Convective Outlook: Sat 20 Aug 2022 |
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What do these risk levels mean? |
VALID 06:00 UTC Sat 20 Aug 2022 - 05:59 UTC Sun 21 Aug 2022
ISSUED 06:40 UTC Sat 20 Aug 2022
br> br>ISSUED BY: Dan
An upper trough will swing northeastwards across the British Isles on Saturday, the associated cold pool aloft atop warm SSTs and diurnal heating inland providing another day of scattered showers spreading inland across portions of Scotland and Ireland from the Atlantic. Of particular interest is a rather active cold front in a strongly-sheared environment (40-50kts DLS). Occasional sporadic lightning strikes will be possible, perhaps more especially Saturday afternoon and evening as 500-700 J/kg CAPE builds in response to diurnal heating of a relatively moist low-level airmass (11-13C dewpoints) across southern Scotland and northern England. Towards the evening, as the trough axis begins to eject to the North Sea and the left exit region of the northwesterly jet approaches, there may be an uptick in activity along the front, before a gradual weakening trend is then anticipated towards late evening and overnight as the front continues to advance southwards into north Wales and the north Midlands. The main threat will be squally winds and and a spell of heavy rain, although the front aligned almost parallel to the steering flow will pose the risk of locally high rainfall totals as several cells potentially run over the same area. Forecast profiles suggests winds will be fairly unidirectional with height, generally limiting the tornado threat (especially given a more linear mode is favoured), although the CAPE/shear combination may encourage some rotation within updrafts.