March 2016


Period: From March 2016      Issued on 11.03.2016 using data to the end of February 2016

Summary

The outlook for March is for the continuation of above normal river flows and groundwater levels across large parts of western Britain in response to wet weather in February and throughout the winter.  Further south and east, groundwater levels are expected to remain above normal in central southern England; otherwise river flows and groundwater levels are likely to be within the normal range, albeit with some localised examples of both above normal and below normal flows and levels.  Rainfall projections suggest that there is a slightly higher chance that spring will be wet than dry (this signal is stronger still for March).  Despite this, the three-month outlook suggests that normal to below normal river flows are likely for most regions of the UK (albeit there is some disagreement between methods for parts of western Britain) and there is an increased likelihood of below normal groundwater levels in parts of eastern England.

Rainfall

Based on projections released by the Met Office on 18th February: For March, there is an increase in the chance of above-average precipitation, and a decrease in the chance of below-average precipitation, compared to usual.  Predictions for UK-mean precipitation for the 3-month period (March-April-May) are that above-average precipitation is slightly more probable than below-average.  Overall, the probability that the UK-average precipitation for March-April-May will fall into the driest of our five categories is 20% and the probability that it will fall into the wettest of our five categories is around 25% (the 1981-2010 probability for each of these categories is 20%).

River flows

River flows for February were above normal across northern and western parts of the UK, notably so in parts of central Scotland and northern and south-western England.  Flows were in the normal range along the east coast of England and for most of south-east England.  The outlook for river flows in March is for an increased likelihood of above normal flows in western and southern Scotland, north-west England, the West Midlands and Wales.  Elsewhere river flows are expected to be in the normal range, although with localised examples of both above and below normal flows.  For the three-month outlook there is less agreement between the different methods for Wales, northern England and the Midlands.  Regional average river flows for these regions are projected to be normal to below normal, although the outlook for some individual catchments is for above normal flows.  Elsewhere, the three-month outlook is suggestive of normal to below normal river flows, although there is variability between individual catchments.

Groundwater

February groundwater levels in the Chalk were above normal in responsive aquifer units along the south coast of England but normal or below in eastern England.  Levels remained notably or exceptionally high in the limestone and sandstone aquifers of northern England and southern Scotland.  For March, it is likely that groundwater levels will continue to be above normal in the Chalk of central southern England and notably or exceptionally high in northern England and southern Scotland.  There is also an increased likelihood of above normal levels in the Permo-Triassic sandstones of the West Midlands.  The outlook for the next three months is for a similar pattern.  In addition, there is an increased likelihood of below normal levels in parts of the Chalk and limestone of eastern England, most notably in Yorkshire and Lincolnshire.

Further information - March 2016

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