August 2016


Period: From August 2016      Issued on 11.08.2016 using data to the end of July 2016

Summary

The outlook for August is for river flows to be normal to above normal in many areas of the UK, particularly in parts of western Britain.  Over the next three months, river flows are more likely to be within the normal range, and normal to above normal in East Anglia.  The outlook for groundwater levels in August is for a continuation of normal to above normal levels across most of the aquifers in the UK.  Groundwater levels are expected to remain above normal over the next three months in some aquifers in northern Britain.

Rainfall

Whilst Scotland, Northern Ireland, north Wales and parts of northern England received above average rainfall in July, most of southern England and south Wales was substantially drier than average.

For August, above-average precipitation is considered slightly more probable than below-average. For August-September-October as a whole, the forecast for UK precipitation suggests that the chances of above- and below-average rainfall are fairly balanced. The probability that UK precipitation for August-September-October 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 July were normal to above normal across the majority of the UK, with the exception of south-west England where flows were below normal.

In August, the outlook for river flows across most of the UK is for normal to above normal flows.  This signal is particularly strong in parts of western Britain; elsewhere the outlook is less clear.  The suggestion of below normal flows for south-west England in August is likely to have been offset by wet weather at the start of the month.  Over the next three months, river flows for the majority of the UK are most likely to be in the normal range although the outlook is for normal to above normal flows in East Anglia.  There remains a greater likelihood of above normal rather than below normal flows in parts of western Britain, although there is lower confidence at this three-month timeframe.

Groundwater

Groundwater levels in July continued to be normal to above normal in most aquifers in the UK, with notably to exceptionally high levels persisting in the Permo-Triassic sandstones of northern Britain.

Groundwater levels in August are expected to remain in the normal range or higher in almost all of the aquifers of the UK.  This includes the Permo-Triassic sandstones in northern England and southern Scotland, where the outlook suggests above normal to exceptionally high levels will continue.  Predicted exceptionally low levels in the Carboniferous Limestone of south-west Wales may be offset by wet weather at the start of August, although levels are likely to remain below normal.  Uncertainty surrounding the timing of the onset of autumn recharge means that the groundwater outlook over the next three months is less clear.  Current predictions suggest a continuation of the normal to above normal levels for most of the UK, with sustained above normal levels in the Permo-Triassic sandstones of northern Britain.

Further information - August 2016

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