Model Output Discussion - May and Early Summer!

[Frosty.]

Here's some charts from the GEFS 6z.

Edited May 31, 2019 by Frosty.

[Methuselah]

I think peeps' location-based perceptions are coming in to play a bit here, chaps:

When I see a pattern like that forecast for next week, I have an instant 'emotional' response: I imagine sunny mornings, a brief build-up of convective clouds, only for those clouds to get blown away as the sea-breeze sets in -- sunny afternoons with reasonable temperatures...

Someone living a hundred miles from the coast, though, might imagine something altogether different: a sunny start giving way (by late morning) to a mostly cloudy weather with heavy showers and downpours...and none too warm?

At the end of the cliche, we'll all have to like it or lump it. It's weather!

[Tamara]

2 hours ago, Frosty. said:

Looking at the GEFS 6z mean I'm seeing plenty of summery potential beyond next week and as I've said, next week is sunshine and showers with temps close to average.

Thanks for your customary posting of the latest ensemble means and which is much appreciated by many I am sure - I know you provide these for the right intended reasons and without knowingly trying to create reaction from others or mislead anyone 

As you know, from my point of view the diagnostic approach to the outlook has stayed consistent with pros and cons as to how the pattern may evolve beyond the unsettled phase next week.   It continues to be a case of having valid reasons to suggest improvement beyond this time -  mindful as previously stated in equal detail what could alter such an improvement. 

The ensemble members can give a broad numerical modelling view, as a snapshot in time, of how each model perceives the signals influencing the synoptic pattern, but changes to these can occur over a period of days rather than necessarily from from one suite to another in a single day period. NWP can be prone to reversing trends as much as accelerating them based them on changing interpretations of signals - so the diagnostics prove highly useful in terms of trying to identify when such changes might happen and/or point to the likely outcome(s) within that given time.

I also think that the continuing reference to operational outputs, even less of a reliable snapshot of time for obvious reasons, is proving especially unhelpful in distorting perception (and not helping stabilise mood swings) according to the particular modus operandi of the poster on each occasion

As I see it, the GEFS has been a little progressive in terms of creating the impression of the pattern improving as soon as later next week and I think the potential advection of heat from the east has rather helped create this illusion as well in what has remained an unstable pattern surrounding the longwave trough. The real improvement chances have always been beyond this time - any heat equation injected into the unsettled pattern has always been an 'add-on' to create a little interest. But all the main model ensemble suites (ECM,GEFS and GEM) all point to this improvement beyond this to varying but quite reasonable degrees.

The VP200 tropical convection anomalies clearly show up the suppression phase over the Pacific and active phase in the Indian Ocean that is responsible for the step up in trade winds which is creating the La Nina-esque type pattern downstream to the Atlantic and European sector in the coming period - the distinct amplified Atlantic ridge and longwave trough response over the UK. Quite the change there from the sustained and robust array of westerly wind bursts associated with the recent convectively coupled kelvin wave progression through the Pacific earlier this month

 

The eastward progression of propagation of this activity, is on the slower side of the envelope. This is in contrast to the fast propagating CCKW related phase of tropical convection in recent weeks. Hence why it is unlikely that the trough solution will lift out properly until the supressed phase in the Pacific starts to fade out in advance of the convective zone proceeding through the Maritime region towards the West Pacific. This sequence changes the rossby wave response further downstream with the result that amplification responses also shift further downstream to assist pressure rises in the wake of the trough.at the same time as allowing the heights to the east to link up with this pressure rise and improve conditions. 

Present estimates do not suggest this evolution advancing sufficiently till towards the mid month period - so the extended ensemble suite reflection of improvement are not too far away from the diagnostic guide. The timing of associated rises in angular momentum tendency, as the tropical signal propagates, also clearly coincide with both the tropical>extra tropical diagnostic and the extended ensemble suite suggestion

The caveat, as before, is that the tropical cycle retains some progression to allow that rise in momentum tendency - the diagnostic equally shows that any lack of verification of propagation implies a greater struggle to change the downstream pattern. Answers to that question however simply cannot be properly answered immediately, by anyone - and require a watching brief to check progress. On that basis, any gloomy prognostication bases on snapshot modelling is as counter intuitive and misleading as any, allegedly, over optimistic one.

