Parts of B.C.’s South Coast remain under weather warnings Thursday as the first of three expected atmospheric rivers hit the province.
Fraser Valley, Metro Vancouver, Howe Sound and West Vancouver Island remain under a rainfall warning.
Between 50 millimetres and 80 millimetres of rain is expected to fall in the Fraser Valley, Metro Vancouver and Howe Sound.
Environment Canada said the rain will be the heaviest Thursday as the storm moves across the South Coast. The heavy rain will ease Thursday night as the system moves out of the region.
Rainfall amounts are expected to be lower than the Nov. 13 to 15 event, which caused widespread and devastating flooding, landslides and mudslides that killed five people.
The mayor of Abbotsford will be keeping a “careful eye” on the Nooksack River over the next few days, as the heavy downpour of another atmospheric river begins.
He said he doesn’t know how much more the existing system will take and he expects a call from the mayor of the Washington border city of Sumas the moment its sirens go off for flooding.
“We’ve done everything to get ahead. Our dikes are at a now at a level that they were before,” he said.
“What I am worried about — and I mean worried, not just concerned — is what will the Nooksack do.”
The Ministry of Forests, Lands, Natural Resource Operations and Rural Development is maintaining a flood warning for the Sumas River, including the Sumas Prairie and the surrounding area.
In addition, the River Forecast Centre is upgrading the South Coast to a flood watch, including Sea‐to‐Sky including areas around Squamish, Whistler and Pemberton, the Sunshine Coast, Howe Sound, the North Shore mountains and the Lower Mainland including areas along the Fraser Valley and around Hope.
The organization said rivers are expected to rise on Thursday with the potential for the highest flows around the Sunshine Coast, Howe Sound and the North Shore corridor.
While the rivers in the Fraser Valley are expected to rise, it will be more typical for fall storms, the forecast centre said, but flooding may be worse due to flood response, recovery efforts and damaged infrastructure.
The second storm on the weekend is currently forecast to bring higher rainfall totals with warmer conditions resulting in additional snowmelt, the forecast centre added.
There is potential for flows to reach 10‐year to 50‐year levels (or higher), likely occurring Sunday or Monday.
On the Nooksack River in Washington State, the Northwest River Forecast Centre (NOAA) is currently forecasting the potential for the Nooksack River to reach overbank flood stage at Cedarville and Ferndale on Friday and again on Sunday, with ongoing risks again later next week, the forecast centre said.
A flood watch has been issued by the National Weather Service for Whatcom County and the Nooksack River. The forecast centre said overflow from the Nooksack River into the Sumas River drainage is possible, especially if more rain falls into the Nooksack River watershed.
Meanwhile, a winter storm warning is in effect for Highway 3, Paulson Summit to Kootenay Pass and the Trans-Canada Highway, Eagle Pass to Rogers Pass.
Hazardous winter conditions are expected in these areas, Environment Canada said.
The strong weather system will bring widespread snowfall from Thursday and into Friday.
Friday is expected to be dry before the next storm system moves through on Saturday with another big one coming next Tuesday.