Saturday was slightly less cold than the previous three very cold days as the thermometer slowly rose to a maximum of 4.1C at 13.16. There was no sunshine but the high pressure was slowly relocating and beginning to cut off the flow of very cold air and allow the slightly warmer air to edge in from the west with its associated cloud. Thick cloud cover overnight, acting as a duvet that minimised loss of warmth into the atmosphere, meant no air frost but with a minimum of 0.8C at 00.31 early Sunday that we did have a slight ground frost. The maximum was 3.0C below my 40-year average and likewise the minimum was below average, just, with -0.2C. Once again, under the centre of the high pressure, there were hours when the anemometer dod not turn with a maximum movement of just 5mph on one occasion.
Sunday after first light revealed the total cloud cover. The centre of the high pressure is slowly drifting south over Brittany that will produce a significant change in wind direction to come from the south all day, a much warmer direction, at the same time the warmer air to the west is slowly edging closer.
Being under the centre of the anticyclone means there is little variation in gradient between the high and low-pressure, hence the calm conditions with little or no air movement. The barometric pressure reading at 08.00 was 1039.7mb being the highest pressure since 11th January 2024.
In the shade there is still a coverage of frozen snow that will slowly melt away over the next day or two. Automatic rain gauges are great for live monitoring of precipitation, also rate of fall, but not accurate on timing when snow or sleet falls. After a snow event I bring in my Met Office type copper rain gauge at 08.00 and slowly melt the snow before measuring accurately. With near freezing weather during many hours, as we have experienced this week, any snow in an automatic rain gauge will only melt under the influence of sunshine or when the temperature recovers significantly thus it will only register the precipitation slowly many, many hours later or even days after the event.
