Rest of November 12 – Thoughts & Analysis

16 Nov

Well there goes the first half of November and with only 2 weeks left of autumn, until December starts, this autumn has been quite an unusual one.  The distinct lack of unsettled and zonal conditions has been noteworthy, despite quite potent stratospheric developments which can aid the development of this trend towards more zonal conditions through autumn.  We are yet to see any significantly cold conditions, despite some frosts at times.  The first half November has followed suite really with a mix of conditions being evident.

The second half of November has clearly been a talking point for some time, particularly in relation to the potential development of colder weather and a broader change in synoptic pattern.  In this blog I’ll attempt to summarise my thoughts and information to give an idea and suggestion of what I believe will develop during the second half of the month.  As an early disclaimer, of sorts, it should be noted that the second half of November is a forecasting challenge for many reasons.

For the time being I expect rather unsettled conditions to continue across the UK and the reason for this is the following broader synoptic pattern across Europe;

High pressure remains influential across southern and eastern areas of Europe as low pressure remains slow-moving in the vicinity of the UK.  As a result for the UK the next week or so looks unsettled.  Without going into the details, areas of low pressure look set to bring showers, longer spells of rain and some windy conditions as well.  This is highlighted well by the latest GFS ENS mean chart for the middle of next week;

So now that is out-of-the-way, what about the all important final quarter or so of November and perhaps into early December?…Is it likely to turn colder I hear you ask?…

My answer at the moment is; yes.  I also expect it to become somewhat drier than average as well.  The below image was a tricky one to try to put together but I believe it summarises the broader synoptic patterns by late November and into early December.  Clearly I expect higher pressure to become dominant to the north or north-west of the UK whilst pressure becomes lower across more southern areas of Europe.  There are definite uncertainties over the final location of any higher pressure and this will be crucial to any potential cold spell.

 

 

The longer range forecast models, of late, have been persistently showing a trend towards higher pressure to the north of the UK in some shape or form.  This type of synoptic develop at this time of year often leads to what is known as a negative North Atlantic Oscillation (-NAO) and essentially ‘kills off’ any low pressure systems and zonal conditions that the Atlantic can bring to the UK.

I have to admit the final location of any higher pressure is unknown, but to give one example and that is with higher pressure more directly over the UK is the 00Z ECMWF model;

This is one of a number of possible solutions towards the end of November.  If this synoptic pattern were to materialise then generally the UK would potentially enter into a period of colder conditions with a risk of frosts and fog by night, depending on cloud amounts.  At this time of year high pressure across the UK more often than not doesn’t equal mild conditions, particularly if the high pressure becomes relatively slow moving across the UK over a number of days.  What you should also note on that ECMWF chart is how there are similarities to my chart.  Note how pressure becomes lower across southern Europe and Mediterranean, whilst clearly pressure is rising in and around the UK.

So in summary, for the time being I expect predominantly unsettled conditions to carry on with a particularly unsettled week next week for many areas of the UK, but especially across the north and west.  I will then ‘stick my neck out’ and make a bold suggestion of a significant pattern change by late November and into early December which will take the UK into a colder and drier spell of weather.  Clearly, and as mentioned earlier, the details are unknown, but my outcome is for late November to now turn colder, particularly compared with of late.

As ever it’ll be interesting to see how things develop and materialise, but the winter woolies may well be needed by late November and into early December.

Regards to all,

M.

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2 Responses to “Rest of November 12 – Thoughts & Analysis”

  1. Stophe November 16, 2012 at 9:43 am #

    Thanks Matt.

  2. Doctor Col November 16, 2012 at 11:40 am #

    Good stuff, Matt. I am hopeful for some cold, hard frosts in Dublin for my birthday. Thanks for this.

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