Model output discussion - hot spell beckons but then what?

[summer blizzard]

We know its bad when at 7pm on an August Saturday there is no 12z comment.

Needless to say its pretty much low after low even if as Tamara alludes to they try pump a weak ridge first. Another low arrives Friday (quite a large feature) then another for day 11 (runs south and is deepending as it arrives) before a larger feature towards day 15 (a moist SW flow could bring some large rainfall totals).

Not a shred of settled weather on the horizon from that run.

[MP-R]

16 minutes ago, summer blizzard said:

We know its bad when at 7pm on an August Saturday there is no 12z comment.

Needless to say its pretty much low after low even if as Tamara alludes to they try pump a weak ridge first. Another low arrives Friday (quite a large feature) then another for day 11 (runs south and is deepending as it arrives) before a larger feature towards day 15 (a moist SW flow could bring some large rainfall totals).

Not a shred of settled weather on the horizon from that run.

Indeed it is such a pain these lows are timed for the weekend. Another weekend of plans potentially scuppered. Then another one ganging up for the Bank Holiday weekend. Each one is coming in further south too despite drawing up pretty warm uppers ahead of them. Not far to the east over Europe there will be high temperatures.

[Frosty.]

Longer term the GEFS 12z mean shows a marked improvement, at least further south, as it has for a while now. Increasing chance of high pressure and warmer temperatures towards the end of august which ties in with the thoughts of those who cannot be named!!.

 

Edited August 10, 2019 by Jon Snow

[Methuselah]

A bit of a warming trend, post Day 9, but other than that, no real sign of any long-lasting fine weather...?

   

   

Though, it's fair to say that once the deep low has passed pressure and T850s look likely to slowly rise, towards the SE. One run. One model!

   

And, in the meantime, the doomsayers can delight in the inevitability that Autumn'll start on Day 22!

[Frosty.]

The end of the Ecm 12z operational is encouraging with a ridge encroaching from the west!

Edited August 10, 2019 by Jon Snow

[Methuselah]

57 minutes ago, Jon Snow said:

Longer term the GEFS 12z mean shows a marked improvement, at least further south, as it has for a while now. Increasing chance of high pressure and warmer temperatures towards the end of august which ties in with the thoughts of those who cannot be named!!.

 

Just had a butcher's at my local NW forecast (GFS-based?) for next weekend, karl: minima of 17 and maxima of 19-20C -- so daily means of between 18 and 18.5C...I don't know about you but, to my mind, that'll be feeling warm and humid?

[Don]

19 minutes ago, Ed Stone said:

Just had a butcher's at my local NW forecast (GFS-based?) for next weekend, karl: minima of 17 and maxima of 19-20C -- so daily means of between 18 and 18.5C...I don't know about you but, to my mind, that'll be feeling warm and humid?

Indeed.  I cannot see this month being below average at this stage, despite the unsettled theme for now.  Still feeling humid today, despite the breezy conditions!  I still feel that the final week of the month could be hot.

[Frosty.]

Well what can one say about tonight's Ecm 12z ensemble mean at day 10?...I will say this, it's better than any of the days before it, especially for the south!

[JeffC]

1 hour ago, Ed Stone said:

A bit of a warming trend, post Day 9, but other than that, no real sign of any long-lasting fine weather...?

   

   

Though, it's fair to say that once the deep low has passed pressure and T850s look likely to slowly rise, towards the SE. One run. One model!

   

And, in the meantime, the doomsayers can delight in the inevitability that Autumn'll start on Day 22!

Not being a doomsayer, but seeing is believing, especially given the last few days!

[Gael_Force]

6 hours ago, Tamara said:

Yay! Job completed.

You just never know... there's going to be a lot of those beasts cantering over the snowy (sunny) uplands this winter. 

Good job on the weather analysis too. 

[Methuselah]

10 hours ago, JeffC said:

Not being a doomsayer, but seeing is believing, especially given the last few days!

And it might be a long time in coming, Jeff? Eye-candy at Day 16?

   

And, the GEFS 00Z ensembles...

   

   

Plenty of cooler, more comfortable nights to enjoy, though.

[Frosty.]

The Ecm 0z is looking unsettled but day 10 + shows an improvement as ridging encroaches from the south & west.

 

Edited August 11, 2019 by Jon Snow

[Mr Frost]

Morning all!

Glorious spell of Summer weather (warmth, mild nights, plenty of sunshine, thunderstorms/convection) has finally ended here - pretty much non stop since July 31st)

Definitely feels like Autumn out there today! (Currently 14c, cool NNW wind and raining - far cry from the 22c yesterday)

1 hour ago, Ed Stone said:

Plenty of cooler, more comfortable nights to enjoy, though.

We get to enjoy cool nights and a comfortable sleep 9 months of the year in the UK and Ireland - bring back the muggy/humid nights! It’s Summer after all!

