Model Output Discussions 12z 01/06/2017

[Man With Beard]

The overall pattern change is looking even better this morning than it did yesterday morning, but increasingly I'm now looking at the detail. The fly-in-the-ointment is how that mini-low is going to move beneath the high.

The GFS op shows how it might just get stuck over the SW, which would be incredibly unlucky. UKMO at T144 is similar to the GFS, so possibly something similar afterwards

    

However, I would say the GFS is almost worst case scenario, simply because accurate placement of that low is very hard to do at this stage.

The GEM and ECM handle the incoming low at T144 differently, and both result in good outcomes for the UK. The GEM has more of a cut-off at T144 - meaning the low stalls further SW between T144 and T240:

  

The ECM pushes the low through to the north, resulting in a less settled day for NW parts during next week, but like the GEM, allows a good build of high pressure over the UK:

  

Ensemble means don't really back one outcome or the other, but you'd take both of them at this stage:

  

Finally, how hot it gets depends on where any mini upper-trough develops to our SW. Many more ensemble members develop it in a place favourable for 30C plus temperatures this morning. The member below shows pretty much the depth and location the upper low would need to bring 35C+ temperatures to the UK:

In short - you can't get much more summery than what the models are offering this morning

 

[Nick F]

Definitely the potential on models this morning for heat to return to the far south, at least, by this time next week, as an upper trough digs south to the west of the British Isles by middle of next week, causing the flow to back ahead of it and force a dome of hot air to spread N and NE from Iberia across France / Low Countries and clipping southern UK. How the trough evolves is not certain this far out and the heat may be more reluctant to reach UK or could spread further north. Anyhow, GEFS and EPS 850mb temp anomaly shows nicely the heat plume spreading NE from Iberia next week, the  blues dropping down to the west over the Atlantic showing the trough digging south

00z GFS showing 31C across far south of England next Wednesday afternoon.

As often with plumes spreading up from Iberia and reaching the UK, there could be some thunderstorms breaking out too, as cooler air aloft tries to overrun from the west with approach of upper trough.

Before then looking rather quiet on the weather front. Some rain tomorrow and again Saturday for the north, but the south dry again for several days with warm sunshine bar the odd rogue shower.

Edited July 12, 2017 by Nick F

[stodge]

Morning all

Interesting to see the discussion evolving as always. I don't frankly see the heat-wave of which some speak. I do see the possibility particularly for the north to enjoy a spell of fine, settled weather which would no doubt be most welcome while the south looks more at risk from a thundery incursion as the LP splits the two HP centres.

The GFS OP at T+240:

ECM 00Z at the same time:

Stronger ridge and the LP kept far to the south but the wind isn't coming from the south but from the NE so warm yes and potentially humid but I don't see big heat from that chart.

GEM 00Z at the same time:

The positioning of the HP cell is very different from both GFS and ECM and clearly there's detail to be resolved.

A noticeable and refreshing E'ly breeze for southern counties (probably about my favourite type of weather) but potentially very warm/hot for NW Scotland and N Ireland.

GFS 00Z OP breaks down the spell rapidly in FI with a surge of mid-Atlantic ridging but obviously that's a very long way off and does run contrary to the views of Exeter and other forecasters who suggest some longevity to the warm/very warm spell.

[Frosty.]

Even if we don't get a heatwave, I expect a warm / very warm wave!

[Methuselah]

3 minutes ago, Frosty. said:

Even if we don't get a heatwave, I expect a warm / very warm wave!

The next two-weeks look pretty 'heatwavish' to me, Karl? if 5-7 consecutive days' @ around 26-28C don't make a heatwave, I don't know what does...It doesn't have to break a shedload of records?

[stodge]

Just now, Frosty. said:

Even if we don't get a heatwave, I expect a warm / very warm wave!

Yes, and again it's a question of degree (or degrees I suppose).

I see 25-30c from the 00Z charts as perfectly possible (and of course London might nick a degree or two above that).

What I don't see is much above that and indeed with a NE'ly flow many southern areas will be more in the mid 20s.

Conversely, the set up will lead to higher temperatures in areas which have not fared so well this summer to date. The GEM 00Z OP is brilliant for high temperatures in the NW of Scotland and N Ireland and 30c in a glen somewhere is possible I suppose. NW England might do well off the ECM set up - great news for the Lakes at the start of the summer tourist season.

