VALID 06:00 UTC Sat 08 Dec 2018 - 05:59 UTC Sun 09 Dec 2018
ISSUED 21:55 UTC Fri 07 Dec 2018
ISSUED BY: Dan
A complex pattern over the British Isles on Saturday, with upper ridging generally stunting convective depth at first, with the exception of the Northern Isles where deeper convection will likely exist due to the proximity to the upper low over the northern North Sea.
With time, heights will fall as upper troughing develops and continues to sharpen as the trough axis slides southeastwards across the British Isles. This will deepen the convective layer, with cold air aloft atop relatively warm SSTs generating a few hundred J/kg CAPE in an environment with very strong DLS. This more favourable environment will evolve over Ireland during the afternoon hours, then extend across England and Wales during Saturday night.
Numerous showers are likely to develop, especially over open seas but moving well-inland courtesy of both strong steering flow and notable upper forcing. A few sporadic lightning strikes and small hail will be possible from the most intense cells. Some damaging gusts of wind will also be possible, and given the environment a tornado cannot be ruled out.