After a relatively calm and sunny day on Tuesday the thermometer lifted above average again, just, with a maximum of 14.7C being 0.6C above my long-term average. Thicker cloud built up in the afternoon, thanks to the depression that had been lurking over Brittany, throwing up a large area of cloud that produced light rain just after 16.00. Another light rain shower triggered the automatic rain gauge at 00.52 that raised the daily precipitation to just 1.0mm. Considerable rain ran up the east and west coasts during the day and to the west overnight. The low of 4.6C was logged at 05.59 early Wednesday being also above average, just, at +0.9C.
Wednesday after dawn revealed broken cloud scudding fast across the sky. Overnight, the depression had decided to move north and visit the UK, continuing to move north to the west of our region. We have been, and continue to be on the periphery of the depression, however, the wind strength increased markedly during the late evening and overnight as we were close to the centre of the depression. The minimum barometric pressure of 994.1mb was logged, the lowest since 28th January. The first indication of rising wind strength was observed just after 22.00, building to a peak of 33mph at 02.14, but close to that peak for several hours. As the day progresses the cloud is likely to break up and thin as the depression eases away, allowing some variable sunshine with the wind slowly decreasing.
The temperature of 6.7C at 08.30 felt more like 5.0C outside due to considerable wind chill. Wind chill could be called the ‘feels like’ temperature being different to the actual air temperature, which measures air temperature, relative humidity and wind strength at five feet (human height) as well as an understanding of how heat is lost from the human body during cold and windy days.
There is no official definition of wind chill as definitions vary globally, dependent on how it is measured. In the UK, a system called the Joint Action Group for Temperature Indices is used to realistically measure wind chill. This calculates wind chill by measuring how much heat is lost from a person’s bare face at a walking speed of 3mph.
As the depression moves away the barometric pressure is rising rapidly at over 4mb every three hours.