Bertwhistle
15 June 2017 18:46:22

Originally Posted by: Stormchaser 


 


Only four days away now yet still a significant difference between UKMO and  GFS in terms of how strong the section of the ridge to the west of the UK is versus that to the east.


GFS has actually reverted more toward the stronger western feature compared to the previous two runs. Typical! At least it doesn't result in anything worse than some fresher air although it does turn rather cool near and along the eastern coasts.


 


Pleasing to see the HP ballooning strongly across the UK on the UKMO run while GFS also has it drifting steadily east. The models have converged here in terms of the SLP pattern, but UKMO has brought less in the way of cool air into the circulation so it would likely be warmer for central parts than what GFS shows. Slack winds mean cooling of easternmost parts should be mostly down to sea breezes on this day.


Not clear whether it would still be very warm in the far south; it's a fine margin between that and something more like 22-24*C.


 


As the ridge slows its progression and retains decent strength, and with the shallow low heights over Europe not giving rise to heat lows (cool air unable to achieve sufficient temp gradients far enough from the ridges) there are signs of a classic extended fine spell for the UK with temps gradually heading back upward after the freshening up Mon-Tue (latest to occur down south, if at all here).


 


Given these two runs, it will be interesting to see whether ECM backs down with it's development of 'heat lows' from Europe and interplay of those with what has also tended to be a stronger N. Atlantic jet than UKMO and GFS are predicting. This latter disagreement likely relates to ECM propagating some MJO activity east from the Atlantic to the Indian Ocean while GFS and UKMO keep it stalled out in the Atlantic. The 12z update of the ECM projections for the MJO kept the propagation but weakened the magnitude of it quite a bit so there's hope for the model to tone down the jet stream strength this evening. Fingers crossed as it offers a means of getting the very fine weather right up north.



Excellent, detailed analysis SC; thanks. I think also that a persistence of HP, leading to continuous compressive warming & drying; and an increasingly dry surface, could give way to higher temps than the 'baseline' model. Hampshire could be a good place to be over the next week +.


Bertie, Itchen Valley.
'We'll never see 40 celsius in this country'.
bledur
15 June 2017 18:46:27

Any forecast for next week i have looked at shows a breakdown next week from Tuesday with either a thundery low developing over Biscay and pushing slowly N.E or a front crossing from the west putting us back in a westerly flow and unsettled or mixed thereafter. Sunday , Monday look fine and hot though.

Bertwhistle
15 June 2017 18:49:51

Originally Posted by: bledur 


Any forecast for next week i have looked at shows a breakdown next week from Tuesday with either a thundery low developing over Biscay and pushing slowly N.E or a front crossing from the west putting us back in a westerly flow and unsettled or mixed thereafter. Sunday , Monday look fine and hot though.



The point there is that, despite an implicit and superficial consensus of outcome, the two routes are not in agreement, meaning there is no consensus. The two outcomes are as different as a breakdown, and not a breakdown. An increase in different routes to the same end, is actually a decrease in confidence.


Bertie, Itchen Valley.
'We'll never see 40 celsius in this country'.
bledur
15 June 2017 18:59:55

Originally Posted by: Bertwhistle 


 


The point there is that, despite an implicit and superficial consensus of outcome, the two routes are not in agreement, meaning there is no consensus. The two outcomes are as different as a breakdown, and not a breakdown. An increase in different routes to the same end, is actually a decrease in confidence.


Well i dont know what that meansConfused  BigGrin but i am going to keep a close watch on the forecast next week as we are getting busy with haymaking. Whats cut now will make Sunday ,Monday but at the moment next week looks a bit iffy as thundery lows out of Biscay can deposit a fair bit of rain in my area.

Stormchaser
15 June 2017 19:51:53

 


ECM increases the persistence of the HP compared to its previous few runs. Could it actually be the model playing catch-up to GFS for a change? Looks impressive for the SW on Thursday with the highest temps in this region which is different to the tendency of many recent summers.


As for Friday, well...



Given the run-up of often very warm and dry conditions, light winds and only gradual destabilisation, I daresay that'd have the hottest spots pushing close to the mid-30s.


We do then finally see the breakdown overnight into Saturday with a fresher, showery sort of day to follow. Sunday sees things improving in the south but remaining dodgy up north... too far ahead to pay much notice to at this time though. It gets there via extensive blocking across the Arctic including Greenland, but ECM's been having a thing for that on and off for a good few weeks now without success. I reckon as long as global atmospheric angular momentum (GLAAM) doesn't fall as much as GEFS has been predicting (usually a safe bet), things shouldn't deteriorate too much in the 10-16 day range (a big GLAAM fall encourages the Azores High to ridge N rather than NE, with a trough dropping in across the UK and surrounds. No surprise to see GFS doing just that at the moment but in theory it's a load of dog doings!).


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Rob K
15 June 2017 19:54:48
Cheers for the analysis SC. That ECM run is a toasty one for sure!
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Gusty
15 June 2017 21:02:50

Some very high temperatures on offer next week as high pressure setting itself up slap bang over the UK will create our own heat pool. 850Hpa's do not necessarily need to be approaching 20c to achieve the mid 35c at the surface given this potential setup.


