Valid: Sunday 19th August 2012

Issued For: Heavy Rainfall, Localised Thunderstorms


  • Heavy rainfall could lead to localised flooding
  • Weak Wind sheer and instability leading to thunderstorm development

Forecast Detail

During Sunday morning and into the afternoon an area of rainfall associated with a waving warm front will push across South-West England and into Wales spreading up into North-West England giving accumulations of 5-10mm quite widely with localised totals in excess of 20mm which could lead to some localised flooding, whilst embedded thunderstorms are considered unlikely, the odd rumble of thunder cannot be ruled out.

Later in the afternoon we’ll also see a short-wave feature pushing close to South-West England, whilst there is some uncertainty about this, the instability brought by this short-wave combined with weak wind sheer could lead to some heavy thundery showers across the far South-East corner leading to locally high rainfall totals.

Orange Zone: Weather Warning Issued

A slow moving area of rain associated with a warm front will lead to totals in the region of 5-10mm with local falls of 20mm, localised flooding is a possibility within this area.

Yellow Zone: Weather Advisory Issued

Slow moving isolated thunderstorms may develop during the later part of the afternoon in this zone, due to fairly poor lapse rates and weak sheer storms are unlikely to be too severe in nature, however brief localised flooding and dangerous driving conditions may arise in any stronger cells that develop, a weather advisory has therefore been issued.

South-East England may see some slow moving, torrential downpours develop later in the day leading to dangerous conditions due to a Short Wave feature creating instability, however there is some uncertainties to the extent of this development.