Football fields in Tacaster, North Yorkshire, were also totally submerged after heavy downpours. (Daily Mail)
It seems the ground has been saturated across much of Britain since April. I believe the trigger for this wild turn from drought to flood was the transition from a back to back La Nina to El Nino. A possible contributor to the ‘excessive’ rainfall this year may be the cold PDO vs unusually warm AMO, the same warm AMO which produced a record arctic ice melt at the end of summer.
The warm AMO has likely helped juice up Atlantic lows making them stronger as well as containing more moisture. Warmer water releases more heat and ultimately more energy to the atmosphere and part of the energy is moisture. A predominantly negative NAO during summer, compared to the positive last summer, meant the rainfall has been both, for the most part, non-stop but it’s combination of increased energy released into the atmosphere from a warmer North Atlantic and the colder than normal air aloft thanks to a mean trough sitting fixed over the UK this summer and autumn created the perfect environment for persistent and unusually heavy rains.
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Another aspect to consider is the persistency in a blocking high this year over Europe. While the Atlantic jet has been active, a blocking high over both the North Atlantic and over Europe, meant and remains the case now, that low pressure systems have frequently tracked between between the twin high pressure systems, driving lots of heat,m energy and moisture into the UK from the sub-tropics (Southwest). The high over Europe stops these systems from pushing through quickly and so a slower moving frontal system, combined with greater amounts of rain coming from the sub-tropics, the energy from a warm AMO and cold from trough, all brought about an exceptionally wet year and right up until the final week of 2012, we yet again deal with significant and for some, devastating flooding.
The flooding in the past few days across parts of England, Wales and eastern Scotland has been just as devastating as the frequent flooding events we have witnssed over the past 9 months. June, July were particularly bad, less so in August when we saw the warmest weather of the entire summer. September was nasty again while October brought respite before yet more severe flooding occured in November. Even within the last 2 weeks of the year, yet more flooding has hit and hard.
Here is some video from the latest flooding.
In recent times, flooding has been easier to come by with any sort of heavy rain, what I mean is that with very saturated ground, really any rain that falls, will produce flooding. I’ve seen flood waters lie in fields surrounding Dumfries since spring. The frequency of the heavy rain has meant, these flood waters have lay there for ‘months’.
Of course all the moisture lying over Britain does have a feedback to the atmosphere which can encourage more rain to fall. The moisture in fact increases the humidity level of the air and so this can have an effect on rainfall rate and distribution too.
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I must remind everyone, where the rain goes: the cold goes. All you people with flooded homes better be prepared to freeze once this rain passes. Joe told you so!