Model Output Discussions 12z 01/06/2017

[Frosty.]

I think it's fair to say the ukmo 12z doesn't look as good as yesterday regarding early next week. As for today, very autumnal miserable 11c with heavy persistent rain across the north..I want my summer back!!

Edited June 28, 2017 by Frosty.

[Singularity]

It seems pretty clear now that the splitting jet idea was most likely a red herring, though it's not entirely a dead option yet (occasionally they spring back but it is rare once inside the 5-day range).

So we are indeed left with the underlying theme of a bit more ridging from the Azores into Europe which serves to improve our prospects but not entirely prevent those Atlantic systems from having a bit of influence.

  

GFS (left) seems a bit aggressive with next week's first low plus the strength of the jet stream in the mid-Atlantic, which leads to all sorts of trouble over the following few days.

UKMO (right) offers a more reasonable way forward, with the spell of rain Monday night or early Tuesday affecting northern parts most with not a lot down south (GFS does at least show agreement on this aspect), clearing soon enough to allow a pleasant day or afternoon for most except perhaps in Scotland. The timing could well change of course, for better or worse (more likely worse if it does change, as it's pretty good where it stands).

Faced with these two runs alone, I'd be thinking okay, we've seen the GLAAM-correction introduce more ridge influence for the first half of the week and are still waiting for it's full effect to become evident in the charts for the second half. BUT there is that shocking ECM 00z run lurking in the darker corners of my mind. It found a way to stall-out next week's first trough in a way that effectively held the door open for the Atlantic troughs to march in regardless of what the Azores High would rather get up to... and the GFS 12z has followed a similar train of thought but with a flatter overall pattern. 

 

Now, credit where it's due, GFS does show the Azores High fighting back a bit as it very well should, but the stalling low has done enough to keep things changeable across the UK.

So it is that I have been given the impression that next week may well be very forgettable overall as far as the weather is concerned. 

Unless, that is, the split jet either returns for early-mid next week (low probability) or turns out to be the behaviour exhibited by the next trough in line (higher probability; little support for that at this time, but then there was little for the early-mid week low to be so weak while crossing the mid-Atlantic when it was at over 5 days range).

Unless a tropical event upsets the GLAAM trend next week, the overall (I must stress overall; smooth rides are rare in the UK) improving trend should continue into the week after, so there's some hope to be had even then .

[knocker]

The changes in 12 hours with the gfs are not good and do not fill one with confidence. Basically it's to do with handling the upper low that spawns from the main trough over NE America and at 00z tracked east to the south west of the UK now doesn't as can be seen by comparing the charts for 00z Tuesday. Thus we now have a surface over the Hebrides and a showery NW airstream over the UK at 12z Wednesday.

Edited June 28, 2017 by knocker

[Gael_Force]

10 minutes ago, Singularity said:

Unless a tropical event upsets the GLAAM trend next week, the overall (I must stress overall; smooth rides are rare in the UK) improving trend should continue into the week after, so there's some hope to be had even then .

Where are you seeing an improving trend for week after? The two week trend seems to be downwards but maybe I'm reading this wrong as I have the link but not the skill to determine what it means other than it says Nina atmosphere.

 

Edited June 28, 2017 by Gael_Force

[mb018538]

Pretty disappointing after on offer on the 12z, yesterday's improvements long gone to be replaced by more generally unsettled junk. Summer very much on hold.

[Frosty.]

4 minutes ago, mb018538 said:

Pretty disappointing after on offer on the 12z, yesterday's improvements long gone to be replaced by more generally unsettled junk. Summer very much on hold.

Nobody should be surprised, the models look like the latest update from Exeter 're next week.

[Singularity]

54 minutes ago, Gael_Force said:

Where are you seeing an improving trend for week after? The two week trend seems to be downwards but maybe I'm reading this wrong as I have the link but not the skill to determine what it means other than it says Nina atmosphere.

 

You're reading it right, but what I'm doing is adjusting for the usual bias which has continued to be evident even with the tropical Pacific featuring a localised Nina-like signal .

