We are starting to the see the transition now from land to sea-generated convection as we head towards the autumn months. Broad upper low will sit over the British Isles on Saturday, with an associated surface low drifting from Northern Ireland to the Scottish Borders / North Sea by the end of this forecast period. Cool mid-levels atop relatively warm SSTs and increasing land surface temperatures during the diurnal cycle will create an unstable environment, with numerous showers developing and rotating around the main parent low.

This then gives a rather broad area at risk of lightning (hence the large LOW threat level), albeit each individual shower has a relatively low chance of producing lightning, and hence makes it rather difficult to highlight specific areas to upgrade to SLGT. One main inhibiting factor may be excessive amounts of cloud reducing the amount of insolation in places, especially associated with wrap-around occlusions. Nonetheless, some lightning is expected, and we have included a SLGT where forcing might be better during the afternoon/evening hours.

The most intense showers will be capable of producing gusty winds, perhaps a brief funnel, and also small hail.