Author: Eric Gilbert

The Atlantic air has returned us to the days of low cloud with mist in the air and from time to time drizzle and very light showers. The total rainfall over the past day was just 2.3mm bringing the total for January to 65.9mm with the mean being 92.6mm. The thermometer did rise just above the mean (6.9C) with a maximum of 7.6C that slowly drifted down to a minimum of 6.4C at 03.07 this morning making this the second warmest night this month.
Dawn has broken, or at least it is getting a little lighter, with the treat of a Song Thrush singing its heart out. But the day is gloomy, the very low could is again covering the Marlborough Downs and Savernake Forest producing light drizzle.

The intermittent light rain developed late afternoon yesterday with the heaviest falls between 4.30 and 6pm. The total rainfall was 16.0mm, making it the wettest day since 21st November, however, this only brings the monthly total to 69% of the 32-year average.
Also significant were the much milder conditions, no frost, due to the change from the Continental Air to Atlantic Air. During the afternoon the temperature was around 8C but during the evening this rose to 10.1C, the joint warmest day this month, but since midnight has slowly declined to give a reading of 6.8C at 08.00.
This morning is dull and damp with very low cloud resting on the tops of the Marlborough Downs restricting visibility to around 1100m and virtually no wind.

It was a much warmer day yesterday thanks to the more southerly air flow, which brought 2.82 hours of strong sunshine between the broken cloud and a maximum of 7.8C, the highest for twelve days. There was a brief, if sharp shower, just before 2.30pm when small hail (< 5mm) fell within the rain totalling 0.9mm. Overnight the thermometer fell to a minimum of 1.4C at 04.26 that gave a brief ground frost, which recovered slightly to 2.9C at 08.00 as there is now almost total cloud cover, but high, in advance of the advancing rain. It is the first morning with an above zero temperature after twelve days of frost at daybreak.

After a frosty start again yesterday there was a brief glimpse of the sun before cloud built up and the first rain (light) in ten days fell late afternoon. More substantial rain fell after 3am this morning with the total for the past twenty-four hours being 5.6mm, which brings the total for January to 46.7mm. This is exactly 50% of the January average when we are almost at the end of the month.
Both our local rivers, The Kennet and Og, are running extremely low. This is due to the below average rainfall over the past few months, November excepted, when precipitation can percolate down through the ground to refill the aquifers rather than evaporate from ground and plant life. There is a rule of thumb that this period occurs from mid-October to mid-March. The 32-year average for mid-October to the end of the year is 230mm and we have received just 151mm, a significant deficit of 79mm. The period from January to mid-March has an average rainfall of 183mm and to date, with just six weeks left in this period, received 47mm.
Another factor is that from mid-October to the current time, 42mm has evaporated into the atmosphere out of the total precipitation of 198mm. If we don’t receive significant rainfall in the next six weeks, our rivers will begin to dry up in the higher reaches when summer arrives.

With the winds strengthening from the south east yesterday morning the maximum just after 3pm was 1.2C but combined with a significant wind chill if felt like -4C. During the afternoon the wind backed into the east and began to slowly decline as did the temperature with the thermometer dropping to its lowest at 22.45 when a minimum of -2.2C was noted. These changes have been brought about by the gradual decline of barometric pressure over last two days to its lowest this morning at 1009mb, a drop of 30mb from its peak of 1039mb on the 18th.
The thermometer has been slowly rising over the past ten hours and had reached -0.4C at 08.00. This morning is dark and grey with thick cloud sufficiently low to be obscuring the tops of the Marlborough Downs.
Yesterday was another dry day, the tenth consecutive, making seventeen dry days this month with total rainfall at 41.1mm, 44% of the January mean.