Issued 2024-03-28 09:16:06
Valid: 28/03/2024 0800 - 29/03/2024 0600
Deep upper low core will be slow-moving over Ireland on Thursday. A deep surface low, named Storm Nelson by the Spanish Met Service, to the south of Ireland this morning, will track NE across Wales this afternoon and S Scotland by midnight. Cold mid-level temperatures of the upper low close to the west atop moist S to SE surface flow – will produce steep lapse rates which will yield around 300-500 j/kg CAPE. Heavy showers and scattered thunderstorms will spread NE across S. Ireland, England and Wales through the day. Lightning is already noted at breakfast time in the SW approaches and western English Channel, SW and CS England along with S Wales will have the greatest risk of a thunderstorm, surface heating in sunny spells will likely increase the risk as colder air aloft and increased forcing for ascent moves in from the SW.
30-40 knots of deep layer shear forecast suggests any storms may organise in clusters. Tight isobars on the SE side of the low tracking NE will produce strong synoptic-driven winds of 50-60mph near southern coasts, but convective downdrafts could also produce strong and perhaps isolated damaging gusts of 60-70mph here. In addition, strong low-level shear is indicated across SW England as surface winds back against strong SW flow aloft – so there is potential for strong updrafts in any storms to rotate to produce an isolated tornado here. So a Severe area has been delineated for SW England for the risk of damaging wind gusts and isolated tornadoes. Heavy showers and thunderstorms could also be accompanied by hail and intense rainfall leading to localised flooding.
Issued by: Nick Finnis
Issued by the Netweather forecast team whenever there is a risk of storms or severe convective weather, these discussion based and in depth forecasts will highlight the areas at risk and give an in depth description of the risk and the factors surrounding it.