Pressure peaks and troughs

Air pressure is probably the least celebrated meteorological statistic, most probably because unless you’re staring at a barometer all day you can’t ‘see’ it.

High pressure brings mostly fine weather while low pressure usually brings wind and rain – though it is the gradient of the isobars that can measure the impact each system can bring.

Steep falls and rises in pressure bring the most memorable events, in my case the October 1987 storm.

During the next week there will be a notable fall in pressure – but how will it compare with the past recent years? Looking at my own stats, a relatively small but complete set of 9am barometer readings back to May 2013, it does look like it will be notable.

The table below shows the numbers to beat.

As with many of these events the most impactful weather was found in the north of Scotland. The first period coincides with Storm Caroline.
The Met Office blog says Caroline brought a max gust of 93mph at Fair Isle and transport disruption and closed schools across the Western Isles.

Of course what goes down also comes up and pressure rises can be even more notable. In February 2016 the pressure rose 50mb in just three days, a week or so after Storm Imogen.

According to the Met Office FAX charts the 9am pressure in London on March 11th will be around 988mb, which would represent a fall of 48.6mb from 9am on March 6th.

The early March storms singularity

Storms in late February / early March occur in 88 per cent of years, according to Philip Eden’s study on singularities.

This year looks no different although the drop in air pressure looks like it will happen just in the nick of time.

The GFS op for the March 9th compared with the situation on the 2nd

A look at the past eight years shows the effects of the pattern are quite pronounced.

And a look nationwide reveals the following named storms occurred around this period.

Storm Jake, March 2, 2016

Storm Ewan, February 28, 2017

Storm Emma, March 1, 2018

Storm Karine, March 2, 2020

And going back further reveals a notable storm in the 19th century.

Luke Howard’s meteors

Attention on the bright meteor seen over the UK earlier this week got me thinking about the meteors frequently mentioned in Luke Howard’s Climate of London volumes.

Howard had a keen interest in all things atmospheric, not least this celestial phenomena. Many of his personal accounts are mentioned over a period of a decade or so including accounts of meteors overseas.

April 4, 1807

February 1, 1808

July 12, 1808

December 16, 1808

March 22, 1809

May 1, 1809

July 18, 1809

January 26, 1811

April 1, 1811

November 7, 1812

April 23, 1813

July 29,1813

February 2, 1816

December 12, 1816

August 6, 1817

Decenber 8, 1817

January 28, 1818

February 6, 1818