Sunday 25th October
Saturday was dominated by the almost continuous light rain and drizzle that eventually amounted to 22.2mm. The rainfall for the month now stands at 113.7mm against my 43-year average of 90.8mm.
Saturday was an unusual day as the temperature began to rise during the evening, rather than fall away, reaching a maximum of 15.1C at 20.37, which was 0.2C above average and the warmest day since the 15th. At that time a very narrow band of heavier rain arrived, thanks to a cold front passing overhead, and of course, being a cold front it heralded in a cooler air stream. The thermometer then began to fall, dropping 5C over the next two hours, to eventually produce a minimum of 9.C at 02.46, early Sunday, that was 1.8C above average. As the cold front passed by the wind veered into the northwest. The peak gust of wind on Saturday measured 34mph at 21.39 following the peak gust of 32mph at 12.46 on Friday.
Sunday after dawn revealed an almost clear sky with a few light clouds scudding rapidly across the sky. The barometric pressure is rising rapidly that will give us a fine, dry day but the strong winds will continue for most of the day, peaking around midday, as Storm Boele eases away from Scotland. There is a significant pressure gradient between the exceptionally low pressure over Scotland and the Azores high to the southwest, hence the strong winds again today and for tomorrow.
Both Storm Austen and Storm Boelo deepened rapidly as they approached the UK. There are rare occasions when the barometric pressure drops a significant 24mb or more in 24 hours. This is known as explosive cyclogenesis, or headlined as a ‘weather bomb’, this occurred for both storms at their centre. I have analysed the local barometric pressure for both storms and found that over Marlborough the pressure dropped 22.6mb for Storm Austen and exactly 24mb for Storm Boelo. The details were 1010.5b to 987.9mb for Storm Austen and 1013.3mb to 989.3mb for Storm Boelo.
As a matter of interest, the centre of Storm Boelo measured 964mb at midnight when centred over Scotland, whilst the standard atmospheric pressure at sea level is 1013.25mb. The highest pressure for the UK was 1053.6mb at Aberdeen on 31st January 1902 and the lowest with 925.6mb at Ochtertyre, Perthshire, on 26th January 1884.
Monday will see the next depression edging in from the Atlantic. As its winds rotate anticlockwise it will usher in a strong breeze from the southwest that will produce a much warmer day with the maximum temperature a degree or two above average, following a wet morning.
Later on Tuesday and into Wednesday the forecast pressure charts indicate that the Azores high will attempt to push a ridge of high pressure across the UK behind the departing depression, which will begin to calm down the wind and squash out any showers resulting in mainly dry days for the rest of the week.