‘Once in a 100 years’ extreme weather event caused Donegal flooding

Intensity of rainfall overwhelmed drainage systems and destroyed bridges, says Met Éireann.

A “once in a 100 years” extreme weather event was responsible for the widespread flooding and devastation that struck the northwest, according to Met Éireann.

The suddenness and scale of rainfall overwhelmed drainage systems and destroyed older bridges in Co Donegal. It was concentrated on the Inishowen peninsula over a two-hour period from 7pm to 9pm on Tuesday, according to meteorologist Gerry Murphy of Met Éireann.

Malin Head had 63mm of rain within a six-hour period. “It was the intensity of the rainfall that was too much for waterways [and] for drainage systems that weren’t adapted for them,” he said.

An average wet day results in 25mm of rain in a 24-hour period.