The computer giveth and the computer taketh away ...

More than a bit, I'd say. GFS not only brings in the low but keeps it hanging around with very modest temps. At least ECM suggests that the warmth will return fairly quickly

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I will be a real shame if those prospects of better weather don't come off because that ridge of high pressure which is forecast to be around on Monday looks really impressive on both the GFS and the ECM. The BBC does show quite a deep area of low pressure to the west of that ridge of high pressure, but I was kind of hoping that this ridge of high pressure would at least be strong enough to divert that low pressure system northwards towards the far N and NW of Scotland instead of just allowing that low pressure system to move in across the country, relatively unimpeded or allowing that thundery low to come up from the south and take over the pattern.

Had that been the case then perhaps, we might have been looking at a really good week next week, otherwise the omens aren't going to be looking so good after all, for my break in the Scottish Borders next week. In the meantime though, we have yet another waving weather front to deal with over the weekend before we even get to that, although I will reserve what I think about that for the moaning thread.

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Looks to be following a similar pattern to much of this summer with blasts of heat appearing in the ensembles at relatively short notice. If memory serves me right the GEFS was showing a very flat picture about 7 days ago, but now we have 2 surges of +15C in the next week more or less nailed on.

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The models will probably change back by next week. Sometimes in these scenarios I stop looking too far ahead for fear of plume disappointment. As you say, long as it has HP over UK (regardless of temps) that'll do for me...

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Its the same as ever. Never ever put faith in output more than 96 hours ahead. No real exceptions. 

We'd be far saner (if a bit more bored) if NWP was limited to this timeframe. 

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Indeed and I think this pattern will persist throughout the summer and so should a +NAO pattern (unlike several recent summers).

There is also decent evidence of a cyclical behaviour with heatwaves around the 20th of June, July and August and with the 2nd halves of each month being warmer than the first halves. This probably emanates from the quasi-cyclical tropical forcing.

 

 

The models today have an explosive theme about them come middle of next week.

Very warm to locally hot by that point to.

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Absolutely, Joe. Whilst I love a bit of heat, I'd happily sacrifice high temps in favour of low-20's and settled/sunny over the longer term

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Yes it looks like a step back from the models in terms of the long settled spell that seemed to be on the cards. GFS in particular parks low pressure over the UK after day 12. But of course much can change!

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That is what has happened all summer so far a break down is forecast and then a huge step forward and summer's still on.

"Day 12" - Ignore. As Brian has pointed out, GFS repeatedly goes flat in mid-term and has been poor all summer in it's latter stages. What we have seen is repeated Azores ridging allowing bursts of heat in between more benign and often warm weather here and that kind of pattern once established can go on throughout summer as it is a recognised UK pattern. 

According to GFS 06z summer is over.

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I'm not so sure that summer ever really started here to begin with in this neck of the woods here in Edinburgh (apart from that one weekend in the middle of June were we reached 25C on both days).

 

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I've seen much worse.... Anyway for the hottest of GFS runs I don't think I've seen any hotter then P5 in today's 00z.

Yes a downgrade from a HP dominated outlook but its more of the same from recent weeks. Plumes followed by the odd wet day and a few warm days in between. It's still around T120 so plenty can change.

Though a more humid thundery outlook is the form horse now.

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I wonder if we'll ever get to a stage where taking any notice of model output post 72 hours will have any point?

 

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Well, the models were giving an indication of a warm-up early next week at T144 or more. OK the detail hadn't been pinned down, but it indicated that next week was likely to have a hot spell.

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We do seem to have a bit of a disconnect between very nice looking synoptic charts and 850s for the next few days, and rather poor actual temperature and sunshine forecasts. I assume this will be one of those weeks where cloud and blue sky battle it out for supremacy, and it's at times like this reality and forecasts can be far apart.

For example today: BBC this morning said 24C at Wimbledon, sunny until afternoon then clouding over. The automatic outputs range from cloudy 22C on the iPhone app and BBC website to 24C quite sunny on weatheronline. Actually it's been 21C (probably 22C at a push), cloudy all day but clearing in the afternoon. All under the same general pattern.

Next few days: as someone pointed out GFS suggests moderate amounts of cloud around and maxes pegged back into the mid 20s. Arpege, with exactly the same overall synoptics, has a much cloudier but still warmish Saturday, and a much brighter Sunday with maxes hitting 29C. We have the BBC weather website and some very miserable looking weather presenters showing a cloud fest and modest temperatures for the next 7 days, and so do most of the automated sites. Yet the pattern midweek just looks hotter than what they are suggesting.

We did have a bit of this in 2003: in early July there was what looked like it ought to be a settled sunny spell but was extremely cloudy, with one day seeing the sun peak out and temperatures soar to 29C. Then a cold front, a new ridge and a clear few days with a peak of 33. Let's see.

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Yes we had the opposite "problem" last weekend when Saturday was forecast as cloudy almost all day but in the event it was a proper sunny scorcher. In fact I would have preferred a bit of cloud as I was sat out at a music festival all afternoon and it was rather too hot without shade.

Cloud amounts under HP are notoriously hard to forecast.

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Interesting the strong agreement between the models of the trend out to 5-7 days that's been evident over the past few runs - something that is quite unusual IMO. When a trend to a different outcome has been shown it tends to have been backed up by the OPs in the other models.

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I'm having a big barbecue next Friday for about 30 people. The last few runs on all models have worried me intensely. I was starting to get complacent earlier this week, expecting a scorcher. Now it's touch and go whether I get rain, or cool breezy weather. Scorcher is out of the window.

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I like the Arpege charts- have they been improved to show clearer temperatures away from the zones of steepest thermal contrast (you know- where the therms are so close together it's hard to pick the right number for your location)? Really clear for the next few days.

 

 

 

 

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I'd like to bank P08 of the 12z GEM ensemble. Yes, GEM.

Obscure? Yes, but it's quite simply the hottest model run I have ever seen. Go and take a look.

(P20 isn't bad either)

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Sadly the trend has gone into reverse across most major models again. Just once again proves the volatility in trying to predict confidently more than a few days ahead. Next week is very much up in the air at the moment with a brief burst of warmth followed by a spell of something much more changeable again. Pretty much a repeating pattern this summer with it looking worse the further north you go.

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The models haven't changed much from yesterday unless you cherry pick an op run to make your point.

PS: A senior admin wasn't banned on TWO but one or two members may have their accounts deleted today.

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The ECM 0z is considerably different to the UKMO and GFS and offers a lot dry weather after the midweek blip..the models are and remain in a fairly volatile state and what appears certain is a brief significant warm up in the south. It's been a very interesting summer thus far and as Brian has said a few times there appears to be a repeating pattern of warm bursts followed by slightly more changeable. I think this is most likely to continue with the best of it remaining in the south. ECM certainly strongly backing another big push from the Azores next week. More runs needed as ever

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