High barometric pressures - but nowhere near record levels

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High barometric pressures - but nowhere near record levels

Postby Stephen Burt » 2014 Dec 30, 22:46

Pressure has been high these last few days - 1044 mbar in Brittany yesterday, so 1042-1043 mbar over south-west England.

A recent post on this forum implies that the recent values were at near-record levels ... but this is a long way from the truth, even for south-west England. It's just that we've not had many really intense anticyclones for over 20 years now, which in fairness probably covers many 'personal' record lengths (so I'm not having a go at anyone in particular!)

The most intense high affecting the British Isles in recent years - the last quarter-century or so - was in January 1992, when the barometer reached 1049.2 mbar at Sennybridge in South Wales on 27 January. Nowhere in the British Isles has surpassed 1047 mbar since that date, and even occasions of 1045-1046 mbar have been few and far between.

Since 1949, the highest barometric pressures recorded in south-west England occurred in Feb 1964 - Plymouth reached 1048.3 mbar on 7th. So you'd need a 50 year record to include that.

It might then come as a surprise to know that the second-highest barometric pressure in the UK was recorded in south-west England, just 1/2 mbar below the UK's all-time highest, 1053.6 mbar recorded in Aberdeen in January 1902.

On 28 January 1905, the MSL barometer reached 1053.1 mbar at Falmouth Observatory at 11h, the highest since records began there in 1870 and a value that has not been remotely approached since.

It's hard to believe the barometer rising above 1050 mbar in these islands, but it has happened in the past, even in south-west England. Now that's a record!

There's more on this and other high pressure events in the article I wrote in Weather in February 2007, which is available online (to RMetS members) via the RMetS website.

It's already almost 60 years since 1050 mbar was reached anywhere in the British Isles (1050.9 mbar at Belmullet in NW Ireland, on 16 January 1957), and yet this value was attained somewhere in Britain in 1808, 1820, 1896, 1902, 1905, 1907, 1926 and 1932 before 1957. Note four times in just 12 years between 1896 and 1907, but not since 1957. I wonder if we'll see this again in my lifetime? Who knows, it could be next month ... or not for another hundred years!

Stratfield Mortimer, Berkshire - central southern England
51.4°N, 1.0°W, 60 m AMSL, station grade A - AAAA47R
Records commenced here 1987 - local records available back to 1862
The Weather Observer's Handbook: www.measuringtheweather.com
Stephen Burt
Posts: 247
Joined: 2011 Dec 02, 19:36
Location: Stratfield Mortimer, Berkshire; a well-exposed rural site, 10 km SW of Reading

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