The outlook for June is for normal to above normal flows in northern parts of the UK, and normal to below normal flows further south. The three month outlook also suggests a broad contrast between northern and western areas, where normal flows are most likely, and southern and eastern areas where there is a higher chance of below normal flows. For groundwater, the current situation is likely to continue through the summer; groundwater levels are likely to be predominantly in the normal range but with below normal levels in parts of southern and north-east England.
The latest predictions for UK precipitation favour near-average rainfall for June. For June-July-August uncertainty is large but, on balance, below-average seasonal rainfall is more probable than above-average. The probability that UK precipitation for June-July-August will fall into the driest of five equal categories is between 20% and 25% and the probability that it will fall into the wettest of the five categories is 15% (the 1981-2010 probability for each of these categories is 20%).
River flows in May were mostly above normal in north-west Britain and Northern Ireland. Elsewhere, flows were in the normal range or below, with below-normal flows mainly in south-west England and in some eastern catchments. The one month outlook is for a similar situation: normal to above normal flows are likely in northern parts of the UK, and normal to below normal flows are likely across much of England and Wales. For the three month outlook, the most likely outcome is for normal flows in northern Britain and Wales but across most of England there is an increased likelihood of below-normal flows, reflecting the dry spring coupled with projections that slightly favour below-normal rainfall. Below normal flows are likely in some groundwater-fed catchments, particularly in south central/south-west England.
In the Chalk, May groundwater levels were mainly normal in the south-east, but levels were below normal (and notably low in some boreholes) in parts of southern England and Yorkshire. Levels were mixed in other aquifers, with exceptionally high levels persisting in parts of the Permo-Triassic sandstone. The one month outlook suggests a similar situation will continue in June, although levels in the Permo-Triassic are likely to be notably high rather than exceptional. The groundwater situation is unlikely to change significantly through the summer; the three month outlook suggests normal levels will dominate, but with below-normal levels persisting in parts of north-east and southern England (although there is a possibility that levels in some parts of Wessex may return to normal).