Model Output Discussion 12z 23/05/13

[AWD]

But we can also suggest that the risk of this being eroded from the south is there, That isn't being prophetic.. but it is attempting to look at how the pattern might evolve.

Might be worth putting some (on-topic) model related links on here to constructively demonstrate that.....

Its some way out, but this signal has remained consistent for some time, and although the NAEFS ensembles are not infallible like other data, they do often tend to provide consistent signals for the further outlook that provide useful reflections of background factors. This underpins the analysis that has been given by some already today and also reflects the latest METO update which has mentioned this N/S split signal previously and is returning to it once again at this time.

So therefore it is realistic to question how long a more settled period might last, and maybe all the more reason to make the most of it while it does so.

Indeed. The 0z London EC ens show rainfall scenario's increasing after the first week of June, with the Op one of the more drier options in it's final frames;

Temperatures favoured to remain around average too, which of course at this time of year is still nice and warm and BBQ friendly;

Little sign of any true heat (ie high 20's) building. This also backed up by the Birmingham ens, with average temps the most likely course during the next couple of weeks;

And again, the threat of some rainfall from the end of next week onwards;

A look at the final EC ens frames;

There doesn't look to be any major threat of a deep trough coming down over the UK if and when the forthcoming settled spell ends, Greenland and environs look to be hogging that for now. What does look probable is a slow relaxation in SLP during the second half of next week, allowing showers to break out. Obviously at this timescale it is impossible to be any more specific than that, but I would say the south is currently more favoured than the north for this scenario.

CFS V2 model also showing a trend to lower pressure mid month;

The current 500mb anomaly charts show a clear positive anomaly to the north/north east of the UK;

Along with the NAEFS anomaly charts Tamara posted above all suggest the core of heights to progress to the north of the UK during next week and more especially next weekend, allowing a relaxation of pressure to the south of the UK where showers could start to break out. This also evident in the latest Met Office forecast with their suggestive north/south split with the north always closest to the pressure cell.

So what would I plump for over the next fortnight or so.

- A settled spell of weather with variable cloud amounts and some good sunny spells (this of course will be dependant on a regional basis). Temperatures around average (broadly speaking). This scenario likely until at least mid week.

- Midweek and into next weekend we may see a relaxation of pressure to the south of the UK as the core of heights moves to the north of the UK. This may allow showers to break out over the south.

- Into the following week and to be honest, I'm not too sure yet but I would again favour a showery regime, these more favoured in the south with perhaps some more persistent rain at times to. More settled for the north still. Possible that convective fans may have some interest into week 2, which would be good. Temperatures broadly average.

Edited May 30, 2013 by AWD

[Summer Sun]

Taking a look at the Birmingham ensemble we see temperatures hitting average from early next week onwards to mid June

 

 

Rainfall remains low through-out with the only slight peak around June 8th

 

[phil nw.]

As we are now on the doorstep of the Summer 3 months it's Interesting to note the switch in the overall NH setup from the -ve NAO/AO pattern that persisted through March and well into April with those Polar +ve height anomalies ensuring plenty of Arctic air flowing into mid-latitudes.The image on the right is forecasted T48hrs.

 

 

 

If we click onto this animation of the 500hPa pattern we can see through May how things have evolved-the Greenland heights right at the beginning of the month quickly collapsing as the final effects of the late Winter Stratospheric warming ended with Polar upper air temperatures falling off again.

 

 

This upper cold pooling has been very persistent and we have seen long periods when the UK and W.Europe have been targeted by the cold upper troughs ensuring lower than normal temperatures both on land and in the surrounding seas

The reversal of those height anomalies  should ensure this Summer starts with a more typical UK outlook than we have seen in many recent years with more energy going north of the UK and increasing chances of warmer air moving into our latitudes.

Edited May 30, 2013 by phil nw.

[Barry12]

24 hours in and high pressure builds into the whole of the UK, bringing the first day of the settled and warmer spell under way. 42 hours in and only north of the UK isn't under the high pressures control, cooler than Friday but still feeling pleasant in the sunshine. 72 hours in and it's another fine and settled day as a ridge moves in. 96 hours in and it's another fine and increasingly warm day with 70F being reached. 120 hours in and it's another warm and mostly settled day as winds turn more North Easterly. 144 hours in (sorry it's late - I was eating, that's if anyone cares) and it turns increasingly humid as the air comes from the East, warm for all apart from eastern coasts. 168 hours in and it's warm for all, but with some showers breaking out, especially to the North of the UK. 192 hours in and it's much the same, warm with some showers breaking out.

 

Edited May 30, 2013 by Barry95

[Summer Sun]

UKMO is fine and settled for the weekend

 

 

The new working week see's the high firmly in place with lows getting forced up to Iceland and Greenland

 

 

Edited May 30, 2013 by Gavin.

[Summer Sun]

A warm easterly is knocking on the door this afternoon

 

 

UKMO heading towards an easterly as well

 

 

Edited May 30, 2013 by Gavin.

[Milhouse]

Warmer air edging our way on the GFS 12z next week

 

Not a million miles away from this from June 1970. 29.1c at RAF Lakenheath.

 

[Summer Sun]

A warmer GFS this afternoon thanks to an easterly not often we say that!!

 

Welcome the heat from the east

 

Edited May 30, 2013 by Gavin.

[Weather Boy]

For that we would need winds to come from a more easterly direction to enable some heat to be drawn towards the UK. Not out of the question given that upper temperatures are set to rise over Europe soon.

 

 

Well, that is consistent with the anomaly chart that Tamara posted.  It seems that the most likely eventual breakdown at this point (with apologies for talking about a breakdown before the fine spell has even started) would be from the south or south-east.  If that happened, that would tend to suggest a continental encroaching of low pressure in the south, rather than a more common Atlantic based attack. 

