Bromfield, Shropshire - sudden rise in temperature last night

[Freddie]

Interesting sudden rise in temperature just before 02:00 today. A clear and cold evening with light or calm winds, a slight air frost and some patchy fog. Around 01:30, as the pressure gradient tightened ahead of the next Atlantic system, the breeze started to stir the nocturnally cooled air. By 02:00 the speed was 5-8 knots, enough to mix down drier and warmer air from above the inversion. The result was a rapid clearance of the fog and a five degree rise in temperature in 5-10 minutes.