Mindful of these cautions and caveats, which in truth once provided as balance and information to help the thread, should not thereafter require to be endlessly inserted and repeated with every post as means to try to ease the truly tiresome battles of attrition on this thread that persist, there nevertheless  continues to be, at the very least, reasonable evidence to back an improvement towards, or by mid June. Especially as stated in recent posts the background to global relative momentum is set more favourably than other years at this specific time of seasonal change and should help the process of the trough lifting out in tandem with the shift in rossby wavelength re-configuring the pattern.

 

[Frosty.]

The ukmo 12h is an increasingly unsettled and cooler run with an upper trough in control next week..so a mixture of sunshine and showers, some heavy with thunder, even some longer spells of rain and becoming breezy / windy for a time, especially further n / nw...hints of some improvement by T+144 hours further s / se.

Edited May 31, 2019 by Frosty.

[Methuselah]

Some may argue (and maybe quite successfully) that the 12Z has gone off on an altogether different tack:

 

Edited May 31, 2019 by Ed Stone

[Methuselah]

And now we have HP coming from the west and southwest? And, who put that big yellow Klansman over the UK?

 

[Methuselah]

Aaah, voila...la modelle par excellence. 

 Pardon mon Francais!

Snotmagnet UK!                                                                               

Edited May 31, 2019 by Ed Stone

[thestixx]

2 hours ago, Tamara said:

Thanks for your customary posting of the latest ensemble means and which is much appreciated by many I am sure - I know you provide these for the right intended reasons and without knowingly trying to create reaction from others or mislead anyone 

As you know, from my point of view the diagnostic approach to the outlook has stayed consistent with pros and cons as to how the pattern may evolve beyond the unsettled phase next week.   It continues to be a case of having valid reasons to suggest improvement beyond this time -  mindful as previously stated in equal detail what could alter such an improvement. 

The ensemble members can give a broad numerical modelling view, as a snapshot in time, of how each model perceives the signals influencing the synoptic pattern, but changes to these can occur over a period of days rather than necessarily from from one suite to another in a single day period. NWP can be prone to reversing trends as much as accelerating them based them on changing interpretations of signals - so the diagnostics prove highly useful in terms of trying to identify when such changes might happen and/or point to the likely outcome(s) within that given time.

I also think that the continuing reference to operational outputs, even less of a reliable snapshot of time for obvious reasons, is proving especially unhelpful in distorting perception (and not helping stabilise mood swings) according to the particular modus operandi of the poster on each occasion

As I see it, the GEFS has been a little progressive in terms of creating the impression of the pattern improving as soon as later next week and I think the potential advection of heat from the east has rather helped create this illusion as well in what has remained an unstable pattern surrounding the longwave trough. The real improvement chances have always been beyond this time - any heat equation injected into the unsettled pattern has always been an 'add-on' to create a little interest. But all the main model ensemble suites (ECM,GEFS and GEM) all point to this improvement beyond this to varying but quite reasonable degrees.

The VP200 tropical convection anomalies clearly show up the suppression phase over the Pacific and active phase in the Indian Ocean that is responsible for the step up in trade winds which is creating the La Nina-esque type pattern downstream to the Atlantic and European sector in the coming period - the distinct amplified Atlantic ridge and longwave trough response over the UK. Quite the change there from the sustained and robust array of westerly wind bursts associated with the recent convectively coupled kelvin wave progression through the Pacific earlier this month

 

The eastward progression of propagation of this activity, is on the slower side of the envelope. This is in contrast to the fast propagating CCKW related phase of tropical convection in recent weeks. Hence why it is unlikely that the trough solution will lift out properly until the supressed phase in the Pacific starts to fade out in advance of the convective zone proceeding through the Maritime region towards the West Pacific. This sequence changes the rossby wave response further downstream with the result that amplification responses also shift further downstream to assist pressure rises in the wake of the trough.at the same time as allowing the heights to the east to link up with this pressure rise and improve conditions. 

