VALID 06:00 UTC Sat 03 Jun 2017 - 05:59 UTC Sun 04 Jun 2017

ISSUED 17:45 UTC Fri 02 Jun 2017

ISSUED BY: Dan

Atlantic upper trough will swing NE-wards across the British Isles on Saturday, accompanied by cooling aloft helping to steepen lapse rates and generate a few hundred Jkg^-1 CAPE in response to SSTs/diurnal heating inland. Scattered showers will develop during the day across many parts of Scotland, Ireland and the Republic of Ireland, orchestrated into bands with the aid of showery occlusions moving through in the flow. Showers will tend to be more isolated across England and Wales given drier profiles. There will be a broad but fairly low risk of lightning in any one location, hence the large LOW threat level issued. Slightly better instability will be present in parts of Scotland, where a (reluctant) low-end SLGT has been issued - but concerns exist over lack of any notable wind shear to help organisation (best wind shear will be in the morning, so not in phase with best instability later in the day), and perhaps cloudiness proving an issue too from occlusion debris. Nonetheless, should a stronger cell develop then hail 1.5-2.0cm in diameter would be possible locally. Given slack flow and elements of low-level convergence, a brief funnel or weak tornado would also be possible with this activity.