Convective Outlook: Fri 19 May 2023

LOW SLGT MDT HIGH SVR

What do these risk levels mean?

Convective Outlook

VALID 06:00 UTC Fri 19 May 2023 - 05:59 UTC Sat 20 May 2023

ISSUED 06:23 UTC Fri 19 May 2023

ISSUED BY: Dan

A frontolysing cold front will drift slowly southeastwards across England and Wales on Friday, around the eastern flank of an upper high over the Atlantic. Early patchy rain over northern and eastern Britain should gradually dissipate through the morning, while convective overturning helps low-level cloud erode through the day. Increasing surface heating should yield 200-500 J/kg MLCAPE in a zone from northern England through the Midlands to central southern England, where developing low-level convergence should aid moisture pooling in the vicinity (Td 10-13C). This, in conjunction with a strip of mid/upper-level shear vorticity sliding southwards over the area should result in an environment supportive of developing a scattering of heavy showers and a few thunderstorms. Cells will tend to slowly mature as they drift to the SSW, so this combined with a sea breeze that will likely develop inland from the south coast suggests the best chance of one or two thunderstorms is probably from the south Midlands into central southern England. The strongest deep layer shear will be generally displaced west of most of the shower activity, but any cells across the West Midlands, Wales and SW England that can gain sufficient depth to tap into the stronger flow aloft may become somewhat better organised - although here there will likely be more in the way of mid-level capping. Given vorticity stretching along CZ in the development stage, a few funnel clouds may be possible. Wind gusts up to 35mph and hail to 1.0cm in diameter may be possible with the strongest cells.