Convective Outlook
VALID 06:00 UTC Wed 19 Oct 2022 - 05:59 UTC Thu 20 Oct 2022
ISSUED 07:18 UTC Wed 19 Oct 2022
ISSUED BY: Dan
An upper low will remain anchored to the southwest of Ireland on Wednesday, with a series of shortwaves rotating around the main parent low providing the focus for clusters of showers/thunderstorms, primarily elevated in nature above a notable warm nose at 800-850mb. As such, several rounds/waves of activity are likely through this forecast period as these shortwaves engage/destabilise the 14-16C 850mb Theta-W plume covering much of Ireland, Wales and England. During Wednesday daytime most of any lightning activity is anticipated across parts of Wales, W / SW England and Ireland, but the focus will likely shift northeastwards during the evening and night hours as the main plume begins to finally shunt northeast ahead of a cold front.
Model guidance varies as to the timing / location / extent of potential elevated convection, and so naturally there is some uncertainty over the specific details.
However, broad themes can be identified - activity in the morning over the Irish Sea, eastern Ireland, Wales and W Midlands / SW England will probably weaken towards midday. A new wave may then develop late afternoon and into the evening over SW England and the Celtic Sea, moving northwestwards into Wales, W Midlands, Irish Sea and S + E Ireland. Here, model guidance appears fairly consistent with an active cluster of thunderstorms evolving and as such a MDT was introduced for the potential for greater lightning coverage. Parts of east and perhaps southeast England may see an uptick in activity during the early hours of Thursday, although this is very sensitive to the timing of the next shortwave which if delayed may push the main focus beyond this forecast period. Towards the end of the night, a frontal wave will approach Cen S / SE England, having evolved from convection initially over the Bay of Biscay and western France earlier in the night - much of this will likely be non-thundery, but a few embedded thunderstorms may be possible on the leading/eastern edge, therefore generally favoured towards SE England. Localised flooding will be the primary hazard, especially in parts of Ireland where there may be scope for 50-70mm locally.
