Convective Outlook: Mon 16 May 2022
LOW
SLGT
MDT
HIGH
SVR
What do these risk levels mean?
Convective Outlook

VALID 06:00 UTC Mon 16 May 2022 - 05:59 UTC Tue 17 May 2022

ISSUED 06:51 UTC Mon 16 May 2022

ISSUED BY: Dan

At 06z Monday, an instability axis extended from Merseyside to East Anglia as a tongue of relatively high 850hPa Theta-W continues to sporadically destabilise in the vicinity of a marked trough lifting northeastwards. As such, pockets of showery rain are likely along this zone, and a few elevated thunderstorms continue to be a possibility - earlier CAM guidance had suggested a relative uptick in activity for a while on Monday morning in eastern England, for example. This instability plume will slowly weaken and clear to the North Sea, and thereafter the attention largely turns the post-trough environment as increasing amounts of sunshine and resultant surface heating will yield 400-900 J/kg CAPE beneath a zone of cool mid-levels stretching from Northern Ireland/north of Ireland across to the Midlands and northern England.

Scattered showers and a few thunderstorms appear likely to develop in these areas, drifting to the northeast, during the afternoon and first half of the evening. Forecast profiles suggest cloud tops in the strongest cells could exceed 30,000ft, and while shear is modest for much of the day a small mid-level jet maxima will run across the north Midlands and northern England during the late afternoon and evening hours, and so during this timeframe cells may become a bit more organised and longer-lasting. Some CAM guidance suggests thunderstorms may grow into a small cluster over northern England (especially Yorkshire) during the evening hours, perhaps even scope for a supercell given the magnitude of CAPE (over 800 J/kg) and increasing shear. If a strong storm can evolve later in the day, then it may produce hail 2.0-2.5cm in diameter and as such have tentatively included a SVR. Given the slack flow across NW and NE England, these areas would be favourable for perhaps a couple of convergence-driven funnel clouds.