Paul Knightley
EF5
Not a report as such as I wasn't anywhere near this.
An occluded frontal system associated with an area of low pressure moved across western parts of the UK on Wednesday night, bringing heavy rain and hill snow (during what has been a historically wintry week for late October in the UK!). Around midnight, the precip on the back of the front across SW England turned more convective, as the upper trough moved in. A small circulation area moved across south Devon and became slow moving near Exeter. Just north of this, persistent low-level convergence beneath steep mid-upper lapse rates caused a back-building multicell thunderstorm to develop, with the core located over and around the small market town of Ottery St Mary. This dropped over 50mm, and perhaps 70mm of rain in just a couple of hours, and copious amounts of hail (the hail itself small marble size at most, but generally smaller).
The terrain in the area is very hilly, with a high and rapid run-off rate for such intense preicp. Flash-flooding was the result, and this washed much of the hail down into the town, where it built up to be several feet deep in places.
Such occurrences are not without precedent in the UK, but they are fairly rare, with the last one being in Cornwall a few years ago.
See links below:
http://news.bbc.co.uk/1/hi/england/devon/7700167.stm
http://www.thisisexeter.co.uk/floods
An occluded frontal system associated with an area of low pressure moved across western parts of the UK on Wednesday night, bringing heavy rain and hill snow (during what has been a historically wintry week for late October in the UK!). Around midnight, the precip on the back of the front across SW England turned more convective, as the upper trough moved in. A small circulation area moved across south Devon and became slow moving near Exeter. Just north of this, persistent low-level convergence beneath steep mid-upper lapse rates caused a back-building multicell thunderstorm to develop, with the core located over and around the small market town of Ottery St Mary. This dropped over 50mm, and perhaps 70mm of rain in just a couple of hours, and copious amounts of hail (the hail itself small marble size at most, but generally smaller).
The terrain in the area is very hilly, with a high and rapid run-off rate for such intense preicp. Flash-flooding was the result, and this washed much of the hail down into the town, where it built up to be several feet deep in places.
Such occurrences are not without precedent in the UK, but they are fairly rare, with the last one being in Cornwall a few years ago.
See links below:
http://news.bbc.co.uk/1/hi/england/devon/7700167.stm
http://www.thisisexeter.co.uk/floods
