Aside from my obvious greatest hit the 'high pressure watch' I suspect this could be one of the more active and exciting threads I have made in the MO board. 

Models broadly want two shots of warm air from the south east, one beginning next tuesday and the other towards the end of the week. Temperatures getting above the 30C mark are pretty much guaranteed unless there is a major pattern change (very unlikely); I am skeptical of the near record breaking temps the GFS in particular is showing but it cannot be ruled out.

We shouldn't underestimate the storm risk either; I'm seeing a rather uncommon number of double digit LIs which is a very rough cutoff for possible tornado activity. However, I think instead of seeing -12, the models may downgrade to closer to -6 when the time comes.

Well your post is clearly not based on anything the models are showing. I would expect at least one day of 30-31C here given what is currently shown on the output.

Could be watered down or shunted further east of course - and there is always that nagging feeling in the back of my head that something will go wrong.

But, it's worth keeping in mind that 30C in Leeds isn't uncommon - it occurs more years than not, and was pretty much an annual occurrence between 1990 and 2007 (I use 1990 as  the start because data for Leeds only goes back to the late 1980s). So in reality, what is currently shown for us isn't really exceptional at all, but is pretty much what we got most summers before 2007.

Another BIG disappointment coming up,me thinks.

Well not all of the model esemble runs are showing nationwide 30C heat, it's just a lot of people are choosing to ignore it. The fact is at this range with our climate it would be silly not to expect some kind of reasonable downgrades in the comming few days, especially those further north, and west.   

Perhaps so.  All people are doing is discussing the models.  Personally, anything over 25C IMBY would be a good achievement.  I usually get a few days (say 6) over 25 a year and maybe 1 over 28.  If the plume is still on target by the end of the weekend then we can be sure for some real heat, but there is only one thing  more difficult to achieve in Britain than extreme summer heat, and that is extreme winter cold.

Time will tell.  But in the meantime people should enjoy the charts for the fun and fantasy they are.

I'll be on UK heat watch from Norway, where it will be much cooler and probably wetter.  In fact, it will be positively cold when we arrive in Tromso and areas further N.  Typical that I am going to miss this heat - it's been a long time coming.

David

Northallerton

The heat is really arriving as a result of low pressure forcing it north as opposed to an established High Pressure set up where heat can build under stable synoptics. The plume will be under attack immediately from the west. The only unknown is how quickly the fresher air will displace the theta-e plume

Tromso can get pretty warm during the summer. Here is a graph of recorded temperatures last July...

http://weather.cs.uit.no/cgi-bin/wtstat?time=201406110000&type=monthcenter&zoom.x=699&zoom.y=60

For that week it topped 29.5C 

This is actually not necessarily the case. The LI is one of numerous parameters that feed into the equation when forecasting tornado risk, and certainly not the major player. Tornados in the UK can easily occur in quite 'stable' conditions in terms of CAPE and convective potential because other parameters which arguably have more influence in generating tornados here are more prevalent, for example speed and directional shear. A high LI could well generate numerous storms locally, but they won't necessarily be a tornado risk, especially the sort of storms and convective complexes that occur in summer plume set-ups.

But speed and directional sheer are useless if there are no storms or only weak convective activity. In fact sheer plays a rather large role in lake effect snowfalls, but 850s are still often the first port of call. In reality I wouldn't use LIs in short term tornado forecasting, but at this sort of range I think its perfectly justified to do this given that we are looking at the sort of environment that might be favourable. 

Indeed Neil. Folks need to look beyond the seductive colours on CAPE/LI maps and understand that moisture and instability mean nought unless there is a sufficient forcing mechanism to initiate convection.

But this is like using Skew T diagrams to forecast snow at 144hr. What is the point of using advanced techniques if the benefits to be gained are lost in the uncertainty of a medium term forecast?

Not well forecast but it's the hottest day of the year today 27c in Gravesend. 850s about 12c today for that area.

Current max temps on the high res GFS maps:

29 June: 26C

30 June: 29C

1 July: 31C

2 July: 33C

3 July: 28C

4 July: 31C

5 July: 25C

Making it, if that came to pass, a notable hot spell probably edging 34c but nothing near record breaking. The date record that looks most vulnerable is the 4th. But yesterday evening we were looking at charts showing 37C which certainly would be record breaking.

Lets keep tabs on this.

Hellen Wlletts just now on the Beeb temps could peak mid 30s next week!

Carol Kirkwood certainly peaks in the mid-30's

This is Heat Watch not Cougar Watch

There's a list of hottest temps for each day of the year here, if you want to do some sorting... 

http://torro.org.uk/site/hightempsyear.php

27.8c today in Gravesend