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1 hour ago, mushymanrob said:

it does, but sadly no other model suite suggests this. all indications are pointing towards troughing establishing as the main driver after the current warm spell departs next week.

Surely not! Above average heights and ridging according to this! :D

noaa.thumb.jpg.d32794f1ad6d827817d8ba53cf55b2a3.jpg
 

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Gfs 06z turns its pretty unsettled from the middle of next as troughing takes hold and pretty much remains there for the entire second half of the run. It’s really the first time since the end of April there is persistent signal for unsettled conditions to be dominant over the U.K. At moment far enough to away not to cause any concerns but increasingly likely that after a promising start August after the first tercile may default to a pattern so familiar over the past fifteen years.

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26 minutes ago, mb018538 said:

Surely not! Above average heights and ridging according to this! :D

noaa.thumb.jpg.d32794f1ad6d827817d8ba53cf55b2a3.jpg
 

yep, unfortunately thats been updated and downgraded to this now...... but low confidence, so it might not happen..

 

poor.gif

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2 hours ago, c00ps said:

It's not a strange obsession - there's nothing better than those cold foggy November days.

I think they'll be a blip again after 5/6 days then a cooler, still warm, settled period, then a blip and so the cycle continues until the snowdrifts come in December 😉

Snow drifts followed by the north sea and English channel frozen solid  allowing Wolves to cross from Europe and of course net weather crashing every night .back to the models ,an indication from today's charts that we have 5 days of v WARM to hot conditions then possibly a thundery breakdown ,after that if indeed the COOLER air arrives I think we are going to be kept WAITING .But I do have a gut feeling  that some very interesting synoptics will be around  next week , great forum keep the posts COMING Gang ,cheers Stellas all round .

 

 

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Despite the up/downs/inconsistency of the OP runs this past day or two the ensembles are rather telling. 

Hot conditions this weekend lasting into early next week look more likely than not to be replaced by average (below average in the North) temperatures with low pressure having more of an influence over high pressure. Still a way out in terms of reliability but I think the broad trend is strengthening. 

GFSENS06_52_0_205.thumb.png.e9f30713f72091ff487b5dc748eed343.png

GFS goes almost full autumnal with the 06z

Rain.thumb.png.7262a4e5f4b477f7510688c443f81d81.png

I go on holiday to Devon for 2 weeks on Saturday, so seeing charts like this for me wasn't really a surprise haha

 

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Going from these model outputs, could anyone tell me if it will be particularly wet or just cloudy ?

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30 minutes ago, richep said:

Going from these model outputs, could anyone tell me if it will be particularly wet or just cloudy ?

mixture.... breezy, periods of rain if and when we get systems cross us, sunny periods with some showers with the usual caveat - best in the southeast, poorest in the northwest.

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2 hours ago, Singularity said:

Regardless of how exactly that plays out, bigger questions arise beyond next Wednesday. The Nino background points toward a quick departure of the plume-fuelled low with high pressure arriving from the southwest as the Azores High is suppressed and effectively displaced across our lands, setting in motion a path toward another plume attempt, probably by early the following week. Yet the modelling continues to be very reluctant to head down this route, with just some hints past day 10 in the ensembles and some GFS runs (but not even slightly in the case of the 06z, which goes so far from the Nino state pattern, it's actually insane). 

Even the ECM 00z, which managed to move some ridging back through Europe and far-SE UK by day 10, is at that time inflating a huge ridge out across and to the NW of the Azores. That's Nina-like behaviour, not Nino-like.

 

While the Arctic High development does influence the latitude of the jet stream, it doesn't control where the troughs and ridges setup; the tropical forcing has the last word in that. So this is a matter of how the models are reading the tropical situation. For some reason, they often struggle badly with standing wave formations in the atmosphere such as the Nino-configured one recently/currently coming together. This was what led to the 'broken promises' of last summer, when for a time the models showed the fine weather of June and early July continuing well on through July, until the manifestation of a La Nina standing wave was factored in properly and... it all fell apart. This time around, we have the opposite situation, more or less.

This assessment is made with some degree of certainty. Why then are there no or limited direct correlations between ENSO and sea level pressure patterns for the North Atlantic / European sector at this time of year?

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3 hours ago, Singularity said:

As anticipated, the big heat plume to the south is likely bring about some manner of unstable weather for a time next week, and the models are firming up on this today, though not in terms of the smaller-scale detail which could yet make the difference between a step up to very hot conditions for as much as two days in a row, and a simpler cut-off of ongoing quite hot weather from the weekend during either Tue or Wed next week. The GFS 06z is a little slower with the trough movement on Monday, at first resulting in weaker interaction with the 'heat low' over Iberia, before the upper trough moves over and kicks things off proper. That upper trough may yet be slowed down too, though.

