Model Output Discussion - May and Early Summer!

[Guest]

2 minutes ago, Snowy L said:

2 days of slightly above average temperatures followed by weeks of crap is not typical summer weather.

Yep, UK payback weather in full swing! Not looking for the start of the Cricket World Cup either!! 

[Tamara]

14 hours ago, Alderc said:

A poor set of 12z’s across the board, you can have all the knowledge in the world but a warm start to June bar the 1st day, maybe the second in the extreme south east looks unlikely. A very unwelcome and relatively deep fetching northerly becoming likely into next week, that was the forecast for this week off course so it could, and probably will be watered down somewhat. 

Gfs ensembles now progging the 3-10th comfortably below average, 48hrs the mean was pretty much 10c @ 850pha through to the end of run. 

It might alright people saying ‘summer doesn’t really start until late June’ but in a country where at least 9-10months of the year is cold and dull every downgrade 1st May - 1st October is frustrating. 

If I might interject at this point.

It might well be worth adding a bit more flesh to proceedings and come at this yet another way in terms of objective diagnostics vs model "hugging" hunches and speculative extrapolations of individual operational outputs

For this purpose, lets take the updated ECM 0z ensemble at day 10 - which is a reasonable estimate of where we are likely to be based on current state of affairs. It also rather illustrates the points I was trying to make yesterday in terms of the pressure void to our east.

 

 

Lets then compare it to how it might be reflected by the diagnostic Global Wind Oscillation plot, which is a phase depiction of wind-flow patterns in the tropics and extra tropics and shapes the jet stream patterns which carve out placement of pressure systems. Described here in deliberately simplified parlance.

For this purpose we take the latest GWO plot, based on its typical consolidated lag time - at present time of typing to 25 May.

This reflects a very low amplitude signal which has ebbed and flowed around a weak phase 0,4,5,6,7,8,0 type orbit for some quite considerable time - identifying the pale pink warm neutral/weak Nino signal standing wave circulation feedback in the Pacific.

So once again in deliberately simplified terms - the predicted phase correlation for that EC ensemble plot is,very roughly speaking, around a Phase 8,0 position - according to month and seasonal wavelength. This phase progression is reflective on the GWO spectrum of some loss of angular momentum tendency having taken place upstream early next week which has amplified the Atlantic ridge to our west, and, downstream of that ,digs the longwave trough close to the UK.

What is important here is how the GWO is likely to progress as we head through early June. Based on the supressed phase of tropical convection across the Pacific as the MJO has retuned to the Indian Ocean, then some increase of trade winds, as identified yesterday, is behind the upstream loss of momentum as -ve frictional torque mechanisms scrub some of the recent strong westerly inertia from the atmosphere. This trade wind uptick visible, shaded blue, in the Western and Central Pacific towards the dateline here

But this is far from the whole story. With relative global atmospheric angular momentum comfortably above average (though still to account for some slight downward adjustment c/o the Pacific suppression phase)….

 …..this will still likely leave the AAM budget of the atmosphere with a supported floor, ahead of the next uptick in the "mini ENSO cycle" as the low frequency tropical signal in the Pacific is allowed to re-emerge and add further westerly inertia to the atmosphere and re-boot angular momentum tendency. AAM forecasting still, steadfast on this

 

Such support and uptick having the effect of re-orbiting the GWO back through Phase 4 towards the Nino attractor Phase 5....the signal to lift out the trough and pressure rise from the south (likely as suggested yesterday that the boundary of the heat will still be fairly close by and conceivably ready to advect back northwards and westwards). It remains something to keep watching in ensemble suites in the coming days, as this story is far from complete....

What could go wrong?

The importance of re-energising of westerly momentum across the Pacific to neutralise the trade increase is a vital key here to support AAM and prevent a deeper slide. Any shortfall would add incentive for a more durable trough solution and retain a more amplified ridge profile in the Atlantic to lock the longwave trough in.

What can quite conceivably go right (aka AAM forecast)

Its also true though that if the atmosphere just stays as it is, then summer seasonal wavelengths on their own should work in our favour and increasingly means that just a persistence of the present GWO orbit regime inclines the trough to edge back westwards the closer we get towards the later part of June and into July. Any ideal scenario of repeated vigorous westerly wind bursts however, that pushes the GWO into higher phase Nino attractor orbit 5,6 and 7 starts to flag up the possibility of 2006 and 1983 type scenarios with prominent Western European heat ridges duelling with thundery cut-off lows to our west and south west....But that is for another time perhaps...

Edited May 28, 2019 by Tamara

[Fourty Point Three Degrees]

Well I wouldn't be so quick to write off the next 10 weeks based on one poor output, although the first half of June '19 doesn't look good, the late Spring and early June of 1995 had a constant Northern wind due to Atlantic blocking before the high moved in and intensified giving way to heatwaves in late in June and July.  
 

[knocker]

9 minutes ago, Tamara said:

If I might interject at this point.

