[Model Output Discussion - Mid Summer Onwards]

8 minutes ago, Downburst said:

Yes but the overall trend is there are heavy low pressure systems incoming, just what direction they come is the question in my opinion. I'll be on a boat for 5 days from mid week next. 

Yes, Ireland has been shown with heavy rain on several different models and runs. It’s more about what happens further East and South.

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24 minutes ago, Methuselah said:

There's not much point in over-analysing individual model runs just now -- Met. Office Ten-Day Trend: 

 

Just look at that confidence index!! Red from 3 days out. And of course listen closely to what Alex is saying about 4(!) different models showing 4(!) different scenarios by Tuesday.

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2 hours ago, Nick2373 said:

I tend to look at trend with the GEFS And see if there is any difference in the ppn spikes they have been pretty much the same now for the last three days with very little change, It will be a up and down affair the 10 days or so from the 17th onward with temps below and just above with heavy rain or showers at times. with temps closer to average cant see anything remotely warm or super warm like of late.    

Appreciate that but at the end of the day the GEFS is still the GFS just with adjustments made for initialisation (from actual observations, which are used for the general GFS runs). That isn't of much help when the actual GFS differs from run to run at 5 days out and when there's nothing even close to consensus comparing to the ECM. Or indeed when historical data is not very useful because of record SSTs and record heat across many areas of the planet.

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2 minutes ago, ANYWEATHER said:

I think it's standard normal fare to be honest ,but as you say there is still much too play for in the model output ,but next week's weather does look rather volatile. .......

So did this week, this time last week

Also don’t think possibly 28 degrees on Saturday is standard fare, especially after the heatwave we’ve just had

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29 minutes ago, ANYWEATHER said:

We already have seen one face of Autumn last week, and now we are just about to see the other face of Autumn. ....

 

18 minutes ago, Nick2373 said:

 

00z speaks for its self really, useable weather up till the 17th then its dig your wellies and umbrellas back out. Looks like Autumn arrives back in the west and then spreading Eastwards paying for the warmth of late. 

Considering ECM and GFS 00z runs start to diverge significantly by day 5, I would not be comfortable to make any calls on what things will look like post Sunday (in all honesty, even Saturday/Sunday could still end up different to what it looks like at the moment). It was just a few days ago where there was no sign of anything but "normal" autumn weather from yesterday onwards to the end of every run. What seems to be on the cards now for the weekend wasn't shown anywhere but a small minority of individual members in each run.

Of course logic and history imply that we are well overdue to switch to westerlies, showers and temps in the mid teens but...

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Looked at the last three GFS runs as well as the other models and I’m sticking with what I said yesterday. No point looking at anything post day 5. So much flip flopping!

Up to 28 on Saturday seems to be forming up though which is nice

 

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53 minutes ago, RainAllNight said:

Now it looks more likely again than this morning that the big blue monster is going to get us...

And quite opposite on the GFS lol. Three attempts to push up warm air up north between end of this week and end of run. Might as well look use my crystal ball.

If correct we will of course also experience quite some storm in between which will now also flood the west of Scotland (although not all of Ireland any longer)

[Model Output Discussion - Mid Summer Onwards]

20 minutes ago, adrianh said:

Good for easterlies though if we get the right synoptics? - A warm north sea and a cold enough easterly = snow showers was my understanding

Anything can happen but I don’t see it and neither do the longe range forecasts. Not a single month from October where 2m temps don’t look to be above or significantly above average. Not just in the UK.

ECMWF | Charts

CHARTS.ECMWF.INT

Same goes for 850hPa temps.

ECMWF | Charts

CHARTS.ECMWF.INT

 

Then again… models are struggling at 3+ days at the moment. But gut feeling for me is a stormy period thanks to record SSTs followed by benign, boring and mild winter weather.

