Convective Outlook: Wed 05 Aug 2020
What do these risk levels mean?
Convective Outlook

VALID 06:00 UTC Wed 05 Aug 2020 - 05:59 UTC Thu 06 Aug 2020

ISSUED 06:36 UTC Wed 05 Aug 2020


As the forward side of an upper trough, and associated PVA / divergence, engages with a frontal boundary this will lead to increasing instability as cool, dry air aloft overspreads a warm, moist low-level airmass. Consequently embedded deep convection is possible, bringing the risk of sporadic lightning across southern Ireland and the Celtic Sea during Wednesday morning (15-20% chance), heading across the Irish Sea towards Wales and NW England - however, by this stage the upper trough will be relaxing, and so there is likely to be a weakening of activity as it approaches western Britain. Nonetheless, a few isolated lightning strikes will still be possible into the afternoon hours associated with the passage of the trough - primarily W + N Wales into northern England (10-15% chance). A few isolated lightning strikes will be possible elsewhere from weak embedded elevated convection, but the risk is considered fairly low (5-10%).

Most activity will have weakened and/or cleared to the North Sea by mid-evening. It is worth noting that the latest 00z guidance has markedly reduced the signal for deep convection compared to NWP output during Tuesday, and so the risk of lightning today now looks lower.