Archive | July, 2012

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.

Late July and Early August 12…What’s Expected.

17 Jul

Well there goes half of July and clearly when coupled with June is half of the summer done and dusted.  It doesn’t take a rocket scientist to realise that half of the summer, at least, is no doubt wetter than average, cooler than average and most probably for many areas, duller than average given the relentless unsettled and cyclonic conditions.  At the beginning of July, in my last blog, I was looking at the month ahead and up to present the signal for cyclonic conditions, which I highlighted, has and continues to be dominant.  I did mention in my last blog of a potential change later in the month and that now looks likely.

So what has the second half of July got in store, at the moment I expect the following broader synoptic patterns to evolve;

The evolution throughout the next 7 to 14 days of July is most certainly shaping up to be one of change.  Clearly throughout the last number of weeks or more the jet stream has been either over or even to the south of the UK at times.  I continue to expect that to be the case within the short-term bringing further unsettled conditions.  However, as we progress towards and beyond this coming weekend there is a clear sign for the jet stream to retreat towards the north and north-west of the UK.  This is forecast to allow the high pressure that has been bringing many central and particularly southern areas of Europe some glorious summer weather to date, to influence the weather further north.  It also gives the opportunity for the Azores high pressure to come into play as well.  This can be seen on the below GFS ENS chart for example;

Note on the above image how low pressure declines to the north of the UK, whilst higher pressure is far more influential across a large portion of Europe, with the exception of perhaps say Scotland and then more particularly Scandinavia.  It is this evolution which I expect to take place throughout the remainder of July which, without question, will signal an improvement in conditions across the UK than compared with of late, especially across England, Wales and perhaps Ireland.  The crucial and still uncertain area of the forecast however, is just how influential will the high pressure across the UK become?…The reason why this is crucial is because if the main area(s) of high pressure remains to the south or south-west of the UK this wouldn’t signal a nationwide improvement in conditions, with further unsettled conditions possible at times in the north and west.  However, some of the forecast models (namely the ECMWF) continues to show high pressure engulfing most of the UK later in July.  At the moment I don’t support such a large pressure rise across the UK.  It is possible, but unlikely at this stage, but clearly this area of the forecast is very important and will need addressing on a more short-term basis in the next week or so.

So in summary for the remainder of July, an improvement is likely…High pressure looks likely to influence the weather more, particularly across England and Wales and especially across southern areas of England. Scotland and Ireland may well remain more unsettled at times, but as I have highlighted above this is heavily reliant on the finer details.

So, a change for late July, does August look like being sunny, hot and high pressure dominated?…

Unfortunately I don’t believe it will be, or at least not the first half of the month.  Here’s my expected broader synoptic pattern into early August;

At the moment I expect lower pressure to return to the UK and unfortunately bring a mixed outlook.  Clearly the details surrounding the first half of August are highly uncertain, but I have attempted to highlight in the above graphic what I believe will happen and that is for southern and eastern areas of Europe to continue as they have done so far this summer and be dominated by high pressure and warm conditions.  Low pressure and a general trough-type pattern, I believe, will return to the UK and many other northern areas of Europe during the first half of August.  The signals are relatively weak, I have to admit, so confidence levels aren’t particularly high, as they shouldn’t be really for a longer term outlook.  But that being said, up to date the information which I have analysed and studied to produce these longer term thoughts and analysis have been more right than wrong, so at the present time I stand by my suggestion of cooler and unsettled conditions returning.

The longer range GFS ENS also highlights this broader pattern as well and matches the above graphic;

Any high pressure in late July declines to the south or south-west of the UK and the negative pressure anomaly to the north of the UK becomes more extensive once again.  Clearly parts of the south of the UK may have some better weather at times, but the broader scale pattern brings back the more unsettled, westerly regime to the UK and other northern areas of Europe.

So, here’s to late July and hopefully some long-awaited better weather, but at the moment it may well have to be a case of make the most of what we get within the next 7 to 14 days as early August may well not continue the improvement and actually head back to what we have had throughout the summer so far….unsettled conditions.