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22 minutes ago, ANYWEATHER said:

Models at this time of year are always throwing up doomsday synoptics, 

Well there aren’t any doomsday synoptics and the issues don’t lie, as they usually do, in what we would consider FI. There are differences, at times massive differences, from run to run and model to model even as close as three days. 
 

It shouldn’t come as a surprise of course as models use huge amounts of historical data and there simply is no precedent for the SSTs and a number of other parameters.

[Model Output Discussion - Mid Summer Onwards]

I think it’s safe to say that we are getting to a rare one day at a time scenario with the models. The differences between the last few GFS runs even as early as midweek are unbelievable. Let’s see what the ECM shows in the next hour.

Going by the 00z GFS, Ireland is getting flooded while almost the entire Eastern half of the UK barely sees a drop of rain until at least a week from today.

Latest GFS with two attempts of pulling up warm/hot air from the south as far north as Newcastle where a previous run was flooding cold air down south as far as central France!

Let’s ignore the differences in wind speeds

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Wow what a difference between GFS and ECM. Model chaos

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This is a nightmare for the models and I would agree with some other posters that a large part of it is down to the record SSTs.

Spot the difference between GFS and ECM for the 18th (feel free to do the same comparison much earlier than that...)

 

[Model Output Discussion - Mid Summer Onwards]

1 minute ago, mb018538 said:

ARPEGE is showing a wide area of 34-35c on Sunday.....which looks incredibly optimistic. I think something closer to 33c in one or two spots, but an area that wide seeing above 34c just isn't going to happen.

Not sure if overly optimistic. 32.6 was the official high temp yesterday. For a whole swathe of the SE there are no official stations but even here where we are always a degree or two lower due to a limited see breeze we reached an unofficial 32.1. By Sunday the ground will be even more dry, there's another push of hot air from the South.

Wouldn't write it off. It's only about 2.5 degrees more than yesterday.

[Model Output Discussion - Mid Summer Onwards]

6 hours ago, alexisj9 said:

I'm more worried about before winter, tbh. Still we'll see what happens. My thinking is the jet stream will pack a punch with its storms this year, 

If the latest GFS is anything to go by, of course unlikely to verify as in deepest FI, then you might be on to something...

Storm #1 around the 18th

Storm #2 around the 23rd

Storm #3 looks like the same track a few days later

Gusts of 75mph along the South Coast, sustained 10m winds of 50mph and >200m of rain in some areas.

 

 

[Model Output Discussion - Mid Summer Onwards]

42 minutes ago, legion_quest said:

It was only poking fun, hence the winky face. Do try and have some fun from time to time, might make the day even brighter! 

Always having fun. Sitting in the sun with a cocktail, taking a break from work

[Model Output Discussion - Mid Summer Onwards]

28 minutes ago, MattStoke said:

They did include the word 'likely' which allows for some doubt.

Indeed. Language matters

25 minutes ago, legion_quest said:

Couple of 'definitelys' in there though...hard to measure doubt with a definitely.

"After near record or record daytime and most definitely nighttime temps we are likely looking at something more normal from around Tuesday, although still above average temps and below average rain (possibly some exceptions in the far NW) and generally drier and warmer the further SE you are. No washout, nothing cold, no strong winds and most definitely nothing autumnal (away from the far NW where what’s currently shown is normal)."

Where appropriate... The first instance is based on the fact that at least three MetO owned sites exceeded the previous September record this morning and of course also the unprecedented duration of the period where a tropical night is occurring at least somewhere in the country during this current heatwave; the second is because there is no chance of what would be considered autumnal weather during the period to the end of the GFS run.

[Model Output Discussion - Mid Summer Onwards]

To add to my previous post, let’s throw in the 00z ECM for the same time and the low to the NW of the UK has vanished.

[Model Output Discussion - Mid Summer Onwards]

3 subsequent GFS runs plus 1 ECM thrown in, all with very different solutions. Enough said.

Midnight Saturday 16 Sep on GFS 12z, 18z and 00z as well as ECM 18z below.