Present estimates do not suggest this evolution advancing sufficiently till towards the mid month period - so the extended ensemble suite reflection of improvement are not too far away from the diagnostic guide. The timing of associated rises in angular momentum tendency, as the tropical signal propagates, also clearly coincide with both the tropical>extra tropical diagnostic and the extended ensemble suite suggestion

The caveat, as before, is that the tropical cycle retains some progression to allow that rise in momentum tendency - the diagnostic equally shows that any lack of verification of propagation implies a greater struggle to change the downstream pattern. Answers to that question however simply cannot be properly answered immediately, by anyone - and require a watching brief to check progress. On that basis, any gloomy prognostication bases on snapshot modelling is as counter intuitive and misleading as any, allegedly, over optimistic one.

Mindful of these cautions and caveats, which in truth once provided as balance and information to help the thread, should not thereafter require to be endlessly inserted and repeated with every post as means to try to ease the truly tiresome battles of attrition on this thread that persist, there nevertheless  continues to be, at the very least, reasonable evidence to back an improvement towards, or by mid June. Especially as stated in recent posts the background to global relative momentum is set more favourably than other years at this specific time of seasonal change and should help the process of the trough lifting out in tandem with the shift in rossby wavelength re-configuring the pattern.

 

Thanks for your in depth analysis Tamara, one thing always comes to mind though, see your paragraph here: "

 

The VP200 tropical convection anomalies clearly show up the suppression phase over the Pacific and active phase in the Indian Ocean that is responsible for the step up in trade winds which is creating the La Nina-esque type pattern downstream to the Atlantic and European sector in the coming period - "

 

 

Pacific conditions are often quoted/attributed to being factors in the conditions here, but in turn, don't the conditions here affect what's happening there, like El Nino causing drought in Australia when causing the opposite in South America?

 

 

 

[Frosty.]

The Gem 12z becomes trough dominated as per all the other output but later on there are signs of recovery, especially by day 10 with high pressure poised to build across the uk and if that happened the temperatures would be on the rise soon after..it certainly supports the idea being floated around of a general improvement towards / during mid June.

Edited May 31, 2019 by Frosty.

[Frosty.]

The GEFS 12z mean shows increasingly unsettled & cooler trough domination next week as this midweek snapshot indicates but gradually over time the idea is that the trough (s) eventually fill and there's an increasing chance of something a bit more settled thereafter and warmer too but equally we could still be at risk of further troughs and cooler air instead.

Edited May 31, 2019 by Frosty.

[Methuselah]

It's 12Z ensembles time, and they are, to put it mildly, somewhat less than stupendous!

  Though plants and ducks may disagree?

 

[MATTWOLVES 3]

What a bizarre day 7 chart, there looks like a large void has devoloped over the NW Atlantic and now an aliens head seems to be parked over the UK looking out across the Atlantic and saying.... That's enough from you now.... Time for some settled weather to bask the British Isles. 

Is it.... Isn't it.... Pressure rise that is... 

 Come on me beauty.... Build in.... 

Its certainly better than recent output.. My only concern at the end was high pressure trying to build North... And I would say to that...... Oyyy... Noooooo

Edited May 31, 2019 by Mattwolves

[knocker]

After Sunday the ecm has the UK under the auspices of the upper trough. A general overview is slack low pressure on the surface with showers, the occasional longer spell of rain,  and temps a tad below average

Edited May 31, 2019 by knocker

[Frosty.]

Tonight's Ecm 12z ensemble mean goes from this to this so next week is going to be unsettled, cooler and fresher with sunshine and showers but also some longer spells of rain, however there are signs that at least for southern uk towards T+240 the weather may improve.

Edited May 31, 2019 by Frosty.

[damianslaw]

A slowly moving pattern from Sunday onwards, a brief bit of warmth for the far SE corner of the UK, but the trough is quickly set to invade all, and linger in situ for a number of days, locked in situ in seems, but in time filling in situ or simply fizzling with heights set to build in from off the azores (in time...) - not a great start to summer it has to be said.