 

Regardless of how exactly that plays out, bigger questions arise beyond next Wednesday. The Nino background points toward a quick departure of the plume-fuelled low with high pressure arriving from the southwest as the Azores High is suppressed and effectively displaced across our lands, setting in motion a path toward another plume attempt, probably by early the following week. Yet the modelling continues to be very reluctant to head down this route, with just some hints past day 10 in the ensembles and some GFS runs (but not even slightly in the case of the 06z, which goes so far from the Nino state pattern, it's actually insane). 

Even the ECM 00z, which managed to move some ridging back through Europe and far-SE UK by day 10, is at that time inflating a huge ridge out across and to the NW of the Azores. That's Nina-like behaviour, not Nino-like.

 

While the Arctic High development does influence the latitude of the jet stream, it doesn't control where the troughs and ridges setup; the tropical forcing has the last word in that. So this is a matter of how the models are reading the tropical situation. For some reason, they often struggle badly with standing wave formations in the atmosphere such as the Nino-configured one recently/currently coming together. This was what led to the 'broken promises' of last summer, when for a time the models showed the fine weather of June and early July continuing well on through July, until the manifestation of a La Nina standing wave was factored in properly and... it all fell apart. This time around, we have the opposite situation, more or less.

Maybe things are not going as planned because it is too early for the el nino forcing in our neck of the woods. Even when it gets to full steam, most of the forecasts show a weak el nino this coming winter. 

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Posted (edited)

According to the GEFS 6z mean we would be looking at quite a prolonged cooler atlantic spell (around a week or so) coolest and most unsettled further n / nw and then around mid August there are signs that the azores high could become more influential again bringing fine and warmer conditions back across most of the uk.

21_348_500mb.png

21_348_2mtmpmax.png

21_372_500mb.png

 

Edited by Frosty.
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8 minutes ago, johnholmes said:

Signals dictate models,  models do not dictate signals....

 

very, very true Tamara, and thank you for your usual well argued, if a bit difficult to follow at times, on a part of meteorology that is far from my usual habitat.

But the models depict the signals as the signals we see as a projection are model based. It's all horribly complex and interlinked. 

The only thing that can 'lead' anything is real time initiation data. 

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9 minutes ago, CreweCold said:

But the models depict the signals as the signals we see as a projection are model based. It's all horribly complex and interlinked. 

The only thing that can 'lead' anything is real time initiation data. 

Such as the recent ECMWF upgrade

https://www.ecmwf.int/en/about/media-centre/news/2018/ifs-upgrade-improves-extended-range-weather-forecasts

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GEM 12z taking a more fitting route though still with the Atlantic pattern looking dodgy by Thursday.

GFS 12z almost manages to at least restore the ridge quickly, but then angles the jet all wrong... or at least, supposedly wrong based on the GSDM/ teleconnection theory.

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Looking at the ukmo 12z, next week is set to become more unsettled and considerably cooler.🙂

UW120-21.gif

UW144-21.gif

UW144-7.gif

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No plume on the 12z. I guess you could say more settled but only very slightly better

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56 minutes ago, knocker said:

Indeed! HPC weather modelling is using a distributed cluster of compute nodes each dealing with a section of the atmosphere, running calculations forward in time based on the inputs to each section, updating all to the new time frame then going again - I'm not disagreeing, but I find it hard to see how teleconnection patterns can be plugged in to this evolution... woukd be interesting to hear otherwise though!

Samos

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50 minutes ago, Tamara said:

There are correlations made pretty much every week with evidence firmly based on tropical>extra tropical momentum processes that are (and have been on countless occasions) fully identifiable and demonstrable in real-time. That   is, if one is open minded enough and prepared to accept a full diagnostic approach to global wind-flow and Jetstream behaviour that uses a phase framework to identify how accelerating and decelerating wind-flows and changes in their trajectory relate to anticipated pattern change.

This process is actually relatively easier to accomplish in the summer in the absence of the traditional winter-time polar vortex - which much more closely defines a relationship interplay between the troposphere and the stratosphere that affects pressure patterns close to the ground. In that sense, upstream developments in the Pacific linked to ENSO, have less feedback interference in the summer and can be even more easily correlated.

