Model Output Discussions 12z 03/05/2016

[William of Walworth]

In reponse to MWB's post in particular (foot of previous page) :

Excited as some get about full-on Spanish plumes they do tend to have a tendency to be shortlived and unstable. More moderately warm and SW sourced (and less hot) HP incursions are my preference.

(Especially with our full week's holiday (Shropshire) lined up for the week starting Mon 8th August!)

Thanks to Frosty for highlighting at least the possibility of more HP-build of that kind, shown on SOME recent runs for the first full w/e of August onwards.

But as ever, this summerlover has to be very cautious about FI, and I continue to fear  the downgrade ...

Edited July 27, 2016 by William of Walworth

[knocker]

Some support tonight from the EPS for HP ridging from the south west into the UK as the upper trough becomes positively tilted over the westerly part of the Atlantic for a brief time. Perhaps lasting from around 5th to the 9th when heights start building again in the western Atlantic ( a scenario also favoured by the GEFS) and thus the trough once again becoming influential vis the UK. The temps during this HP interlude only a little above average in the south and remaining below in Scotland.

[MP-R]

Another GFS run showing more settled than unsettled. I hope charts like these continue to show and verify for the 10th-14th period - very important for the Bristol Balloon Fiesta. It's done well over the last few Augusts. Only ex-Hurricane Bertha in August 2014 brought a wet day for it, and thunderstorms early on 12th August 2012. Much more akin to August:

 

[Frosty.]

Tonight's Ecm 12z ensemble mean shows encouraging signs by day 9 and especially 10 with support for the Azores high ridging across the south of the uk. Let's hope the models continue to firm up on a decent spell of fine and warm weather between early and mid August. 

[knocker]

Today

A shallow low will traverse the north of England accompanied by a band of rain moving east. Driest area will be central and north Scotland.

The GFS this morning. The low mentioned above will track NE leaving the UK in a slack showery NW regime until Monday. Then some brief ridging until a rather complicated low pressure system arrives from the west Tues/Weds with accompanied fronts bringing wet weather to most. This also travels into southern Scandinavia leaving the UK again in a brief NW, replaced by an even briefer ridge, before the next perturbation arrives 00z Saturday with some more rain. Temps distinctly cool at the beginning but rising to around average by the end.

[knocker]

The GEFS anomaly this morning not looking too clever for sustained HP encroachment in the middle period. Still room of course for day to day variations in the phasing as previously mentioned with the south being the beneficiary. It's still pushing positive height rises in the western Atlantic as we move on which is not great news.

[Frosty.]

10 hours ago, William of Walworth said:

Thanks to Frosty for highlighting at least the possibility of more HP-build of that kind, shown on SOME recent runs for the first full w/e of August onwards.

 

Cheers William, at least we should have some occasional warm and settled interludes to look forward to and I remain hopeful something more substantial could pop up.

[knocker]

The ecm det. not dissimilar to the GFS

[Man With Beard]

1 hour ago, knocker said:

The GEFS anomaly this morning not looking too clever for sustained HP encroachment in the middle period. Still room of course for day to day variations in the phasing as previously mentioned with the south being the beneficiary. It's still pushing positive height rises in the western Atlantic as we move on which is not great news.

Unfortunately I have to agree - height rises for D8 onwards are now tending to occur either in the wrong place or in the same places we've already seen this summer. Few optimum ensembles this morning for a UK High. Still time for a shift back though.

[knocker]

3 minutes ago, Man With Beard said:

Unfortunately I have to agree - height rises for D8 onwards are now tending to occur either in the wrong place or in the same places we've already seen this summer. Few optimum ensembles this morning for a UK High. Still time for a shift back though.

Indeed there is and one lives in hope but the EPS was never on board with the GEFS so await what it produces later. I have to say I'm not filled with optimism and we may have to settle for brief incursions of the Azores which will only really benefit the south.

[coldcomfort]

24 minutes ago, Man With Beard said:

Unfortunately I have to agree - height rises for D8 onwards are now tending to occur either in the wrong place or in the same places we've already seen this summer. Few optimum ensembles this morning for a UK High. Still time for a shift back though.

Ditto.....I've spent the last 20 mins searching the overnight outputs for some, even one straw to clutch, but unless I'm missing something they/it eluded me. Really can't go hanging my coat on a few optimistic ensemble members against the kind of background pattern still being touted right across the model suite...polishing a turd is not going to stop it being a turd!

Edited July 28, 2016 by coldcomfort

[Frosty.]

14 hours ago, Karl. said:

Agreed Tamara, lovely post again 

I think it's clear that this summer isn't going to become wonderful, e.g.. not expecting an August like 1995 but your last sentence sums it up in a nutshell really.

Tamara hit the nail on the head last night, best make the most of settled interludes which will come along from time to time and one such interlude is still on track for early August according to the GEFS 00z mean.

[mb018538]

Pretty cack output today, looks like we might go a whole summer without a decent high pressure cell parked over us....high and low pressure in the opposite places to where we want them. Of course they are bound to flip back to normal, and the Azores high/Iceland low/Greenland low combo will no doubt make winter mild again like last year.

[Man With Beard]

4 hours ago, knocker said:

Indeed there is and one lives in hope but the EPS was never on board with the GEFS so await what it produces later. I have to say I'm not filled with optimism and we may have to settle for brief incursions of the Azores which will only really benefit the south.

