Convective Outlook: Fri 14 May 2021
LOW
SLGT
MDT
HIGH
SVR
What do these risk levels mean?
Convective Outlook

VALID 06:00 UTC Fri 14 May 2021 - 05:59 UTC Sat 15 May 2021

ISSUED 06:28 UTC Fri 14 May 2021

ISSUED BY: Dan

As with previous days, scattered showers and weak thunderstorms are likely to develop on Friday in response to diurnal heating and aided by low-level convergence and orographic forcing - and so more likely over western areas given fairly extensive low cloud in eastern parts. Forecast profiles suggest convection will struggle to gain much depth, and will likely merge into areas of showery rain at times. That said, a few isolated lightning strikes and small hail will be possible - especially over Ulster where a slightly stronger storm is possible in an overall environment with steeper mid-level lapse rates and 15-20kts shear. As such, a low-end SLGT (25-30% chance) has been introduced. Mid-west Wales considered 15-20% chance.

Frontal rain will push into Munster during the afternoon, and this will steadily track eastwards across Ireland and central/southern Britain through Friday night. This will be followed by an unstable airmass as cold air aloft overspreads relatively warm SSTs and so an increase in shower activity is likely over the Atlantic/Celtic Sea during the early hours of Saturday. Convection will be fairly shallow in depth, at least initially, but perhaps offset by a strongly-sheared environment which may allow a few isolated lightning strikes to occur near some coasts. Some small hail and gusty winds may be possible from the most intense cells.