Category: Commentary

Wednesday saw more cloud bubbling up with reduced sunshine, just under 6 hours, that combined with the northeasterly breeze meant a cooler day than on Tuesday. The thermometer slowly rose to a peak of 12.8C at 14.12.

During the evening the thermometer slowly fell away but by 23.00 had fallen no lower than 4.7C. However, later in the night, as the light breeze dropped out, a hard frost occurred with a minimum of -2.9C at 06.06 on Thursday.

Thursday began with bright sunshine after dawn in clear skies with the thermometer recovering to 3.2C at 08.00. At that time the barometric pressure, still centred over the UK, read 1034.4mb, which is the highest pressure for over a month.

By the end of today we will be half way through the month, which so far has been very dry with little forecast over the next few days under the influence of the anticyclone. The precipitation to date is just 7.4mm against the 37-year average of 58.5mm.

During the 7.7 hours of sunshine on Tuesday, and thanks to the light winds, maximum gust of 10mph, the thermometer rose to a maximum of 13.5C. This was the warmest day since the 4th but still 0.8C below the average.

It was another dry day, the tenth this month. The rainfall total for April currently stands at 7.4mm while the moisture lost through evaporation from ground sources and plant life is equivalent to 22mm of rainfall. The previous two months brought below average rainfall totals and with no significant rain in the forecast for severval days we are experiencing a significant dry period.

The thermometer did eventually drop below freezing overnight at 02.00 on Wednesday morning that gave a minimum of -0.3C at 03.56.

Muted sunshine on Wednesday after dawn, through thin high cloud, raised the temperature to 2.8C at 08.00. The anticyclone is still centred over the UK with light winds continuing.

The high pressure now centred over the UK has been intensifying over the past twenty-four hours, as a result it has blocked the flow of Arctic Air but left a pool of very cold, static air over the UK. The thermometer on Monday, during 6.7 hours of sunshine, rose to a maximum of 9.7C, however, this was again below average (-4.3C).

The thermometer fell steadily downwards during Monday evening and at 22.39 dropped below freezing (-0.1C), just six minutes later than the previous night. The past night has been the coldest since 11th February win a minimum of -3.9C at 06.20 on Tuesday morning being a significant 8C below average. In fact we have only had one day and night with temperatures above average.

Tuesday saw bright, if muted sunshine for the first hour but a fog bank, which had been lurking to the north of Marlborough from the Thames Valley, rolled in over the Downs so that by 07.15 the visibility had reduced to 200m. The sun disappeared half an hour later so that by 08.00 the temperature was still below freezing with a reading of -0.4C.

The anticyclone has dampened out the wind of previous days and dropped out entirely for many hours overnight thus allowing the frost to intensify. The barometric pressure at 08.00 was 1033.7mb

The welcome 6.9 hours of sunshine on Sunday, intermittent in the morning but more sustained in the afternoon, encouraged the thermometer to rise to a maximum of 9.7C, This was up 4C on the very cold Saturday peak but still 5.4C below the 37-year April average.

A brief light shower of small hail (less than 5mm in size) was observed at 13.00.

The thermometer fell steadily during the late afternoon and evening to reach freezing point (-0.1) at 22.33 on Sunday evening. It continued falling until reaching a minimum of -2.6C at 02.52 early Monday morning. At that time the advancing weather front would have started to ease in the initial cloud with humidity starting to increase after 03.10. The radar showed thick cloud and precipitation arriving over this area at 04.10, which by daylight could be seen as a covering of snow but had ceased by 05.30. In the calm conditions there was a level 1cm of snow that began to slowly melt as the thermometer had risen to 2.0C at 08.00. The equivalent liquid from the melted snow amounted to 0.8mm.

Throughout daylight hours on Saturday an area of thick cloud persisted over the area initially producing drizzle that then became light rain for almost twelve hours. It was an exceptionally cold day with the thermometer rising just a couple of degrees from that at dawn to a maximum of only 5.9C, which was a significant 8.4C below the 37-year average and the coldest since 7th March.

It was the first sunless day since 20th March with the UV peak of 1.4, which is at the lower end of “Low”.

During the early evening the temperature dropped to 2.0C and the precipitation turned to wet snow with a daily total of 6.2mm. This was the wettest day since 26th March and brought the monthly total to 6.6mm when the average is 58.5mm.

The cloud eventually thinned overnight and allowed the temperature to drop to -0.6C at 05.05 on Sunday morning that saw very brief bright intervals between occasional breaks in the cloud, which was thinner and higher than on Saturday.