Issued 2018-08-13 05:48:04
Valid: 13/08/2018 00z to 14/08/2018 00z
Upper trough towards the eastern side of the UK this morning will drift away eastwards into the Low Countries this afternoon, weak ridge building across the west, shallow surface low situated over south North Sea at noon, with associated wrap around occlusion close to east coast of England, the low deepening a little as it moves east across Denmark by midnight. Heavy showers and a few thunderstorms likely to develop across eastern England this afternoon.
... E ENGLAND ...
Models indicate surface breeze convergence / moisture pooling not far inland of east coast of England this afternoon, steeper lapse rates towards the east closer to colder air aloft of exiting upper trough and scope for some surface heating will generate sufficient instability combined with lift of convergence to support heavy showers and increasingly into the afternoon a few thunderstorms too. Steering flow towards eastern UK will be fairly slack, so main threat will be slow-moving showers/storms bringing a risk of localised flooding.
Issued by: Nick Finnis
Issued by the Netweather forecast team whenever there is a risk of storms or severe convective weather, these discussion based and in depth forecasts will highlight the areas at risk and give an in depth description of the risk and the factors surrounding it.
Thunderstorms - Severe thunderstorms unlikely to occur, slight risk of hail, gusting winds and localised flooding.
Slight Risk - A slight risk of severe convective weather exists. Hail >2.0cm diameter, wind gusts exceeding 50mph or 5-10% risk of a tornado within 50 miles of a point, or > 30% risk of localised flooding.
Moderate Risk - A moderate risk of severe convective weather exists. Hail 4-5cm in diameter, or wind gusts of 60-70mph, or a 10-15% chance of a tornado within 50 miles of a point, or >50% risk of localised flooding.
High Risk - A high risk of severe convective weather exists. Rarely, if ever used on the UK. Hail >5cm, or wind gusts in excess of 80mph, or >20% risk of a tornado within 50 miles of a point, or >70% risk of localised flooding.