GFS 00Z OP is less inspiring to this observer as is the 06Z OP - ridging from the west or south west means a west or north-west flow across the British Isles. Atlantic-sourced air is cooler so it's 20s rather than 30s for most but it would be generally benign and especially so for places like Devon and Cornwall (and of course the Scillies).

 

[Frosty.]

It's good news about the Gem 00z, last night's 12z was rubbish.

What I want to see is a prolonged summery spell, not a few fine days and a breakdown!

[Man With Beard]

GFS 06Z - ooops!

Thankfully @johnholmes will be on here soon to remind us not to get hung up on each individual operational run!!

General picture is - main trough lifting far from Scotland, lots of settled weather, some minor troughs mixed-in - GFS still following this bigger picture, just that the minor troughs have our name on them!!

It's either 7 settled days next week, or 5/6 settled days ... for the south, a continuation of the summer to date, but for the north, a massive improvement regardless of which one we get.

Heatwave claims? I was playing them down yesterday, but entirely justified this morning to me. The ECM has that 12C 850Hpa line well into the UK from T168 to T240, and 10C over almost all populated areas. At this time of year, optimum conditions will bring ground temperatures in optimum locations of 25C-28C in the north / 28C-32C in the south from that. That qualifies as a heatwave to me?

Next Wednesday/Thursday certainly on my watch for 30C in the SE, a little way to go yet of course.

    

[knocker]

And of course John is completely justified in saying this  Even more so when talking  about tricky evolutions a week away Just for the record the 06z is a disaster for heat wave rampers.

An upper trough that becomes negatively tilted promoting some brief WAA into the south before deconstructing and sweeping the warm air away opening the door to cooler air incursions from the north west.

Edited July 12, 2017 by knocker

[Scorcher]

Hopefully the GFS 06Z is a rogue run- very disappointing after what we've seen this morning.

It's only one run but it is a worry nonetheless. The 06Z runs aren't the most accurate but can pick up trends.

Really hoping for a prolonged nationwide spell of warm/hot sunny weather rather than the usual couple of hot days and a breakdown.

[Frosty.]

To me, the Ecm 00z ensemble mean looks better than last night's 12z.. certainly better further south, anyone agree?

[Ross Andrew Hemphill]

I'm liking what I'm seeing for us up North, finally summer showing its hand here after a disappointing season... 30C!?!?!?!?! 

[mushymanrob]

47 minutes ago, Frosty. said:

Even if we don't get a heatwave, I expect a warm / very warm wave!

this is the point, currently we are not expected to have a strong high sat right on top of us, or even just to our east. the anomalies dont suggest heights over us - yet- so it depends on what constitutes a 'heatwave'. personally i use the old bbc weather chart 25c (which was coloured a red/orange colour) as opposed to yellow (and blue for 0c and below) as the benchmark for what is 'hot'.

some gfs runs have the 10c isotherm 'upper' right over the country for at least a week,, that would be a heatwave, other runs suggest the high uppers coming and going, so max temps in the mid 20's perhaps.

and as i mentioned earlier, we have cloud to factor in, as we could easily have dry overcast conditions.

but overall, the outlook is dry (apart from any thundery breaks) , probably with a lot of sunshine, temps warm, very warm or hot, and that looks very much the likely pattern through the height of summer and into early august which i think will probably make this summer 'the best' since 1995.. (for the bulk of the country - i understand favoured areas have had some decent summers).

at flippin last!

[Scorcher]

I'm not bothered about weather we will get 'heatwave' in all honesty. Would much prefer a couple of weeks of 25-27C much like 2013.

As has been mentioned, western areas could do pretty well from the potential setup we're seeing from the ECM for example.

The above average SSTs are also in our favour in a NE flow.

[Frosty.]

Agreed, plumes are great but tend to be very short- lived affairs, what I'm still seeing today from most of the output is a prolonged summery pattern and at last, the arrival of summer proper across northern uk..I would rather see weeks of warmth and sunshine than a few hot days followed by cooler / atlantic.

Edited July 12, 2017 by Frosty.

[Methuselah]

3 minutes ago, Scorcher said:

I'm not bothered about weather we will get 'heatwave' in all honesty. Would much prefer a couple of weeks of 25-27C much like 2013.

As has been mentioned, western areas could do pretty well from the potential setup we're seeing from the ECM for example.

The above average SSTs are also in our favour in a NE flow.

