Model output discussion - summer rolls on

[Singularity]

Temps wise, they have been oddly slower to rise today despite lighter winds for most, but the calmer air may allow a later maximum than usual so perhaps another couple of hours of climbing temps still to come.

 

Anyway - I just wanted to briefly highlight just how out of kilter UKMO remains relative to the other models for this weekend;

  

It really is amazing, and if by some minor miracle the low does stay weak and slow, it will be one of the greatest single-global model victories I've seen in a long time (I say global as ARPEGE is quite similar as of the run's end at +108).

[Alex]

Having been in the background for a while, I feel it is time to post with this extraordinary spell upon us.

Re the next 48hours, the GFS has been correcting itself each run, steadily coming into line with the other models in regards to the high uppers and stalling of the front to the west.

My gut feel is that the July record is under threat but I doubt the August one is yet! With potentially thunderstorms breaking out and some cloud around, I expect 36c is most likely across East Anglia and the Southeast. Favoured spots must be places that have done well this week like Central Suffolk but also Essex and Kent could also be a challenger. 

Re this weekend, my thoughts are that it will get cooler but I expect temps to hold up to the mid 20s across the far SE, elsewhere early 20s with some showers around.

Going forward, I expect some more heat plumes but also sense that August will be wetter than June and July as thunderstorms will likely become more apparant in a more unstable setup.

Looking back at analogues, September could well also be interesting - further plumes and stalled lows look more likely than normal at first and when the Atlantic does break through we could see some very eventful weather! 

 

 

[Jo Farrow]

The Met Office said that back in August 2003, when 38.5C occurred, the 1000-

850 hPa thickness was 142.5 to 142.8 dam. Not quite that is showing on Friday. Never mind sunshine amounts/Cloud/TS.  36.7C July record does look likely to be beaten, and exciting week. Glad I'm not in it though. 

[mb018538]

Thanks for that jo!

temps rising a tad slowly today, a couple of 30c recorded now though ....the real scorching heat looks like tomorrow and Friday. With that front forecast slightly more to the west, a real chance of that July record going on Friday. Amazing.

[Frosty.]

The GEFS 6z mean becomes exceptionally good with high pressure / strong azores ridging and hot temperatures gradually returning across england and wales during the course of next week, becoming warm / very warm further n / w too...no end in sight to this wonderful summery pattern apart from the odd blip (this weekend / start of next week).☺

Edited July 25, 2018 by Frosty.

[nick sussex]

What’s interesting about the possible mid 30s temperatures is if you look at the bare 850s you might not expect that .

This is where the extended dry spell is key for those high temps, dry ground is a better conductor of heat.

[Djdazzle]

7 minutes ago, nick sussex said:

What’s interesting about the possible mid 30s temperatures is if you look at the bare 850s you might not expect that .

This is where the extended dry spell is key for those high temps, dry ground is a better conductor of heat.

Which begs the question - if we can potentially achieve 37C with 16 / 17 uppers, would could be achieved with uppers above 20?

[Tamara]

So, the much anticipated eventual pattern evolution that started occupying thoughts at the start of this month to Atlantic trough and Scandinavian ridge aligning exceptional heat are now fully in focus - with a spectacular convective undercut to end this week in parts of the country. Yet another milestone in this amazing summer that wants to keep on building... and then rebuilding.

And, also as envisaged, NWP is now fully gunning for the next re-load. Rinse and repeat.

How do we maintain faith in the extraordinary pattern further prevailing?

First and foremost to answer that - the here and now. The Global Wind Oscillation is now fully capturing the shift in upper tropical forcing to the Pacific and the atmosphere showing all the hallmarks of embracing the beginnings of an El Nino standing wave to keep growing in the rest of the summer and into autumn . The importance of the first embedded plot is less to do with any question attached to performance of model seasonal forecast looking ahead - but more the early imprint of the standing wave which is already recorded.

