Category: Commentary

Under the influence of the cold air mass brought on a northerly breeze that gusted to 18mph, the thermometer struggled to reach 2.1C at 12.01 on Monday being almost 6C below average. After the very early morning light fall of snow no more fell during the daylight hours.

Overnight the wind fell out completely for long periods with the thermometer dropping to -1.2C at 04.54 before lifting to -0.3C at 08.00 on Tuesday.

A few light flakes of snow were observed at first light on Tuesday, not enough to cover the ground. However more light snowflakes began to fall just after 08.15 from a narrow band of precipitation travelling in on a very light northwesterly air movement.

The barometric pressure at 08.00 on Monday was the lowest since November 2010 with a minimum pressure of 969.9mb as the centre of the deep depression was overhead Southern England. By Tuesday a rise of almost 20mb, as the depression eased away and began to fill slowly, gave a current reading of 987.5mb, still very low.

Although the barometric pressure had been sliding for twenty-four hours and was quite low on Sunday we enjoyed 4.8 hours of sunshine, predominantly in the morning. The thermometer eased upwards to reach a maximum of 6.2C in the brisk westerly breeze that was 1.8C below the average.

The thermometer hovered around 1.5C late evening but just after midnight began to fall steadily to reach a low of -0.3C at 04.48 producing a short lived frost.

The first precipitation from a narrow weather front brought snow that started just before 06.00, with a modest layer in evidence, that soon turned to wet snow. Some pavements were icy after the cold night from the first rain and sleet to fall. It was mostly seen on gardens and lawns rather than hard surfaces. However, this quickly turned to rain and any evidence of snow melted as the thermometer rose to 0.7C at 08.00 although snow could be seen at 09.00 on the slightly higher fields rising to Savernake Forest.

Saturday was another gloomy, drizzly day with thick cloud ahead of Storm Bella. During the evening the wind began to pick up, but fortunately not as strong as the warnings given. A peak gust of 38mph was logged at 01.29 in the early hours of Sunday. The strong winds began t abate after 02.00.

The southerly air stream allowed the thermometer to recover from the cold northerlies of previous days and reach a maximum 9.4C being 1.4C above average. As the rain band eased away Sunday morning the temperature dropped away to read 5.0C at 08.00

The rain began in earnest just before midnight and brought us the wettest twenty-four hours since the 14th November with 17.7mm. This brought the monthly total to 106.2mm, which is 14mm above the 36-year average.

Sunday morning saw the showery back end of the main rain band with broken sky and occasional showers. The wind has now backed into the west and is much calmer.

The centre of Storm Bella will migrate down across the country in the next twenty-four hours with extremely low pressure centred over southern England on Monday. The barometric pressure has dropped 45mb since 08.00 on Saturday and is forecast to fall another 10mb by Monday morning. The wind direction with change considerably during this period but be much lighter in strength.

The ridge of very high pressure brought us a sunny and fine, if chilly, Christmas Day. The northerly wind for much of the day was much lighter than the previous day with a maximum gust of 13mph. However, the very cold night meant the thermometer struggled to reach 3.3C during daylight hours being 4.7C below average, which meant it was the coldest Christmas Day since December 2010 when the thermometer only reached a chilly -0.1C.

During the late evening, the thermometer having fallen to a minimum of -0.6C at 19.47, saw it reverse the trend and begin to recover as the wind had slowly backed into the west.

Boxing Day arrived dull and gloomy with thick cloud from the approaching Storm Bella. As a result the thermometer at 08.00 read 4.4C and the air mass then coming from a southwesterly direction.

The barometric pressure has been falling for the past twenty-four hours having already dropped 11mb with a current reading of 1022mb. This is the result of approaching Storm Bella that in the North Atlantic has two centres of exceptionally low pressure close together with readings of 955mb and 965mb. Warnings have been given of exceptionally strong winds, up to 50mph, will arrive in this area around midnight.

A transient ridge of high pressure brought very different weather on Thursday with blue skies, four hours of sunshine and the first dry day since the 9th. However, the very brisk wind from the north meant a cold day with the thermometer struggling to reach a maximum of 4.7C at 12.47, which was 3.3C below average and the first below average maximum since the 5th. There was also significant wind chill that outside it felt at least 2C colder than that registering on the thermometer.

Overnight the thermometer fell steadily to reach a minimum of -1.2C at 06.47 being 3.6C below the 36-year average.

The cold air from the north meant it was the coldest Christmas Eve day since 2010 when the thermometer that year refused to move above freezing with a maximum of -0.1C. The cold northerly airstream persisted this past night that meant it was the coldest night since Christmas Eve of 2010 but then the frost was severe as the thermometer dropped to -6.8C.

Christmas Day in 2020 arrived with blue sky and the promise of more sunshine thanks to the high pressure that is at its highest all month with a current reading at 08.00 of 1033.6mb. The thermometer at that time registered -0.6C but wind chill meant it felt more like -2.9C. There was a little whiteness however that was not snow on Christmas Day but frost!