[weathermadbarnsleylad]

1 hour ago, damianslaw said:

A slowly moving pattern from Sunday onwards, a brief bit of warmth for the far SE corner of the UK, but the trough is quickly set to invade all, and linger in situ for a number of days, locked in situ in seems, but in time filling in situ or simply fizzling with heights set to build in from off the azores (in time...) - not a great start to summer it has to be said.

I'm glad we have at least another 11 weeks after next week of meteorological summer for a chance of a prolonged warm/hot/calm spell. 

[Don]

1 minute ago, weathermadbarnsleylad said:

I'm glad we have at least another 11 weeks after next week of meteorological summer for a chance of a prolonged warm/hot/calm spell. 

I'm sure the heat lovers will get their fair share of warmth this summer.

[weathermadbarnsleylad]

Why oh why. Its like somebody has sneezed and aimed at the UK. A week today from the 18z terrible chart to say the least. 

Edited May 31, 2019 by weathermadbarnsleylad
Missed text

[MATTWOLVES 3]

Blinding run beyond a week on the FV3, just look at the heights taking over with +16 uppers into the SW... not bad from a model that usually advertises cold pools... It  could be dropped in future runs, or it could become a new trend.. 

Edited May 31, 2019 by Mattwolves

[weathermadbarnsleylad]

20 minutes ago, Mattwolves said:

Blinding run beyond a week on the FV3, just look at the heights taking over with +16 uppers into the SW... not bad from a model that usually advertises cold pools... It  could be dropped in future runs, or it could become a new trend.. 

A bit too far away for my liking but it's hope @Mattwolves let the trend be our friend lol

[weathermadbarnsleylad]

Just now, weathermadbarnsleylad said:

A bit too far away for my liking but it's hope @Mattwolves let the trend be our friend lol

Ps @Mattwolves don't look at gfs18z 

[Fourty Point Three Degrees]

2 hours ago, thestixx said:

There's been lots of high pressure around us this year, Azores, Scandinavian, Euro.... We'll hit the jackpot at some point. 

Yep dont forget to include the high pressures most favourite spot of all during summer months, plonked over Greenland. They must have wonderful blue skies and crisp warm days June to Aug throughout while laughing at UK. . But sods law for the position we're in right now and take a look at the 18z that's just rolled along, it ends in the most awful way. Hopefully some major model and ensemble improvement to appreciate in the coming days.

Edited May 31, 2019 by 38.5*C

[northwestsnow]

9 minutes ago, 38.5*C said:

Yep dont forget to include the high pressures most favourite spot of all during summer months, plonked over Greenland. They must have wonderful blue skies and crisp warm days June to Aug throughout while laughing at UK. . But sods law for the position we're in right now and take a look at the 18z that's just rolled along, it ends in the most awful way. Hopefully some major model and ensemble improvement to appreciate in the coming days.

It is but one GFS operational, and after years of model watching  think its fair to say i wouldn't put much stock in an operational - the model, IMHO, is junk.

Stick to EC/UKMO and more often than not, it will give a better indication of where we are heading..

We know the first 10 - 15 days of June is not going to be great, esp the further NW one heads, the hope is things settle down post mid month- or in Exeters words,may settle down.

Edited May 31, 2019 by northwestsnow

[MATTWOLVES 3]

4 minutes ago, northwestsnow said:

It is but one GFS operational, and after years of model watching  think its fair to say i wouldn't put much stock in an operational - the model, IMHO, is junk.

Stick to EC/UKMO and more often than not, it will give a better indication of where we are heading..

Point well made NWS, and it speaks volumes when the old GFS and the new one are a million miles apart at the same time frames, apperantly the US invested millions in these models due to the fact, they kept on being upstaged by the Euro!! It looks to me like they need to invest many more millions, because for me they leave a lot to be desired. 

[StormChaseUK]

18z has just terminated Summer.

I was hoping I was wrong earlier today and I still hope summer will return in July/August but at this rate.. strewth