Most of Tuesday was fine, with some sunshine, but the warmth meant showers built up in the late afternoon with thunder heard at 17.16 followed by heavy rain that lasted until just after 21.30. Hail was observed at 17.25, classed as ‘small’ by the Meteorological Office, being less than 5mm in diameter. Another 10.1mm of precipitation yesterday took the monthly total to 49.6mm being 82% of the 39-year May average.
The sunshine lifted the temperature to a peak of 18.2C at 16.10 being 1.0C above the average. The overnight minimum of 8.8C was logged at 02.45 early Wednesday that lifted to 11.0C by 08.00, which was 1.9C above the average.
The barometric pressure dropped to 1009.5mb on Tuesday, the lowest since 23rd April, as another depression ganged up on the UK, moving closer in from the Atlantic.
Initially Wednesday arrived with total cloud cover but shortly after 07.40 sunshine broke through the gaps in the variable cloud cover. The centre of the depression this morning is just off the west coast of Scotland, not a deep depression thankfully, and will continue the westerly breeze, but light as yesterday. This unstable airstream will mean that further showers will build as the temperature rises. As the warming air rises it cools and the moisture contained in it condenses into showers. If the updraft is strong the raindrops will rise very high into much cooler air and then form hail.