Author: Eric Gilbert

Friday was the last of the very warm and dry days under the resident high-pressure this month. A maximum of 21.6C was logged at 15.56 being the second highest this month and 7.4C above my long-term average. The day was also notable for the light breeze, there was a peak gust of 9mph but much of the day was calm. There was also a significant change overnight as thin cloud drifted up from the south that minimised loss of warmth into the atmosphere resulting in a minimum of 3.3C at 02.18 being, just 0.4C below average.

The thin and broken cloud was evident after dawn although by 08.00 the weak sun had lifted the temperature to 9.2C making it the second warmest start to a day at that time this month.

The anticyclone that has dominated our weather all month has moved away, far to the east, and we are now coming under the influence of a depression in the eastern Atlantic. This low pressure will bring weather fronts across the country today and is already throwing up more cloud that will thicken as the day progresses. At the moment there is little indication of any precipitation over the weekend.

It is suggested that the name “Pink Moon” was given by Native Americans to represent the colour of the wild ground phlox.

It took a while for the sun to burn back the cloud on Thursday beginning to breakthrough around 10.00 and then strongly after 11.00. The maximum of 15.9C was logged at 16.48 in the strong late afternoon sunshine being 1.8C above my long-term average. Overnight was a repeat of previous evenings with the temperature falling steadily. The thermometer logged freezing air (-0.1C) at 05.23 early Friday and getting back above freezing at 06.48 after the sun got to work. The minimum of -0.4C was recorded at 06.07 being 4.1C below average. Although the cloud limited the morning sunshine the high solar pf 737W/m2 was the second highest all month after the peak of 835W/m2 on the 4th. The peak gust of just 9mph made it the equal calmest day this month.

Thankfully, no cloud drifted across from the east overnight so the sun shone strongly after it had lifted above the horizon raising the temperature to 4.9C by 08.00. It has been a remarkably calm start to the new day with the anemometer stationary for long periods, in fact there was a movement of just 1mph just before 23.00 last night and nothing again until a movement of 2mph at 04.31, 04.32 and 04.33 early this morning then calm again.

The barometric pressure charts show the anticyclone beginning to move eastwards over the next day or two, towards the Mediterranean, with the depression to the west getting closer. The barometric pressure has already dropped a significant 7mb since yesterday. This signals the change to a more unstable weather pattern with the wind on Sunday projected to come from a more westerly direction after the cool easterly quarter that has plagued us all month but offset by the strong sunshine. At the moment the forecast charts don’t show any significant rainfall over the next few days although two weather fronts are likely to cross the country on Sunday.

The apple trees are showing signs of the buds beginning to open so over the next week I will include images of the various stages as the blossom begins to fully open attracting the bees.

Wednesday brought us the coolest day this month as the thermometer only peaked at 14.7C being just 0.6C above average with the easterly breeze being the strongest for three days. However, it was very sunny and dry. Cloud could be seen on the radar easing in from the east during the late evening, approaching London, that saw the thermometer dip to a minimum of 1.2C at 05.19 producing a short lived ground frost but no air frost being 2.5C below average, however, it was the least cool night for three days.

No glorious sunshine to greet the new day on Thursday as we were under total quite thick cloud cover. Once the sun begins to work on the cloud it should slowly lift and break up to give another fine day.

The anticyclone has begun to contract and drift southwards. Its centre this morning is just of the southwest cast of Wales with a centre pressure of 1033mb so very close with pressure here at 08.00 of 1032.1mb, the highest pressure since the beginning of March.

We have two fine, sunny and warm days ahead before the weather pattern changes. The forecast Jet Stream track shows it making a significant change with it beginning to loop south of the UK putting us on the north side of the stream, being the cooler side, having looped north of the UK for all of this month.

An arc of cloud drifted across the sky mid-morning on Tuesday until around 14.00 with variable cloud that did slightly limit the rise in temperature until after that time. However, over the past five days the maxima have steadily fallen downwards with 21.8C,18.6C,16.8C,16.2C and 15.8C respectively under the cool northeasterly breeze having travelled over the cold North Sea. The same is true with the overnight minima, that under clear skies, I have logged 4.4C, 2.5C, -0.1C, -1.2C and -1.4C respectively. The cooler air has slowly seeped into the ground with the temperature at a depth of 5cm reflecting that trend with 8.7C, 7.6C, 7.3C, 6.9C and 6.3C respectively. We must realise that the maxima were all well above average for early April whilst, excluding the minimum of 4.4C on the 5th, the remaining minima were all well below average.

Wednesday began again with strong sunshine soon after sunrise with another sunny, dry and warm day ahead.

The anticyclone has continued to slowly build and will continue to dominate our weather until the weekend with a consequent air stream from the northeasterly quarter.

The cloud radar over the past few hours has seen variable cloud drifting in from the cold North Sea and approaching Reading up to 08.00, but hopefully, as the sun gains in strength, this will burn back before it reaches our area.

March was an exceptionally dry month and that trend has continued into April with now twelve consecutive dry day, eight of them in April. The warm weather and drying wind has seen over 3mm of equivalent rainfall lost daily through evaporation from the ground and plant life and now totals 24mm for April.

The image is of blossom in Priory Gardens, Marlborough.

The maximum of 16.2C on Monday, logged at 16.12, made it the second coolest day this month even though we had wall-to-wall sunshine and the wind was much lighter. However, the distinct variation was the wind direction that had backed a few degrees to come from the north east after a cooler night, even so the high was 2.1C above my long-term average.

Looking at the data for the last three days the UV high was almost identical as was the peak solar radiation and evaporation. The output from my 12 solar panels for each day showed a beautiful, smooth normal curve thanks to the unbroken sunshine even if there was very thin high cloud that limited peak solar generation.

There were no clouds overnight to minimise the loss of warmth into the atmosphere, as a result the temperature slowly declined to register a minimum of -1.2C at 06.33 before the sunrise at 06.28. In fact the temperature dropped to freezing (-0.1C) at 04.56 and did not rise above until 07.09, resulting in just over two hours of air frost. It was the coldest night since 16th March being 4.9C below my long-term average.

As mentioned above, the sun got to work immediately after sunrise lifting the temperature to 3.8C by 08.00.

The anticyclone has built a little since yesterday as the depression slowly fills and begins to move away. It repositioned a little over the past twenty-four hours as the centre moved further north, hence the wind from the northeast after seven successive days with a strong easterly. The barometric pressure read 1027.6mb at 08.00 Tuesday, the highest all month.

The image is of a Snake’s Head Fritillary in Stonebridge Meadow, Marlborough, taken an hour after dawn with ice particles still in evidence after the brief frost.