Month: December 2024

Monday was the last of the gloomy, low cloud starts to a new day as the high pressure slowly departed and the breeze picked. The thermometer hovered around 7C all day but the maximum, most unusually, was logged overnight with a high of 8.0C at 01.49 early Tuesday. Thereafter, it eased downwards to reach a minimum of 7.7C at 08.00. Another twenty-four hours with a minimal diurnal range, difference between maximum and minimum of just 1.4C. There was no ran and no UV light triggered the sensor.

Tuesday revealed a cloudy sky again after dawn but much higher than of late. The depression is getting closer with the barometric pressure having lost another 7Mb since Monday with a reading of 1022.2mb at 08.00. The wind is beginning to pick as the squeeze as the difference between high and low pressure begins to take effect.

The low just off Scotland has been deepening with a current centre pressure of 987mb. As it gets closer to the UK the winds will increase dramatically over the next thirty or so hours. With Christmas in the past and strong winds ahead I have changed the three images that now show damage in the gales of 1984 in Savernake Forest, hopefully nothing like that over the next forty-eight hours.

It was such a pleasure to have brief sunny intervals that were observed around midday on Sunday after the six dark, gloomy and damp days. As a result the thermometer crept up to 8.6C at 15.14 being the warmest day for four days and was 0.5C above average. The continuous cloud overnight meant little change in temperature overnight as the thermometer only dropped to 6.6C by 07.52 early Monday.

There was a significant change in our weather just after 14.00 on Sunday as the humidity dropped below 100% as the weak cold front passed through. It was also the first day since the 22nd when no precipitation fell, which had been mainly in the form of drizzle.

Monday revealed another cloudy start to a new day but the air was for the first time a little drier as the humidity at 08.00 read 96%, after six continuous days at 100% through day and night. The wind will be principally from the southwest quadrant and still relatively light.

The recent high pressure, that acted as a dome trapping stale air beneath it is still very slowly easing away, down 2mb since Sunday but still very high. A weather front is approaching on Tuesday that will see a succession of depressions running along it that will bring wet and very windy weather, especially on Wednesday.

Saturday was the last of the very calm, damp days and nights under the persistent cloud cover. The maximum of 6.3C that occurred at 13.32 was slightly up on the two previous days but still below average at -1.8C. The minimum was also below average at -0.1C, the first time for over a week, with a low of 2.3C logged at 23.58 just before midnight. Light drizzle occurred also as on previous days from the thick, low cloud amounting to 0.3mm.

Sunday began as the previous six days still under the thick, low cloud that limited visibility to 300m after dawn. The humidity at 08.00 once again read 100%, the sixth successive day with 100%.

The soil temperature, read at 08.00 at a depth of 5cm, has seen a slight decline over the past four days thanks to the lower maxima and minima with 8.4C, 6.5C, 6.1C and 5.1C today respectively.

A weak cold front will pass over our area around midday that will bring a slightly drier and brighter air stream behind it, a very welcome minor change in our weather. The large area of high pressure is still influencing our weather and will do so for another two or three days before colder, brighter weather arrives midweek, but not before it gets very windy on Tuesday and Wednesday.

Friday was a repeat of previous days with total, low cloud cover all day trapped under the high pressure. The misty conditions worsened as the morning progressed that saw visibility slowly descend to 200m by 11.00. The mist descended in the evening again but not as thick as previous days. Drizzle was often felt outside and amounted to just 0.6mm. The was once again very little variation between the maximum of 5.9C, being 2.2C below average, and the minimum of 4.2C, which was 1.7C above average, recorded at 06.56 early Saturday.

The maximum over the last four days has slowly fallen away with 11.2C, 9.7C, 6.4C and 5.9C respectively. The same pattern is seen in the minimum values over the last four days with 8.4C, 6.2C, 4.9C and 4.2C respectively.

I cannot see a pattern in the records over the past 40 years where the humidity at 08.00 was 100% for five consecutive days and persisted throughout each twenty-four period.

The other significant feature over recent days has been the lack of air movement due to the minimal gradient variation with maximum air movement of just 13mph, 10mph, 7mph and 6mph respectively being almost under the centre of the anticyclone.

Saturday began as previous days but it was mist masking the Marlborough Downs and Savernake Forest rather than fog.The temperature at 08.00 registered 4.4C, the coolest morning since the 23rd.

The high pressure that has trapped the stagnant air below it is very slow declining and easing eayswtads over France. Three low pressure systems are Deve,oping in the eastern Atlantic that will slow begin to influence our weather from later on Sunday into next week. The barometric pressure at 08.00 was logged at 1029.8mb, down from the peak of 1036.1mb on Thursday.

Thursday continued the recent trend of calm, moist air with occasional light drizzle that amounted to 0.3mm. Due to the persistent cloud cover over the past twenty-four hours the cloud did not allow any sun to raise the temperature but at night acted as a duvet to minimise loss of warmth into the atmosphere, clear skies would have seen the thermometer drop considerably at night this time of year. The maximum of 6.4C was 1.6C below average whilst the minimum of 4.9C logged at 17.46 early evening of Thursday was 1.5C above the average.

Once again, due to the persistent thick cloud, the diurnal range was minimal, a variation between night and day of just 1.5C.

Friday after dawn was a repeat of the last three days with the thick, low cloud producing misty conditions once again masking the Marlborough Downs and Savernake Forest.

The recent high pressure that produced the calm days with little wind to stir up the air, is beginning to slowly recede towards the Continent with the first signs, towards the weekend, of low pressure systems edging in from the Atlantic, however, this probably will not be noticeable until Sunday.