VALID 06:00 UTC Fri 16 Jun 2023 - 05:59 UTC Sat 17 Jun 2023

ISSUED 06:43 UTC Fri 16 Jun 2023

ISSUED BY: Dan

A rather complex evolution is anticipated on Friday, as a relatively high Theta-W airmass, originating from the subtropics, is advected northwards across Ireland as southwesterly flow aloft strengthens on the eastern flank of a slowly advancing upper low over the Atlantic. An occlusion will drift progressively northeastwards across southern and central Ireland through the day, associated with an area of cloud and showery outbreaks of rain. There may be some pockets of embedded thunderstorms within the broader area of showery rain, but confidence on how much lightning will occur is rather low given the messy mixture of stratiform and convective rainfall. There is scope this zone could fragment somewhat through the day, perhaps most likely in western areas, which may allow a degree of surface heating to occur. As such, a few thunderstorms could develop, again more likely in western/southwestern areas, but much of this potential will depend heavily on how extensive the cloud/rain is along the occlusion - and therefore confidence is low. Ulster will likely see more insolation, and so arguably here - especially across central/western areas - there may be better potential for a few heavy showers/thunderstorms to develop. Given stronger flow aloft than recent days and backing of the low-level winds coupled with decreasing humidity with height, if sufficient heating occurs to allow surface-based thunderstorms to develop then there would in theory be scope for cell organisation/multicell clusters that could potentially produce hail up to 2cm in diameter and wind gusts to 40mph - a SVR was introduced for isolated marginally-severe hail. In general, low confidence in local detail precludes any higher threat levels from being included.