VALID 06:00 UTC Wed 22 Mar 2023 - 05:59 UTC Thu 23 Mar 2023

ISSUED 07:33 UTC Wed 22 Mar 2023

ISSUED BY: Dan

A broad upper vortex will reside over the Atlantic to the west of Ireland, with several embedded shortwaves migrating northeastwards in the strong southwesterly flow aloft. Many parts of the British Isles have some risk of convection at some point during this forecast period, but the deepest convection will likely be over Ireland closest to the upper low and troughs arriving from the Atlantic. Cold air aloft overspreading the British Isles will steepen mid-level lapse rates, while modest surface heating may yield as much as 500 J/kg CAPE. During the afternoon hours, PVA on the forward side of an approaching shortwave will likely encourage broad lift over Ireland, overlapping favourably with diurnal heating. As such, scattered showers are likely to develop, but may ultimately merge into longer spells of showery rain as one or two more organised features run northeastwards from the Atlantic. This casts some uncertainty as to how much lightning activity will occur, partly limited due to fairly moist profiles at times, despite forecast soundings suggesting potential for ELTs to -40C. That said, the kinematic environment is impressive for UK/Ireland standards with as much as 50kts 0-6km shear and decent backing of the low-level wind field. Therefore, any cells that can remain semi-discrete could potentially acquire supercell structures and may also produce marginally-severe hail and pose a tornado threat - but this risk is thought to be relatively low given the potential for convection to become rather messy. Nonetheless, the potential is worth monitoring. Tentatively introduced a low-end SLGT over Ireland.