Convective Outlook: Fri 20 May 2022
LOW
SLGT
MDT
HIGH
SVR
What do these risk levels mean?
Convective Outlook

VALID 06:00 UTC Fri 20 May 2022 - 05:59 UTC Sat 21 May 2022

ISSUED 06:46 UTC Fri 20 May 2022

ISSUED BY: Dan

An upper trough will swing eastwards across the British Isles on Friday, with cooling aloft yielding a few hundred J/kg CAPE in response to diurnal heating. The forward side of the upper trough will also engage with the high Theta-W plume over the nearby Continent to create another wave of thunderstorms over France, the Low Countries and Germany, with CAM guidance indicative of a significant damaging wind event (derecho) from Belgium/Luxembourg and across portions of Germany. This thunderstorm activity should remain clear of the UK, but may pass close to the Strait of Dover during the morning hours. Otherwise the main attention will be with the rather messy mixture of dynamic and convective rainfall spreading eastwards across many parts of Ireland and Britain.

The greatest risk of some sporadic lightning will be during the afternoon and early evening across northern and eastern Ireland and Northern Ireland, perhaps also extending across the Irish Sea into SW Scotland and close to the Isle of Man, with showers that follow the earlier frontal rain. A couple of other (very marginal) SLGTs have been included where some slightly deeper convection could evolve during the second half of the afternoon and into the first part of the evening, and may just produce a few lightning strikes - but unlikely to be too widespread, and certainly possible that very few occur at all. NE Scotland may also be another area to monitor. In all cases the risk of lightning will reduce overnight as instability wanes and ridging develops aloft.