london - Ireland, Northern Ireland and Scotland are bracing for one of the most powerful storms in decades, with forecasters warning it will threaten lives and cause widespread damage.

National forecasters in both Ireland and the UK issued the most severe weather warnings on Thursday over the impact of Storm Eowyn, which is expected to hit the Irish coast in the early hours of Friday before moving northeast towards Scotland. Forecasters warned of life-threatening dangers as the storm brought wind gusts of about 100 mph (161 kph).

Met Éireann has issued a rare national red warning for high winds between 2am and 10pm, the most serious yet. Coastal flooding in low-lying and exposed areas”

Simon Harris, who is expected to take over as Taoiseach later on Thursday, urged people to heed the warning.

"The risks to lives are extreme and real," he said. "You need to be careful. Don't travel. Don't go near the ocean."

The Met Office also issued a red wind warning for Northern Ireland and central and south-western Scotland on Friday.

Paul Gundersen, the agency's chief meteorologist, said: "We reserve red alerts for the worst weather, which can threaten lives and cause serious damage, as was the case with Storm Eowyn. "

Gunderson said winds could reach 80-90 mph quite strongly for periods of time, especially along exposed coasts where gusts could reach 100 mph. The record wind gust in County Down, Northern Ireland, was 124 mph in January 1974

It is the first red warning issued in Northern Ireland since the Met Office switched to impact-based warnings in 2011. All schools in Northern Ireland are advised to close on Friday.

The Met Office warning applies from 7am to 2pm in Northern Ireland and from 10am to 5pm in parts of southern Scotland.

Scotland's First Minister John Swinney said police would later issue formal "do not travel" notices for areas covered by red weather warnings, and local authorities would make decisions on school closures later on Thursday.

"We have to be clear. People should not travel," he said.

The rest of the UK - England and Wales - will also face disruption, with all parts of the country receiving a warning sometime on Friday.

"It's worth noting that even those staying away from red alert areas may still experience damaging weather, travel plans may be severely affected and some may experience power outages," Gunderson said.

Dr Ambrogio Volonte, a senior research fellow at the Department of Meteorology at the University of Reading, said Eowyn's structure reflected some of the "most powerful storms in recent decades" and that its "predicted intensity puts it firmly among our Ranking of the strongest storms” ever experienced. "