Convective Outlook: Mon 17 May 2021

LOW SLGT MDT HIGH SVR

What do these risk levels mean?

Convective Outlook

VALID 06:00 UTC Mon 17 May 2021 - 05:59 UTC Tue 18 May 2021

ISSUED 06:48 UTC Mon 17 May 2021

ISSUED BY: Dan

Little change is expected on Monday, with broad upper troughing covering much of north and northwest Europe. Diurnal heating will yield 300-600 J/kg CAPE and showers will easily develop with modest surface heating, especially aided by low-level convergence zones and orographic forcing, showers/weak thunderstorms then drifting generally to the ESE with time. As with the past few days, deep layer shear will be weak resulting in pulse-type storm mode for the most part, with cold pool/outflow aiding development of daughter cells nearby. Forecast profiles suggest winds will be fairly unidirectional, however as sea breezes develop the backed low-level winds may result in a slight increase in bulk shear from Yorkshire down to Kent, and this could in theory aid storm longevity a little. The strongest cells during the afternoon and early evening could perhaps produce hail 1.0-1.5cm in diameter and local wind gusts of 40-50mph. Showers/weak thunderstorms will gradually decay through the evening hours, however a few will drift towards the Channel Islands from the northwest with a small risk of lightning, and showers are also likely to return close to SW England and S Wales during the early hours of Tuesday which may produce the odd isolated lightning strike.