I  read @Singularity post as a reasoned and measured assessment as to how the synoptic pattern might evolve - one that reads between the lines of, rather, than takes NWP at face value. I would also personally , as per usual, question any post that makes definitive conclusions about NWP and then attempts to extrapolate these forward "with some degree of certainly" to use your own words.

I know your stance earlier this year was to reject any part that tropical>extra tropical momentum processes played in the SSW this year (and which in terms of the tropospheric pathway came about through the east based a-typical nature of the La Nina composition in the Pacific).

However ,and alternatively  if one does accept the very real part played in ocean/atmosphere feedback in winter through tropical convective imprint of such an ENSO arrangement  that propagated to the extra tropics and then to the polar stratosphere via mountain torque mechanisms -   then why should the relationship be different under an ENSO regime in summer where rossby wave dispersion wavelengths have evolved further towards a warmer sub water and SST ENSO imprint since the winter, and we have seen how such a process has resulted in the anomalous ridge arrangements seen since the final -AO effects of the SSW diminished during April ?

Once cannot deny the timetable of events as has occurred and deny one part of an equation, yet accept the other. As much as you most certainly accept stratospheric dynamics and post as authoritatively and "with some degree of certainty" as you usually do on them - but reject as unproven the tropospheric tropical momentum>extra tropical momentum processes that are trigger to events within the polar field.

These processes do not take a holiday in summer along with the winter-time polar vortex. They are intra-seasonal phenomena that are in a permanent state of flux and occur 24/7 all year round. :)

In terms of the present pattern, as discussed in recent posts, the switch east in the locale of low frequency tropical convection is set to dominate the synoptic pattern for the rest of the summer and into official autumn. I think based on recent evidential analysis,  this can said with at least a reasonable degree of confidence, if like everything else it can't ever be said with wholesale certainty.

EMON_phase_51m_small.thumb.gif.d3b47aaffc6e5a9a463712dfea1a7e34.gifECMF_phase_51m_small.thumb.gif.32aff261fe72d9f553596a0ef8e60a44.gifdiagram_40days_forecast_GEFS_member.thumb.gif.5532cb6e37f150c1980fa5c11f665aff.gif

 

On that basis, and as  @Singularity quite rightly reasons, the newly establishing El Nino standing wave as governed by this low frequency tropical convective signal in the Pacific is going to ebb and flow around downstream trough/ridge solutions in both the Pacific and Atlantic. It occurred at relatively short notice in the models after mid July and this pattern is ever more likely to recur and keep recurring the longer times goes on. While the signal does ebb and flow and is never wholly constant, it is not wise in my opinion to extrapolate an Atlantic ridge and southward digging trough solution sustainably longer term- and better to try to measure intra day NWP not as face value absolute, but as a snapshot in time.

Signals dictate models,  models do not dictate signals....

If the demonstrable correlations are so clear then you will have no difficulty in providing charts to prove it? Data is king, anything else is at best conjecture and supposition, at worst waffle -

86_29_195_22_213_10_15_47.thumb.gif.70c9caee02d69898d44e058787d10d48.gif

The above is August Nino 3.4 correlated with SLP - nowhere is there a significant correlation (around +/- 0.3) let alone a signal for definitive locations of troughing or ridging (similar can be seen with other tropical Pacific indices and lag times).

There is a veritable raft of literature investigating if there is a link then it is of secondary importance e.g. non-stationary in time, linked indirectly through Indian Monsoon, Sahel rainfall, tropical Atlantic and Caribbean temperatures and rainfall, 'new' teleconnections eg. the "circumglobal teleconnection" or the "North Atlantic-Eurasian" teleconnection etc

Note, nowhere did I mention NWP, nowhere in the above post or previously do I reject tropical influence - to do so would be foolhardy in the face of the research but once again it must be evidenced, number one rule "correlation does not imply causation". Linking SSW with the summer conditions? Here is the NH geopotential anomaly chart post SSW in March -

1817447261_500zanMar18.thumb.png.94df52bd7e79ac7684e7ad700d8123c8.png

And here it is in May -

1950629349_500zanMay18.thumb.png.5a1a317b511e78fd07539545d7c9a8d6.png

they could hardly be more different, almost polar opposites. (The only interesting suggestion was that the late reformation of the strat vortex may have influenced the predominant early summer polar troposphere vortex)

And with regards to AAM this does not define circulation patterns it is an indicator of them and importantly, this is not all some recent concept. Going back to the critical work on energetics with the Lorenz energy cycle in the 1950s, the potential energy - kinetic energy cycle largely determines atmospheric flow - caused largely by temperature contrasts it is the eddies which take the AAM with them not vice versa. It was good to see in the video in the teleconnections thread that Ed Berry is quick to acknowledge the work of Lorenz which remains more or less the standard approach to global circulation.

