Weather Watch: Downpour which caused floods is worst on record

Image of the jet stream and surface pressure of storm arriving on Valentines Day 2014
Image of the jet stream and surface pressure of storm arriving on Valentines Day 2014

The devastating flooding dominating the UK headlines recently has led to anger and blame being pointed in various directions.

Whilst everyone has their own opinions on whom or what’s responsible, one thing is irrefutable – it has certainly rained a lot!

This winter (December to February) is likely to be the wettest in over 250 years of records across England and Wales.In the central southern/south-east England region covering Bucks, where records date back to 1910, we have already far exceeded the previous wettest winter of 1915, when 437mm fell. It is therefore no great surprise that we’ve witnessed so much flooding across the country – akin to that of autumn 2000 during the wettest year on record, summer 2007 and March 1947.

The 1947 flood affected 30 counties and was the result of heavy rain and a rapid thaw following seven weeks of exceptional snowfall. That led to some of the worst flooding on record across the Thames Valley.

Last week, I discussed how our exceptionally wet and windy winter was associated with the record-breaking low temperatures seen recently in the US and Canada; the link being a very active polar jet stream, which in turn has been driving storm after storm across us.

In fact, this is only one part of a much bigger global chain of events. Higher than normal sea temperatures in the tropical west Pacific and the resulting increased rainfall there, have led to changes in the intensity and location of the Pacific jet stream. This has affected the behaviour of the jet stream across North America and the Atlantic. An unusually strong ‘polar vortex’ high up in the stratosphere has also had a major impact.

These so-called ‘teleconnections’ between weather patterns across the globe and high up in the atmosphere are a reminder that the weather has no geographical boundaries and that the atmosphere is a hugely complex system, one that must be treated as truly global by the models used for weather forecasting.

Back to the here and now and after a mainly dry day today, it’ll be wet overnight and at first tomorrow, windy with sunshine and showers on Friday, but then a mostly fine weekend!



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