Convective Outlook: Sun 26 Apr 2020
LOW
SLGT
MDT
HIGH
SVR
What do these risk levels mean?
Convective Outlook

VALID 06:00 UTC Sun 26 Apr 2020 - 05:59 UTC Mon 27 Apr 2020

ISSUED 18:58 UTC Sat 25 Apr 2020

ISSUED BY: Dan

Heights will gradually fall during Sunday over the British Isles, as the upper ridge recedes to the Continent allowing a sharpening upper trough near north Scotland to begin to sink southwards. The net result is a gradually strengthening mid-level westerly flow, while the surface pattern remains rather slack and conducive to low-level convergence and confluence in response to diurnal heating, surface troughing and the approaching weak cold front from the north.

... WALES / MIDLANDS / EASTERN ENGLAND ...
A zone of slightly higher surface dewpoints (8-10C) was located over Wales and SW England on Saturday, and this is expected to gradually advect northeast across the Midlands towards eastern England on Sunday as the mean surface flow veers from the east round to the southwest. Moisture pooling along convergence zones, and also aided by orographic forcing, will provide the focus for a few scattered heavy showers to develop during Sunday afternoon and early evening. 
Overall, the environment is slightly more conducive for lightning than compared with the previous two days, however 100-300 J/kg CAPE, somewhat marginal mid-level lapse rates, weak shear through the cloud-bearing layer and restricted depth of convection suggests that any lightning will be isolated, and most areas will remain void of any such activity. The risk is generally considered 15-20% in any one location.

... S IRELAND ...
Depending on the speed of the weak cold frontal boundary from the north, slightly higher surface dewpoints may linger over the far south of Ireland, which may aid in the development of isolated showers during the afternoon hours should a convergence zone become established. However, given the restrictions mentioned in the above paragraph, the risk of lightning here is considered very low (10%).

... SCOTLAND ...
Throughout this forecast period, scattered showers will affect parts of Scotland - especially in northern and western parts. While shear is much stronger here, it is generally confined to above the cloud-bearing layer, and so given otherwise meagre CAPE and limited convective depth the risk of lightning is also considered very low (10-15%).