It might well be worth adding a bit more flesh to proceedings and come at this yet another way in terms of objective diagnostics vs model "hugging" hunches and speculative extrapolations of individual operational outputs

For this purpose, lets take the updated ECM 0z ensemble at day 10 - which is a reasonable estimate of where we are likely to be based on current state of affairs. It also rather illustrates the points I was trying to make yesterday in terms of the pressure void to our east.

 

 

Surely that constitutes a model 'hug' and im any case I'm not sure I would agree with your 'void' to the east

 

[Derecho]

13 hours ago, ANYWEATHER said:

Good Evening All!  The brefiest of Plumes but looking at the profile could be some serious rainfall with that brief plume across central and southern Britain

For once I can't dispute the all the content your post 

The rainfall is not too much of a concern for Sunday however with thunderstorms favoured for those further North and East (as things stand!) but GFS can overestimate CAPE. Current forecast CAPE for Sunday looks pretty good it must be said!

I think my concern is that heat is building over the continent and if the cooler air is sluggish to make inroads then this could lead to some serious rainfall in eastern areas. This GFS chart shows my overall thinking...

It's clear that to the west there is going to be some cool air but just how far east this moves is uncertain. ECM is rather more bullish leading to a cool showery flow from the WNW. If the GFS comes off however we could get areas of low pressure forming in the north sea meaning things could turn thundery and humid in the east although maximum temperatures would still be a little poor.

A brief plume though, but will it end with some good thunderstorms on sunday?
 

Edited May 28, 2019 by Quicksilver1989

[knocker]

4 minutes ago, 38.5*C said:

Well I wouldn't be so quick to write off the next 10 weeks based on one poor output, although the first half of June '19 doesn't look good, the late Spring and early June of 1995 had a constant Northern wind due to Atlantic blocking before the high moved in and intensified giving way to heatwaves in late in June and July.  
 

Are you engaging in Bulverism as I'm not aware of anyone saying that?

[Polar Maritime]

Starting to warm up by Friday and into the weekend with temps possibly touching 26/27c in some spots by Sunday. Scope for thunder storms into the early hours of Monday morning as cooler air pushes in from the West.

 

 

[Fourty Point Three Degrees]

3 minutes ago, knocker said:

Are you engaging in Bulverism as I'm not aware of anyone saying that?

i was referring to the input that said "2 days of above average temps followed by weeks of crap is not typical summer weather. " in one of the above posts.

[Badgers01]

20 minutes ago, knocker said:

Are you engaging in Bulverism as I'm not aware of anyone saying that?

That’s today’s new word learnt !! 

Edited May 28, 2019 by Badgers01

[ANYWEATHER]

Morning, well we go into meterological summer with the same undulating jet stream which seems to been around forever Of course it's not always a bad thing it does not mean it's going to be constant bad weather, I think this year farmers and growers can look forward to bumper crops with plenty of moisture but also a good measure of sunshine too....

Edited May 28, 2019 by ANYWEATHER

[Frosty.]

Looking at the Ecm 00z ensemble mean, next week we are under the influence of a cool showery trough so a mixture of sunshine and showers, some heavy and thundery seems likely, beyond that there are hints of improvement further s / e with less showers and a recovery in temperatures.

[DR(S)NO]

19 minutes ago, Badgers01 said:

That’s today’s new word learnt !! 

Indeed.....Today’s Lesson

Bulverism is a logical fallacy. The method of Bulverism is to "assume that your opponent is wrong, and explain his error." The Bulverist assumes a speaker's argument is invalid or false and then explains why the speaker came to make that mistake, attacking the speaker or the speaker's motive.

[MATTWOLVES 3]

35 minutes ago, Badgers01 said:

That’s today’s new word learnt !! 

I've got to be honest, I had to look this word up... I thought he was referring to an eating disorder when I first clocked it.. What a couple of days we have had, just the other day things were looking very rosey for a longer spell of settled Conditions, now we literally have low pressure anchored over us by Sunday.... In the words of the Queen.... One is not amused.. 

I just hope that this from the 6z gets watered down nearer the time, very unsettled conditions to the North of the country... Amazing to see how high pressure is bringing most of Europe fine summary conditions. 

Edited May 28, 2019 by Mattwolves

[MATTWOLVES 3]

The only positive words I can find for this at day 8 are its a long way off!! 

[Frosty.]

9 minutes ago, Mattwolves said:

The only positive words I can find for this at day 8 are its a long way off!! 

Dare I say welcome rain!!..I'll get my coat..and brolly

Edited May 28, 2019 by Frosty.

[chrisbell-nottheweatherman]

3 minutes ago, Frosty. said:

Dare I say welcome rain!!..I'll get my coat..and brolly

Very much so down here!

[Guest]

Another dire run from GFS beyond the weekend and while yes it’s only one run, actually now it’s a rapidly deteriorating trend over the past 48hrs, hard to see the first half of June coming out with any better than an average CET. As I said last night I really don’t like troughing getting ‘anchored in’ so early in the season looks like the Baltic’s will be the place to be for sun and heat in early June. 