Looking at the mean and spread you can see the point at which a slight upward trend (which has already been a little underestimated in recent days) is countered by the bias and then overcome, with a marked step-up in the strength of the bias upon progressing into lower-res (past +192 when it comes to GEFS).

It is inevitably an act of presumption on the part of those who apply this method which can fall foul of smaller-timescale events such as tropical cyclones and equatorial Kelvin waves. So we continue to be without a 'crystal ball' for weather prediction (obvious to anyone following any weather forum for any length of time), but something is better than nothing .

Truth be told though, there is more 'La Nina-ness' going on than was expected to feature this summer when looking ahead as of mid-late May, so we're looking at a less fortuitous run of events than what once looked likely to be the case, and I still can't see enough reason to anticipate anything particularly noteworthy this side of at least mid-July - but this is of course subject to change.

[Frosty.]

I honestly believe we will see more hot weather this summer but not until the second half of July, not before but that doesn't mean there won't be some fine warm days here and there before mid July because I'm sure there will be, especially further south-east but it looks generally changeable / unsettled mainly from the atlantic for the next couple of weeks at least..based on the current models.

Edited June 28, 2017 by Frosty.

[mb018538]

ECM is dreadful too....think we'd better batten down the hatches again, the small window we had yesterday looks to be shut, and we're back where we started! 

[Frosty.]

5 minutes ago, mb018538 said:

ECM is dreadful too....think we'd better batten down the hatches again, the small window we had yesterday looks to be shut, and we're back where we started! 

Can't you just post some charts instead of saying its dreadful? some might like it!

[mb018538]

Sure!

Here's the ecm 168 chart...lovely stuff!

[Frosty.]

2 minutes ago, mb018538 said:

Sure!

Here's the ecm 168 chart...lovely stuff!

mmm nice, low pressure and the azores high..in the azores..thank you!

[A Frayed Knot]

Don't look that dreadful to me ' could be worse

[Frosty.]

25 minutes ago, A Frayed Knot said:

Don't look that dreadful to me ' could be worse

Could be better..

[Fourty Point Three Degrees]

1 hour ago, mb018538 said:

Sure!

Here's the ecm 168 chart...lovely stuff!

Remember about the same length of time before the end of May and ecm was showing worse.

[knocker]

As expected no significant changes with the ecm anomaly this evening with the low and trough Canada/Greenland still dictating affairs. Thus still the westerly uper flow with systems tending to track NE as the Azores ebbs and flows

cannot post the 11-15 but earlier Dan Leonard posted the 00z version which is not hugely different. Hopefully some of this ridging will begin soon be in out vicinity.

"Interesting early July pattern per the EPS: Ring of ridging thru all mid latitudes; hot US, Europe and Asia"

.

[Frosty.]

In a nutshell, tonight's Ecm 12z ensemble mean doesn't look too bad for the south with some fine rather warm spells due to occasional ridging from the azores, changeable yes but generally the worst of the unsettled / atlantic weather for n / nw uk but not all bad there either.

Edited June 28, 2017 by Frosty.

[knocker]

Another very wet day for the north and Scotland, and currently these parts, before the upper low sinks south east and the Azores ridges north east. Briefly some drier weather but it does herald the transition to the new regime and the start of the UK being at the mercy of the interaction of the trough(s) and the high pressure to the NW/N and SW/S or in other words the cooler/warmer airmasses. Not to waffle anymore about this but just taking two charts down the line that illustrate this very well. They are not to be taken as this is what is going to happen. As it happens in this case to cooler air has the upper hand.

As mentioned above the Azores ridges NE as the low moves away but the next low from the west skirts n Scotland and it's associated fronts traverse the country over the weekend south east bringing some light precipitation.

From here the next brief skirmish with the HP but by 12z Tuesday the next shallow low has arrived and is centred over Ailsa Craig with it's associated fronts crossing the UK so another cloudy and wet day for many.with temps around average. This low tracks into the North Sea and points east but is quickly replaced by another shallow low arriving in a similar position by 12z Thursday.

