Tuesday 12th May
After a sunny start to Monday the cold front crossed the area around midday that meant cloud built late morning with a few spots of rain observed at 11.55, as I walked back from town, and proper rain at 12.55. However, the heavy shower was very brief, lasting less than ten minutes, and only produced 1.0mm of precipitation. The warmest part of the day was just before the main rain arrived with a maximum of just 12.9C at 12.20. That made it the coldest day of the month, in fact it was the coldest day since 12th April, due to the flow of Arctic air on the northerly breeze. The high was a significant 4.4C below my May average. As the front moved away the cloud moved away and left us with clear skies and at this time of year and the wind dropping out completely, resulted in a cold night. The thermometer dropped to freezing at 01.35 and did not get back above freezing for almost 5 hours at 06.18 with the minimum of -1.6C recorded at 05.10, which was 11 minutes before sunrise in Marlborough at 05.12. Any tender plants left uncovered in the garden will be looking very sick this morning after the prolonged and sharp frost, I sadly have a few, most are OK.
A minor ridge of high pressure is currently across the country that produced variable sunshine at the start of the new day on Tuesday, but it won’t last, as another cold front will travel from the north, crossing air area around midday bringing more cloud before it and after it, which will result in minimal sunshine either side of the front.
This morning the forecast surface charts show six low pressure systems circling the UK from Iceland to the Continent, an unstable situation. We have a few more cool days ahead with possible rain showers on Wednesday as three small troughs of low pressure, within the overall low pressure area, cross down the country. The wind is likely to be strong in the afternoon as these mini-disturbances arrive.
The rest of the week appears to be dominated by overall low pressure to the east and high pressure over the Azores. This will mean winds funnelling down between the two systems arriving from the west and northwest up to Saturday, slightly less cold than the recent Arctic air but cool with temperatures by day and night still depressed.