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Extra - September 25, 2012
Dry late-summer in the Southeast
All change now

By Philip Eden

It may seem odd to say it, following the wettest summer quarter over England and Wales for exactly 100 years, but from July 15 to September 22 there has been very little rain in many parts of Southeast England and East Anglia.

During that ten week period only 40mm of rain has fallen in London, while some districts in Essex and Suffolk have collected just 30mm. This represents between 20 and 40 per cent of the long-term average rainfall in this corner of the country.

Towards the end of those ten weeks, the effects of this dry spell began to show: in this southeastern quarter of England the ground became rock hard with deep cracks, and in some areas lawns turned decidedly yellow. At my local allotments association in Bedfordshire last week several people came up to me and, without a trace of irony, complained about the lack of rain.

It should be emphasised that it is only East Anglia and the Southeast that have stayed dry since mid-July; most other parts of the country were wetter than average throughout August and the first half of September.

The weather has now changed even in this dry southeastern corner, courtesy of a depression which can be traced back to a former tropical storm, codenamed "Nadine". It is interesting that, until last Saturday morning, our television forecasters resolutely refused to make the link between misbehaving mid-latitude depressions and former tropical storms or hurricanes. Maybe the shadow cast by the Great October Storm of 1987 still looms large.

This is a shame, because ex-hurricanes and tropical storms are particularly difficult to forecast. They have large amounts of warmth and moisture within their circulation, especially in the upper atmosphere, courtesy of their tropical origins, and both the warmth and the moisture provide extra energy upon which the depression feeds. This means that the computer models sometimes fail to handle the development of these "lows" accurately, and occasionally forecasts can go badly wrong.

With that caveat in mind, it does look as though the coming week will be very disturbed, with strong winds and heavy rain at times in many parts of the UK. But there are already signs that the weather may become rather more settled again at the beginning of October.

By Philip Eden

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