Regards to all.

M.

July 12…What’s To Be Expected?…

3 Jul

Well there goes one summer month, that’s if you can call it a summer month and clearly June has gone down in the record books for various reasons, most particularly in terms of precipitation.  I’m sure many were expecting that after the scenes and pictures from various areas of the UK over the last number of weeks, as low pressure brought persistent rain and flooding to parts of NW England and Cumbria and then also the severe thunderstorms late in the month.  Overall quite a month, clearly not for the right reasons, but a month which all the medium and long-range models highlighted would be unsettled and clearly it was…

Early July is up and running and as you may have gathered from the shorter range forecasts and information, a change of month hasn’t brought a change in the weather and unfortunately I don’t expect any changes in the near future;

Throughout the first half of July I expect and predict that the predominantly unsettled synoptic pattern will continue.  The broader synoptic pattern is likely to maintain a trough across the UK, whilst higher pressure is dominant across Eastern Europe and more importantly to the North-west of the UK.  As we have experienced for numerous weeks now, high pressure to the North-west of the UK in summer is never a good place for it to be.  The importance is that it is likely to maintain the trough and unsettled conditions across the UK and there is little signs of this pattern, which has been evident for numerous weeks, changing.  This can also be seen within the latest ECMWF and GFS ensemble mean charts;

Both charts have a marked trough of low pressure across the UK, with pressure generally higher to the North-west of the UK and also across more Eastern Europe where it has been for weeks.  Note as well, the usual summer-related main Azores high pressure continues to be held well to the south-west of the UK, with little or no sign of this influencing the weather across the UK as July progresses.  The persistence of the predominantly cyclonic conditions is also represented well within the latest GFS ENS atmospheric pressure graph, randomly selected for Central areas of the UK (Northern England);

 

That really is quite a shocking prediction at the moment with also relatively good, if not very good ensemble model agreement that up to the 18th or 19th of the month at least, the atmosphere pressure is unlikely to get above 1020mb, which for the time of year, is again, shocking. You can also clearly see that directly associated with this signal for relatively low pressure is the consistent signal for precipitation across the bottom of the graph as well throughout the forecast period, which continues to support the likelihood of further precipitation, some of which could be significant at times as well, not just across Northern and Western areas of the UK, but also across Southern regions too.

So in summary, I have quite high confidence to suggest that the first half of July will continue (unfortunately) in the same pattern that we have had to endure throughout June.  Low pressure is set to dominate and as a result further relatively cool conditions are forecast with perhaps some additional large rainfall totals at times depending on the specific events and details as the next few weeks progresses.

So, what about the second half of July?…Any potential changes?…

Unfortunately, at the moment I don’t envisage any significant changes;

Given the time frames involved then clearly confidence levels do drop away, but what I do expect is further unsettled and cyclonic conditions to continue after mid-month as well, at least for a time.  I have highlighted this as an issue in some of my previous blogs and that is particularly during the summer, long-term pressure trends become insignificant and weak given the nature of the weather during the summer and at the moment that is the case for say the final 7 to 10 days of July.  As a result the far end of July may well begin to see a pattern change.  It is often a time for the broader synoptic pattern to change if it has been ‘stuck in a rut’ for a long time, so as a disclaimer please acknowledge the above image with some open thought and also hope that the final week or so of July may begin to see a change to something warmer and more settled.

So in summary and it doesn’t bring me any joy to highlight this, but the first half of Summer 2012 looks to be a complete washout with the first half of July now expected to be unsettled and predominantly cool.  The second half of July may well maintain these unsettled conditions, particularly for at time after mid-month, before perhaps changing at the end of the month.  Clearly however, overall July may also now turn out to be quite poor as well, particularly if 2 or 3 of the 4 weeks of the month do end up being predominantly unsettled.

As ever, all thoughts and comments are welcomed and as usual I’ll review the first half of July mid-month and also take a closer look at the second half of the month and into early August…Here’s hoping by then there is something on the horizon in terms of summer-like weather, as clearly these weeks and months are ticking by!.

Regards to all,

M.