The outlook for November is for river flows to be within the normal range across the UK, except in the south-east where flows are likely to be below normal for November and the next three months. Groundwater levels in the Chalk aquifer of the south-east are likely to be below normal for the next three months, whilst groundwater levels elsewhere across the UK are likely to be normal to above normal.
Rainfall during October was generally low across much of the UK. Parts of the south-east saw less than 30% of the 1981-2010 average for October. Less than 90% of the average rain fell on southern and central England, north Northern Ireland, and eastern England and Scotland. Localised areas of up to 150% of the average fell on north-western England, Northumberland and western Scotland.
The Met Office 3-month Outlook issued on 26th October indicated that above-average precipitation is more probable than below-average precipitation for November-December-January.
The probability that UK precipitation for November-December-January will fall into the driest of five categories is around 15% and the probability that it will fall into the wettest of five categories is between 25% and 30% (the 1981-2010 probability for each of these categories is 20%).
River flows in October were spatially variable, with normal to above normal flows across the majority of the UK. Above normal and notably high flows were prevalent across northern and western England, and western Scotland. Following a dry October in the south-east, river flows generally fell reaching notably and exceptionally low levels in some catchments.
River flows in the south-east are likely to remain below normal for the next three months, with low river flows expected in some catchments. As this period covers the winter months, that are critical in the UK for soil moisture and groundwater recharge, this forecast could have implications on the longer term into 2018. Elsewhere in the UK, river flows are expected to be normal for November, with some indications for above normal flows. The forecast for this area over the next three months exhibits considerable uncertainty.
Groundwater levels in October remained below normal to notably low across the majority of the southern Chalk aquifer. Elsewhere, groundwater levels were within the normal range, with the exception of south-western Scotland where levels remained exceptionally high.
Over the next three months, groundwater levels in the south-eastern Chalk aquifer are likely to remain below normal. Elsewhere in the UK, groundwater levels are likely to be normal to above normal for November. The notably high groundwater levels that have persisted throughout the year in the Permo-Triassic sandstones in northern England are likely to return to normal to above normal levels over the next three months.