The mid-month statistics for May (1-17 May) show the month got off to a dry start, although the heavy rain yesterday brought up rainfall totals in some areas. It has also been a sunny and moderately mild early May for many.
The anticyclonic theme that dominated the UK weather in April continued into the start of May, meaning in some regions there was little rainfall aside from the rain on Wednesday. East Anglia and most of Scotland have been particularly dry so far this month, with only around 10% of the whole-month average up to 17 May. It has been wetter towards the south-west and west, with some places in the Lake District and western Wales already approaching their monthly rainfall averages. From a national perspective, the UK has so far seen 44% of the whole-month average so far.
Following the heavy rainfall on 17 May, Dorset and Hampshire are now at 79% of their long term average for the whole of May. South Farnborough in Hampshire for example had only received 12.8mm of rain up to 15th May, just 24% of the monthly average. The rain over the past two days has pushed the total up to 52.2mm which is 99.7% of the site’s average for the month. On average South Farnborough sees only 9 days in May with more than 1mm of rain recorded so it’s not that unusual for a large proportion of the monthly average to fall in a few notably wet days.
In contrast, Loch Glascarnoch in the Scottish highlands has so far this month received only 6.4 mm of rain, just 7% of its monthly average. Overall Scotland has so far received 19.5mm which is 23% of its average rainfall for May.
Temperatures for the month so far have been close to average from a UK perspective, with the mean temperature being just 0.2°C above the long term average. Northern Ireland has been the mildest region compared to its long term average with mean temperatures 1.1°C above the average so up to 17 May.
With the widely settled conditions, there were some rather chilly nights for the time of year with air frosts in certain areas. Ground frost was even observed in rural Devon on the morning of 10 May. Cloud-cover and high humidity meant an unusually warm night on 15/16 May with minima of 15 °C in places, and the highest temperature of the year so far was recorded at Gravesend in Kent with 25.8 °C on the 16th.
In line with the milder temperatures in Northern Ireland, sunshine hours have also been highest in this region. Northern Ireland has seen 92% its average monthly sunshine hours already this month with 168.2 hours. In contrast some eastern counties in England are some way below where you would expect them to be by this point in the month, with Suffolk and Norfolk recording 36 and 37% of their monthly average sunshine hours respectively. The UK as a whole has recorded 63% of its average monthly sunshine.
|Provisional 1-17 May 2017 data||Mean Temp||Sunshine Hours||Precipitation|
|Actual (°C)||Diff to average||Actual hours||% of average||Actual (mm)||% of average|
Shouldn’t the third column in the table be headed ‘Anomaly’ or ‘Diff from avg’, rather than ‘diff to average’ ?