However, Sussex will be warmer today with almost continuous sunshine.  Certainly looking a encouraging start for summer up north , even though prone to increased cloud amounts compared to further south. Get the wind in the east and you will be tops in the NW.

C

Edited May 21, 2020 by carinthian

[Djdazzle]

43 minutes ago, Leo97t said:

This does almost feel like may-tune 2018 shifted a month back - the extent of high pressure shown by icon/gem/ecm only comparable to July 2018. Still worried about why the gfs is so keen to break it down and is refusing to correct although perhaps a very gradual improvement on yesterdays run this morning

Remember that GFS can be good at sniffing out a change in pattern, but then tends to overdo it. It did spot this week's mini-breakdown, but then proceeded to fire up the Atlantic. I wouldn't be too concerned. As you say, it has tended to improve on its last couple of runs.

Edited May 21, 2020 by Djdazzle

[Methuselah]

Monday's looking GREAT!

[MATTWOLVES 3]

16 minutes ago, Djdazzle said:

Remember that GFS can be good at sniffing out a change in pattern, but then tends to overdo it. It did spot this week's mini-breakdown, but then proceeded to fire up the Atlantic. I wouldn't be too concerned. As you say, it has tended to improve on its last couple of runs.

Very true.. Its gr8 at spotting a pattern change... Only problem is when the other models come on board... The GFS then drops the idea Tell you what though what a difference a year makes.... This time last year wasn't we under very cool and unsettled conditions moving into June... Temps at times hardly double figures, and stonking big heights over Greenland... Completely the opposite this year with low heights in that vicinity... Perhaps a positive sign moving forward. 

Edited May 21, 2020 by MATT☀️

[mb018538]

16 minutes ago, MATT said:

Very true.. Its gr8 at spotting a pattern change... Only problem is when the other models come on board... The GFS then drops the idea Tell you what though what a difference a year makes.... This time last year wasn't we under very cool and unsettled conditions moving into June... Temps at times hardly double figures, and stonking big heights over Greenland... Completely the opposite this year with low heights in that vicinity... Perhaps a positive sign moving forward. 

Certainly an Icelandic and Greenland low at this time of year is usually good news for the UK. Long may it continue!

[Methuselah]

Just now, mb018538 said:

Certainly an Icelandic and Greenland low at this time of year is usually good news for the UK. Long may it continue!

Indeed. And what better place for it to linger?

    

[Zak M]

And there looks to be a lot more on the way... according to the GFS 06z! 

   

[mb018538]

10 minutes ago, Zak M said:

And there looks to be a lot more on the way... according to the GFS 06z! 

   

Looks great. As long as it stays decent out to day 10 then I think we needn’t worry about day 10-15 at the moment!

[Methuselah]

25 minutes ago, mb018538 said:

Looks great. As long as it stays decent out to day 10 then I think we needn’t worry about day 10-15 at the moment!

No worries, mate...After a rather feeble incursion from northwesterlies, things are progged to settle down again by Day 16!

    

[shaky]

Fantastic output this morning!!gfs has cancelled the annoying breakdown from the northwest and now has a stronger high near or over uk day 7-10!!ecm and ukmo look brilliant!!?

[Djdazzle]

5 minutes ago, shaky said:

Fantastic output this morning!!gfs has cancelled the annoying breakdown from the northwest and now has a stronger high near or over uk day 7-10!!ecm and ukmo look brilliant!!?

Yes, GFS seems to have dropped those vile retrogression charts that it was showing yesterday! Still has HP moving slightly west, but close enough to keep most fine, warm and settled.

Edited May 21, 2020 by Djdazzle

[Singularity]

Even allowing for CFSv2's positive bias to AAM (typically about 0.5), it looks like it will resist dropping any lower than the neutral range (within 0.5 of zero) during the next fortnight.

Then, there are signs of a rise in AAM, in response to a powerful convectively coupled Kelvin wave (CCKW) propagating east across Indonesia and then the Pacific. Some uncertainty on how much amplitude it retains, mind. Plot below gives a general idea but will be distorted by other factors such as tropical cyclones - currently it's really underselling the intensity of the CCKW.

 

All of this, combined with an already well-established positive NAO pattern (low heights centred over or very near to Greenland), suggests an atmosphere hostile to moving ridges to the west of the UK & W. Europe for long at at time - and rarely by very much anyway - for at least the first half of June... and with a good chance of it being more than that.

Summer 2020 will be all about how long the atmosphere can resist the forcing from the Pacific Ocean toward a La Nina state of negative AAM.

[Man With Beard]

EC clusters for early June looking a little less certain than in recent times; here's day 11 and day 15

  

Higher chances of a more prolonged wetter period if cluster 1 verifies, but also reasonable chances of continuing ridges from the Azores High, or a stubborn ridge to the east developing, both of which may continue to promote drier and warmer weather to many parts of the UK (less so further north on cluster 2).

Overall though, with the absence of a strong ridge over Europe and lower heights becoming more established towards Iceland, a best guess it that there'll be at least some interruptions to our early summer weather as the new month begins.

[Methuselah]

Nice to see the GEFS 06Z mean trundling along at around 5C...once tomorrow-Monday's welcome coolness moves away:

    

    

Farmers in these parts really do need some rain though!

[MATTWOLVES 3]

It's a good mean from GFS 6Z out to day 10 and perhaps beyond, not really much point going any further as its to subject to change.. 

[mb018538]

ECM mean out to day 10 looks reasonable enough....

[chrisbell-nottheweatherman]

36 minutes ago, General Cluster said:

Nice to see the GEFS 06Z mean trundling along at around 5C...once tomorrow-Monday's welcome coolness moves away:

    

    

Farmers in these parts really do need some rain though!

If this morning's ouputs verify in terms of continued high pressure in our part of the country, there may be problems with crops later in the season, which, allied to a shortage of workers to process vegetables from the fields, won't do much for the cost of such items (for members who don't know, most of Britain's salad vegetables, asparagus and other tender crops are grown in eastern England, particularly the Fens of Lincolnshire, Cambridgeshire and Norfolk.

[Mike Poole]

3 hours ago, Singularity said:

Even allowing for CFSv2's positive bias to AAM (typically about 0.5), it looks like it will resist dropping any lower than the neutral range (within 0.5 of zero) during the next fortnight.

Then, there are signs of a rise in AAM, in response to a powerful convectively coupled Kelvin wave (CCKW) propagating east across Indonesia and then the Pacific. Some uncertainty on how much amplitude it retains, mind. Plot below gives a general idea but will be distorted by other factors such as tropical cyclones - currently it's really underselling the intensity of the CCKW.

 

All of this, combined with an already well-established positive NAO pattern (low heights centred over or very near to Greenland), suggests an atmosphere hostile to moving ridges to the west of the UK & W. Europe for long at at time - and rarely by very much anyway - for at least the first half of June... and with a good chance of it being more than that.

Summer 2020 will be all about how long the atmosphere can resist the forcing from the Pacific Ocean toward a La Nina state of negative AAM.

The CFS AAM chart in your post looks wrong until you click it, here it is:

Agree with your final statement, this will probably determine when indeed if the summer goes downhill.

[Mike Poole]

Good start this afternoon from the ICON, setting up the HP train: