Archive | June, 2012

Mid-June to Mid-July…Thoughts & Analysis

19 Jun

With the days and weeks ticking by and the summer solstice just days away, the question on many people’s minds is; “when is summer going to arrive?…”

Clearly the last number of weeks have been very poor indeed for the time of year and that week or so of hot and sunny weather at the end of May is a long, distant memory unfortunately.  As I highlighted in my last blog (https://matthugo.wordpress.com/2012/06/08/flamin-june-and-not-because-its-hot/) this has primarily been down to the track of the jet stream, once again being much further south than it should be for the time of year and in-keeping with previous summers as well.

This blog is to focus attention on the remainder of June and take a look at the early part of July.  Unfortunately the outlook doesn’t look good.  What can be the case during the summer is that the pressure patterns become very ill-defined and dis-organised and this can sometimes make looking at the longer term very difficult indeed, particularly compared with autumn and winter when these pressure patters are often more defined.  However, it is interesting to note that there is a strong and consistent signal and unfortunately that signal is for low pressure to dominate.

The last few weeks have clearly been dominated by a trough-type pattern across the UK and many other north-western areas of Europe, whilst high pressure has been far more influential across parts of central and eastern Europe and given latest forecast data I expect that trend to continue now throughout the rest of June.  As with present day, a few better days are possible, but broadly speaking the rest of June looks low pressure dominated with further showers or longer spells of rain and with temperatures only reaching average values at best.

In summary, June 2012 could well go down as one of the wettest and coolest in many years and be one of the worst summer months in quite a long time.  I’m not a statistician, but clearly time will tell on this one, but no doubt many various pieces of information will be available by the end of the month highlighting this fact.  To summarise this pattern on forecast weather charts, the GFS and ECM ENS mean for the 28th/29th of month highlight this perfectly;

So, a new month and a change in the weather to go with the onset of July?…From my opinion the answer to that is no unfortunately and this is where a “don’t shoot the messenger” disclaimer may well be required!…

The longer range forecast models and the expected longer range trends leads me to believe that the pattern which June will end on will continue into the opening week or more of July, at least.  So that signals further unsettled conditions across the UK and that north-west corner of Europe, whilst higher pressure and summer-like weather remains firmly locked away to the south and the east of the country. The GFS ENS mean chart, now out to the 5th of July, has been consistently in agreement with the ECM ENS charts for low pressure and unsettled conditions to maintain themselves across the UK and the below chart highlights this;

Clearly, low pressure is dominating across the UK on the above chart, whilst pressure is higher to the south and east in general. Clearly from a meteorological perspective 2 to 4 weeks is a very, very long time and this signal, particularly as early July progresses could change.  However, what is of concern is that this signal for low pressure to continue to affect the UK is consistent and the longer range models haven’t wavered at all in terms of perhaps bringing a more settled and anticyclonic pattern to the UK.

So in summary, the unsettled conditions look set to continue, most certainly throughout the remainder of June, bar the odd day or two of better weather and that is likely to then continue into the opening week of July.  Clearly where we go from there, as I have highlighted above, is open to change given the time frames involved, but given the consistency of the signal for low pressure to persist across the UK then I wouldn’t be surprised if the first half of July remains unsettled and predominantly cool.  If that is the case then clearly we would need to see a significant improvement in conditions during the second half of July and into August to ‘rescue’ this summer…

Regards to all,

M.

 

Flamin’ June!…and not because it’s hot!

8 Jun

Well the first official summer month is well and truly up and running and no doubt the phrase “flamin’ June” has already been uttered up and down the country, but clearly not because of sunshine and heat, but because of torrential rainfall and very strong and unseasonal wind speeds!…

What isn’t a surprise however, is the change to more unsettled conditions.  At the latter half of May I took my usual look at the potential trends for the forth coming month and at that time there was a clear signal that the significant heat and sunshine that was evident during the latter stages of May would not continue into early June.  This full discussion with thoughts for June can be found at the below link and in fact some of the forecast charts discussed at the time are matching the actual synoptic conditions of present day very well indeed!

https://matthugo.wordpress.com/2012/05/30/from-high-pressure-to-low-pressure/

Today’s blog is taking a more specific look or advancing on the above blog to provide some additional answers as to why the unsettled conditions are now present and how long they are likely to last.

As usual, one of the best places to start is the jet stream;

This jet stream pattern can then be followed down to more surface levels, which using the below surface chart clearly shows where the main area of low pressure is to the West and South-west of the UK;

Note how the Azores high pressure is being held well to the west and south-west of Spain and Portugal.  This is a text-book sign that the jet stream is dominant just to the north of it and suppressing what is meant to be a feature of the weather much further north and east, affecting France and the UK during the summer, for example.  It’s clear to see that across the UK and also within the Central-North Atlantic low pressure is dominating the weather.

So is this likely to change…Again lets take a look at another jet stream chart but into next week;

As I have highlighted before, once you progress beyond a certain time period, it becomes important to look for broader trends in the synoptic evolution rather than the details.  Just as a re-cap, troughs in the jet stream indicate unsettled and often cool conditions, whilst ridges signal higher pressure at surface levels and clearly warmer and drier conditions.  Now unfortunately the variety of forecast models continue to signal a trough-type pattern across the UK until the middle of the month at the earliest with model agreement and also consistency.  As a result we are likely to be ‘stuck in a rut’ now for some time with predominantly unsettled conditions dominating the weather.

The second half of June may well signal a change however.  Some longer term forecast models and information do signal a pattern change with the jet stream changing to allow more ridging and hence higher pressure to affect the UK and one particular model, the GFS ENS, highlights this well;

Note how the Azores high pressure is being allow to build North-eastwards towards the UK in what is a perfect example of how the Azores high pressure can bring the UK some of it’s best summer weather conditions, particularly if the high pressure builds across the UK and then becomes slow-moving as well.  I did highlight within the last blog (link at the top) that the second half of June could well see an improvement in conditions and given the latest forecast data I stick by that prediction.  So June could well turn out to be a month of two halves to say the least, the first being particularly poor, but with the potential for better weather in the second half.

I’ll take a closer look at the second half of June and into early July later next week, but for the time being you’ll have to keep the BBQ covered, the patio furniture fastened down and the summer shorts and t-shirts on standby, as low pressure is here to stay…

Regards to all,

M.