Those extreme temperatures in 1976 were achieved with 850Hpa's in the range 13-15c IIRC.


A fascinating situation potentially. Its a rare beast to get high pressure aligned favorably and for a persistent period so close to the solstice.


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Jiries
15 June 2017 23:24:00

Originally Posted by: Gusty 


Some very high temperatures on offer next week as high pressure setting itself up slap bang over the UK will create our own heat pool. 850Hpa's do not necessarily need to be approaching 20c to achieve the mid 35c at the surface given this potential setup.


Those extreme temperatures in 1976 were achieved with 850Hpa's in the range 13-15c IIRC.


A fascinating situation potentially. Its a rare beast to get high pressure aligned favorably and for a persistent period so close to the solstice.



Interesting indeed and this weekend 30C temps are foretasted despite uppers only 13C.  With near to longest day, already dry ground will help to boost higher temps next week.

picturesareme
15 June 2017 23:58:53

Originally Posted by: Gusty 


A fascinating situation potentially. Its a rare beast to get high pressure aligned favorably and for a persistent period so close to the solstice.



2013... 2014... perhaps 2017?? Still rare with 3/5 summers?


 


2010 also had a lot of high pressure around June and some spots did hit 30C ,but after such a cold winter if i remember rightly the seas around NW Europe & UK were unusually low still? This effecting any real heat being built.

Rob K
16 June 2017 06:31:32
ECM again really ramping up the heat again this morning, but GFS less keen on letting the warmth get so far north.
Yateley, NE Hampshire, 73m asl
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Solar Cycles
16 June 2017 07:44:12

Originally Posted by: Rob K 

ECM again really ramping up the heat again this morning, but GFS less keen on letting the warmth get so far north.

Fingers crossed it stays South of Nottingham from next Wednesday.

bradders
16 June 2017 07:57:09

We are on holiday in Whitby next week. Not sure what the weather`s going to be like there, but taking some wet weather gear just in case.



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Brian Gaze
16 June 2017 08:54:39

It's worth noting the last GloSea5 update strongly supports above average temps in July and August. In the medium term a mixed period still looks the forn horse, but the long term seems promising. There doesn't seem much to suggest a pattern change im our hemisphere. I'd not be surprised if this summer turns out to be very warm.


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Solar Cycles
16 June 2017 08:58:37

Originally Posted by: Brian Gaze 


It's worth noting the last GloSea5 update strongly supports above average temps in July and August. In the medium term a mixed period still looks the forn horse, but the long term seems promising. There doesn't seem much to suggest a pattern change im our hemisphere. I'd not be surprised if this summer turns out to be very warm.


Up until last winter I rated the GLOSEA5 but since then it's cannon fodder like the rest of the long range models, of course that's not to say it's wrong for July/August but I'm highly sceptical of any forecast beyond 10 days.

Rob K
16 June 2017 10:23:39
I can't understand why the surface temps on the GFS are so low.

With 850s of 15C across the south coast surely it would get higher than 25C?

http://www.theweatheroutlook.com/charts/gfs/06_132_uk2mtmp.png?cb=729 
Yateley, NE Hampshire, 73m asl
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Rob K
16 June 2017 10:27:00

Even 24 hours later with the 850s at 16C+, the max temp is only given as 26C.


 



 



Yateley, NE Hampshire, 73m asl
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moomin75
16 June 2017 10:36:50
All goes bang earlier on this morning's 6z. Then a generally unsettled weekend next weekend.
Witney, Oxfordshire
100m ASL
moomin75
16 June 2017 11:01:22

Originally Posted by: Brian Gaze 


It's worth noting the last GloSea5 update strongly supports above average temps in July and August. In the medium term a mixed period still looks the forn horse, but the long term seems promising. There doesn't seem much to suggest a pattern change im our hemisphere. I'd not be surprised if this summer turns out to be very warm.


I think more mixed medium term is a good call Brian. The models are starting to show signs of a more unsettled spell towards the end of June, but with insane heat to our South I think you aren't going to be far off the mark with a warm to very warm summer overall.


Witney, Oxfordshire
100m ASL
Brian Gaze
16 June 2017 12:42:47

Originally Posted by: Rob K 

I can't understand why the surface temps on the GFS are so low.

With 850s of 15C across the south coast surely it would get higher than 25C?

http://www.theweatheroutlook.com/charts/gfs/06_132_uk2mtmp.png?cb=729


GFSP is supposed to correct that problem, but I'm not convinced:


 


Brian Gaze
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Hungry Tiger
16 June 2017 13:31:38

Originally Posted by: moomin75 


I think more mixed medium term is a good call Brian. The models are starting to show signs of a more unsettled spell towards the end of June, but with insane heat to our South I think you aren't going to be far off the mark with a warm to very warm summer overall.



I had my feelings that we were going to be for a good summer when in March I heard that Tenerife had 34.5 in early March. Well since then I have seen at least 4 situations which have shown that the Azores high is far better and strongerr this year than it has been in ages.


I am 65% certain we're in for a good or very good summer this year.


 


 


 


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