On 10/03/2021 18:09, N_Cook wrote:
In the local record maximum rain rate as 530mm/hour (sic 0.53m/hr) 00:15
27 Dec 2020 for a short duration. The owner , an ex metman , cannot
confirm it as genuine or not, but looks iffy. Later a short burst of
340mm/hr, overall 23mm in 6 hours. Could they be genuine extreme
rain-rate records?

That would obviously be an extreme value and represents consecutive tips
in about one second. While not impossible, I'd be quite sceptical that
it was genuine. But difficult to be sure without seeing a log of the
data (eg a wlk file), preferably with a short archive interval. If it
was just an isolated pair of tips I've be very sceptical, but it
obviously depends what was happening in general to the rainfall record
at the time.

An issue like this certainly can be artefactual. If it's an old gauge
then there could be contact bounce in the reed switch. Or if the front
cover to the ISS is not making a good seal then water can get in and on
to the contacts in the plug/socket from the rain gauge, giving
spuriously high rain rates.