In uk.sci.weather on Mon, 20 Oct 2003 at 11:49:44, Chris Malcolm wrote :

If you watch at higher than usual resolution there are sometimes some
very fast small changes, e.g., a sudden tweak about half minute to a
minute before a rainstorm starts, and another before it stops.

If we ever get one of those again, I'll let you know.
--
Paul Hyett, Cheltenham

Email to pahyett[AT]activist[DOT]demon[DOT]co[DOT]uk