The small village of Coverack in West Cornwall was badly damaged by flooding after a storm brought torrential rain to the area on 18 July 2017.
By Ian Mills (EUMETSAT)
On the morning of 18 July two large storms could be seen in the Sentinel-3 image from 10:49 UTC (Figure 2), positioned over Brittany, France and the English Channel.
These storms moved north to affect southwest England during the afternoon, however, although they brought heavy rain, they were not responsible for the flash flooding in the Cornish village of Coverack.
As the storms moved north to the east of Coverack during the afternoon, a new storm cell can be seen forming over/near the village at 12:45 UTC (Figure 1, top right, click to expand).
This storm cell remained stationary near the village for about three hours, producing heavy rain which caused flash flooding and considerable damage in Coverack.
On the Meteosat-10 Severe Convection RGB animation, 18 July 09:00–17:00 UTC (MP4, 3 MB), it can be seen that as the first storm cloud moved to the east a daughter cell formed on the southern edge at 12:00 UTC.
It shows in the animation as a light yellow cell and is an indication of the rapid formation and strong updraughts of the storm cell. It is likely that this cloud was triggered by convergence from the outflow from the larger cell and the southerly surface wind.
A second cell generated to the west of the main cell at around 12:45 UTC very near Coverack. Further cells generated over and around the Coverack catchment area causing heavy rain and flash flooding in the village during the early afternoon.
In the Meteosat-10 High Resolution Visible animation, 18 July 09:00–17:00 UTC (MP4, 3 MB) small overshooting tops (bright white dots) can be seen forming near and over Coverack during the afternoon.
Meanwhile in the enhanced Meteosat-10 infrared animation of the same period (MP4, 4 MB) the blue colour shows there were cold cumulonimbus tops between -60 and -65 C.