Convective Outlook: Thu 20 Feb 2020
LOW
SLGT
MDT
HIGH
SVR
What do these risk levels mean?
Convective Outlook

VALID 06:00 UTC Thu 20 Feb 2020 - 05:59 UTC Fri 21 Feb 2020

ISSUED 06:46 UTC Thu 20 Feb 2020

ISSUED BY: Dan

A sharp upper trough will swing eastwards across the British Isles on Thursday. On its forward side, the trailing cold front (having developed a wave initially) will exhibit a marked temperature gradient and wind veer, with strong low-level shear immediately ahead. As a result, elements of line convection are expected to develop along the front, although the depth of convection (especially compared to many of the recent events during the past month) will be notably shallow - as such, the lightning risk is considered very low. However, an isolated tornado cannot be ruled out where line segments fracture, perhaps allowing brief spin-ups. Either way, some squally bursts of rain (including strong straight line winds and small hail) will be possible as the cold front tracks eastwards during daylight hours.


Immediately behind the cold front, a few scattered showers may occur which may pose a slightly better potential for lightning given greater proximity to both forcing and cold air aloft. Elsewhere, steep mid-level lapse rates will overspread Ireland, Scotland and northern England as the main cold pool / trough axis swings through. As such, numerous showers will affect these areas, some producing sporadic lightning and hail up to 1.5cm in diameter. A low-end SLGT has been introduced where lightning is considered more likely to occur.