Author: Eric Gilbert

Wednesday 30th.
The very wide weather front that escaped around the northern ridge of high pressure on Tuesday, brought unexpectedly more thick cloud and precipitation than was forecast by the experts or thought to be possible by me. There were several areas of rain and drizzle that crossed our area, which deposited a very welcome 7.2mm that took the monthly rainfall to 28.4mm being 47% of my 41-year average. This was the wettest day since 7th June when 7.9mm was recorded. The welcome rain refilled two of my large water buts with around 400 litres, so minimal watering of garden last night. The persistent cloud and lack of sunshine limited the rise in temperature so that the maximum of 21.0C, logged at 14.44, was 1.7C below my long-term average. The cloud cover meant the opposite overnight providing us with a mild night as the thermometer did not sink below 15.1C in the early hours of Wednesday at 03.44 being 3.2C above average.

The start to Wednesday revealed total cloud cover from the back edge of the weather front with little increase in temperature by 08.00, when 15.7C was logged. The humidity at 08.00 read 90.3%, very high, that resulted from the mild night and precipitation over the past twenty-four hours. Hopefully, there will be more sunshine later today as the disturbed area from the weather front edges away.

Although we had the persistent cloud on Tuesday there has been little change in the barometric pressure that read 1020.2mb at 08.00, down just 1mb since Monday, as the ridge of high pressure from the Azores High is still extending over the UK, however the low pressure systems over Scandinavia with another over Iceland are relatively close by and having an influence on our weather as yet another weather front is now likely to cross our area on Thursday, travelling around the northern edge of the anticyclone. Last night the experts varied between two hours of light rain and seven hours of thundery rain on Thursday. Today there is more agreement that Thursday could bring multiple showers during daylight hours.

The original mansion at Compton Acres was demolished in the 1960s, along with the Arts and Crafts English Garden. The area was sold for development into flats, leaving the themed gardens as the Compton Acres of today.

Tuesday 29th.
Monday saw the sun return with temperatures returning above average by day with a maximum of 24.3C late in the afternoon at 17.17, being +1.6C. The day was dry with the UV level peaking at a value of 7.0 at 13.47, in burst of strong sunshine, which was just into the ‘Very High’ category. The evening gave us a clear sky but after midnight cloud drifted in from the west on a weak weather front that had sneaked in around the northern edge of the anticyclone. Very light rain from the weather front started just after 05.30, that was minimal, with just 0.4mm recorded by 08.00.

Tuesday after dawn revealed the total, thick cloud cover that brought the very light precipitation, which had ceased by 07.00. There has been a significant change in wind direction overnight that will see it come from the south west until later today when it reverts back to northwest.

The July rainfall now stands at 21.2mm, which is just 35% of my 41-year average or minus 38.6mm from the average. July rainfall has seen as little as 10.1mm in 1999 and 127.2mm in the wet July of 2007. The many hours of strong sunshine with so little rainfall has meant much moisture has been lost through evaporation, which averages almost 4mm per day this month. In fact, the equivalent loss of rainfall through evaporation from ground sources and plant life this month now totals 103.1mm.

The barometric pressure has varied little over the past two days, the northern edge has receded a little allowing the cloud to drift around its north eastern periphery so no great quantity, which will mean sunshine and showers over the next few days with near average temperatures. The barometric pressure reading at 08.00 was 1020.5mb, down just a millibar since yesterday.

Compton Acres consists of five themed sub-gardens: an Italian garden, a rock and water garden, a heather garden, a Japanese garden and a less formal woodland garden called the “Wooded Valley”. The picture is of an Emperor dragonfly at Compton Gardens.

Monday 27th.
Sunday gave us a cool and cloudy start although it brightened up in the afternoon, however, the northwesterly breeze and limited sunshine meant a cooler day. The maximum of 21.6C was logged at 15.54 being 1.1C below average. The UV level was also much lower with a value of 4.1, the second lowest after the showery day on the 6th, rated as ‘Medium’ strength. It was the nineteenth dry day this month.

