Tag Archives: Weather in London

April 2018: four seasons in one month

I normally headline these monthly reviews by referring to the most notable weather but this April, often a fairly non-descript mid-spring affair, offered pretty much every type of weather. bluebells

The mean temperature finished 11.7C, 1.9C above average and the warmest for four years.

Rainfall was 55mm, 129 per cent of average and the wettest for 6 years.

Sunshine was just 110 hours, the dullest for 40 years and the 16th dullest since 1881.

Hidden in the positive monthly anomaly was the warmest April day in a local record going back to 1959: 29.1C on the 19th – a figure that represents a positive anomaly of 15.5C and occurring at the start of the warmest April heatwave since 2011. It was remarkable that such an anomaly happened so close to a record negative anomaly the previous month.

Yet, just over a week later, temperatures lurched cold again with one of coldest last days of April on record. Though the 24hr record wasn’t broken the noon-6pm record going back 60 years was beaten.

The wettest day occurred on the 9th with 10mm falling.

Air frosts: 0, Ground frosts: 1

sunset 22nd

18th warmest

29.1

rainapril30
April 30th provided a timely reminder after the heatwave to ne’er cast a clout till May is out. A low pressure system in the North Sea brought a thoroughly miserable day though even more rain fell across the Channel.
april30
It was a month with some amazing sunsets. This one, on April 30th, happened just as the sky cleared before dusk

 

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Record low pressure of February 25th 1989

The low pressure system that brought widespread rain and snow on Wednesday reminded me of another event where very low atmospheric pressure helped many low-lying areas experience heavy snowfall.

The unusually deep depression ran along the Channel on February 25th 1989.  Its central pressure of 948mb has been unequalled over southern England since, the value was some 13mb below the lowest on record at the Kew observatory.

Though temperatures reached around 6C in the morning they fell away as the day progressed. This and falling pressure helped turn the rain to snow.  Accumulations were fairly wet in the London area but further north over East Anglia some notable falls were recorded.

greenwich

MetO 25021989
Courtesy of the Met Office

GFS 25021989

summary 25021989
Courtesy of the Met Office
summary2 25021989
Courtesy of the Met Office

London Grimness index

The last three months in east London have been sunnier than average – hard to believe as we move into a regime of easterlies that will bring showers and anticyclonic gloom.

Screen Shot 2017-12-21 at 21.30.14
A sunless outlook from the Met Office last December

With no sun and short days  it is no surprise that many are probably already feeling short-changed in the solar stakes.

A blog by XMetman on a ‘grimness index’ got me thinking how London fairs in terms of sunshine, temperature and rain in any given winter season.

Using the same criteria, and assuming that most people welcome sunshine, it can be seen that since the least grim winter of 2007-08, the season, over the past 10 years, has been growing steadily worse.

Screen Shot 2017-12-21 at 21.51.54The grimmest winter, considering statistics back to 1881, was, ironically, the 1978-79 ‘Winter of Discontent’ when, again ironically, ‘Sunny Jim’ Callaghan was in Downing Street as widespread strikes coincided with the coldest winter for 16 years. On looking at the Top 10 of grim winters it is striking how most coincide with depressing world events, the Great War, World War 2 and the Korean War!

grim index

The Tory ‘Crisis? What Crisis?’ campaign was probably my first memory of a general election broadcast.