Then you have this from Tony Gilbert on UKWW
Slight Risk of Isolated Thundery Showers 12z to 23z UK & Ireland
Sadly I can only give a brief heads up today due to lack of time;
Quasi stationary low sits just NE of Scotland. A number of isolated thundery showers expected to develop to day as per map. Highest risk of thunder, central Ireland.
Weak DLS and LLS. Fairly limited convergence with slightly elevated LCL suggests anything severe unlikely. Though GFS give the chance of CAPE to 500 j/kg and WRF much higher at 1000 j/kg. So in many ways we have a low shear / high instability outlook.
Now all aside I have noted a zone where buoyancy will be quite exceptional; Devon through to Dorset this afternoon. Convection is likely to develop within exceptional 'Potential Instability'. Very dry air at mid level over moderate surface moisture could set the scene for stronger updrafts. An isolated FC or two cannot be rules out for this zone. Steering winds are slow and very weak at mid levels. This condition can make updrafts fold quite rapidly possibly resulting in point deluge. Flooding will be possible. Any folding storm in this zone will also be capable of producing gusts to 40kts today