A NE flow would do me fine too, as I'm getting rather fed-up of sweating buckets...Should the models be in the right ballpark, areas other than in the dreaded saarfeast could come off really well...The weather in NW Highlands, in 1995, was spectacular!

[Frosty.]

6 minutes ago, Ed Stone said:

A NE flow would do me fine too, as I'm getting rather fed-up of sweating buckets...Should the models be in the right ballpark, areas other than in the dreaded saarfeast could come off really well...The weather in NW Highlands, in 1995, was spectacular!

To be honest Pete, I'm happy for the south-east to have plenty more glorious weather as long as it extends to the rest of the uk too..it's been an abysmal excuse for a summer so far up north in comparison to the heat and sunshine for the SE..hoping for a nationwide spell of high summer weather and there is significant support for it!

Edited July 12, 2017 by Frosty.

[Snowy L]

1 hour ago, Ed Stone said:

The next two-weeks look pretty 'heatwavish' to me, Karl? if 5-7 consecutive days' @ around 26-28C don't make a heatwave, I don't know what does...It doesn't have to break a shedload of records?

I wouldn't call 3-5C above average a heatwave. I think some of the awful weather has made us forget we should be seeing 20-24C in England and Wales during mid July.

[stainesbloke]

6 minutes ago, Snowy L said:

I wouldn't call 3-5C above average a heatwave. I think some of the awful weather has made us forget we should be seeing 20-24C in England and Wales during mid July.

Agreed, 26C in the SE in July isn't a heatwave, maybe anything over 28C would qualify. 

[Man With Beard]

4 minutes ago, stainesbloke said:

Agreed, 26C in the SE in July isn't a heatwave, maybe anything over 28C would qualify. 

I always use the 80F marker as my definition of "heatwave".

Perhaps 25C would be more appropriate north of Manchester

[knocker]

This is all a bit pointless but to put into perspective and what the ecm, for example is actually saying.

Monday - ranging from 16C in the far north to 23C in the south

Tuesday - better, 21C in the far north and 24c in the south (generally above average)

Wednesday - 17C in the north but England and Wales warm 24-27C (Wales and the west significantly above average)

Thursday - another warm day with 20C in the north 24-27C in the southern half of England.

Friday - Another warm day with temps a fair bit above average with 23C in Scotland and 25-27C in England

And all change this evening

And sticking to the METO definition of heat wave rather than every individuals own would simplify the discussion. Oh wait, it's not relevant in the thread anyway.

Edited July 12, 2017 by knocker

[Man With Beard]

1 minute ago, knocker said:

This is all a bit pointless but to put into perspective and what the ecm, for example is actually say.

Monday - ranging from 16C in the far north to 23C in the south

Tuesday - better, 21C in the far north and 24c in the south (generally above average)

Wednesday - 17C in the north but England and Wales warm 24-27C (Wales and the west significantly above average)

Thursday - another warm day with 20C in the north 24-27C in the southern half of England.

Friday - Another warm day with temps a fair bit above average with 23C in Scotland and 25-27C in England

And all change this evening

As you know from discussions in past years, I always mentally add 2-3C to the ECM raw temperatures. Went wrong once last August but usually correct!

[Coopsy]

17 minutes ago, Snowy L said:

I wouldn't call 3-5C above average a heatwave. I think some of the awful weather has made us forget we should be seeing 20-24C in England and Wales during mid July.

The met office would. Officially a heatwave is 5 consecutive days where temps are 5oC above the average.

[knocker]

7 minutes ago, Man With Beard said:

As you know from discussions in past years, I always mentally add 2-3C to the ECM raw temperatures. Went wrong once last August but usually correct!

And as you know, or should, I'm not saying the ecm is correct merely stating what the model is showing. If everyone wants to discuss what the max temps are going to be in their own opinion a week away that's fine but it's way above my pay grade. And I still feel discussions on whether a heat wave is immanent, and what constitutes one, is not relevant to this thread.

Edited July 12, 2017 by knocker

[danm]

22 minutes ago, Snowy L said:

I wouldn't call 3-5C above average a heatwave. I think some of the awful weather has made us forget we should be seeing 20-24C in England and Wales during mid July.

Agreed. 

Depends on location, but for down here in London 24c is about average for July/August. Anything from 25c to about 28c is warm and above that would be hot (in my opinion). A heatwave is then several days of temperatures upwards of 28c.