And so on and so on but by 12z Saturday a deeper low has arrived just north of Scotland thus the UK in a NW flow with possible gales in Scotland. Just another example of the N/S bias in these set ups. So continuing unsettled next week with periods of rain, more particularly in the north with temps around the average. The detail as we get later in next week is of course subject to revision as slight inter run variations in these fluid patterns tend to get quite quickly magnified.

Oooh

 

Edited June 29, 2017 by knocker

[knocker]

Needless to say the ecm is taking a different route than the gfs vis next weeks evolution. It once more has the upper trough spawned from the main trough over the NE seaboard on Saturday tracking east as a cut off low, and not phasing with the main trough, so that by T132 it is ENE of Coruna. This allows the ridge/weak high cell to hang around over the UK at the beginning of next week but we are also back to the scenario a complex area of low pressure forming in western Europe (including the UK), as the Atlantic and Iberian troughs merge and thus some very inclement weather on Thursday with perhaps thundery outbreaks. Then showery as the wind veers northerly as the low tracks east by Saturday.

I wouldn't bet the farm on the evolution next week the detail of which is a long way from being nailed down.

Edited June 29, 2017 by knocker

[mb018538]

UKMO ran out of isobars for the UK next week
:



Looking better towards the SE, with most of the rainfall and unsettled weather concentrated towards the NW. The Jetstream is running along a more normal track next week rather than the huge dip we've just been through....net result is average weather. No signs of any heat or settled weather at this time.

[summer blizzard]

The Euro this morning is bar early next week quite unsettled with persistent low pressure easily moving east of the UK. 

The GFS this morning has a weaker Atlantic and is thus better for the south of the UK as we lose a lot of the unsettled weather but the persistent theme illustrated at days 0-5-10-15 is that the Azores High wants nothing really do with us. It just sits a tad west of the Azores and stays there, changing orientation a little. 

[Singularity]

Hmm so now there's a sort-of-cut-off low type scenario being put forward by ECM and what may be a fully fledged one by UKMO.

Having begun by checking up on GFS this morning, it was a relief to see that it's very mobile solution was not well supported, but ECM does go on to produce an outcome disturbingly similar to what's taken place over the past two days which is highly undesirable. UKMO would probably go a similar way but take 12-24 hours longer to do so.

Arguably ECM/UKMO offer more hope than GFS in that the deterioration of conditions is further out in time with more chance of it being modified toward something less troublesome. I can still see some scope for a Scandi High to develop in the 6-10 day range which could bring about a warmer solution with showery weather focused toward the S/SW (or ideally out to sea.... I dare to dream), but this is pure speculation on my part.

[Man With Beard]

A little reality check ... that Scandi High I was looking for a couple of days ago isn't really materialising. Back to the drawing board!

D8 and D15 mean charts from the GFS - the Azores High looks stuck far to the SW - unlikely to get hot weather while such a situation persists - the only possibility would be if a cut-off low gets caught in the flow near Biscay (a little like on the UKMO T144) allowing a small window for air to travel S to N on its east flank. Realistically, more coolish showery weather for the first half of July seems a better bet right now.

  

[knocker]

And there is nothing about this morning's anomalies that fill one with optimism

[mushymanrob]

On 28/06/2017 at 11:51, mushymanrob said:

........... and here it is, overnight a ridge appears thus supporting the models suggesting a lengthier (but not long) settled spell next week instead of the transient ridge.  ok, its not overly strong, but the 8-14 day chart failed to spot it as it did last time. this is what i have been expecting, as it fits in with the longwave pattern . interestingly the anoms are steadfast in their height rises over scandinavia, something the ops havnt yet properly agreed with, but will, and overall theres good grounds for optimism. imho the outlook is looking promising for at least some pleasant summers weather, and something hot is, id suggest, likely.

ok, its all gone t up... i broke the cardinal rule (successive runs in agreement) and let my hopes and expectations get in the way. i was hoping the next chart would conform or even grow that weak height anomaly. it didnt. oh well..