Thunder, lightning strikes, flooding and torrential downpours - NI's thunderstorm warning is worse than originally thought

A thunderstorm weather warning issued for Northern Ireland earlier this week applied to Friday only but experts at the Met Office have reviewed the alert and have now extended it to both Thursday and Saturday.

Thursday, 5th August 2021, 5:29 pm

Thursday

The first thunderstorm alert is active between 1.00pm and 10.00pm on Thursday - the alert applies to all of Northern Ireland except the north coast.

"Persistent rain in the morning will clear eastward in the afternoon with more scattered heavy and thundery showers breaking out," reads the warning on the Met Office website.

"These will be slow moving with accumulations of 10-20mm in an hour and 30-40mm in 3-4 hours, with a few locations potentially seeing 40-50mm in 6-9 hours.

"Some localised flooding and disruption to the transport network is possible. Showers will continue through the evening and overnight, but easing in intensity."

Friday

The second thunderstorm weather warning issued by the Met Office for Northern Ireland applies from 4.00am to 11:59pm on Friday.

"Heavy showers are expected across much of the UK on Friday," reads the alert on the website.

"Within the warning area these showers and thunderstorms will be slow-moving and may cause localised surface water impacts.

"Rainfall totals will vary considerably and not all locations will be affected by the heaviest showers.

"However, where the showers do occur there is potential for 20-30 mm of rain in a short space of time and during the course of the day there is a chance that some places could see as much as 80-100 mm build up."

An Asda store in Ballyclare flooded after a thunderstorm and torrential rain last week. (Photo courtesy of NI Weather & Flood Advisory Service)

Saturday

The third and recently issued thunderstorm weather warning issued by the Met Office for Northern Ireland applies from 4.00am to 11:59pm on Saturday.

"Heavy showers are expected to break out across much of the UK again on Saturday," said the Met Office online.

"The heaviest showers are expected within the warning area where some of the showers will be slow-moving and thundery.

"Not all locations will be affected by the heaviest showers, with some areas escaping much in the way of rainfall. However, where the showers do occur there is potential for a further 20-30mm of rain in a relatively short time period and during the course of the day there is a chance that some places could see as much as 50-70mm building up."