Hopefully the end of August delivers something hot once again - this GFS chart for 23rd August would be perfect if all that heat in France would push North West!

It is a big ask at the moment for that to happen but I will continue to hope for the best!

Have a good Sunday everyone!

Edited August 11, 2019 by Mr Frost

[Jonathan Rhodri Roberts]

Looking better for the south from 9 days or so time, high pressure returning but how influential it'll be throughout the following 4 weeks of summer who knows? 

[mb018538]

With no real recovery forecast in either the AO or NAO any time soon, it looks like the earliest we may see any change is the final 7 days of the month - and even this isn’t a gimme.

https://www.cpc.ncep.noaa.gov/products/predictions/814day/500mb.php

NOAA 14 day outlook still looks about as bad as you’d wish to see.

[Dangerous55019]

Morning everyone. 
I've just cast my eyes over the monthly CFS charts. Well, what can I say? It looks like autumn has arrived here in the UK, with low pressure more of less over us!. 
But then at the end of August, it looks like autumn is starting to fade (or at least catch its breath), and summer conditions arrive thanks to a high pressure riding in from off the Atlantic, just in time for the start of autumn! 
As ever, this is the low resolution CFS, and I am but a mere amateur, and above all else the weather will do whatever the weather will do. 

[MP-R]

2 hours ago, Mr Frost said:

 

 

Perhaps this is what summer will look like more often after October 31st... 

Signs of pressure rises after next weekend but that of course means another week of wasted time. ECM looks less ridiculously autumnal than the GFS. 

I’m personally hoping for at least a week of settled sunshine between the 20th and 27th. After that it can do what it likes as I go away in search of summer for the third time this year lol.

 

[Methuselah]

Not much cause for optimism in today's GEFS 06Z ensembles...

   

   

[Methuselah]

A little ray of hope, from the GFS 12Z!!

   

[Singularity]

The ridge development is starting to show a bit more, albeit tentatively, in the modelling.

Even if the NAO does find a way to stay negative, that doesn’t preclude a drier and warmer spell if the blocking high is far west enough. Something I forgot to mention the other day when I was thinking more in terms of UK-Scandi trough persistence.

Tamara has as usual summarised as well as anyone could the reasons why changes are anticipated, and please take note of what she says regarding the methodology here.

Its not just pattern matching. In fact, I’ve tried that with the GWO/AAM/tropical zonal winds and its not produced any confident results. It instead involves applying known cause & effect while allowing for distorting factors such as the drastically changed Arctic troposphere and (more intermittently) lower stratosphere. 

Heres one simplified take: If you know that the tropics and mid-latitude patterns are intrinsically connected, and then the tropics change substantially, it makes intuitive sense to anticipate changes in the mid-latitudes too .

[Bristawl Si]

6 hours ago, MP-R said:

 

I’m personally hoping for at least a week of settled sunshine between the 20th and 27th. After that it can do what it likes as I go away in search of summer for the third time this year lol.

 

Snap! Off to The Algarve on Aug 28th for 2 weeks

[Frosty.]

Take a look at how the GEFS 12z mean improves between the mid and longer range!..we may yet salvage something good from August, at least southern uk!

 

[Methuselah]

Today's GEFS 12Z ensembles have what looks like a signal-for-improvement commencing at around Day 7!

    

   

Well...sort of!

[ICE COLD]

Wow next weekend looks very stormy . ECM 12z for Saturday and Sunday. 

[SMU]

Evening -

As it stands I feel summer is draining away...

If we look at how prominent the polar cell has been this year & how its ongoing influence over NW Europe, now add in a slight 'seasonal' retreat of the Ferrel cell ( just perhaps 2-4 degrees south ) further compounds the problem.

The base condition now means that the mean location of the warmth has been relocated into Southern France & the UK will be in cool westerly air even occasional polar air. ( ECM introduces the 0c isotherm to the UK late on in the run )

Just as an aside the Stratospheric Vortex has been running along the minimum baseline pretty much all summer breaking many many date records for minimum speeds ( Easterly ) - The only caveat to that is the bandwidth across record negativity to record 'weak' negativity is only about 5 M/S

* Key dates. ~ 1st of September or thereabouts where the stratospheric vortex becomes 'official' for 2019/20 - could that be a record 'late' date

Also October 1st-15th where the vortex strength has a bandwidth of 10M/S which at which point a continued trend of creeping along the baseline ( or record weakness ) would certainly be more significant than early Sept.

Outlook for all of August - Negative NAO pulsing -1/-2 indicates wet & windy as the jet hits runs through the UK-

September analogues for the 9 negative NAO summers (since 2006 Is that the NAO makes a sharp transition to positive as heights build over Scandi ...

One to keep an eye on...

The Tamar region anomaly showing due to ice loss....

This linked into Scandi could see some Warm Autumn weather in the form of SE winds ...

It just depends on how quick the -NAO relaxes ...

Edited August 11, 2019 by Steve Murr