Convective Outlook: Sun 29 Jul 2018
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Convective Outlook

VALID 06:00 UTC Sun 29 Jul 2018 - 05:59 UTC Mon 30 Jul 2018

ISSUED 09:13 UTC Sun 29 Jul 2018


UPDATE 09:13 UTC A SLGT may be introduced to S + E Scotland for this afternoon / evening if confidence increases a little

An upper low will drift westwards away from the Hebrides on Sunday, but leaving strong mid/upper flow across the British Isles. A marked shortwave will round the base of this upper low, quickly running northeastwards - over the Irish Sea by mid-afternoon - reaching the Northern Isles during the late evening. This will drive a surface low and frontal system northeastwards across England, Wales and parts of Scotland, with a broad warm sector characterised by dewpoints of 16-18C. A mid-level dry intrusion will overspread the area during the afternoon hours, resulting with SMZ (shallow moist zone) conditions.

It is likely that, after an initial period of dynamic frontal rainfall, convective elements will develop during the afternoon and early evening hours. Strongly-sheared profiles, including some backing of the low-level winds, will allow line convection segments to form capable of producing some heavy bursts of rain and gusty winds. Lightning is considered a fairly low probability due to limited cloud depth and rather meagre instability, though these types of scenarios often produce low and turbulent cloud bases.

Close to the low centre, towards northern England / southern Scotland, a period of stronger forcing and shear overlapping some marginal instability (with dry intrusion aloft) will evolve during the afternoon and early evening. Some slightly deeper convection could develop on the wrap-around feature, perhaps capable of produce some sporadic lightning and strong gusts of wind - but confidence is not high enough to upgrade to SLGT for now. This area of interest will continue to slide NNE-wards towards the Northern Isles.

On Sunday night, an increasing coverage of showers will develop over western Ireland and the Hebrides as an upper cold pool approaches from the Atlantic - perhaps with some isolated lightning activity.