Convective Outlook: Tue 28 Sep 2021
LOW
SLGT
MDT
HIGH
SVR
What do these risk levels mean?
Convective Outlook

VALID 06:00 UTC Tue 28 Sep 2021 - 05:59 UTC Wed 29 Sep 2021

ISSUED 07:07 UTC Tue 28 Sep 2021

ISSUED BY: Dan

Tuesday is quite frankly a very messy day, with a lot of uncertainty over the specific detail. An initially broad upper trough near Ireland will sharpen and extend as it becomes increasingly negatively-tilted and pivots northeastwards across the UK/Ireland, particularly during the evening and night hours. This will result in increasing PVA/divergence, and initially convective clusters will tend to morph into larger areas of showery rain as a result, with a new low centre likely developing over the North Sea by the early hours of Wednesday. Given a complex mixture of convective and frontal rainfall, and spread of possible solutions amongst model guidance, it is rather difficult to identify specific areas with a better lightning potential than others. The environment over England and Wales in particular may be favourable for line segments, capable of producing squally conditions and perhaps isolated tornadoes - however, the conditions overall are less conducive than was the case on Sunday night / Monday morning, with the greatest risk probably southern coastal counties where the most vigorous convection is likely fuelled by the warm SSTs. Gusty winds and hail may also accompany some of the showers/storms in Ireland and western Scotland. A few low-end SLGTs have been issued, but confidence is low on how much lightning activity may actually occur.

Overnight, the steering flow will change to a northwesterly, and showers may become increasingly focussed in parts of NW England and NW Midlands - climatologically, the Manchester area and just to the north tend to produce lightning in such setups.