 

Also, and as shown in the second plot above, the tropical >.extra tropical shift of forcing as described already is represented by highest orbit of the GWO since the huge tropical momentum propagation that led up to the Feb SSW event - currently a high amplitude Phase 4. On the cusp of entry to the El Nino attractor phases 5,6,7 of the GWO

In synoptic terms this translates to greater amounts of net westerly winds being added to global wind-flows and propagating via rossby wave dispersion into the extra tropics to support repeated downstream amplification and perpetuating the anticyclonic heat domes - that have been intensifying over many weeks now without sufficient inertia to move them away. The tripole SST imprint in the Atlantic continuing to imprint and reinforce the summer feedback processes

What is significant for August is the integration of that fledgling El Nino standing wave ocean/atmosphere coupling that is representative of the eastward shift in upper tropical forcing that has started occurring and implies that the Pacific rossby wave dispersal forcing is on an auto-repeat - and thus likely to transfer to another MJO phase orbit into the Pacific (Phases 5 to 7) into the new month.

This mirrors the recent sequence, with a temporary shift back in angular momentum as the current wave fades in line with passage of the kelvin wave before yet another boost upwards as the re-coupling occurs over the Pacific. 

 

The subsequent re-coupling being stronger than the first time around. And so on, and so forth.

This implies a very likely further orbit back to, at least, elevated GWO Phase 4 which endorses NWP suggestion of ridging returning in the early August period to further build on the heat stoking processes of the summer-  and which will keep simmering over vast swathes of mainland Europe to the south and east, regardless of the temporary re-set of the pattern that happens closer to the Atlantic trough this weekend and into the early part of next week and which will bring some welcome rain to many who have not seen any for weeks.

Irrespective of likes, dislikes, personal risks and hopes and wishes of holiday-makers and the tourist industry, do weather enthusiasts justify pursuing the challenge to records very possible into the new month?

You bet

The benchmark set for that of the next couple of days is relative to old records - but also to be potentially matched and even exceeded into the new month. It is, and will continue to be watched very closely

 

Edited July 25, 2018 by Tamara

[mb018538]

Very true - which is why a shot at 40c this year with the ground as it is.....perfectly possible. A lot of rain over the next week could have a slight effect, but if it’s torrential most could just run off anyway.

[Singularity]

Oh yes. Great summery by Tamara as usual - the timing and 'shape' of the tropical cycles is looking to be close to optimal this summer for challenging all-time temperature records in the UK.

The largest uncertainty in my mind is how well we hold onto the dry end of the soil moisture feedback component. Thunderstorms aside (very high rain rates won't perculate into the ground very well), the models show wide areas seeing something between 5 and 30 mm between late Thursday and early Tuesday (could be some overestimation in there though; we know GFS and ECM go a bit bonkers with convective initiation and coverage). Now as far as I can imagine, anything less than 10, maybe even 15 mm is probably not going to bring about more than a temporary increase in surface soil moisture, as that which gets into the soil will have a lot of dry material lower down to continue on into.

Beyond those amounts, I'm not sure how much and lengthy an impact may be had in the face of renewed dry weather and very warm to hot temps (with very hot following if the soil dries out enough) - perhaps someone knows of a way to estimate the required amount based on measured soil moisture content?

 

12z runs rolling out. Let's see if UKMO can achieve a sensational victory .

Edited July 25, 2018 by Singularity
Thinking Forward

[shaky]

You gota laugh at the gfs!!it takes the plume further west on friday on this run aswell!!a failure at short notice!!could be some spectacular thunderstorms in places!!

[Singularity]

 

Hmm. Look how the secondary low out west has become more elongated and weaker... will it go the way of the UKMO 00z and hold the system back west until Monday, as a shallower feature?

Yep - I have the capacity to continue to focus on the weekend when Friday is far more interesting .

[MattStoke]

Finally the GFS has the highest uppers further west on Friday and mid 30’s possible at surface level as a result. You can normally add 2/3 degrees to raw GFS output as well.

[Guest Delete Me]

8 minutes ago, MattStoke said:

Finally the GFS has the highest uppers further west on Friday and mid 30’s possible at surface level as a result. You can normally add 2/3 degrees to raw GFS output as well.

What do you reckon for Stoke tomorrow then Matt?

