Issued 2018-11-11 07:58:54
Valid: 11/11/2018 00z to 12/11/2018 00z
Slow-moving upper and collocated surface low will continue to rotate to the west of Ireland on Sunday, pulling an unstable S to SWly flow across England, Wales and Ireland, supporting heavy showers and isolated thunderstorms across southern and western counties.
… S IRELAND, WALES, MIDLANDS, LINCS, S ENGLAND and E ANGLIA …
Cold mid-level air circulating around upper low to the west and advecting NE across the UK atop seasonally warm sea surface temperatures of seas around southern and western coasts will produce steep lapse rates and locally strong pockets of instability moving inland from southern coasts with S/SW steering flow – supporting organised areas of heavy showers and some isolated thunderstorms with stronger updrafts. These showers/storms will be capable of producing isolated hail and gusty winds but more of concern, due to training of strong cells, some intense rainfall over a short space of time leading to localised surface water flooding of roads and some flash-flooding from water courses – particularly across southern counties of England.
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.