VALID 06:00 UTC Tue 21 Mar 2023 - 05:59 UTC Wed 22 Mar 2023

ISSUED 21:52 UTC Mon 20 Mar 2023

ISSUED BY: Dan

A fairly pronounced shortwave trough will quickly migrate northeastwards across Britain during Tuesday morning, exiting to the North Sea by the afternoon. Successive runs of the GFS have trended towards a quicker clearance, resulting in a fairly narrow window for deep convection. Modified forecast soundings at 12z, beneath the trough axis, suggest convection could potentially reach ELTs around -30C (tops around 20,000ft), but this reduces fairly quickly through the afternoon as the upper trough departs and warming/drying occurs aloft as heights rise in advance of an approaching upper ridge. This will also likely occur in conjunction with a drying boundary layer as mixing continues through the day, the net result being convection tending to become shallower from both above (most substantially) and from below with cloud bases rising through the afternoon. Therefore there is a small window from late morning to early afternoon where a few lightning strikes could occur across NE/E/SE Scotland, N/E England and Midlands from any intense/loosely organised cells (especially given reasonable cloud-layer shear) but this will be a reducing risk through the afternoon.