I'd say the ECM mean at T240 is a little more encouraging at getting at least a short period of summery weather to many for the wkend 6/7 August with the upper high slightly more dominant than the trough. I've started to analyse the ECM T240 mean archives and so far, in a very small sample it must be said, I've been impressed, as it was only a little less accurate than the ECM T144  op run. I hope to publish more results sometime in August

Edited July 28, 2016 by Man With Beard

[Frosty.]

18 minutes ago, Man With Beard said:

I'd say the ECM mean at T240 is a little more encouraging at getting at least a short period of summery weather to many for the wkend 6/7 August with the upper high slightly more dominant than the trough. I've started to analyse the ECM T240 mean archives and so far, in a very small sample it must be said, I've been impressed, as it was only a little less accurate than the ECM T144  op run. I hope to publish more results sometime in August

I agree Man With Beard, the Ecm 00z ens mean does look encouraging in the timeframe you mentioned, at least for the south of the uk, it's similar to the 12z last night.

[knocker]

34 minutes ago, Man With Beard said:

I'd say the ECM mean at T240 is a little more encouraging at getting at least a short period of summery weather to many for the wkend 6/7 August with the upper high slightly more dominant than the trough. I've started to analyse the ECM T240 mean archives and so far, in a very small sample it must be said, I've been impressed, as it was only a little less accurate than the ECM T144  op run. I hope to publish more results sometime in August

I've already looked at this MWB and T240 is about as good as it gets. In the EPS ext period we find height rises in the western Atlantic so more influence from the trough and temps average in the south and generally a little below. Not hugely different to what I posted yesterday evening with possible the HP hanging around for three days or so in the south. This is still subject to future changes of course but the signs are not good.

Edited July 28, 2016 by knocker

[Frosty.]

1 hour ago, Man With Beard said:

I'd say the ECM mean at T240 is a little more encouraging at getting at least a short period of summery weather to many for the wkend 6/7 August

The Gfs 6z op run shows very short periods of fine summery weather, especially across the s / se but overall it's an unsettled run with very variable, often average or cool temperatures, even the very warm, humid days trigger heavy rain and storms but this is a run where no two consecutive days are the same, it's constant chopping and changing with everything thrown in the summer mix, apart from the kitchen sink.

[Frosty.]

With my optimistic hat on I've taken a snapshot at T+240 hours on the GEFS 06z mean which shows a decent incursion of the Azores high / ridge...now, flicking through the 6z perturbations shows a relatively small number of unsettled outcomes but a larger number of anticyclonic scenarios, I haven't shown all of them, some of those show highs building in or ridging but this gives you a flavour, a few of them are juicy with a strong anticyclone centred over the uk at day 10 with the odd hot one.. No guarantees of course but at least we should have further settled interludes as Tamara said last night.

Edited July 28, 2016 by Karl.

[mb018538]

Seems to be a few vigorous low pressure being spun up in the last few runs - the jet has woken up big time!

I don't buy those GFS ensemble members showing an anticyclone over the UK....it's just akin to 2 or 3 in winter showing the -5/-10 isotherm over the UK, and come the time it's nowhere to be seen. I think generally unsettled with 1 or 2 days of temps up to 25c in the SE is about the best we can hope for.

[mb018538]

How about this for a horror chart - pass the sick bucket!


 

[Frosty.]

1 minute ago, mb018538 said:

I don't buy those GFS ensemble members showing an anticyclone over the UK....

Fair enough but the Gefs 6z mean shows Azores ridging into the UK at T+240 as does the Ecm 00z ens mean..so I wouldn't rule out an anticyclone in control at day 10, there are more settled than unsettled ensembles in that period which is why I'm looking at it with interest.

[coldcomfort]

Just now, mb018538 said:

Seems to be a few vigorous low pressure being spun up in the last few runs - the jet has woken up big time!

I don't buy those GFS ensemble members showing an anticyclone over the UK....it's just akin to 2 or 3 in winter showing the -5/-10 isotherm over the UK, and come the time it's nowhere to be seen. I think generally unsettled with 1 or 2 days of temps up to 25c in the SE is about the best we can hope for.

Not sure you will be far wrong with this assessment and the winter cold chasing analogy is a good one. Obviously we should all see a few decent days across the next 10-14 and there's no question that things could be (and may get) a whole lot worse, but looking at the overall pattern going forward and then adding in the MO's latest 16-30 day output there's still nothing to suggest the kind of August most of us crave.  

[Man With Beard]

2 hours ago, knocker said:

I've already looked at this MWB and T240 is about as good as it gets. In the EPS ext period we find height rises in the western Atlantic so more influence from the trough and temps average in the south and generally a little below. Not hugely different to what I posted yesterday evening with possible the HP hanging around for three days or so in the south. This is still subject to future changes of course but the signs are not good.

OK Knocks will take your word for it ... I've lost my link to the extended ECM ensembles for the Iceland area (showing a bit of the UK) - anyone got it to hand

[Dangerous55019]

Looking at the Saturday 6th of August chart in particular as I have a barbecue that evening. 
Its worth remembering that by then a big chunk of the UK will have left the world of the lingering twilight, so with the jet steam stepping up a gear at about the same time, could this be one of the first autumnal storms of the season is this chart comes off?? 

[mb018538]

UKMO this evening continues the NW/SE split up to 144 hours, with low pressure the dominant feature, heading straight for the UK at about 168 hours....heat to be found down south across Iberia, and sent up to the east of Europe once more.