It can and it did in 1976 for example. We shall see, but since I am on holiday in the UK for the last 3 weeks of July, it would be just my luck if the weather turned.

Originally Posted by: Maunder Minimum 

Tropical forcing has been behind our good fortune of late.

At the moment that support is dwindling a bit as what we’ve had doesn’t allow as much ridging NE from the Azores as you reach July, but the state of the oceans is increasingly supportive of an adjusted and very helpful forcing re-establishing during the next week or so.

Summers that turn and don’t turn back are ones that see the same forcing throughout; what works well for May-June does not for July-August.

With this one, we’re on the cusp of seeing the forcing change just when we need it to for sustaining an overall fine picture. It’s all very poised. How long it hangs for before the trigger is pulled will dictate how much of an unsettled spell we have.

Even during this poised period, there may be enough help from the N Atlantic SST profile to limit the extent to which troughs get in across the UK (those cold anomalies are further west than in 2015 for examle, as is the favoured location for trough deepening - this tending to keep the jet more S and flatter out to our west but on a SW-NE alignment that sees it travel north of the UK.

Fascinating times are with us... and the chance of a rare feat; more than 2 decent months out of those spanning May and August!

Originally Posted by: Stormchaser 

Surely though, given the very solar activity which we have just now in addition to some really cold SSTs over the Atlantic, this shouldn't really be happening just now. If anything, I would have thought that this would resulted in it getting colder overall as it did towards the end of the winter and the first half of the spring.

I know that Gavin P. did predict a decent start to the summer but then, he did go on to predict in that forecast that there would then be a deterioration from July onwards.

Because of that, I would say that if this deterioration doesn't end up happening and if the pattern which we have just now was to go for a good part of the rest of this summer, there then has to be some other factor in play here which is making that happen, and which hasn't been picked up on any of the summer forecasts which I have seen (including the one from Gavin P.).

It would therefore be nice if the experts out there could get to the bottom of that and thus, be able to improve future model output in the years to come as a result.

Originally Posted by: johncs2016 

looking at it another way, pressure patterns have stayed rather unusual with more anticyclonic set-ups, so conversely the SSW impact has over ridden low Atlantic SSTs or sunspot activity.

Originally Posted by: White Meadows 

At the end of the day chaos still drives most UK weather from week to week. The correlations in summer between our weather and ENSO, the PNA pattern, solar irradiance, Atlantic SSTs, even the NAO and AO which are direct forcing and right on our doorstep, are there but pretty weak. That's why seasonal forecasting in the UK remains a mug's game.

That said, stochastic forecasting (i.e. getting the feel for the way the weather seems to want to behave) does have some merit because of autocorrelation and persistence, and the fact the human brain can process patterns to give inferences eve if it doesn't understand them. Persistence suggests that we'll see more regular outbreaks of Easterlies and North Sea / Scandinavian highs this summer than usual. But then again as commented above, what applies for May-June more often than not doesn't apply for July-Aug.

Interesting to look at the 200hPa wind maps in the GFS runs. These are the closest we get to a map of the jet stream(s). Every year a significant shift takes place in late June after the solstice: during spring there are 2 distinct jets spaced far apart - one strong subtropical through North Africa, the other polar front jet anywhere from Iceland down to France depending on the synoptics. After the solstice the subtropical jet shifts North markedly (as it's doing now), the Med dries up even if it's been very wet up to now, and the gap between the two narrows. This means that whatever happens over us, it stays more settled further South, and it also means therefore that bad weather is less likely to come up from due South or for a blocking high to sit on top of a European low. If there's a blocking high it will cover France too, and won't extend so persistently so far to the North. If there's a diving low it will sit slap bang over us and the near continent and deliver a deluge, rather than diving further South and drenching the Med. We see that in what's happening to the Iberian trough right now - it struggles to expand South Eastwards so goes spinning up into the Atlantic.

Originally Posted by: TimS 

Yes, and in 1995. 2003 and 2006 too (2003 was one of those summers where all 3 summer months were much warmer than average). And many more. Of course there's no saying whether this summer will be like any of those, but it's possible. Not sure why people are so pessimistic.

Originally Posted by: LeedsLad123 

  Although in the past few years it’s tended to break up just as schools do and Augusts have been fairly poor.  We’re due a good one!  My glass is half full!  

Originally Posted by: Caz 

Good post there Caz. When you think that the legendary summer of 1976 ended in the August Bank Holiday as did the hot summer of 1995.

My thoughts are with the likes of the summer of 1959 - although I wasn't around to remember it - I've read loads about it in meteorological documents and I'm hoping this summer emulates that one.

Originally Posted by: Hungry Tiger 

GFS 12Z is AMAZING. This is starting to look like a classic summer.

Originally Posted by: moomin75 

The large changes between the GFS 12z and the previous few runs can be traced back to a southward dip in the jet stream that forms on Friday and hits peak on Saturday. The 12z is just that little bit less pronounced with this Fri-Sat i.e. it keeps the jet flatter (first two images; 06z on left, 12z right).

As a result, less in the way of cool polar maritime air is drawn south (second two images, same relative positions) - note, to the south of Iceland, how much less southward progress the bold 0 isotherm has made.

This in turn means that there is more of a thermal gradient in the vicinity of Iceland, as more cool air is retained to the north of warm air. This leads to a stronger and much more coherent jet heading WSW-ENE to the north of the UK (third two images).

At this point, the stage is set for what follows a good way into the following week; that jet to the north of the UK builds more in the way of high pressure across from the Azores while also preventing as much ridging toward Scandinavia. Not only that, but the Iberian trough has less in the way of cool air to interact with. So, it stays more south, and pressure stays higher across the UK.

With more energy diverted away NE of the UK, and a stronger thermal gradient maintained across the regions north of the UK, the Atlantic trough can't make inroads like it did on the previous runs, even next Friday the main jet is still running north of the UK:

Only with some amplification of the upstream pattern (buckling of the jet) is GFS able to find a way to bring the Atlantic trough more into play for the UK. At this time we reach a new conundrum; this is where tropical forcing could step in at just the right moment to keep any Atlantic trough intrusion brief and limited (as I detailed more this morning), but GFS is clearly not interested at this time (but it does have a bias away from the desired forcing, so it may be worth favouring ECM at that range - but then, that's usually the case anyway ).

Originally Posted by: Stormchaser