The named storms of 2015-16

Here’s a fond look back at the extratropical lows designated by the Met Office and Met Éireann as a named “storm” during the autumn, winter and spring of 2015-16.

The A-K of UK storm names of 2015-16, with links back to the Met Office web page:

Name Date named Date of impact on UK/Ireland
Abigail 10 November 2015 12 – 13 November 2015
Barney 16 November 2015 17 – 18 November 2015
Clodagh 28 November 2015 29 November 2015
Desmond 4 December 2015 5 – 6 December 2015
Eva 22 December 2015 24 December 2015
Frank 28 December 2015 29 – 30 December 2015
Gertrude 28 January 2016 29 January 2016
Henry 30 January 2016 1 – 2 February 2016
Imogen 7 February 2016 8 February 2016
Jake 1 March 2016 2 March 2016
Katie 25 March 2016 27 – 28 March 2016

 

Is our weather getting more stormy?

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Courtesy of the BBC

Now that we are getting into the stormy part of the year I thought that I would have a look back and see if the weather in the UK was getting more stormy in recent years. I don’t have access to climate statistics or any detailed anemograph records for the last 145 years, but I do have some thing that is probably a whole lot more useful in helping me to find the answer to that question a lot quicker, and that is the daily National Centers for Environmental Prediction [NCEP] reanalysis data back to 1871. Simply put, that is a grid of six hourly daily pressures values [MSLP] on either a 2° or 2.5° grid for the whole world. The Climate Research Unit [CRU] at the University of East Anglia [UEA] have done all the hard work really, because they used this reanalysis data to calculate daily statistics for the Objective Lamb Weather Type [LWT] series. Apart from producing a daily LWT, a by-product of these calculations is a Gale Intensity or Gale Index [GI] value. So there are a couple of caveats with anything that you find when using the LWT series, and those are that the GI is for a fixed place [55°N and 5°W]  in SW Scotland, and the GI is just for the 1200 UTC observation, so it’s a little basic. But the good thing is that the data series is long and easy to use. The first chart is of annual gale index values since 1871, and a s you can see from the linear trend the index is 6.9% higher now that it was at the start of the series.

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That 6.9% increase in the annual gale index since 1871 equates to an increase in 12.9 more days of gale in a year during that time. Incidentally the GI does not directly correspond to a wind speed in knots, so that a GI of 30 or more is equivalent to a gale (34-40 kts), a GI of 40 or more is equivalent to a severe gale (41-47 kts), and a GI of 50 or more is equivalent to a storm (>=48 kts).

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The anomaly chart below shows more clearly when the gale index began to increase, and as you can see it’s been mainly since around 1980 that it’s shown a concerted increase. 1990 for instance was a remarkably stormy year, but equally there have been occasional quiet years like 2010.

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If you look at the seasonal analysis through the year, all seasons show a similar ~7% increase in GI. This is the chart for Winter which shows an extra 5.8 gale days since 1871.

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So the short answer to the question that I posed in my title is, yes, that’s if the gale index in the objective LWT series is anything to go by. Why it’s getting stormier is another question, and one that I am not even going to try to answer!

 

Dutch top 10 storms

According to the Royal Netherlands Meteorological Institute [KNMI or Koninklijk Nederlands Meteorologisch Instituut] the top ten storms that have affected the Netherlands in recent years are:

  1. January 25, 1990
  2. January 3, 1976
  3. April 2, 1973
  4. November 13, 1972
  5. November 27, 1983
  6. October 27, 2002
  7. February 26, 1990
  8. February 1, 1983
  9. December 24, 1977
  10. January 16, 1974

They don’t say how far they go back but I bet they stop before the 31st of January 1953. They do describe how they work out the magnitude of the storms in their list though, and rather gratifyingly they use the same simple method that I came up with! All that they do is add all the mean speeds from a network of their observing stations and take the average over the duration of the storm. The problem that I found with this method is – defining the exact start and end of a storm – i.e. when do you start and stop counting. Anyway I do seem to have SYNOP data for 9 out of the 10 storms (#4 occurred before the start of my SYNOP records) so here are plotted charts for each of them in what should be descending order:

Synops for Thu, 25 Jan 1990 at 1800 UTC

#1

Synops for Sat, 3 Jan 1976 at 0000 UTC

#2

Synops for Mon, 2 Apr 1973 at 1800 UTC

#3

Synops for Sun, 27 Nov 1983 at 0600 UTC

#5

Synops for Sun, 27 Oct 2002 at 1200 UTC

#6

Synops for Mon, 26 Feb 1990 at 1200 UTC

#7

Synops for Tue, 1 Feb 1983 at 1200 UTC

#8

Synops for Sat, 24 Dec 1977 at 1200 UTC

#9

Synops for Thu, 17 Jan 1974 at 0000 UTC

#10

As you can see they all seem to follow a very similar scenario. A low tracks across the central North Sea and on into Denmark or northern Germany, surface winds strengthen to gale force from the south or southwest, before veering to the west or northwest. It’s so different from the British Isles because we are an Island and are far more exposed than the Dutch are to storms from a variety of quarters.