Convective Outlook: Sun 04 Aug 2019
LOW
SLGT
MDT
HIGH
SVR
What do these risk levels mean?
Convective Outlook

VALID 06:00 UTC Sun 04 Aug 2019 - 05:59 UTC Mon 05 Aug 2019

ISSUED 22:55 UTC Sat 03 Aug 2019

ISSUED BY: Dan

Heights will gradually fall through Sunday in advance of the approaching upper low over the Atlantic. A shortwave will slide northeastwards across England and Wales, coinciding with peak diurnal heating, while Ireland becomes subject to the cold pool associated wth the large-scale trough axis swinging northeastwards.


A rather complex and messy picture is likely to evolve, with scope for both elevated and surface-based thunderstorm activity possible. In a broad sense, embedded pockets of elevated convection will be possible on Sunday morning over the Irish Sea / Scotland / W Wales, with other pulses developing over northern England during the afternoon - lightning activity is questionable within this timeframe.
However, provided there is sufficient clearance for surface heating of the warm, moist low-level airmass (dewpoints 15-18C) then up to 1,000 J/kg CAPE will be possible in places, with a risk of scattered showers and thunderstorms developing almost anywhere within the Scotland / England / Wales SLGT and MDT zones - particularly late afternoon and into the evening hours. 

The best multi-model agreement on where coverage of thunderstorms may be greater exists over the north Midlands and parts of northern England, and so a tentative MDT has been introduced. The primary hazards will be hail up to 2.0cm in diameter and localised flash flooding, especially given how sensitive the already saturated ground is.
Additional elevated convection (showery rain) may develop over East Anglia / SE England during the evening hours before moving offshore.

Other additional scattered showers and thunderstorms are likely to affect central, western and northern Ireland - especially during the afternoon and early evening, before probably merging into a more dynamic area of showery rain as they exit eastwards to the Irish Sea. Main hazards here will be localised surface water flooding, and perhaps an isolated tornado.