July 2013


Summary

River flows in July are likely to be in the normal range or below across most of the UK. Across all aquifer areas, groundwater levels are likely to be normal or above normal in July. The model-based outlook suggests the groundwater situation is likely to be similar over the next three months. 

Rainfall

Latest predictions for UK-mean precipitation slightly favour near-to-below-average rainfall for July. However, this is not the case for the July-August-September period as a whole, for which no particular category is favoured. The probability that UK precipitation for July-August-September will fall into the driest of our five categories is around 20% and the probability that it will fall into the wettest category is around 20% (the 1981-2010 probability for each of these categories is 20%).Click here for more detailed information on the Met Office long-term forecast. [rainfall outlook based on Met Office forecast issued 5 July 2013] 

River flows

June river flows were in the normal range across most of the UK, but below average in some catchments in Scotland and western England, and above average in parts of southern England. (click here For further information on the situation at the end of June). The one-month-ahead outlook is indicative of July river flows being below normal across much of Britain, but flows are more likely to be in the normal range in parts of Scotland and northwest England. A comparison with historical analogues, coupled with the 3-month groundwater outlook, implies that river flows are likely to be higher than normal over the next three months in some permeable catchments in parts of the Chalk of central southern England. For full information on the river flows outlook, click here.

Groundwater

June groundwater levels continued to decline and were normal or above normal across most of the Chalk and Jurassic limestone aquifers, while levels across the Permo-Triassic were above normal, and exceptionally so in some northern boreholes. (click here For further information on the situation at the end of May). The model-based outlook suggests that, even under the lower rainfall projections, average groundwater levels for July are likely to be above normal in the Chalk and Permo-Triassic outcrops in southwest and northwest England, and normal elsewhere. The three-month ahead outlook is also suggestive of average levels being in the normal range or above for most aquifers, with above average levels more likely in the Jurassic limestone and parts of the Chalk and the Permo-Triassic aquifers. There is significant uncertainty in the model projections this month and comparisons with current observations suggests they may be over-estimated; overall, considering both model- and observation-based sources of information, the likelihood is that levels will be in the normal range or moderately above normal across all aquifers. For full information on the groundwater outlook, click here.