Convective Outlook: Wed 29 Jun 2022
What do these risk levels mean?
Convective Outlook

VALID 06:00 UTC Wed 29 Jun 2022 - 05:59 UTC Thu 30 Jun 2022

ISSUED 06:31 UTC Wed 29 Jun 2022


Longwave upper trough will linger over the British Isles on Wednesday, with the main axis over Ireland. A shortwave will lift northwards across England into Scotland during the day, and this will provide the main focus for the greatest instability (200-500 J/kg MLCAPE) and deepest convection. Numerous showers will likely develop across Britain and Ireland in response to diurnal heating and low-level convergence/orographic forcing, however for the most part convection will tend to be capped around 650mb (13,000ft) by warming/subsiding air aloft in the wake of the earlier shortwave and so the risk of lightning in any one location is rather low (but non-zero). Across the far north of England into Scotland, deeper convection is anticipated with tops potentially around 23,000ft and the better chance to utilise the stronger flow aloft to aid in cell longevity/intensity. As such, a few sporadic lightning strikes will be possible, primarily within the low-end SLGT. A couple of funnel clouds will be possible almost anywhere where vorticity generated by low-level convergence, aided by onshore breezes, is stretched by developing updrafts.

During the evening and night a second shortwave will swing northwards from the western English Channel to reach southern Scotland/Northern Ireland by the end of the night. This will likely engage with the trailing frontal boundary near SE England to generate a frontal wave with outbreaks of rain becoming more widespread for a time, drifting northwards. Increasing instability as cooling aloft occurs to the west/in the wake of the frontal wave will likely aid the development of showers during the evening/night hours which may produce a few odd lightning strikes almost anywhere across England, Wales, southern Scotland and eastern Ireland - but the risk is deemed broadly too low in any one location to justify any additional SLGTs at this stage.