Below is a quick summary of the storms over Somerset as seen by the
Cobbacombe radar: the assessment is based upon the 2x2km radar product (5
minute scans). Note that the radar it not 'truth' - but is useful is these
instances to look at the spatial pattern of rainfall.

Units are in mm (or mm/hr) and time is GMT.



Timeline:

0900Z: Showery rain 2mm/hr approaches Portland, with heavier cells ~8mm/hr
around 1000Z

1200Z: band of rain progresses northwestwards, up to ~16mm/hr, stretching
from south Devon across to Dorchester: one cell (~8mm/hr) tracks up the Exe
estuary. This band clears to the north west, although further cells track up
the Exe.

1500Z: first echoes of significant rain develop in the east of the region
over Shaftesbury: these develop in a matter of ~10 minutes, producing rain
rates 32mm/hr, and move very slowly WNW.

1600Z: quite extensive area of heavy rain (10mm/hr) established over
Yeovil/Frome/Shaftesbury area. Another cell(s) develops to the SW over
Crewkrene.

1700Z: Large expanse of rainfall over much of eastern Somerset (8mm/hr). A
very heavy cell develops over Crewkerne (32mm/hr).

1800Z: Whole system moves WNW, with most of the heavy cells declining in
intensity through until 2000Z, when mostly 4mm/hr regions left.

2200Z: band of moderate/heavy rain from Brixham to Clovelly.





Total rainfall (midnight 28/29th through midnight 29/30th May 2008):



Total weight of water that fell within 100km radius of the Cobbacombe radar
was in excess of 251 million tonnes!



Highest total for the day was at Batcombe (north of Bruton/east of
Evercreech) with a total of 70.1mm. Surrounding areas also had high totals
(e.g. 67.9 and 60.1mm) which suggests that this total is plausible -
although strong gradients were present: 6km to the west of Batcombe, the
Bath and West showground had only about 20mm (being between a 22.3 and
18.9mm estimate).



Around Crewkrene, scene of flooding at Vinney Bridge, the highest local
total was 58.1mm at South Perrott, near the source of the River Parrett.



80 square kilometres had 50mm or more rainfall:

One 4sqkm near Dunkeswell (59.3mm); 16sqkm to the south and east of
Crewkerne (up to 58.1mm); 32sqkm to the southwest of Gillingham (up to
67.3mm); 28sqkm to the East and North of Bruton (up to 70.1mm)



1460 square kilometres had 25mm or more rainfall:

Obviously the 25mm+ region(s) were far more extensive than above. Main areas
were the eastern 'foothills' of Dartmoor, along the Exe estuary (and to the
southwest of Exeter); north of Honiton towards Wellington and Wiveliscombe;
to the south and east of Chard and Crewkerne; south and east of Yeovil;
Sedgemoor and Bridgewater. The largest area was stretched northwards from
Sturminster Newton/Shaftsbury to Midsomer Norton and west to Cheddar.



9192 square kilometres had 10mm or more rainfall:

Needless to say, a large area: take an area bounded by Brixham-Clovelly in
the SW, Torrington-Lynton to the NW, Ottery St Mary - Blandford Forum in the
south and the Bristol Channel coast to the North: almost all areas within
the box had 10mm+.