Convective Outlook: Wed 07 Sep 2022

LOW SLGT MDT HIGH SVR

What do these risk levels mean?

Convective Outlook

VALID 06:00 UTC Wed 07 Sep 2022 - 05:59 UTC Thu 08 Sep 2022

ISSUED 08:35 UTC Wed 07 Sep 2022

ISSUED BY: Dan

The upper low to the southwest of Ireland will finally begin to migrate eastwards across the British Isles on Wednesday. Once again, cool air aloft atop a fairly humid low-level airmass will create widely unstable profiles, driving another day with widespread scattered showers and some thunderstorms. Tall, skinny CAPE will probably limit the lightning potential in some areas, but certainly scope for locally high rainfall accumulations and the associated risk of surface water flooding. A broad SLGT has been issued, but there will very likely be large areas that remain void of lightning. Showers may merge into longer spells of showery rain in places, resulting in rather saturated profiles and reducing the lightning potential. Some more organised clusters/lines of heavy showers/thunderstorms could evolve over the English Channel during the late afternoon and through the evening and night hours, as PVA rounding the base of the increasingly negatively-tilted upper trough engages with the residual >14C 850hPa Theta-W plume over France. This activity may also affect the eastern side East Anglia late evening and after midnight, although by this stage some concern exists about upscale growth into broader areas of heavy, showery rain that may reduce the lightning potential. Further thunderstorms may also affect eastern Scotland later in the night too.