Thursday 29 November 2012

November wet spell

The first half of November was relatively dry, but the final week made up for it with 100.4mm between the 24th and 29th.
The month's total at 29th November stands at 148mm which is well above the average 105mm but well behind 2009 which clocked up 181mm.

So a wet month but locally the Esk flow,  though very high at times in the last week was not exceptional indeed it was probably similar to during the wet spell in September (when we had about 70mm over two days).

Further afield the Ouse through York also seems to have peaked at similar concerning but not record breaking levels, while at Malton the Derwent has been higher than any time since new defences were completed. Flooding there was mainly the result of surface water accumulating faster than it could be pumped (up) into the flooded river and on balance the new works must be declared a success although a few property owners may dispute this.

The cause was a classic for serious rain events over the NE of England, with a slow-moving Low Pressure system in the southern North Sea throwing almost continuous rain towards the east coast.
With 'Orographic Enhancement' any high ground such as the moors can expect to receive a great deal of rain in this situation.
If it had been later in the winter there could have been a major snow event from this, so we have perhaps been rather lucky and should hope that future systems do not follow a similar track as sometimes happens if high altitude winds are persistent.