Heavy rain, high winds and King Tides bring potential for Boxing Day flooding, damage in Metro Vancouver

A storm surge in Delta is seen in this undated file photo. (CTV)

A pair of winter storms is forecast to hit the Lower Mainland Sunday night through Tuesday, coinciding with extreme high tides that could cause flooding and damage to coastal infrastructure.

The City of Delta issued a storm surge advisory on Christmas Day, warning that the King Tide forecast for 8:40 a.m. Monday would bring "a heightened flood risk for the Beach Grove and Boundary Bay communities."

"A very high flood risk is also expected to occur on Tuesday, Dec. 27, as a result of a significant storm surge coupled with strong southeast winds during high tide at approximately 9 a.m.," the city added in a statement.

The city's warnings come alongside rainfall and wind warnings from Environment and Climate Change Canada.

The weather agency said Sunday that two storms are expected to bring high winds and heavy rain to Metro Vancouver in quick succession.

The first storm began Sunday night and was expected to continue through Monday morning, while the second was expected to begin Monday night and continue through Tuesday.

As much as 110 millimetres of rain is forecast to fall by Tuesday night in Squamish, with other parts of the Lower Mainland expected to see between 60 and 80 millimetres.

Flood watches are in effect for Metro Vancouver and the Fraser Valley as rain and melting snow raise river levels in the region. 

Environment Canada said the "long episode of rain" may be exacerbated by ice-clogged drains and the inability of frozen ground to absorb more moisture.

The agency also warned that the storms will bring 70-kilometre-per-hour southeast winds, with gusts up to 90 km/h.

"King Tides will coincide with the approach of this frontal system," Environment Canada said. "Swells and enhanced wave action along the Strait of Georgia could lead to flooding, while wave action and debris may cause damage to coastal infrastructure. Coastal sections with a southeast exposure will be the most vulnerable to wave action."

The City of Delta is encouraging its residents to "take all suitable precautions," adding that sand and sandbags are available at several locations in the city.

"The city will be proceeding to Stage 3 of the Staged Flood Preparedness Plan for Beach Grove and Boundary Bay as of Monday, Dec. 26, in response to the upcoming flood risk," the city said. "Portable pumps and generators will be located to the area. As well, city staff will be monitoring conditions and assisting as required."