August 12…Thoughts and Analysis

27 Jul

Well that’s essentially 2 months of “summer” done and dusted, note the air quotes!…The last week or so has finally delivered some decent summer weather to parts of England and Wales, but clearly on a larger, more national scale the UK has still yet to see a proper sustained spell of summer weather across all countries and regions.  Looking back on my last blog and July as a whole and overall the general predictions and indications weren’t far off the mark.  The month as a whole will no doubt be another wet one and probably quite cool, despite this past week potentially offsetting that situation somewhat.

Anyway, moving on to August and to reinforce what my last blog discussed about the first half of the month and also take a look at the second half.  I expect the below broader synoptic pattern to dominate throughout the first half of the month;

 

Unfortunately this is an all to familiar synoptic pattern.  There has been plenty of discussion regarding the breakdown of the current warmth and better weather just in time for the Olympics/early August and I do believe that this general unsettled pattern will dominate throughout the majority, if not all of the first half of August.  What I don’t expect however, is the jet stream to be as active or as dominant as it was throughout June for example.  As a result, despite the predominantly unsettled theme, there is likely to be a chance for some temporary ‘windows’ of better weather, especially across more southern areas of the UK.  Both the GFS  and ECMWF ensemble mean charts highlight this broader synoptic pattern well;

 

Given the broader unsettled pattern then the details are clearly highly uncertain, but what you can gauge from the above two images is that an upper trough and the jet stream become influential across the UK once again, which ties in with my original graphic at the start of the blog.  So, with the exception of some better weather at times across southern areas of the UK in particular, overall I expect the opening 7 to 10 days, if not up to the middle of August to be predominantly unsettled with showers, longer spells of rain and with temperatures generally average at best.  It is also of worth to add that some further large rainfall totals and events may also develop as well in the coming week or two weeks given the progression towards more unsettled conditions once again.

So, will the second half of the month be any better?…

The answer to that is highly uncertain.  Throughout this summer I have highlighted on a number of occasions that summer can often produce highly weak and disorganised pressure patterns and signals and the latest medium and long-range data really does do this for the second half of the month. As a result, this is one of the more difficult and challenging predictions so far this summer which really does have a low confidence and a possibility of changing.  However, the below is what I believe is likely during the second half of the month;

 

Now you might say there isn’t much difference with the earlier discussed image for the first half of month and to an extent you would be correct.  However, there are subtle differences and those differences are that I believe the jet stream may well retreat northwards once again and allow the Azores high to the south-west of the UK to influence the weather across England and Wales in particular.  As a result the second half of August may well be a pleasant end to summer for some parts of the UK, but I do not expect a full-blown recovery towards high pressure, hot temperatures and plenty of sunshine nationwide.  So in a way the prediction is almost a compromise between somewhat better weather attempting to influence the weather from the south and south-west, but still with unsettled conditions affecting northern areas of the UK in particular.

As you can imagine, this particular signal out to 3 to 4 weeks is open to some significant changes, as trying to come to a more specific conclusion is essentially impossible at this range.  However, given a likely unsettled first half of the month in particular and with little or no signs of a major build of pressure to produce a UK-wide spell of late summer warmth and sunshine, then overall I expect August to be an ‘average’ month at best.  Clearly not as poor as the first half of the summer, but a late reprieve is highly unlikely in my opinion.

As usual I’ll take a look at the second half of August in closer details and into the early part of September and Autumn during the middle of August, but for the time being at least, throughout the first half of August, the theme is unsettled once again unfortunately.

Regards to all,

M.

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