Mid-month weather – What should we expect?

7 Feb

It goes without question that over the last week or two forecasting the weather has been both nail biting and also highly frustrating in association with an uncertainty over the specific synoptic evolutions.  With continued changes on a daily basis within the forecast models it made even the relatively short-term forecasts difficult, let alone attempting to get the longer term trends.

Once again we are now looking at a similar trend with regards to constant model changes and divergences within a relatively short time period over the weather at just 4 or 5 days ahead.  Over the last few days there has been a trend for the potential for a mid-Atlantic or even Greenland block of high pressure.  This would bring the risk of further colder conditions as we progress towards the mid-month period.  However, almost the opposite could be said at times with the models the next day showing a more unsettled and Atlantic dominated period of weather which would bring relatively mild conditions, particularly compared with present conditions…so what is the likely outcome?…

Today’s forecast models are interesting, take the UKMO and the ECM for example;

Both these models are attempting or actually do develop a ridge within the Central-North Atlantic and up towards Greenland.  There is also some modest support from the GFS as well, but in a more confused and uncertain state;

Could we be looking at the start of a trend?…This is a distinct possibility but as I highlighted at the start of this blog the models have been subject to constant and often daily changes particularly within the medium to long-term.  When it comes to forecasting the medium and long-term we need to look for forecast model agreement, which there is today as I have highlighted above, but we also need model consistency.  Consistency over a specific synoptic evolution between the various forecast models is highly important to come to a conclusion as to the expected weather within the medium to long-term. Clearly we don’t have any consistency as such with regards to this blocked pattern which would allow the risk of colder weather from the North or North-west.

The latest update of the ECM 32 day model does continue to signal a blocked pattern to the North-west of the UK as well, but in a generally less significant state than previous updates, but this signal has been evident within this model for a good 2 weeks at least.  There have also been signs and signals from other sources that as February progresses the general progression of the synoptic pattern would be for blocking to take place to the North-west of the UK.

The 64 million dollar question is; will this block actually develop and allow for further cold weather?…

…Well with relatively low confidence, given that lack of model consistency, but I do expect blocking to the North-west of the UK in some shape or form towards mid-February.  Whether this unleashes a very cold North or North-westerly air mass across the UK is unknown, the block could simply not be sustained enough to allow this to happen as well.  But in summary I do believe there is a realistic probability that the above charts will become reality and what we need now in the coming days is model consistency over this synoptic evolution.

As ever in meteorology…time will tell.

Regards to all,

M.

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2 Responses to “Mid-month weather – What should we expect?”

  1. Derek February 7, 2012 at 2:18 pm #

    In full agreement Matt. Anything past 4 days is FI and we certainly need way more model agreement across the next 96hrs to start putting money on any sustained event come mid month.

  2. Codge February 10, 2012 at 9:21 am #

    Great update. Much better than TWO forum

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