Category: Commentary

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.

The thick cloud persisted all day on Wednesday giving us another mild day and night with the misty conditions lifting mid-morning but returning overnight. The high of 9.7C was 1.6C above average whereas the low of 6.2C that occurred at 06.56 early Boxing Day was, which was 3.8C above average.

Thursday after first light revealed the misty conditions again to start the new day with light drizzle falling.

The anticyclone has extended eastwards but still maintains a very high pressure over the UK, hence the lack of breeze to move the humid and stagnant air. The pressure reading at 08.00 was 1035.0mb, the highest since 13th November.

HAPPY CHRISTSMAS

Both the maximum and minimum on Tuesday were well above average thanks to the flow of Tropical Maritime Air brought to us on a light westerly breeze. The maximum of 11.2C at 14.03 was 3.2C above average and the minimum 8.4C easy Christmas Day was a significant 6.0C above average.

Christmas Day revealed misty conditions with the high pressure close by continuing the calm conditions and the flow of warm, moist air brought on a west-southwest light air stream. The barometric pressure at 07.45 was 1032.4mb, and still risingas the centre is over Brittany, being the second highest pressure this month.

Once again it was warmer overnight than the previous day. That was thanks to the Tropical Maritime Air stream replacing the Arctic Maritime air that had brought the cold. The thermometer rose to 6.8C at 14.14 on Monday then dropped away to a low 5.5C at 17.45. At that time the effects of the arrival of the warmer air stream were observed as the thermometer began to slowly recover and rise to a maximum of 9.7C at 08.00 on Tuesday. Drizzle was conserved at 16.00, ahead of the warm front from increased cloud cover that produced 0.6mm of precipitation.

At first light on Tuesday, in addition to the warmer air, it was very humid with 100% humidity logged at 08.00 that had produced foggy conditions limiting visibility in Marlborough to 200m.

The centre of the anticyclone is now over the Bay of Biscay with the air circulating clockwise feeding the warm, moist air, now on a very light westerly.

The Polar Maritime Air that covered the country on Sunday, it originated near Iceland and Greenland, was very cool with the thermometer struggling to reach a maximum of 6.2C at 14.42 being 1.8C below the average. Not surprisingly, a cool night followed that saw the thermometer sink to 3.2C at 07.50 early Monday being 0.8C above the average. It was a dry day with just minimal UV light to trigger the sensor at 0.5.

Monday after dawn revealed a sky covered with thin cloud allowing minimal brightness, better than the recent gloomy days, but no sunshine. Thankfully the recent very strong winds have subsided so minimal wind chill, although feeling cold outside.

As the day progresses, the cloud will thicken as a warm weather front approaches and crosses the UK late Monday. This will result in the temperature rising during the late evening and overnight with some possible precipitation, but not white.

The barometric pressure has risen a significant 20mb over the past twenty-four hours as a very high pressure system mid-Atlantic begins to influence our weather allowing much milder weather to arrive on Tuesday for a few days over Christmas. This will allow a wedge of Tropical Maritime air to flood the country.