Similar situation here in France yesterday. The morning was warm and
humid (temp reached 20), and thundery looking, with a light north-
easterly breeze. The pressure fell from 1011 mb at 07:00 to 1003.7 at
15:30. From around 16:00 the wind veered into the south west and
increased, gusting to 35 mph, heavy rain started, there were a couple
of flashes of lightning and the pressure shot up to 1012 mb by 20:00.
Typical cold front progression around these parts. First thunder of
the year! (the last recorded thunder event was in September last
year).

CK, Correze, France