May retrospective

Another well below average month in what is now turning into a regular feature of the UK weather. Even as recently as November 2009 I would have been shocked to see so many below average months in such a short period of time given how warm it had been in the previous 12 years.

May was nowhere near as cold as 1996 but it will still be the second coldest May in 26 years rounded off what is likely to be the coldest Spring in the CET area for well over 100 years. In recent times Spring has seen the biggest increase in temperatures relative to other seasons so this year has come as real shock off the back of another below average winter. Both maximum and minimum temperatures in May have been well below average.

The pattern matching last month did not give any strong signals but showed a slight bias towards below average which is how things turned out. I did indicate a risk (although it was not my preferred solution) of seeing a figure around the mid 10's and we are not too far away from that.

Looking ahead to June 

There are encouraging signs that the first half of June could bring some welcome warmth with a sustained period of above average temperatures. But will it last? I think it is unlikely but we do at least stand a chance of seeing our first above average month of 2013. 

Please place your June CET predictions in this thread. The deadline for entries with no penalty is 23:59 on 31 May. Late entries will be accepted up to 23:59 on 2 June but are subject to a penalty of 0.2C per day for the purposes of the annual competition.

June historic data summary

Here is the usual rundown of historic data for previous years.

2012 (13.5C) saw the first June more than 0.5C below average since 1991 (12.1C) athough it was only slightly cooler than 2011. We had a five year run of very warm June's from 2003 to 2008 with every year being above 15C. The warmest June in recent times was 2003 with 16.1C.

Long run averages:
1971-2000: 14.1C
1981-2010: 14.5C
1988-2012: 14.5C

Here is a chart of the June CET since 1961 with a 10 year moving average



Here are some details of what the models and forecasters generally are saying at the moment. Generally looks fairly warm up to mid-month after an indifferent start. But no signs of a heatwave.

GEFS
http://www.wetterzentrale.de/pics/MT8_London_ens.png
http://www.wetterzentrale.de/pics/MT8_Manchester_ens.png
Good agreement on above average conditions from the 5th to the 11th after a somwhat indifferent start. We need more than a week of warm weather to be sure of an above average month though.  

ECM ensembles (De Bilt)
http://www.knmi.nl/exp/pluim/vijftiendaagse/index.php
Shows an upward trend after a rather cool start.

Weatheronline
http://www.weatheronline.co.uk/cgi-app/reports?MENU=Month-ahead
As usual the forecast is a good week out of date. A cool start but turning somewhat warmer. 

Met office
http://www.metoffice.gov.uk/publicsector/contingency-planners
3 month contintency planners forecast for June to August not yet available. It will appear at the link above.

http://www.metoffice.gov.uk/public/weather/forecast/?tab=regionalForecast
30 day forecast - near average at first although warmer in the NW. After that close to normal but balance of probabilities is for slightly cooler than average conditions.

Pattern matching (just for fun)

This month I have looked at Spring CET's of 7.5C or less going back to 1840 combined with April-May CET between 8.4C and 9.4C and a May CET from 9.4C to 10.9C. There are only 8 matches. 5 years saw a June CET between 13.5C and 13.9C so in the slightly below average category. One year was exactly on the 1971-2000 average and two years were slightly above average, the warmest being 1845 at 14.9C. 

So again no strong signal this month but like May there is a slightly bias towards cooler than average conditions but only a little below average. The pattern matching suggests a June CET somewhere between 13.5C and 14.1C is the most likely scenario. 

So, further indicators on top of the long range models that point towards an average June.

The way it seems to be shaping up, I can see greater potential than in recent years for some warm conditions to establish at times, but the threat of slow moving troughs in the vicinity of the UK is also substantial.

Drawing it all together, and anticipating no major shift in where blocking tends to develop, produces more or less the same result as the models - it looks likely to be a fairly average month overall to me.

I suspect (or should I say hope) that the average whole might end up masking some marked variations between parts of the month, from warm and dry to cool and showery.

For a provisional prediction, I'll say 14.2°C please.

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13.8C for me please.

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That's brave - I think I'll be going for a lower figure than that.

I need another couple of days for my guess forecast.

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I'll take 14c exactly please.

For me it will be... 14.7...

Thank You.

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Below average again. 13.9 for me please.

13.4C for me please

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14.1C please.

The first month with an above-average CET this year in my opinion.

Not excessively so, and there will be spells of unsettled throughout also, but I am going to go for an above-average 14.8c please.

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14.9c

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13.9c. dry start but wet/thundery later on in the month.

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Got to have an above average month eventually 15.1c please.

 

 

 

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I'll go for 14C.

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14.1 please

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13.9C for me please.

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14.6 for me please and thank you

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13.8c please

15.0c please.

I am going to go for a chilly 13.1 C. It just doesn't seem to be able to get warm at all this year.

14.8c for me please.

14.9c for me please.

Warmer start then wobbling around average for the remainder of the month.

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Lets have some optimism amongst the doom please, i will go for 16.9 and go for a splendid June

14.4°c please.

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The contingency planners forecast is now out. Not good news for those who want a warm summer. Both June and summer as a whole have a slightly greater than normal chance of being below average. A La Niña event is also looking possible which on past experience could increase the chances of a colder than average winter.

So the pattern matching analysis does seem to have some support for a continuation of generally cooler than average conditions. Of course there are bound to be some warmer interludes as well but we will probably need to make the most of these.

http://www.metoffice.gov.uk/media/pdf/3/g/A3-plots-temp-JJA.pdf