Convective Outlook: Sat 06 Jun 2020
LOW
SLGT
MDT
HIGH
SVR
What do these risk levels mean?
Convective Outlook

VALID 06:00 UTC Sat 06 Jun 2020 - 05:59 UTC Sun 07 Jun 2020

ISSUED 20:48 UTC Fri 05 Jun 2020

ISSUED BY: Dan

Upper low over the North Sea will gradually slide southwards just offshore during Saturday. Outbreaks of rain associated with the wrap-around occlusion will sink southwards across England and Wales, followed by the upper cold pool which will coincide with diurnal heating to yield 300-700 J/kg CAPE. As a result, a zone of instability will become established across southern portions of northern England into the north Midlands by late morning, shifting gradually southwards across the Midlands and East Anglia during the afternoon and reaching S / SE England towards evening. Several lobes of PVA will be located around the upper low, creating divergence aloft and encouraging broad lift, in conjunction with surface confluence and convergence.

Numerous scattered showers are expected to develop in the aforementioned areas and times, in an environment with 20-30kts deep layer speed shear on the western/southwestern flank of the upper low. Forecast profiles suggest convection could potentially reach up to 23,000ft (ELTs -40C) in places, deeper than on Friday, with reasonably steep mid-level lapse rates. Therefore, some sporadic lightning seems quite likely, especially with any cells that can become semi-organised. Gusts of 40-45mph may be possible with the strongest cells, with some hail also likely. Activity will gradually weaken during the evening hours as diurnal heating subsides, although overnight some weak elevated instability may evolve over NW England into the Midlands, on the western flank of the broad area of rain along the returning occlusion - but the risk of lightning is considered quite low.