Is London heading for a hot summer?

Before I’m accused of going all Daily Express the following is based on winter statistics for the London area and other variables rather than the latest expert hopecast.

Even before looking at the data in depth the chart below shows that a warmer than average summer is more likely after a mild winter. The winter just gone was the third mildest in a record going back to 1797.

combined

There are some real corkers in that list, including 1995 when this area recorded the driest August on record. Other notable summers included 1990 – England in the semi-finals of the World Cup and another notably fine August: the then hottest UK temperature was set that year when a maximum of 37.1C was recorded at Cheltenham – a record that lasted until 2003. The year 1989 also stands out with a notably sunny summer.

So far, so good. But what about rainfall? Some 145mm of rain fell this winter – pretty much on the nose average for this region. Combining warm winters with similarly average rainfall gives the following list.

with similar rain

Though some years have disappeared there are still some decent summers, and notably sunny too. The year 1975 stands out as does the sunniest summer on record, 1911! Both were also very dry summers.

Altough the teleconnection with El Nino is tentative in our part of the world the winter seemed to follow the pattern of most positive ENSO episodes, so it is worth having a look to see where the data goes. The latest forecast by NOAA suggests:

A transition to ENSO-neutral is likely during late Northern Hemisphere spring or early summer 2016, with a possible transition to La Niña conditions during the fall.*

If the forecast goes to plan the second ‘rainfall list’ would narrow further:

Screen Shot 2016-03-08 at 02.44.05

Viewed by graph reveals that ENSO values of all the years decreased over the course of the year. Series 1 is 1998, series 2 is 1983 etc.

Screen Shot 2016-03-08 at 02.48.01

In conclusion, the results would suggest that there is a 66% chance of a decent summer with below average rainfall and above average sunshine. In terms of details June 1st is still a very long off in meteorological terms – so whether it includes any heatwaves that would put it my premier league of hot spells is anyone’s guess at this range.

If it’s anything like 1959, 1975, 1983 or 1998, however, I think most folk will be happy.

*The above contradicts some forecasts which suggest a continuation of the general pattern that persisted during the winter: warm SSTs in the Atlantic / warm water south of the Grand Banks were largely responsible for the cyclonic westerly type of weather that caused the mild weather. In summer this would cause changeable weather rather than long spells of settled weather.

 

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2 responses to “Is London heading for a hot summer?

  1. great analysis, looking forward to it! Just saw a tweet that switch to -ENSO could occur by June, are there any connections with UK summers from dip to -ve enso / trending La Nina status?

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    • Thanks. Yes, it is more or less covered in that blog.
      The list, starting with the most similar pattern to this year, follows:
      1998 and 1983 are most similar in terms of El Nino being over 2 at the start of the year.
      1959 and 1975 also dipped through the year but were both notably sunny.
      It is perhaps simplistic but I think, overall, the data is compelling. And there is obviously the caveat that other variables, such as a huge volcanic eruption, could change things between now and June 1st…

      Like

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