Convective Outlook: Thu 03 Jun 2021
LOW
SLGT
MDT
HIGH
SVR
What do these risk levels mean?
Convective Outlook

VALID 06:00 UTC Thu 03 Jun 2021 - 05:59 UTC Fri 04 Jun 2021

ISSUED 06:27 UTC Thu 03 Jun 2021

ISSUED BY: Dan

Overall, little lightning activity is expected on Thursday. Upper ridge across eastern Britain will continue to amplify, but eventually shifting east such that the ridge axis is over the North Sea by the evening. At the same time, an elongated upper trough will drift across Ireland, introducing cooler air aloft here. On the leading edge a southerly mid-level jet will be present across Ireland and western Britain. Diurnal heating through the day will result in mixing of the boundary layer, and consequently dewpoints will tend to fall with the highest values increasingly restricted to sea breeze convergence in eastern England. This will likely be the focal point for any deep convection that can initiate given some forced ascent, although the subsidence aloft will probably restrict the depth of convection somewhat. Overall the greatest risk appears to be Yorkshire (especially North York Moors) during the evening hours, but whether convection can become sustained enough to produce any lightning is uncertain. 

During the evening and night hours there may be a tendency for elevated convection to slowly increase across east and southeast England. Even at this stage there is some uncertainty over the specific details, but certainly scope for at least one frontal wave to eject from France and migrate northwards during the night (this could be delayed until Friday morning depending on the phasing of the right entrance of the mid-level jet over France). Realistically, any lightning activity will probably decay over the English Channel and so as is often the case east Kent probably has the greatest risk (and even here confidence is not high enough to warrant a SLGT at this stage).

Elsewhere, one other area of interest is central and western Ireland during the afternoon / early evening hours under the influence of the approaching upper trough. A marked dry intrusion overspreads the area, and while the exact evolution is a little messy some modest CAPE could develop in a sheared environment (although very dry air aloft may restrict depth of convection and therefore unable to utilise the strong flow aloft). Either way, there may be scope for a few isolated lightning strikes here.