April 2017


Period: From April 2017      Issued on 11.04.2017 using data to the end of March 2017

Summary

The outlook for April is for river flows and groundwater levels in the south east of England to be normal to below normal, while in the rest of the UK normal river flows and groundwater levels are most likely.

Over the next three months there is the possibility of very low groundwater levels occurring in parts of south-east England (i.e. the Chalk of Kent and Sussex, and possibly the Chilterns). Elsewhere in the UK over this time scale, normal river flows and groundwater levels are most probable.

Rainfall

Rainfall in March was very slightly above average for the UK as a whole. It was drier than average in south-east England, and in parts of the north and west of Scotland, but was wetter than average in a band extending from Wales through north-west England and into the Scottish borders. Early April  has seen little rainfall and some warm sunny weather especially in the south east of England.

The rainfall outlook (issued by the Met Office on 23rd March) indicates that for April, and April-May-June as a whole, below-average precipitation is considered slightly more probable than above-average. Overall, the probability that the UK-average precipitation for April-May-June will fall into the driest of our five categories is between 15 and 20% and the probability that it will fall into the wettest of our five categories is around 20% (the 1981-2010 probability for each of these categories is 20%).

River flows

River flows in March showed marked regional variability corresponding to the observed rainfall as described above. There were very low flows in the extreme south-east of England, and below average flows in north-east Scotland. However between these areas there was a band of above average flows that included some notably high flows.

The outlook for April is for normal river flows across most of the UK, with normal to below normal flows most likely in the south-east of England. Below normal river flows are possible in the smaller catchments of north east Scotland. This outlook is likely  to continue for the coming three months.

Groundwater

Groundwater levels across the southern and eastern Chalk remained below normal for March.  Levels in other aquifers were more mixed, although mostly normal or below normal.

During April normal to below normal groundwater levels are likely to persist in the Chalk aquifers of south-east England, with normal groundwater levels elsewhere. Over the coming three months, and possibly beyond, very low groundwater levels are likely in the Chalk aquifers of Kent and Sussex, and possibly also in the Chilterns.

Further information - April 2017

Comprehensive further information that supports the production of the Hydrological Outlook UK is available here.