Convective Outlook: Sat 21 Oct 2017
LOW
SLGT
MDT
HIGH
SVR
What do these risk levels mean?
Convective Outlook

VALID 06:00 UTC Sat 21 Oct 2017 - 05:59 UTC Sun 22 Oct 2017

ISSUED 21:03 UTC Fri 20 Oct 2017

ISSUED BY: Dan

Upper trough will migrate progressively eastwards on Saturday, marked by cooling aloft and associated steeper lapse rates in response to SSTs / diurnal heating inland. Modest instability will exist, with numerous showers expected over sea and windward coasts initially, extending inland during the day as diurnal heating develops some instability inland.


Greatest risk of lightning exists for southern and western coastal counties where onshore flow will drive frequent showers, though lightning is unlikely to be widespread enough in coverage to warrant a SLGT - hence the broad LOW threat level. Setup is complicated further by occlusions bringing a more dynamic flavour to the rainfall pattern.

Strong, gusty winds will be possible with some showers. Reasonable low-level shear combined with topographical features has in the past lead to the development of waterspouts and / or tornadoes from deep convection - one notorious area where this tends to happen is the Isle of Wight eastwards to West and East Sussex.