Warm advection will be ongoing across northern England and into Scotland during Friday, with the 850mb-900mb layer warming sufficiently to generate some weak elevated instability. Moistening of the profiles as minor impulses crest the northern flank of the upper ridge over the British Isles, will likely lead to some showery bursts of rain developing in places. Overall the risk of lightning is considered very low, but non-zero.

With upper ridging dominating, any convection that attempts to build in response to surface heating will probably struggle to maintain any significant depth / height. However, as the upper ridge gradually retreats to the SE (and heights aloft begin to fall) there may be an opportunity for deeper convection to develop late in the day, aided by orographic forcing and low-level convergence.

The risk looks greatest across N Wales late afternoon, drifting northeastwards towards NW England during the evening. Any convection that can grow sufficiently tall will have the potential to produce some sporadic lightning, but there are some concerns over how dry the forecast profiles are and whether such convection can become self-sustaining given weak support aloft. Either way, additional elevated convection from weak instability may continue to develop over northern England during the late evening and overnight.

There may also be scope for isolated heavy showers to develop in parts of Ireland during the late afternoon and early evening hours.