Author: Eric Gilbert

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.

The breeze on Sunday continued from the cool east that again pegged back the rise in temperature to a maximum of 16.8C, however, this was still 2.7C above my long term average. Out of the wind it felt very warm in the sunshine with the UV level once again at the top end of the ‘Moderate’ category thanks to the very thin high cloud that limited the solar strength to a maximum of 670W/m2 at its peak.

The pattern of numerous hours of glorious sunshine under clear skies again produced the expected cool night as the thermometer very slowly and continuously allowed the warmth to dissipate into the atmosphere with the thermometer only dropping to freezing point of -0.1C at 06.31 early Monday. However, this only lasted for 7 minutes as the sun quickly began to reverse the trend so that by 06.38 the thermometer had returned to 0C. The ground frost lasted for several hours but the air frost was lifted after just 7 minutes.

Monday morning was a repeat of the previous days as the sun shone strongly after the sunrise at 06.30, raising the temperature to 5.7C at 08.00. This will give us another day with likely wall-to-wall sunshine, the maximum well above average and likely feeling warmer with a lighter breeze.

The anticyclone has continued to build over the past two days with its centre closer to the UK, currently over the North Sea, as the depression eased westward and began to fill slowly. This has seen the pressure gradient between the two giants fall thus reducing the wind strength, a little yesterday and will be much lighter over the next few days. The high pressure will move very little over the next few days so more of the same with the wind continuing to come from an easterly quarter and not change direction until possibly Saturday. The barometric pressure has risen 7mb since its low on the 3rd to read 1026.0mb at 08.00 today.

Image from Priory Gardens, Marlborough.

Once again on Saturday, although we had many hours of sunshine, the strong north-northeast then easterly breeze pegged back the temperatures a little although a maximum of 18.6C at 15.58 was still 4.5C above my long-term average but down 3C on the very warm day on Friday. A peak gust of 24mph was logged with the UV level still at the top end of Moderate.

With a clear sky overnight it was not surprising to find that the thermometer dropped steadily to reach a minimum of 2.5C at 06.18 producing a widespread ground frost.

The sun began to shine strongly as soon as it rose above the horizon on Sunday lifting the temperature to 5.1C by 08.00. This is likely to be the last day when the wind from the east is strong, from Monday it will be lighter in strength, thankfully.

The dominant high pressure, that has been with us all month, is likely to continue to bring us dry and sunny days for much of the coming week, just a little relocation after midweek. The barometric pressure has risen 3mb since yesterday.

From time to time I read items in the press, from the weather forecasting site WXcharts, predictions of storms or recently last week on two separate days, snowfall of several inches, which I have never seen materialise. I was interested to read yesterday a comment from a Met Office spokeswomen “that many snow forecasts are based on “one-off simulations” indicating possible extreme weather. These, she said, form, “just one part of the wide range of information used to provide a full forecast picture”. “Different simulations produce different pictures of the weather forecast and one-off, single charts, do not provide the broader forecasting picture.

The picture was taken at Kennet Place during Marlborough in Bloom in 2015 when we were awarded Gold.

The maximum of 21.8C on Friday at 15.38 was a significant 7.7C above my long-term average that made it the warmest day since 19th September (22.3C). The variable cloud in the morning slowly thinned and eventually broke up with strong sunshine after midday. The persistent wind from the east, with a peak gust of 26mph, made it feel cooler producing a modest wind chill.

The past night gave us a minimum of 4.4C, just 0.7C above the average as variable cloud that had drifted in from the east stopped it falling further.

Variable cloud was observed on Saturday after sunrise that initially limited the sun’s strength but by 07.00 the cloud was being ‘nibbled back to the east coast’, a non-technical term I heard from a meteorologist on the TV. The cloud had drifted in from the cool North Sea, which has a current temperature of just 8C.

The forecast charts indicate that the high pressure will be with us well into next week with again tomorrow the strong easterly air flow. There is quite a pressure gradient between the anticyclone and depression, hence the strong breeze these past days.

I have mentioned this week that the brisk easterly had produced a wind chill. I have discovered, to my surprise, that there is no official definition of wind chill as definitions vary globally, dependent on how it is measured. In the UK,a system called Joint Action Group for Temperature Indices is used to realistically measure wind chill. This calculates wind chill by measuring how much heat is lost from a person’s bare face at a height of 5 feet (human height) using wind speed, temperature and humidity data. The temperature today of 7.1C at 08.22 felt more like 5.7C outside.

The strong sunshine on Thursday lifted the temperature to a maximum of 19.2C at 15.19 being 5.1C above average that made it the warmest day since 21st September (19.3C). The forecast cloud was observed arriving from the south at 14.05, thin and broken at first, but by 15.15 it had thickened thus the maximum mid-afternoon. The back track of the cloud radar showed the cloud persistent overnight, acting as a duvet limiting the loss of warmth into the atmosphere, with a resultant minimum of 9.2C at 06.46 early Friday. This low was 5.5C above my long-term average and made it the warmest night since 1st December (10.0C).

There was a little very weak sunshine after sunrise, through a small gap in the cloud over eastern horizon, but after 08.00 there were signs that the cloud was beginning to thin and becoming more broken with the hope of strong sunshine later in the morning.

The depression that had been lurking close to the Bay of Biscay recently has now moved a little eastwards, positioning itself just off the coast of Portugal overnight. The low pressure system produced the warm weather front that crossed our area overnight. Tracking back on the rain radar there was a small area on the edge of the cloud bank, about 80 miles wide, that is likely to have produced the few spots of rain visible on horizontal surfaces after dawn, but not sufficient to be measurable.

The recent anticyclone is likely to be the dominant factor affecting our weather over the weekend and into next week as it drifts a little further southwards and becomes settled over Scandinavia, with more dry and sunny days ahead.

I have mentioned this week that the brisk easterly had produced a wind chill. I have discovered, to my surprise, that there is no official definition of wind chill as definitions vary globally, dependent on how it is measured. In the UK,a system called Joint Action Group for Temperature Indices is used to realistically measure wind chill. This calculates wind chill by measuring how much heat is lost from a person’s bare face at a height of 5 feet (human height) using wind speed, temperature and humidity data.

I thought that the recent picture of the magnolia in Priory Gardens, that I included earlier this week, was worth repeating this morning as the blooms are glorious against the blue sky.