After 4 mainly sunny days, woke up to a sheet of sc (borderline
altostratus) this morning. With the virtually calm conditions the
converging sea breezes pushed it into a thick band of cumuliform cloud
along the centre of the peninsula by 11:00, with increasing breaks on
the coast.

By 13:00 there was a stationary heavy shower over inland (well nearly
a mile inland!) parts of Penzance, with water streaming off the roads.
At my station, about 600 yards inland, just of few spots now and again
between 11:30 & 14:00. On the seafront strong sunshine, with the edge
of the cloud just over head, with a nice deep blue 'hole' in the cloud
over the bay, with the stratoform cloud out to sea. The shower shows
up omn the 13:00 radar.

The very sharp southern edge to the cloud remained for around 4 hours,
from 11:30-15:30, meaning that just a few hundred yards separated
spots with good periods of sunshine from those with none & bursts of
heavy rain.

A particularly good erxample of sea breeze convergence.

There was an onshore sea breeze on the north coast, and calm
conditions in Mount's Bay became a force 4 onshore southerly for a
time during the height of the shower.

Sorry if I've waffled on a bit, but I'm very much an old fashioned
weather (and sea) observer rather than a model watcher, and I find
this sort of thing very interesting.

Graham
Penzance