Storm Agnes is poised to usher in periods of wet and blustery conditions across the majority of the British Isles. Particularly potent gusts are forecast for portions of Ireland, with widespread gusts of 60-80 mph expected, and the potential to reach 90 mph on elevated terrain and exposed coastal areas.
As the day progresses, a squall line is anticipated to form along an approaching cold front, affecting Ireland and Wales in the early afternoon. This frontal system is set to bring heavy rain and gusty winds to various locales, possibly accompanied by isolated lightning strikes.
The heightened risk of severe weather remains in Ireland, where conditions are more precarious due to the presence of 150+ J/KG of 3CAPE along the squall line and wind speeds exceeding 35 knots of Low-Level Shear (LLS). This convergence of factors could lead to a significant transfer of momentum downward, potentially stretching surface vorticity streamwise. In select areas, this phenomenon may result in the development of localized Low-Level Jets (LLJs), elevating the chances of rotation and the potential for brief, spin-up tornadoes.
The bulk of the energy is expected to propagate downward, heightening the potential for spin-up tornadoes and robust wind gusts, particularly in regions designated as slight risk zones, where the squall line's intensity and lightning frequency may be elevated. Eventually, the cold front is anticipated to diminish as it moves through Northern England and Scotland by mid-afternoon, gradually losing its vigor and ultimately dissipating by evening.
You can download the kml file of the convective outlook here
(You can upload the file to windy.com to have the graphic overlay)
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