Showers/thunderstorms will tend to be focussed along several convergence zones that are likely to evolve through the day, one from Dorset/Somerset northeastwards into the south Midlands, another from C/E Wales across the Midlands to Yorkshire/Lincolnshire. These two corridors of activity may merge together towards the evening hours as the trough axis approaches from the west. Additional low-level convergence is expected to also develop near North Sea coasts from Edinburgh down to the Humber. Forecast profiles suggest deep convection to as much as 33,000ft with some reasonably dry air aloft. Lack of strong flow aloft results with rather weak shear, generally 5-15kts through the cloud-bearing layer. That said, the thermodynamic profile may be support for some fairly active thunderstorms at times, but the main hazards (aside from lightning) will be localised flash flooding - especially where multiple cells train over similar areas. The strongest cells may produce hail 1.0-1.5cm in diameter. Showers and thunderstorms will slowly decay during the mid-late evening period.