The 250mb jet over the N Atlantic is modelled as making some very exaggerated dips and curves over the next week or so- one limb taking on an omega shape before cutting back on itself before fragmenting and joining a more polar-orientated limb over Greenland in a week's time. The GFS op translates this into a window for HP to build over the UK from 14th. Whilst the 850s and surface synoptics are too far out to reckon on at that range, interesting that such a meandering jet can be seen as an opportunity for a wide variety of subsequent situations.

 

 

Yes it's the reason why we see the Atlantic rather quiet in this set-up with little movement of lows out to the west, allowing high pressure to gradually influence our second week or June.

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That could be a very useful piece of model interpretation if verifiable. Is that because the models are able to predict HL synoptics generally more easily in summer?

I think so yes, there is less forcing in the system.

 

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I think so yes, there is less forcing in the system.

 

We should therefore see a reduction in spread in the ENS for HL locations, averaged out across the summer of course. Take a bit of time to sort through that lot for the last decade! Currently, Greenland and Reykjavik have fairly close conformity between outputs if you look at the ENS spread, but that is of course just now. And that is 850s rather than SLP, but it would be interesting to see if that's the norm.

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I disagree, all the models are now building strong heights to the NW, that will mean Low pressure in a vicinity until the Atlantic possibly cuts through again later on, all in all below average to cool and very wet at times.

 

yes it’s looking very poor, a pattern reset needed if ever there was one. Some distinctly cool days on offer further out if some of the output is to be believed and the rainfall totals will gradually start to add up. 

Well it's been so dry down here in the S.E. for so long now, this had to happen at some point.

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ECM ensembles show the op once again on the cool side of the pillow.

That being said, despite a gradual improvement, it is a bit of a struggle at the moment. Seems more pronounced given last year!

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We should therefore see a reduction in spread in the ENS for HL locations, averaged out across the summer of course. Take a bit of time to sort through that lot for the last decade! Currently, Greenland and Reykjavik have fairly close conformity between outputs if you look at the ENS spread, but that is of course just now. And that is 850s rather than SLP, but it would be interesting to see if that's the norm.

I haven’t checked recently but the verification stats showed a better performance in the winter than summer - for the reason Shropshire mentioned, ie less energy in the system, but with the opposite effect.  Normal mobile patterns are actually easier to predict. 

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Big flip this morning to more settled conditions. UKMO, GEM AND GFS all have the Azores high building in strongly over the UK as early as 96h. Nice surprise this morning.

 

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Big flip this morning to more settled conditions. UKMO, GEM AND GFS all have the Azores high building in strongly over the UK as early as 96h. Nice surprise this morning.

 

Yes, such are the swings in the MO. It's ironic that the BBC's extended outlook last night highlighted the two scenarios of HP building over the UK from the Azores or the trough hanging around instead, and went with the trough being the most likely outcome. Let's see what ECM brings.

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Big flip this morning to more settled conditions. UKMO, GEM AND GFS all have the Azores high building in strongly over the UK as early as 96h. Nice surprise this morning.

 

Yes, but ECM wants to spoil the party and keep us in a col between LP in the Atlantic and in Scandi. The flip is IMO most noticeable in GEFS where rain (e.g. for Brighton) has almost disappeared after tomorrow's event. Previously there had been lots of on-off activity.

As for tomorrow (Friday's) rain, consensus between MetO & Arpege is for the bulk of it in a narrower path than previously, uo through Dorset/Hants, the Severn,Valley and up to Cumbria and finally spreading out somewhat over Scotland. Sussex, where  really wanted lots for the garden, looks as if it will get shorter bursts of the heavy stuff, A noticeable extra is that gales are expected to develop in the Channel after the depression passes through with 40+ mph gusts on Saturday.

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With the caveat that this is only one GFS ensemble, but what a MASSIVE improvement here.

http://old.wetterzentrale.de/pics/MT8_London_ens.png 

Virtually bone dry after tomorrow's deluge now. Big turn turnaround so must be taken in isolation at the moment, but maybe summer is just around the corner?

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Positive signs for high pressure building next week though it does seem to chop and change on a daily basis at the moment so nothing set in stone yet. Need to get through the 'typical' British summer weather at the moment of sunshine and showers.....

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Big flip this morning to more settled conditions. UKMO, GEM AND GFS all have the Azores high building in strongly over the UK as early as 96h. Nice surprise this morning.

 

I don,t think i trust big flips in the models to be reliable. Just shows there is a lot of un-certainty at the moment and it will probably end up somewhere between horrendously cool and wet and hot dry and sunny.

Interesting that the ENS are flipping from run to run between two very different patterns: wet with lots of plumy scorchers in the mix, vs drier with a much flatter set of 850s. This morning’s GFS is back to the latter

When we get southerly diving jets we also get the opportunity for short lives very intense heatwaves followed by thunder. But last year, whenever things looked like going that way, the pattern flattened out and the dry, settled but not excessively hot weather won through. July 2013 was similar: the really hot scenarios never quite made it, but nor did the big thundery breakdowns.

Last time we had a true southerly plume heatwave was 1 July 2015. Followed by a meh summer.

Let’s see.

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00z ECM mean backing a rise in pressure next week

In central southern Scotland pressure peaks at around 1027mb the Op isn't supported for going above 1030mb a very slow decline again from around the 13th/14th but nothing major with the run ending around 1017mb

 

Further south in London pressure peaks at around 1021mb on the mean on the 9th and 12th a steady fall again towards the end but like above nothing major ending around 1017mn

Heavy showers, thunderstorms and strong winds forecast after the main rain pushes through tomorrow. Wouldn't be surprised to hear reports of tornado's, possibly around the Selsey area.

Oh dear.

Forecast rainfall for tomorrow:

T48 22mm
T30 19mm
T24 9mm
T0 ?

Eminently predictably downgrades and likely for many who garden down here a massive disappointment.

Regardless of models showing a epic unsettled spells, the big feature of this (astronomical) spring has been the severe lack of meaningful rainfall.

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What the 0z giveth the 12z taketh away. Models all over the place. GEM is very poor, UKMO not much better. GFS best of a bad bunch.

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What the 0z giveth the 12z taketh away. Models all over the place. GEM is very poor, UKMO not much better. GFS best of a bad bunch.

Yes some high rainfall totals and the possibility of next Thursday being an exceptionally cold day for mid June.

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Will we move back to a spikier set of GFS ensembles later I wonder? To piggy back on Tim's thoughts earlier.

Certainly a notable flip back from the 12z suite so far, disappointing but it only serves to highlight the volatility in the current output. It'll be interesting to see where the ECM fits in this funky jigsaw.

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