Otherwise, the main attention turns to the post-frontal environment as a substantial negatively-tilted upper trough swings northeastwards across the UK/Ireland, with cold air aloft atop warm SSTs yielding several hundred J/kg CAPE. Showers initially near western coasts will extend will in-land through the day, due to a combination of strong steering flow and diurnal heating inland aiding their longevity / additional development. A few sporadic lightning strikes will be possible just about anywhere, hence the broad LOW threat level - however, particular attention is given to parts of NW England, NW Ireland and W Scotland, especially during Monday evening and night where numerous showers are likely and coverage of lightning may be a little greater. Warming aloft will tend to limit the depth of convection over Wales / SW England on Monday night compared with areas further north, and hence the risk of lightning here is probably greatest during Monday daytime. Hail and gusty winds will accompany the most intense cells.