Sunday 21st June
Saturday was quite a pleasant day with the variable cloud limiting the rise in temperature to a maximum of 23.3C at 14.59, which was only 2.5C above average. There were a few spots of rain observed just after 20.00 but we missed again, the lines of shower activity that moved northeastwards along a corridor between Marlborough and Swindon with a heavy shower just 7 miles north of Marlborough, over Chiseldon. The past night was a little cooler than of late that saw the thermometer drop away to a minimum of 12.3C at 05.11, just after sunrise in Marlborough at 04.50, marking the longest day of the year. The peak UV light rose into the ‘Very High’ category.
The wind fell light just after 21.00 and has been calm overnight up to the time this report was finalised at 08.33.
Sunday arrived with a bank of cloud just above the eastern Horizon that limited sunshine around 07.00. The early morning sunshine had lifted the temperature to 19.5C by 08.00, just 1.2C under the average maximum for June. Today will see the thermometer rise well above the June average as the plume of hot air over the Continent pushes north over the UK, however, the maximum temperature will be slightly moderated by high, fair weather cloud.
The area of high pressure is enlarging and building over the UK with its border repositioning that will see the breeze come from the southeast today and probably east for the following two days. However, it will be light in nature as we come under the anticyclone. The barometric pressure has risen 8mb since Friday resulting in the highest pressure this month with a reading of 1025.3mb at 08.00 and rising steadily.
The extreme heat will arrive on Monday with forecast highs above 30C.
The very hit weather arriving from North Africa and the very hot Continent is trapped under a dome of high pressure
The extreme heat we will suffer under the coming week is all down to the “heat dome” currently squatting over Europe, sending temperatures soaring in France, Spain and Italy, and reaching 40°C in some places.
Heat domes usually occur in summer, when an area of high pressure in the upper atmosphere stays over the same area, as is now happening in Europe.
Air near the ground warmed by the Sun should rise, but is trapped in place by the high pressure, which acts like a lid over the dome. “This allows temperatures to build, day on day, as the sunshine heats the surface,” said a Met Office spokesperson.
This is compounded by a second effect. Air trapped by the lid ends up sinking and compressing, which further raises its temperature.
I am starting a new series of images, these taken at Compton Acres near Poole in Dorset.