B.C.’s record-breaking rainfall generates ‘mind-boggling’ data: Environment Canada

An Environment Canada meteorologist says the province’s latest atmospheric river has generated “mind-boggling” data for scientific analysis.

Torrential downpour in the southern part of B.C. started Sunday, and led to flooding, landslides and mudslides that blocked highways, triggered evacuations, and stranded hundreds.

“We have seen now our fifth atmospheric river of the season. Oftentimes, we won’t get a first one until November,” Armel Castellan, warning preparedness meteorologist, said.

“It is a little bit mind-boggling. We’re going to likely be analyzing these numbers for days and weeks to come because they are that extraordinary.”

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1:42 Aerial view of flooding that led to evacuation of Merritt, B.C.

Castellan described the latest weather event as part of a “parade of storms” that have drenched B.C. since September.

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That month, many areas saw precipitation in excess of 300 per cent of normal, he said, and in October, the excess ranged between 200 and 240 per cent of normal along the south coast.

The District of Hope saw its wettest day on record on Sunday, with rainfall adding up to 174 millimetres, Castellan said.

2:38 B.C. floods: Hundreds evacuated as Abbotsford declares state of local emergency

The City of Chilliwack also reportedly broke records on Sunday, with rainfall of 154.6 millimetres.

Several factors played a role in the atmospheric river’s intensity and impact on the ground, Castellan added, such as burn scars left by the wildfire season, and melting snow on the mountains that wasn’t thick enough to survive the rain.

Temperatures were expected to drop overnight while wind speeds increase, prompting additional concerns about power outages, downed trees, and freezing water on mountain highways overnight and on Tuesday morning.

2:27 B.C. floods: Heavy rain and wind cause chaos in Metro Vancouver

“This low is redeveloping into southeastern B.C. and is going to affect the Prairies. They’re going to be dealing with a headache again for the next couple of days,” Castellan said.

“It’s not as violent as it could be for a flash-freeze type of event, but it is possible because there’s so much moisture out there.”