Model Output Discussion 18z 28/07/13

[Mark Neal.]

That will do, to begin with. High building into us as we go through next week, warm temperatures becoming hot again the general concenus. So high pressure to return! 

Into next weekend it looks good at moment aswell, boding well for another Bank Holiday delight? 

[Frosty.]

The Gfs 12z again shows a warm up next week, especially for the south of the uk and overall the run is dominated by high pressure but there are some complications with a spell of rain on tuesday and friday across the northern half of the BI which would keep those areas much cooler but the sunnier south hots up, this run looks out of sync with the overall trend towards a much warmer and settled outlook shown on the ecm ens mean and gefs 00z & 06z mean but at least it's mainly settled after the weekend apart from next tuesday and friday. 

[Tamara]

A lot of excellent comment has already been given today about the upcoming late summer spell of weather from next week, at least for the south to begin with, so there is little more to add to that at the moment, but one very minor observation about this weekend is that the models have very subtly adjusted the upper colder pool associated with the weekend low back further north again very slightly. The subtle difference I think this might make after the frontal rainfall has gone through all parts by Sunday morning is that shower distribution looks restricted mainly to northern parts and quite a few areas in the south of the UK will only see meaningful rain from tomorrows front and then Saturdays band of rain. It looks pretty much dry from Sunday onwards throughout next week - barring any unexpected showers

 

The other thing to comment on aside from the fine weather aspect is that the fly in the ointment shortwave has become more prominent today and the 12z ECM shows this clearly as a feature that will delay any fine weather to Northern Britain. It is conceivable that some Northern parts of England will also be influenced by this around midweek.

 

 

So as is often the case with developing fine spells in the UK, the evolution is not straightfoward and some further wet weather is looking more and more likely away from the south during next week

 

The end of the week however is still looking more favourable for the greater part of the UK to enjoy some fine and increasingly very warm weather as the replacement High pressure cell after the shortwave departs, migrates just to the east of the UK  pulling up those very warm uppers as others have discussed a lot today

 

 

Patience might be the keyword further north, but the payoff could be a Carnival style Bank Holiday weekend as temperatures soar

 

Edit : The ECM has other progressive ideas in FI this evening and sends a further shortwave in from the west to spoil the Bank Holiday...but this is some way off and obviously not worth taking too much notice of at this stage

Edited August 15, 2013 by Tamara Road

[ANYWEATHER]

Very strange how the ecm picks up the shortwave at t+120 and by t+144 has completely gone! Gfs also all over the place with this feature!

[Frosty.]

The Ecm 12z continues the theme of all the other output in building high pressure into the uk next week, the southeastern half of the uk does best for most of next week, the west and north has more of a struggle initially with troughs pushing up the western side of the uk and then across scotland but for a time later next week it looks settled everywhere, warming up daily next week, especially in the sunnier south & east with temperatures into the mid to high 20's celsius and becoming increasingly humid but then the ecm shows a trough breaking through which indicates a thundery breakdown by the end of next week followed by a slack pattern with sunny periods and thundery showers with temps in the low to mid 20's celsius, this op run is a surprise considering how stable and benign the ens mean charts are looking today.

[Man With Beard]

Very strange how the ecm picks up the shortwave at t+120 and by t+144 has completely gone! Gfs also all over the place with this feature!

 

I feel this scenario (small, deep lows spinning towards us) has happened a couple of times this summer already - but previous attempts got dropped by T72/T96. So it may come to nothing.

[J10]

Given that the wind direction is set to be from an eastetly direction towards next weekend, how can eastern areas be the sunniest?

[ANYWEATHER]

I feel this scenario (small, deep lows spinning towards us) has happened a couple of times this summer already - but previous attempts got dropped by T72/T96. So it may come to nothing.

The models are really struggling on this one, I think its a northern concern, perhaps we can delete this feature in the days ahead  

[Frosty.]

Meanwhile, after what I consider to be a couple of wobbly op runs from the gfs and ecm 12z respectively, the GEFS 12z mean continues to look very settled, warm and anticyclonic from early next week until the end of the run with mid 20's celsius maxima for the south and low 20's c for the north, it's a very settled, benign looking mean, as per the 6z and 00z and Ecm 00z ens mean.

[Frosty.]

Perturbation 6 (GEFS 12z) will do nicely...BANK 

[ANYWEATHER]

Perturbation 6 (GEFS 12z) will do nicely...BANK 

Why on earth do you keep posting charts that wont happen....Bank What...

[lorenzo]

Some encouraging charts for a fine end to August, coincides with going back to work so forgive the lack of excitement having spent time off with the current dross only to see these little gems on the horizon !

 

Shortwave sagas aside the ensembles, CPC analog work and GEFS reforecast also on board to support a decent HP Cell.

 

MJO and GWO are as stalled out as they could be, sitting right on the origins, GWO plots show an interesting Southern Hemisphere Winter season and limited signal for the Westerly Autumn take over of the Jet. A limited signal touched on by Nick and the LP tracking up the GIN corridor. Hints of things to come...

 

Best from GEFS calibrated reforecast, and also tonight the 12z 168 ECM Ensemble mean.

 

 

 

 

 

[Eskimo]

Why on earth do you keep posting charts that wont happen....Bank What...

