Saturday 15th August
Friday was the last of the heatwave days that once again produced a very hot day with a maximum of 31.4C at 14.40. This early peak was due to thin high, fair weather cloud, with a brief spell just after midday of variable, thicker cloud. The peak was down over 4C on the record breaking high of Thursday but still 9.8C above average. A low of 16.2C was recorded at 06.19 being 4.4C above average.
An unusual feature occurred during the evening. I was out watering the garden, as usual, when very large spots of rain fell for a couple of minutes at 19.20, recorded as a ‘trace’ being insufficient to measure. The reason was a narrow band of cloud, perhaps no wider than 5/6 miles across, that had formed from individual shower clouds over Somerset then coalesced as they approached our area. Usually shower activity gives Marlborough a miss. Sadly there were not sufficient spots of rain to even fully wet the dry and hot surfaces.
There was a significant change in our weather overnight, it was not totally calm as during previous nights under the high pressure. The breeze continued during the early hours, up to 10mph, and even more significantly, from the north, a much cooler direction.
The arrival of Saturday was totally different to recent days, gone were the clear blue skies that produced strong sunshine after sunrise. This was due to the back edge of the cold front that had rather dallied on its way across the country yesterday. There were large blobs of cloud over the eastern horizon that limited lengthy sunshine until just before 08.00.
A ridge of high pressure will edge back across the country today that will see the cloud thin and the temperature rise above average once again but probably just below the heatwave threshold.
Looking ahead, the forecast pressure charts indicate that another cold front could cross the country on Tuesday bringing more cloud but unlikely to produce much precipitation, if any, rated at just 30% probability at the moment, and by Wednesday peak temperatures will likely be close to the August average. The reason will be a low pressure system edging in from the northwest as the Azores high recedes westwards.