Potential for flooding as heavy rain continues to drench southwest B.C.

Several weather alerts remain in place for southern British Columbia as relentless rain continues to soak the province's South Coast and raise river levels to the point of potential flooding.

An atmospheric river event has forced the federal weather agency to place Metro Vancouver, Howe Sound, Whistler and Sunshine Coast residents under a rainfall warning. Up to 100 millimetres of rain is forecast to fall in these regions by Wednesday afternoon.

A rainfall warning has also been issued for west Vancouver Island, where up to 150 millimetres is expected by Thursday morning. The east and inland areas of the Island are under a special weather advisory, with 50 millimetres of rain coming to these regions in the same time period, bringing with it the threat of localized flooding.

Several communities in southern B.C. are still reeling after catastrophic flooding in mid-November caused mudslides, destroyed highways and displaced thousands of people.

With some highways still damaged, and the potential for further flooding this week, the B.C. government is extending a provincial state of emergency until the end of the day on Jan. 18 while repair work continues.

Orders restricting travel on Highways 5 and 99 also continue.

Only commercial vehicles and inter-city buses are permitted on Highway 5 between Hope and Merritt; while vehicles weighing more than 14,500 kilograms are not allowed to travel Highway 99 between Lillooet and the intersection with Lillooet River Road near Pemberton.

Flood forecast

Meteorologist Bobby Sekhon said while this is the latest storm to hit the weather-battered province over the past six months, he wouldn't describe it as "extreme.''

"What we're dealing with here is we had a very snowy and cold stretch for the last three or four weeks and the concern, as always, is as we get heavy rain and melting temperatures, that can create a recipe for flooding,'' Sekhon said.

The River Forecast Centre has posted high streamflow advisories for rivers and creeks across all of Vancouver Island and the South Coast.

The advisory means that river levels are rising or expected to rise rapidly, but no major flooding is expected. Minor flooding in low-lying areas is possible.

In the city of Abbotsford, which suffered significant flood damage during last year's storms, staff said dike repairs and sediment removal work meant the city was better prepared for the incoming rains.

A city spokesperson said in a statement that dikes had been raised by half a metre to better protect the crucial Barrowtown pump station.

"City of Abbotsford staff have been out in the field, watching the floodplain areas of the city, including Sumas Prairie, the Lake Bottom area and Matsqui Prairie and have not found any issues," the spokesperson said.

"We do expect some localized flooding in lower-level areas, but nothing as significant as was experienced in the November and December floods."

CBC meteorologist Johanna Wagstaffe says rivers and stream levels should peak by tomorrow.

"By Thursday afternoon we should be on the other side of this for a calmer end to the week," she said.

Avalanche awareness

Warming temperatures and melting snow are also creating ideal avalanche conditions.

Avalanche Canada has raised the risk of a slide on Vancouver Island, the South Coast and Sea-to-Sky mountains to high, meaning very dangerous avalanche conditions exist.

"Human-triggered avalanches very likely," says a post on the Avalanche Canada website, which advises avoiding all possible avalanche terrain until conditions improve.

Snow is expected at higher elevations in B.C. on Wednesday which could also create hazardous driving conditions through mountain passes further inland.

Environment Canada is advising anyone travelling on Highway 3 between Paulson Summit and Kootenay Pass to watch out for snow and freezing rain and to drive according to conditions.

The B.C. government has also closed a section of Highway 1 in the Fraser Canyon due to avalanche risk. Travel is not permitted on this route, between Yale and Boston Bar, until further notice.

For the latest weather alerts visit Environment Canada. For up-to-date driving conditions, visit DriveBC.

Tips for managing trees in extreme weather

The recent mix of snow, wind and rain has taken a toll on trees in the region. 

John Martyn, an Abbotsford- based arborist with JPM Tree Service, says one of the biggest challenges trees face in wet weather is saturated soil. 

"Roots just can't adhere to water the way they can to soil," he said. "So I think that's a particular threat for complete tree upheavals is the saturated soils we could potentially be getting."

Martyn says homeowners should keep an eye on their trees to see if they are at risk.

"As a homeowner, I think you're one of the best assessors of your tree, in many ways," he said. 

"Has that tree moved out of position? Is there a little voice that says, 'Hmmm, that tree looks like it's leaning a little bit more than it usually does. That could be an indicator of some disruption in the root system."

Martyn says they should also look out for a change in colour. He also recommends getting rid of any ivy, which can add weight to a tree.