During Tuesday daytime the main risk (albeit low) will be across Ireland and Scotland, especially Northern Ireland into NW / W / SW Scotland as a shortwave lifts northwards through the afternoon. Strong shear may aid organisation of any cells, capable of producing gusty winds and hail up to 1.5cm in diameter. The lightning aspect is a little more questionable - but a low-end SLGT has been introduced. Slight backing of the low-level winds, and strong low-level speed shear, could encourage some updrafts to rotate with the small chance of an isolated tornado - however, the cloud base heights will tend to increase later in the day as drier air arrives from the southwest.

Overnight, the attention turns to England and Wales - the specific detail is still a little uncertain, but in a broad sense heavy rain along the waving frontal boundary will clear to the North Sea, and during the early hours of Wednesday an environment increasingly favourable for deep convection will gradually spread eastwards. A marked dry intrusion is expected to slide eastwards across southern Britain, atop a very moist low-level airmass. Convective clusters may develop and drift east/northeastwards, although the exact placement varies amongst model guidance from anywhere between the north Midlands to SW / Cen S England. Initially, the depth of convection may be relatively shallow with rather skinny CAPE, but in either case strongly-sheared profiles with some backing of the low-level winds / strong low-level shear suggests potential for convection to become organised with perhaps some rotating updrafts.

Convection may be mostly rooted from a slight warm bulge at ~900mb, with the main hazard locally strong/damaging gusts of wind and perhaps hail, but there may also be scope for an isolated tornado if surface-based convection can also develop - more especially towards the end of the night as the low-level flow strengthens. A low-end SLGT has been issued for the early hours of Wednesday where the best potential overall exists for some sporadic lightning, but confidence is rather low on whether much lightning will actually occur.