Convective Outlook: Thu 18 May 2023

LOW SLGT MDT HIGH SVR

What do these risk levels mean?

Convective Outlook

VALID 06:00 UTC Thu 18 May 2023 - 05:59 UTC Fri 19 May 2023

ISSUED 05:28 UTC Thu 18 May 2023

ISSUED BY: Dan

An upper ridge will cover much of the British Isles on Thursday, generally suppressing the potential for deep convection. Nonetheless, diurnal heating will encourage several low-level convergence zones to develop, also aided by sea breezes advancing inland. Despite mixing of the boundary layer, there may be sufficient moisture pooling along convergence zones (Td 10-13C) to generate a few heavy showers in parts eastern and southern England. Mid-level capping will restrict the depth of convective cloud to very roughly ~15,000ft, and so lightning is unlikely in most places. However, towards the evening hours there may just be the small potential for an isolated thunderstorm to develop given persistent forced ascent from low-level convergence coupled with very slight cooling of the mid-levels as an upper low over the Netherlands drifts gradually southwestwards. Showers will likely persist/continue to develop well into the evening, and perhaps also overnight given potentially some engagement from PVA rounding the northern flank of the upper low over the Low Countries and also shear vorticity arriving from the NW later in the night.