The past night was unexpectedly cool that saw the thermometer drop away to reach a minimum of 8.2C at 06.04 That was just after the time the sun was supposed to rise at 05.24, however, cloud obscured any sunshine. This low was 3.7C below my long-term average.

Monday arrived with total cloud cover, which looking at the back track of the cloud radar indicated a relatively clear night until the cloud eased down just after 05.00, which is why the temperature dropped so low for July. There was a modest recovery in the temperature to reach 12.5C by 08.00.

The high pressure has begun to reassert itself with a rise of 3mb since yesterday. However, the track of the air stream is around its western flank then dropping down over the UK, coming from a cooler northwesterly direction. This is a long track over the ocean, picking up moisture on its way, hence the variable cloud cover over the next few days. The other factor is that the centre of the Azores High is in mid-Atlantic rather than over the UK, when it would have meant much clearer air and higher temperatures.

With very little rain, even in the form of showers, the ground continues to dry out which has seen the rate of evaporation reduce to around 2mm per day when earlier in the month it was up to 6mm a day. The rainfall for July currently stands at 20.8mm with the equivalent loss of rainfall through evaporation from ground sources now totalling 102.0mm.

An example of the flowers at the Compton Acres Gardens near Poole.

Sunday 27th.
The variable cloud on Saturday morning limited the initial rise in temperature that at 11.30 brought a very brief shower of light drizzle that was not measurable. By the afternoon, the cloud diminished considerably, from time to time, that allowed the sunshine to raise the thermometer to a maximum of 24.9C by 17.13, being 2.2C above my long-term average. The variable cloud limited the UV strength with a value of 5.4 at its maximum, logged at 15.40 in a brighter period, the lowest for three days being at the bottom end of ‘High’. Once again overnight cloud cover gave us a mild night with the thermometer not dropping below 13.7C, logged at 05.48, being 1.8C above average.

There was a very brief period of brightness before 06.00 on Sunday but the encroaching cloud soon produced total cover and blocked out any early morning sunshine. As a result the air temperature has only risen a couple of degrees to reach 15.6C by 08.00. The conditions have been calm with the anemometer only very slowly rotating at up to 2mph, but often stationary.

The Azores High has retreated a little and made a slight change in its position. This will bring an airstream around its northern flank, then down across the UK from a northwesterly direction, picking up moisture from the Atlantic as it travels. Cloud cover, combined with this slightly cooler wind direction will limit the warmth on Sunday to a maximum around a degree or two below my long-term average for July of 22.7C. To the north and east of the UK are two large areas of low pressure that are competing for attention against the Azores High. The anticyclone is likely to hold on to its position for a few more days so more calm and sunny days ahead are likely next week with the temperature probably rising above average again.

Compton Gardens has 5 main themed gardens joined by a series of links, including a sub-tropical area.

Friday brought intense sunshine that resulted in the temperature steadily rising all day to reach a maximum of 27.7C at 16.12, which was exactly 5C above my long-term average. It was also the hottest day since the last day of the heatwave on the 13th being just above the heatwave threshold for Wiltshire of 27C. The UV level rose to 7.1, the strongest for a week and into the ‘Very High” category. The persistent overnight cloud cover meant a very mild night with a minimum of 15.9C at 06.36 early Saturday.

The first look at Saturday revealed thick cloud cover. The back track of the cloud and rain radar showed a warm front had passed our way in the early hours that brought low cloud and drizzle between 05.30 and 06.00, which amounted to 0.1mm. This amount was not sufficient to trigger the automatic rain gauge that works on increments of 0.2mm, which is why I continue to use the standard Met Office 5″ copper rain gauge that uses a measuring jar inscribed with 0.1mm intervals.

The high pressure has retreated a little that will allow another weather front, this time a cold front, to pass over the UK during Saturday morning. There is a possibility that this front might produce a light shower or two but it is already fragmenting over the west country. The barometric pressure has dropped 3mb since yesterday, however, it is likely to be the dominant feature driving our weather over the next few days with sunny intervals, variable cloud and maxima around or just above average for July.

Compton Acres, where I captured this wild life, is a “hidden treasure in Poole with 10 acres of stunning gardens filled with shrubs, trees and flowers”.