The UK Centre for Ecology & Hydrology (UKCEH) has just published its monthly Hydrological Outlook at hydoutuk.net.
The UKCEH reports that rainfall across much of Britain was very low in April, continuing the dry period that began in February. Many areas received less than half their normal April rainfall (with parts of northern England and western Scotland below 30% of average). Exceptions were Northern Ireland, southern Wales, Cornwall and Devon which received above-average rainfall.
River flows in April were very low in most areas, with exceptionally low flows in northern England and southern and eastern Scotland. Exceptions were in groundwater-dominated catchments (with flows sustained by the above-normal water storage due to wet winter) and also the south-west (due to the heavy rainfall).
Soil moisture levels continued to decline (particularly in south-east England), with conditions in some areas resembling those seen in summer. April soil moisture levels were exceptionally low compared with long-term averages across many sites in the COSMOS-UK network. Rain later in April helped some sites in western areas to return to more normal conditions.
Groundwater levels in April declined but remain in the normal range across much of southern England. Below normal levels recorded in the Cotswolds, Dorset and eastern Yorkshire.
Outlook for May-July
Current meteorological forecasts (Met Office, 28 April) indicate a hotter-than-average May-July, albeit with near-average rainfall. The dry start to May is likely to be followed by a period of more unsettled weather, especially in western parts.
River flows in most areas are likely to continue to be below normal, with potential for current low to exceptionally low flows to persist into the summer in some catchments. Flows in western Scotland and Northern Ireland are likely to be in the normal range over the next 1-3 months.
The wet winter boosted groundwater levels, but they are expected to continue to decline in most areas, and be in the normal to below normal range across the UK over May-July. Low groundwater levels in some areas are likely to continue for several months in some areas, for example in northern England.
Elsewhere, levels are expected to be normal to above-normal in the South during May, especially in the Chalk aquifer in southern England, but tending towards normal over the three-month period.