Even picking noon on Wednesday 13 Sep gives similarly differing solutions. 
 

So as we were. After near record or record daytime and most definitely nighttime temps we are likely looking at something more normal from around Tuesday, although still above average temps and below average rain (possibly some exceptions in the far NW) and generally drier and warmer the further SE you are. No washout, nothing cold, no strong winds and most definitely nothing autumnal (away from the far NW where what’s currently shown is normal).

 

[Model Output Discussion - Mid Summer Onwards]

If the ECM and GFS are correct then there’ll be decent weather all next week for those south and east of Birmingham. Barely a drop of rain, if any. And still above average temps after the cool-down.

[Model Output Discussion - Mid Summer Onwards]

And this is why you cannot rely on individual model runs or indeed anything post 10 days (in many setups I’d stick with 7, right now maybe even 5 days).

6z for 18 Sep 6PM vs 12z for 18 Sep 6PM could not be more polar opposite of they tried.

 

[Model Output Discussion - Mid Summer Onwards]

12 minutes ago, Alderc 2.0 said:

A fair while? The whole of August couldn’t have been more ordinary if it tried! 

I think the point being made is that August was not ordinary summer. Or at least not what we are used to nowadays. It's was grey, at times too wet and too cool.

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2 minutes ago, Nick2373 said:

00z does show the control and op running off to temps way below average but these are 10 days out, if i was to read into these these would suggest a pattern change for around that date or what could be causing this swing is the new formed storm Lee which is expected to turn into a hurricane at the weekend  Anything past 7 days in my opinion is FI Fantasy Island there are so many factors in play its like playing pin the tail on the donkey past 10 days   

 

So did yesterday’s 00z and as demonstrated by the Mean, both Op and Control are at the lower, at times the lowest end of the scale. Therefore your conclusion is spot on. 7 days+ is FI, add in that there’s no cross-model consensus for this.

NB - my previous post stating the entire run stays above average was for a different location where that remains the case. 

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2 minutes ago, WeatherEnthusiast said:

Turning unsettled next week 

Do you see the little part with the teal bars at the bottom left? The one with the percentages?

Just to demonstrate a situation where there’s NO cross-model agreement:

 

[Model Output Discussion - Mid Summer Onwards]

14 minutes ago, Alderc 2.0 said:

I wouldn’t put too much effort into the models output 10-16days out currently. For the last 8 weeks they’ve struggled with pattern changes. Even rewind a week and the heat was departing many areas by today or tomorrow, now we have a 5day extension on that with the September all time record under threat at the weekend.

As a general rule of thumb, the 5 day output is accurate 90% of the time, by 10 days that's down to 80% and after that you get to down to almost zero very quickly. There are of course always exceptions, both ways, but that would need cross-model agreement or at the very least cross-run agreement. Neither usually applies and therefore we safely ignore anything post 10 days apart from broad trends... which at this point is:

Following unseasonably hot conditions with near record or indeed record breaking temps, significantly above average for the duration, we will likely get closer to something more normal by mid month but still more likely than not to be above average for temps and below average for rain.

[Model Output Discussion - Mid Summer Onwards]

9 minutes ago, WeatherEnthusiast said:

I dont want to get into a row with fellow Netweather colleagues but there is no denying that the low does persist for 4 - 5 days if you look it just spirals around right over the UK!  Temps on the 21st only 8 to 16. 

As I just said in my previous post - "What is shown for Tuesday 19th would, but that is of course so deep into FI that other than taking a quick glance at it, it would be foolish to rely on it."

You said that the 00z runs shows "[lows] D10 to D16 and persisting" and now you post output for days 14-16 which I have addressed and will do once again - it is so far into deep FI that it's not warranted to take into consideration other than a quick glance. This is the GFS and 9 times out of 10 it shows something post D10 that never materialises, especially when it comes to low pressure.