VALID 06:00 UTC Fri 12 May 2017 - 05:59 UTC Sat 13 May 2017

ISSUED 20:23 UTC Thu 11 May 2017

ISSUED BY: Dan

As the frontal boundary continues to lift north on Friday, a slack surface pressure pattern will evolve near the low centre. Diurnal heating will generate several hundred Jkg^-1 CAPE under a broad upper trough, with low-level wind convergence aiding the development of scattered showers and a few thunderstorms for Friday afternoon and early evening, decaying after sunset. A low-end SLGT has been (reluctantly) issued, but some questions remain over both the extent of cloud cover and also a potential warm nose in the mid-levels that may limit convective depth, and hence markedly restrict lightning potential - it is possible very little lightning may occur in the SLGT area. Assuming that parcels can overcome this, then lightning will be possible, primarily within the SLGT area. Main focus will begin in the south of the SLGT area midday/early afternoon, and shift progressively north through the afternoon and early evening.