How do you know that they won't happen? 

[johnholmes]

 

Would agree with much of what you say L although the NOAA chart for 8-14 days ahead has little sign of the actual 500mb ridge which the 6-10 shows. The 6-10 is similar to what the ECMWF-GFS have each shown, although not at the same time, over the past 2-3 days, as has, in anomaly form only the NAEFS.

I suspect that rather than the length of surface high, shown on varying synoptic outputs as being a minimum of 5 days possibly 8-10 days that we will lend up with 3-4 perhaps 5 days of surface high pressure dominated. The UK 6-15 day outlook is perhaps the closest forecast to the actual weather pattern we are going to get. This shows the start being in the south then slowly extending north before the Atlantic returns, how active is far from clear.

[Isolated Frost]

Haha, just looked at the output and it reminded me of typical winter fare, a high pressure cell trying to relocate to Scandinavia; but a sneaky shortwave pulls in the flow and makes it as complicated as a divorce with Max Branning.

Worst case scenario to me is an Azores ridge and a HP cell over us for 2-3 days, giving much of England and Wales sunshine, as well as much of Scotland and Ireland- the upper flow, especially north of 30N doesn't seem at all conductive to zonality up to late August at the least- a very erratic pattern with energy displaced throughout the arctic.

Probably another warm to very warm week in store, after this taste of autumn.

Edited August 15, 2013 by Isolated Frost

[Scorcher]

Why on earth do you keep posting charts that wont happen....Bank What...

 

Not exactly the kind of post you expect from a Regional Forum Host. I reckon if they were showing unsettled conditions you would be all over it!

 

The GFS 18Z run is just rolling out now- I wonder if it will back away from the slight changes that the 12Z run showed compared to earlier runs.

[Captain Shortwave]

Looks like the models are trolling us again. High risk of post traumatic model watching disorder coming up as the models throw shortwaves here there and everywhere which complicate what at first glance seems a simple push of heights north east into Scandinavia. One thing for sure the one which has appeared and disappeared looks like it exists as this chart shows

 

Note the dink in the flow off the eastern seaboard, that's the shortwave. The question is does it develop further or simply die out.

We simply don't know how much of an effect (good or bad) it will have. 

I don't know what to think of the ECM op - I think the model doesn't like the UK any more and wants to put low pressure in charge at any cost 

Edited August 15, 2013 by Captain shortwave

[Tamara]

The ECM individual members this evening give a snapshot at t132 (in between the 12z frames) of where the shortwave may be, to whatever extent it may exist..

 

It does show at least some agreement for the North of the UK to be affected by it, but I think the recent post(s) from our Scottish expert contingent has put some very good context onto that in terms of the general prognosis for the last third of the month. In essence, life goes on post shortwave

[Captain Shortwave]

Ok shortwave back to not existing when it gets close to the UK

It simply gets swallowed up as pressure builds northwards.

 

Superb chart, heat building

Edited August 15, 2013 by Captain shortwave

[MP-R]

GFS 18Z shortening the settled spell quite considerably with the final week of August being shown more unsettled than before. One run though so not to be worried about just yet. This run also shows some sort of heat building towards the end of next week with, I would think, the chance of some thunderstorms as pressure slowly falls from the southwest. A distinctly autumnal weekend to get through then possibly the best week of this month next week to save this August!

[Captain Shortwave]

Last post of the night, very tiring day of travelling

This mean chart

 

 

As Frosty often says

BANK!!!

no one mentioned a big upgrade in the ECM ensembles

 

 

I swear the 12C line wasn't that far north on previous runs, good stuff

Edited August 15, 2013 by Captain shortwave

[Bonjangle]

Not exactly the kind of post you expect from a Regional Forum Host. I reckon if they were showing unsettled conditions you would be all over it!

 

The GFS 18Z run is just rolling out now- I wonder if it will back away from the slight changes that the 12Z run showed compared to earlier runs.

Well said and enough said , Frosty has not replied at all and obviously melted ,  Frosty  get back as we love your post's  as for ANYWEATHER  stay of the sad pills bro , don't do you any good at all .

[fine wine]

Another great set of charts tonight which if they verify would give us a fantastic final third to what has been locally a pretty good month so far. No rainy days and plenty of sun so far and our coolest top temp has been 22c so no complaints here.

[draztik]

Anyweather is absolutely right to be skeptical! The ecm monthly update has just been published, which shows no heatwave conditions other than a brief warm up at the end of next week, and a 4 day period between 30 August and 2 sept! After this date, it is showing progressively cooler temps affecting all areas. In terms of settled/unsettled.. Its a mixed bag! The SE looks like being the best area for warmth and sunshine amounts as we go deeper into sept,(tho it must be said, even here the model shows areas of LP affecting this area at times too) and the NW the most unsettled!

interesting to note, the monthly update also shows a hurricane form - which tracks towards the Carolinas before turning NE and heading into the open Atlantic. So obviously, if this hurricane forms as the ecm sees it, it will have to be tracked as it could well affect our weather here in Blighty!

Edited August 16, 2013 by draztik

[ANYWEATHER]

And being rather sad tonight here is the 18z gfs chart to lighten the load...