A series of intense thunderstorms brought exceptionally severe weather across parts of the UK yesterday, causing flash flooding and disruption in many places.
As the storms tracked across the country our observation sites picked up some very heavy hourly rainfall totals, with Scampton in Lincolnshire seeing 28.4 mm falling in an hour.
Several other sites saw hourly totals in excess of 20 mm. This led to flash flooding of properties, roads, and landslides in places.
More than 111,000 lightning strokes were also detected across Europe, with more than 1,000 detected over the UK in a 5 minute period at the peak of activity yesterday.
Hail stones ‘the size of golf balls’ also caused damage in Leicestershire, according to media reports.
The storms were borne out of hot, humid air which had tracked up from the Azores far to the south in the Atlantic. This air mass tracked up on southerly winds, moving over Spain before reaching the UK.
As a result, much of the country saw warm and muggy conditions, with the temperature reaching 28.4 C at St James’s Park, Central London.
The heat and moisture in the air were enough to cause thunderstorms, but the really intense storms were formed as an Atlantic weather front moved in from the west.
As it ‘collided’ with the warm and humid air mass, air rapidly rose to create towering cumulonimbus storm clouds which were laden with water, and ripe for developing hail, thunder and lightning.
This led to several distinct lines of thunderstorms developing along the boundary where the two air masses met.
As shown in the radar sequences below, one line originated in the Cardiff area of south Wales in the early morning. This moved in an east-north-east direction across Worcestershire, Shropshire, the West Midlands and Leicestershire to clear Lincolnshire by late afternoon.
A second line of thunderstorms reached the Lancashire coast around late morning and moved in a NE direction to reach the Newcastle area later in the day, clearing the north east coast by late evening.
There were also torrential downpours across parts of Northern Ireland and western Scotland. Southern parts of England and Wales saw relatively little rain and periods of warm sunshine.