[MATTWOLVES 3]

The only positive thing about the 1st chart is.... Its a long way off!!! And the only negative thing about the 2nd chart is.... Its a long way off I'm so frustrated I'm laughing, no matter what the time of year... Wether it's Winter or Summer.... Good old GFS always sends us the goods beyond a fortnight!!! Almost like it feels sorry for us.... Hopefully a better run next time. 

[Summer Sun]

55 minutes ago, Mattwolves said:

I've got to be honest, I had to look this word up... I thought he was referring to an eating disorder when I first clocked it.. What a couple of days we have had, just the other day things were looking very rosey for a longer spell of settled Conditions, now we literally have low pressure anchored over us by Sunday.... In the words of the Queen.... One is not amused.. 

I just hope that this from the 6z gets watered down nearer the time, very unsettled conditions to the North of the country... Amazing to see how high pressure is bringing most of Europe fine summary conditions. 

Until that high does one from Greenland and the jet stream can shift north we're going to find it virtually impossible to get any long-lasting warmth/settled weather

[Frosty.]

Looking at the GEFS 6z mean as with other models there is a cooler showery trough for most of next week but beyond that there's a strong recovery to more summery conditions!

[Guest]

1 minute ago, Frosty. said:

Looking at the GEFS 6z mean as with other models there is a cooler showery trough for most of next week but beyond that there's a strong recovery to more summery conditions!

But that recovery is based on the demise of the Greenland heights and central Atlantic block, that’s what was modelled to happen beyond this coming weekend last week but the Greeny high and Atlantic P.I.C are proving just as difficult to eradicate as a Middle Eastern terror cell. 

[Frosty.]

2 minutes ago, Alderc said:

But that recovery is based on the demise of the Greenland heights and central Atlantic block, that’s what was modelled to happen beyond this coming weekend last week but the Greeny high and Atlantic P.I.C are proving just as difficult to eradicate as a Middle Eastern terror cell. 

Whatever the recovery is based on, there's a recovery!!..it's not all doom and gloom as the usual suspects describe!

[Tamara]

1 hour ago, knocker said:

Surely that constitutes a model 'hug' and im any case I'm not sure I would agree with your 'void' to the east

 

On the first comment, you didn't  unfortunately include the relevant part of the post that showed it was a comparison between a model ensemble suite and a diagnostic (GWO plot) as a way of trying to helpfully and objectively assist readers in matching up where the pattern might evolve vs the movement of that diagnostic.

The post yesterday fully explained the context of the "void" but the impression I get is that you knew this when you nevertheless felt compelled to want  to create an illusion of error.

More generally, in view of the continuing snap reactions to individual NWP operational outputs which maybe not unexpectedly and somewhat predictably have persisted since observation was made of them - it might be worth looking at how the extended ensemble clusters incorporated within on the EC ensembles and follow on immediately after that 0z mean chart are picking up on the possible GWO vs NWP evolution to reduce the influence of the trough, which is being extrapolated forward with inevitability by some, and return some influence of higher pressure building from the east and north east

Clusters of that EC 0z ensemble suite reflects the steady trend of atmospheric angular momentum tendency, todays update now posted, staying very buoyed in association with that development

As stated in the previous post, this is worth watching to see if it gains traction for the reasons given - but notwithstanding the cases for and against improvement probabilities provided in attempts of neutral objectivity - it at least provides some scope to stop writing off weeks of early summer before it gets here officially.

It goes without saying that of course people can comment on all kinds of aspects of NWP - but surely its better backed up with more than just deliberately pessimistic hunches that have no foundation up to weeks ahead and seem purely designed to create reaction. This issue pervades this thread most often in winter, but clearly is present at this time of year as well and rather seeks to discredit any attempt at taking out time to try to be objective and helpful as various posters who are enthusiastic about their spare time here try to do.

No-one is attempting, or believes themselves to have wisdom or is some kind of elite over anyone - such an attitude would be anathema. There are all kinds of ways to contribute. But ways which are respectful and manage to drop the need to be either sarcastic, discrediting and/or are reaction seeking.

[MATTWOLVES 3]

13 minutes ago, Frosty. said:

Whatever the recovery is based on, there's a recovery!!..it's not all doom and gloom as the usual suspects describe!

To be honest Karl the ensembles you mention regarding a recovery pretty much tie in with exters thoughts... Although no clear signals are emerging from NWP moving forward, I'm surprised some are so quick to stamp a seal of its done and dusted negativety all over it. Like you say there are some signs of an improvement going forward,but when signals are said to be weak by the big boys and girls, it's foolhardy to make its in the bag predictions beyond a week! Cheers mate

[Guest]

The heavy rain event shown in the GFS 06z in the south east around the 8th June is remarkably similar to events that unfolded in the middle of June 2007 that lead to major flooding, let’s hope it disappears quickly.