|Day 1 Convective Outlook: Sun 19 May 2019|
|What do these risk levels mean?|
VALID 06:00 UTC Sun 19 May 2019 - 05:59 UTC Mon 20 May 2019
ISSUED 06:57 UTC Sun 19 May 2019br> br>
ISSUED BY: Dan
Broad upper trough covers the British Isles on Sunday, with a rather slack pressure pattern. Early in the forecast period some remnant elevated instability will pass close to Orkney and Shetland. Thereafter, provided there are sufficient cloud breaks, diurnal heating of the moist low-level airmass will yield 300-500 J/kg CAPE, with scattered showers likely to develop forced by low-level convergence and orographic forcing. As was the case on Saturday, weak steering flow (and hence weak shear) will lead to very slow movement of showers, bringing the risk of some local surface water flooding.