 

For many of us, this would be preferred as rather than returning to trough based conditions, it would suggest an increasing risk of thunder and humid conditions, and a potential for a rebuild either from the Azores again, or the HP sinking back south - although of course it could go the other way and take control of the whole country, but the potential is there for it to be an unsettled blip rather than an Atlantic rain fest.

 

But, let's enjoy the settled spell once it starts, rather than speculate too much about its eventual downfall.  It doesn't look as if it's going to be too short lived at this point, and I for one are looking forward to it regardless of no temperature records look likely to be broken at this point!

[Frosty.]

This evening's ukmo 12z is a peach again with high pressure intensifying across the uk early next week and only slowly drifting northeastwards, inland areas would be dry and sunny and becoming warm and locally very warm but eastern coasts would have onshore breezes which would keep it cooler with a risk of some sea mist rolling in during the overnight periods which would then burn back to the coast or offshore during the afternoons, no sign of pesky troughs to spoil the party.

Edited May 30, 2013 by Frosty039

[AWD]

A warmer GFS this afternoon thanks to an easterly not often we say that!!

Welcome the heat from the east

Also note the trend of a relaxation in SLP over the south of the UK in association with the small trough to the SW.

This could help develop some decent instability and generate some heafty showers and perhaps some thunderstorms. All speculative though at the stage of course.

[Summer Sun]

An absolute peach of a run from GFS tonight with some very warm maybe even hot air getting dragged into the SE

 

 

With a low tracking up from France there is the potential there for some torrential thunderstorms given the heat across the south

 

 

 

Of course at this it goes belly up further in FI

 

Edited May 30, 2013 by Gavin.

[AWD]

Yup. The 12z GFS shows something for both the sun lover and the convective lover with time;

It won't end up like that but it goes to show the potential for convective weather as the high pushes north and pressure lowers slightly to the south. Mix a bit of humidity in and we could be in business for all.

[Buzzit]

With greatest respect to the GFS 12z OP run in my opinion I would absolutely discount anything showing past +144 due to the significant presuure changes shown post this time.

Edited May 30, 2013 by Buzzit

[049balt]

A breakdown from the south?

 

http://wxmaps.org/pix/prec4.html

[Milhouse]

GEFS mean supporting a very warm easterly

 

 

[Barry12]

With greatest respect to the GFS 12z OP run in my opinion I would absolutely discount anything showing past +144 due to the significant presuure changes shown post this time.

 

I find it hard to take the GFS seriously, it's useless in my opinion.

[Barry12]

24 hours in and the high pressure builds into the whole of the UK. 48 hours in and only north of the UK is not under high pressure, but this is just temporary. 72 hours in and it turns increasingly warm as the ridge moves in, dry for most. 96 hours in and its a beauty, dry and warm for all. 120 hours is again very nice, pleasantly warm and dry for most. 144 hours in and it's again relatively warm, dry for most but some showers possible for the far south of the UK.

 

Edited May 30, 2013 by Barry95

[Panayiotis]

GFS ensembles for my area show the settled spell developing up to the 2nd June, then peaks in rainfall start developing during the latter part of the days and with a steady increase in 850hPa temps suggests convectional showers after the 3rd to the 9th:

http://modeles.meteociel.fr/modeles/gens/graphe_ens3.php?x=202&ext=1&y=140&run=12&runpara=0

Edited May 30, 2013 by Panayiotis

[Purga]

Looks like pretty average temperatures coming up although below average over the near continent so any easterly flow will be quite warm and mostly dry at first but not hot by any means

There are bound to be some areas experiencing warm dry conditions as can be expected at this time of the year. Temps  peaking at around 20C average and maybe a few spots scraping near to 25C whilst nightimes comfortably down below 10C without any unpleasant humid conditions.

 

The threat of the unsettled drift from the south showing up in FI but plenty of dry warmish stuff in the meantime

Edited May 30, 2013 by Purga

[AWD]

GFS ensembles for my area show the settled spell developing up to the 2nd June, then peaks in rainfall start developing during the latter part of the days and with a steady increase in 850hPa temps suggests convectional showers after the 3rd to the 9th:

http://modeles.meteociel.fr/modeles/gens/graphe_ens3.php?x=202&ext=1&y=140&run=12&runpara=0

Indeed, this also evident on the pressure suite;

After a dry and settled start to next week, something more conducive to warm sunshine and scattered heavy showers/storms looking favourable, with SLP relaxing to average values of 1015mb - 1020mb across the south.

GFS Op FI looks to have developed any troughing too much, with something much shallower and average favoured amongst it's ensembles too.

Edited May 30, 2013 by AWD

[Summer Sun]

Another settled run from ECM once more to t120

 

 

[Panayiotis]

Indeed, this also evident on the pressure suite;

image.jpg

Hi AWD, if you dont mind me asking, where can I view these pressure ensembles?

Thanks

Edited May 30, 2013 by Panayiotis

[AWD]

Hi AWD, if you dont mind me asking, where can I view these pressure ensembles?

Thanks

http://www.meteociel.fr/modeles/gefs.php

[Summer Sun]

Hi AWD, if you dont mind me asking, where can I view these pressure ensembles?

Thanks

 

http://www.meteociel.fr/cartes_obs/gens_display.php?x=306&y=141&run=12&ville=Londres&runpara=0&type=1&ext=1

 

And this link for the uppers - http://www.meteociel.fr/cartes_obs/gens_display.php?x=306&y=141&run=12&ville=Londres&runpara=0&type=5&ext=1

 

Looking like ECM is going to take the easterly route as well tonight

 

 

UKMO and GFS to compare at t144

 

Edited May 30, 2013 by Gavin.