[Singularity]

 

 

 

 

GFS 12z is warmer than the 06z overall by day for each of Sat, Sun and Tue. Very slightly so for the preceding Fri but not much in it. Monday omitted as temps are about the same.

Interesting that the run did keep the low weaker and more strung-out, but still managed to get it as far east as the 06z. The main reason the run is warmer is that the less intense circulation doesn't throw as much polar maritime air across us, in fact we're in a wide warm sector on Sunday;

Meanwhile, the weaker secondary low means that the focus of the parent trough comes together during the early part of next week further to the west than previous runs had it;

 

...which helps get the new ridge and associated tropical maritime airmass in faster, with temps likely back into the 30s across the SE by Wed (bias-accounted).

 

The Scandinavian high has gone a strange shape again, but maybe having so much heat associated with it just serves to mess up the stable dynamics aloft, such that even supportive tropical-extratropical forcing is unable to keep it going as more than a ragged feature with relatively low SLP?

[MattStoke]

16 minutes ago, Paul Faulkner said:

What do you reckon for Stoke tomorrow then Matt?

Around 30’C would be my guess. Probably reaching 35’C in some south eastern spots. I think 36/37’C is a bit of a stretch for Friday. Might be a lot of cloud from the approaching frontal systems but you never know. There must be a decent chance if the pros think so and, like I said, you can normally add a few degrees to raw model output.

Edited July 25, 2018 by MattStoke

[Singularity]

Just now, MattStoke said:

Around 30’C would be my guess. Probably reaching 35’C in some south eastern spots. I think 35/37’C is a bit of a stretch for Friday. Might be a lot of cloud from the approaching frontal systems but you never know. There must be a decent chance of the pros think so and, like I said, you can normally add a few degrees to raw model output.

Perhaps the soil-moisture feedback will suppress cloud amounts much as has been seen quite a bit during the past few weeks. This adding to the increased surface heating potential as a double-whammy of influence. Just a thought!

[shaky]

Much better runs from the 12zs!!still close to mid twenties throughout the weekend for central and eastern england and the rain not as persistant crossing the uk sunday into monday and more sporadic!!friday is the day if rain is what your looking for lol!!oh and to add we are back into the oven from tuesday lol!!crazy heat coming out of france!!

Edited July 25, 2018 by shaky

[Singularity]

 

UKMO finally caved in and is a close match to GFS in secondary low advancement - though it's still shallower, amazingly enough.

It stays very close to GFS for +120, but +144 sees a very shallow low pulled out of nowhere and deposited over far-S UK, leaving us looking east instead of west for the heat.

Er, excuse me UKMO, but we've had enough complications now, thank you! 

[Weather-history]

Week on Friday is a scorcher on GFS 12z

 

Edited July 25, 2018 by Weather-history

[Scorcher]

GFS 12Z in FI is absolutely stunning. I can't remember the last time I saw charts like that in August.  I know it's still a fair way off but the evolution is clear already- you can see the high building back in into Tuesday.

It doesn't get a lot better than this for sunshine and heat:

With the heat building up on the continent over the last few weeks and some very high SSTs, we could be looking at some truly historic.

[Dominic Carey]

Wow yet again amazing output today and as others have said apart from a blip or two the heat is continuing.

[Leo97t]

European record broken on the Gfs 12z

[markyo]

9 minutes ago, Scorcher said:

GFS 12Z in FI is absolutely stunning. I can't remember the last time I saw charts like that in August.  I know it's still a fair way off but the evolution is clear already- you can see the high building back in into Tuesday.

It doesn't get a lot better than this for sunshine and heat:

With the heat building up on the continent over the last few weeks and some very high SSTs, we could be looking at some truly historic.

And deadly don't forget. Very much a life threatening scenario.

Edited July 25, 2018 by markyo

[Frosty.]

6 minutes ago, Dominic Carey said:

Wow yet again amazing output today and as others have said apart from a blip or two the heat is continuing.

Yes the Gfs 12z operational shows heatwave conditions returning across the southern half of the uk from the second half of next week, high pressure and lots of hot sunshine.☺