Category: Commentary

Friday gave us a bright start but sharp showers soon began to develop late morning. The daily rainfall amounted to 7.9mm bringing the August total to 74.6mm, which is 8mm above the 36-year average. The wind was often quite brisk, particularly as the rain squalls passed through with a maximum gust of 21mph.

Temperatures by day and night were depressed as the wind in the afternoon veered into the northwest and later north bring much cooler air. The maximum of 16.7C was 4.3C below the August average and occurred late morning at 11.29 and then began to fall back. With the northerly brisk breeze continuing overnight it was not surprising to find that the thermometer dropped well below average with a minimum of 9.2C (-2.4C) in the early hours of Saturday at 03.45.

Saturday arrived with a predominantly cloudy sky and the cool northerly persisting that meant it was the coldest start to a day at 08.00 since 6th June with the thermometer reading only 10.1C. The distinctly autumnal feel to the weather is due to a depression to the east circulating anticlockwise and an anticyclone in the eastern Atlantic circulating clockwise, as they do, bringing the very cool air down across the country from much further north.

After a bright start on Thursday the rain arrived again with a daily total of 14.1mm that brought the month total to 66.7mm, which is exactly the 36-year average for August.

The wind was initially from the southeast but variable in the gusts to 31mph and in the evening made an abrupt change to the north.

Both maximum and minimum were below average, not unexpected with all the cloud and rain, with just 15.0C (-6.0C) at 08.54 on Thursday morning and 10.9C (-0.7C) at 06.42 on Friday. This unusually low daytime temperature made it the coolest day since 18th June when that day had exceptional rainfall. Very unusually the warmth slowly fell away during the daytime and did not rise as is normal during the summer.

At sunrise on Friday radiation fog had formed in the River Og valley. Shortly afterwards a fog bank was observed drifting over the Marlborough Downs from the Thames Valley to the north that began to dissipate by 07.30.

Wednesday, after a cloudy start, gave us 8.7 hours of intermittent sunshine. However, the wind although much less strong than on Tuesday with a peak gust of 22mph, came from the west, a cooler direction. The maximum temperature of 20.2C was 0.8C below the 36-year average. It was a dry day with the UV level reaching ‘High”.

A cool night followed with a minimum of 10.2C at 06.40 on Thursday. This was 1.4C below the average and, after recent rainfall, allowed radiation mist to form temporarily in the River Og valley that quickly dispersed shortly after dawn.

Thursday started dull with a cloud bank over the eastern horizon but by 07.30 the sun was appearing over the cloud edge and by 08.00 shining brightly. However, the cooler night and the sun getting up much later at this time of year, meant the coolest start to the day at 08.00 since 11th June with a temperature of 12.1C.

Storm Francis arrived with a vengeance on Tuesday. After the early morning deluge with 17.1mm reported yesterday before 08.00, another 3.3mm fell during the daytime bringing the monthly rainfall total to 52.6mm. However, we have lost the equivalent rainfall of 68mm due to evaporation from the soil and plant life so far this month.

The other noticeable feature was the strength of the wind as forecast. The strongest gust of wind recorded was 48mph at 15.28. This was the strongest gust of wind recorded during the month of August since the station started in 1984.

The wind slowly subsided in the early hours of Wednesday with a maximum gust of just 15mph.

Wednesday morning was in stark contrast to Tuesday with sunshine shortly after dawn with minimal cloud and dry. A transient ridge of high pressure is providing the improved conditions with the barometric pressure having risen 11mb since the Tuesday minimum, with a current reading of 1010.5mb. Storm Francis is now visiting Denmark.

After a damp start to Monday the afternoon was brighter with 5 hours of sunshine and a peak temperature just above the average (+0.4C) with a reading of 21.4C at 15.52.

The wind strength was moderate on Monday with, during daylight hours, a peak gust of 14mph.

There were a few drops of rain, not measurable, late afternoon on Monday but the real rain arrived overnight beginning at 01.30 Tuesday with an intense burst at 02.15. By the time readings were taken at 08.00, 17.1mm had fallen making the past twenty-four hours the wettest day since 20th July. This rainfall brought the monthly total to 49.3mm, which is still 17.4mm below the 36-year average. The main rain band has now departed as the depression eases north eastwards.

The barometric pressure has been falling since the early hours of Monday as Storm Francis approached the UK. The current reading was 999.2mb at 08.00 and falling rapidly. As the depression deepened the isobars tightened that produced the increase in wind speed since 01.30 Tuesday morning with peak gusts, so far, of 30mph at 07.55, but forecast to increase considerably during daylight hours. The centre of Storm Francis is currently moving northeastwards across Ireland towards the Isle of Man with a central pressure of 981mb. As a consequence the current southerly wind with veer towards the southwest as the day progresses.

Update on Tuesday at 17.50: maximum gust of 48mph at 15.28.