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The Gfs 12z turns into a pretty autumnal run with below average temps and plenty of wind and rain but then it feels sorry for us at the end with some warmth and high pressure for the s / e.

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Posted (edited)

UW144-21.GIF?02-18

The end is nigh perhaps? Who knows but it does look like westerlies will break through after Tuesday though it is worth noting that up to then 30C should be reached each day in the south and 32C could be reached tomorrow, Monday and Tuesday. The GEM does offer a solution akin to some of the runs yesterday but unless the ECM follows this then it is likely an outlier solution.

Arpege maxima

arpegeuk-31-30-0.png?02-18     arpegeuk-31-54-0.png?02-18   

 

arpegeuk-31-78-0.png?02-18     arpegeuk-31-102-0.png?02-19

The risk remains for thunderstorms on Tuesday, it would be nice to see a delicate shift to drift a thundery low north which could edge up the temperatures a little more on Tuesday and also bring more of a bang to procedings.

Edited by Captain Shortwave
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Posted (edited)

Reading the arguments put forward by @Tamara and @Interitus above, slightly confused, genuine question are you talking about the same thing?  As I understand it Tamara is talking about above average AAM affecting the UK, Interitus about El Niño affecting the UK at this time of year, there may be some overlap but these two are not the same thing?

Edited by Mike Poole
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On 29/07/2018 at 18:26, Steve Murr said:

The threat of the record going this year has been very real & the dates earmarked 5th / 6th havent really changed in the last few days - we could still do with more of a southerly component - but we are homing in on a possible shot at 39c. 

Last week we missed due to the upper air being far east & timings - this time around availability of heat looks more significant & the source certainly 4-5c hotter....

 

On 26/07/2018 at 21:22, Mike Poole said:

I don't think the jet has a cat in hell's chance of making a significant breakthrough in August (famous last words), one reason perhaps because of the sea surface temperatures around the UK that you mention.  But into autumn, it will certainly be interesting when the payback comes, but is the Arctic going to be as cold as it usually is at that time?  Here Atlantic SST and anomaly, high as I've seen round Southern UK, over 20C in SW.

image.thumb.jpg.8a0d26cd54da72b6765bfae2a1d15a60.jpg

image.thumb.jpg.23b196b2d411f3e737ba1749e3488f2f.jpg

Now that the models seem to be firming up on the weekend I'll give some thoughts....

I think perhaps some were quick to dismiss the return of the jet in August as it is traditionally dominated by westerlies! All the talk of 40C seems like a long time ago now and we may not catch a plume at all if the Atlantic ramps up any further. A lesson to be learned here, that even if there is strong agreement on plumes and big heat at T240 it can still go wrong. Here is the ensembles from a couple of days back.... compared to today, which shows an increasingly short spell of heat.

DjNx7Pf.pngGFSENS06_52_0_205.png.0e266692559ea4208da8cbe3f6e51c65.png

I think one or two spots could creep into the mid 30s on Friday and it may get a bit higher on Wednesday if the plume alligns perfectly but the chances of that are miniscule now, in fact I believe there is a chance the really warm uppers could miss us altogether.

The problem is the pressure in the mid North Atlantic. Below we can see the synoptic picture for Monday

image.thumb.png.e085ec52bab074018bc6c1e97fecab7f.png

The models have been pushing for a build of pressure over Greenland, which allows a cool lobe of air to move out of this region. This pushes down towards the UK before the plume can really build. Still fine details here and there may change.

However the signal is for some really quite cool weather towards the end of the week and if we get a northerly flow then don't be surprised if we suddenly see deeper lows cross the country as the warm SSTs around the UK will give them more fuel.

There is a lot of posts here about GLAAM and the MJO and El Nino forcing but I'm not convinced by any of these when it comes to the summer months at all. Everything is too finely poised and the large scale circulation patterns are usually so slack which is so important for an area like the UK. I haven't seen any evidence to suggest an El Nino has a forcing effect on this side of the world. There have been plenty of fantastic and awful El Nino summers (this one hasn't even really developed yet). I think the key player may be ocean currents and SSTs in the North Atlantic.

While I don't dispute processes like ENSO, the MJO and SSW's have a big impact during the winter months I do dispute their influence in the summer. We can look at GLAAM, NAO, ROFLMAO, YOLO and such but the one thing that matters in these situations is how the Atlantic is behaving and its influence is becoming stronger again. Though the next few days are a callback to previous days of this glorious summer.

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