|Convective Outlook: Mon 13 Sep 2021|
|What do these risk levels mean?|
VALID 06:00 UTC Mon 13 Sep 2021 - 05:59 UTC Tue 14 Sep 2021
ISSUED 06:28 UTC Mon 13 Sep 2021br> br>
ISSUED BY: Dan
On Monday, an initially positively-tilted upper trough over the Celtic Sea will become increasingly negatively-tilted through the forecast period. As the southerly flow aloft strengthens, relatively high Theta-W will advect northwards from Biscay across France towards southern England. Even at this late stage there is some uncertainty over the exact forecast evolution, but profiles are likely to become increasingly unstable from northern France and across the English Channel on Monday night/early hours of Tuesday. In general, rather moist columns and limited CAPE will tend to limit the lightning risk, with perhaps just the Channel Islands and central/eastern English Channel being the main focus for any sporadic lightning, despite outbreaks of rain being much more extensive further north across the UK/Ireland. It seems plausible that clusters of elevated thunderstorms may develop over northern France, but weaken as they track north across the English Channel.