July 2015


Period: From July 2015      Issued on 14.07.2015 using data to the end of June 2015

Summary

The outlook for July is for below normal flows across much of England and Wales, with the possibility of notably low flows in some areas. In north-western areas of the UK including north-west England, July is likely to see normal flows. This pattern is likely to persist over the next three months, although it is likely that river flows will return to normal across Wales. For groundwater, levels in July are most likely to be normal or below normal, and this is likely to continue over the next three months.

Rainfall

The latest predictions for UK precipitation favour near- or below-average rainfall during July and for July-August-September as a whole. The probability that UK precipitation for July-August-September will fall into the driest of five equal categories is close to 25% and the probability that it will fall into the wettest category is approximately 15% (the 1981-2010 probability for each of these categories is 20%).

River flows

June saw above normal river flows in north-west Scotland, and a mix of normal and above normal flows in Northern Ireland, northern England and Wales. This contrasts with the rest of England, where flows were mostly normal or below, with notably low flows in some catchments. The one month outlook suggests normal flows are the most likely outcome for the north-west of the UK. For most of England and Wales, the outlook is for below normal flows to dominate, but with localised variations: there is an increased likelihood of notably, and possibly even exceptionally, low flows in parts of central England, Wessex and south Wales, while normal flows are likely to persist in some catchments in eastern England. The three month outlook suggests normal to below normal flows across the whole of Great Britain, with below normal flows the most likely outcome across much of England. 

Groundwater

Groundwater levels in June exhibited a very similar pattern to recent months: below normal levels in parts of the southern and eastern Chalk contrasted with normal levels elsewhere in the aquifer. Levels in other aquifers were mostly normal or below, except in some Permo-Triassic boreholes where exceptionally high levels persist. This pattern is likely to continue  through July, with recessions largely unaffected by summer rainfall. Over the three month timeframe, model projections suggest that groundwater levels in some areas with below normal levels may be trending towards the normal range. However, analysis of historical analogues suggests that this may be unrealistic and that below normal levels in Wessex and the Yorkshire Chalk are likely to persist into early autumn. The onset of the recharge season is likely to be delayed in areas in which below normal levels persist in the longer term.

Further information - July 2015

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