An interesting forecast has been bought up on my system.

Its predicting storms tomorrow night and rainfall of 60mm+, never seen that much rain forecast, so you may want to keep an eye on the local weather tonight and tomorrow.

Forecast are updated and uploaded every 3 hours starting at 00:30, so
00:30
03:30
06:30
09:30
12:30
15:30
18:30
21:30

Keep a close eye on it here Wighthobbies forecast

A more detailed report from the forecast is produced which shows the predicted weather for every 30 mins, this will tell us exactly when the heaviest rain will be!
Link to detailed forecast
Stuart