RESEARCH//EVENTS//2023-09-17

Littlehampton-Lyminster tornado

Sunday 17th September 2023

A warm and unstable airmass covered much of the UK on 17 September 2023, with a southeasterly flow between an area of high pressure over Scandinavia and a slow-moving depression to the west of Iberia. Various showery troughs were embedded within this flow, with associated areas of showers and thunderstorms moving north or north-northeast across England and Wales, producing localised flooding in places.

A more potent shortwave trough moved north-eastwards through northwest France and the English Channel during the evening, with an associated area of locally intense thunderstorms. This moved across the English Channel and into parts of southeast England by late evening. It was in association with this area of thunderstorms that the tornado over Littlehampton developed. Weather models and observations indicate that these storms formed in an environment characterised by large Convective Available Potential Energy (CAPE) of around 1000J/kg and substantial vertical wind shear (0-6km shear estimated at 32kt), a combination favourable for organised severe thunderstorms.

During the investigation, a 3.5km damage track, indicative of a tornado travelling from West Beach, Littlehampton to Lyminster, was found. The site investigation was undertaken on 19 September 2023 by TORRO Site Investigator Sarah Horton , and a subsequent visit was made on 30 September 2023.

The full Site Investigation report is available here .

TORRO are very grateful to members of the public for providing information on damage and eyewitness accounts, which are invaluable in helping the analysis of this event. If you have any further information, please get in touch .