On May 28, 8:20*am, "Rob Brooks" bogus
wrote:
At about 0645 BST this morning the pressure *fell by 5.5mb inside the hour.
This is shown on my barograph and also on my AWS Vantage pro, so there is no
instrument failure. *The pressure has *now recovered, but the change on my
barograph looks like some major feature has passed through. I have not seen
a *pressure change of this magnitude in such a short time scale- I can only
assume it was a storm cell that was very close by.

Rob
Farsley
near Leeds

It sounds as if it was thunderstorm-related but extremely rapid
falls can be caused by gravity waves. One of these affected west
London (Sunbury) on about 19 Jan 1977. We had a mercury barometer in
the laboratory and you could actually just about see the mercury
surface falling. I cannot remember the exact figures (it has been
written about, probably in "Weather") but 8 mb in 5 minutes seems to
ring a bell. There were gusts to 30 kn but nothing more in an
otherwise breezy cloudy SW'ly. The expected End Of The World did not
happen.

Tudor Hughes, Warlingham, Surrey