May 2012 – Thoughts & Analysis…

1 May

I’ll start with this well-known phrase:

“Ne’er cast a clout till May be out” – Despite some excellent May months in recent years, this one does indeed look very different and the well-known saying may well have some credence this month!

So, the final spring month is up and running.  What has been evident this spring, so far, is the variety and often extreme conditions across the UK.  The first spring month clearly brought us some extreme warmth and also very dry conditions in what was the 5th driest March overall.  Within a matter of a few weeks we were back to winter in early April with some snow and the rest of April clearly was dominated by low pressure which brought some serious amounts of rainfall to England and Wales and thus produced one of the wettest April months in a very long time.  So for those who like variability then this spring has and looks set to continue to deliver just that.

Taking a look at May and the first half of the month in particular generally looks set to continue where April finished and that is on an unsettled and predominantly cool, if not rather cold, note.  The below is what I believe is likely to be the broader jet stream pattern during the first half of May in particular;

It certainly seems that high pressure will ‘setup shop’ to the west and north-west of the UK for at least the first 7 to 10 days of the month, this can also be seen on both the GFS and EC ensemble mean charts below;

The broader effect of this general signal for higher pressure to the west and north-west of the UK is that the UK itself then becomes stuck in the trough located to the east of the higher pressure to the west.  Referring back to the original image in this blog, you can see that low pressure is expected to be located over the UK and also over north-west Europe in general in association with a trough in the jet stream.  This pattern, I believe, will dominate throughout the first half of May and continue to produce a predominantly unsettled spell of weather with temperatures slightly below or even below average at times, particularly during the first week of the month.  I won’t go into details over the expected weather in the short-term, but it’s safe to say that the rest of this week, into the coming weekend and early next week won’t be warm that’s for sure and some night frosts are possible with a risk of wintry precipitation in the north.

The latter half of the month has a lot of uncertainty evident, as is always the case when looking at longer term trends.  At the moment however, I expect a broader rise in pressure to take place across Europe as the upper trough across the UK and surrounding countries is potentially replaced by a rise in pressure. It can sometimes be more difficult to find trends as we progress towards the summer months because the general weather patterns become more ‘slack’ and disorganized than compared with winter which often produces more significant variation and distinct regions of higher and lower pressure.

So to summarize.  The first half of the month, at least, looks set to be a predominantly unsettled one with further rain, showers and rather cool conditions.  Thereafter, the second half of the month and then perhaps more particularly the final quarter of the month may see a trend towards drier and warmer conditions.  Overall though the final month of spring doesn’t look particularly ‘exciting’ if you are after a repeat of the weather which has been in evidence in recent May months over the last few years.

Regards to all,




One Response to “May 2012 – Thoughts & Analysis…”

  1. steveg4ytk May 1, 2012 at 8:41 am #

    Matt another good blog thankyou. Is there any chance on blog on how to calculate weedspeeds from pressure charts, or how every you do this. Steve

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