(Bloomberg) — Early-September downpours have drenched many Londoners, foreshadowing what forecasters say could be a soggier-than-usual autumn, but that probably won’t be enough to lift the UK’s drought.
Over 28mm (1.1 inches) of rain fell in London during the first four days of this month, more than half the amount the city receives in a typical September, Met Office data show. And it’s not just the capital: Hampshire, Berkshire and Buckingham have all recorded similar precipitation.
While it’s far from monsoon conditions, it could signal a damp and rainy autumn following an usually dry and record-hot summer, said Will Lang, chief meteorologist with the UK Met Office. Seasonal forecasts show a 35% chance of wetter-than-average conditions and a 45% chance of stronger winds across the UK from September through November.
“What we’re picking up on is a slightly increased chance of stronger jet stream conditions and stronger westerly winds, so even more of an Atlantic influence as we head into autumn than usual,” Lang said in a seasonal weather briefing ahead of Monday’s meeting of the UK’s flood task force.
Warmer weather is also forecast, which can boost rainfall by increasing ocean evaporation and helping clouds hold more moisture.
The shift could mean more umbrella days through the season, but it’s unlikely to fill long-term water deficits triggered by the UK’s driest spring in more than a century. Those shortfalls were deepened by a hot summer that only saw 84% of normal rainfall.
“It’s going to take a long while to do anything to reverse those,” Lang said.
Drought conditions have led to mandatory water restrictions and hosepipe bans from Yorkshire in the north, through south Staffordshire and into regions served by Southern Water and South East Water.
Wetter conditions during the autumn tend to increase flood risks, the Met Office said, adding that it’s too soon to make predictions. A combination of very dry weather followed by torrential rain can be particularly risky as the ground absorbs less water, increasing runoff and the potential for flooding.
Some 6.3 million homes and businesses in England are at risk of flooding. Still, almost 93% of the Environment Agency’s most important flood defenses are in an acceptable condition, after more than £100 million ($135 million) was spent on refurbishing them in the past two years, said Caroline Douglass, the agency’s executive director for flood and coastal risk management.
Ultimately, there will be large regional differences in rainfall over the coming months.
Glasgow — one of the UK’s rainiest cities — only received 5% of its typical September rainfall in the first days of the month.
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