Convective Outlook: Thu 30 Apr 2020
LOW
SLGT
MDT
HIGH
SVR
What do these risk levels mean?
Convective Outlook

VALID 06:00 UTC Thu 30 Apr 2020 - 05:59 UTC Fri 01 May 2020

ISSUED 07:13 UTC Thu 30 Apr 2020

ISSUED BY: Dan

An upper low and associated cold pool will reside above the British Isles during Thursday, with a series of shortwaves rotating anticlockwise around the main parent low. These will provide the focus for more enhanced convection / showers, which may merge to give some longer spells of rain (a mix of dynamic and convective rainfall). One such feature will be affecting SW England during the morning, swinging eastwards across central/southern Britain to clear the east coast by evening. Either side of this, sunshine and diurnal heating will aid the development of numerous scattered showers, with a window of lighter surface winds and a greater potential for some low-level convergence/confluence to become established during the afternoon hours across the Midlands towards eastern England - this may aid development of deep convection.

Given 300-700 J/kg CAPE, steep mid-level lapse rates and some marginal shear, a few sporadic lightning strikes are possible. Hail up to 1.5cm in diameter will be possible from the most organised/intense cells. Showers will likely persist well into the evening and night given the proximity of the upper low, but will generally weaken in intensity as daytime heating subsides - the greatest risk of lightning overnight (20%) will probably be over the English Channel.

However, the overall setup is rather messy with fairly moist profiles and there may be quite a bit of cloud at times, especially as an occlusion drifts eastwards during the day, and this casts some doubt over how much/widespread lightning activity will be - it seems unlikely to be as significant as was the case on Easter Sunday, for example. Nonetheless, somewhat reluctantly issued a low-end SLGT (30%) for parts of England.