Flood Warning covers North Shore Mountains as storms hit B.C. coast, with up to 50 mm forecast for Vancouver

In some places, more than 200 mm of rain fell over 24 hours, according to Vancouver Is Awesome. Central Vancouver was forecast up to 50 mm. That gap explains most of what is happening across the region: the storms crossing B.C.'s coast are hitting mountains, river valleys and city streets very differently.

For people in Vancouver, Burnaby and New Westminster, the rain itself is likely to be manageable. The harder questions sit a short drive north, where the BC River Forecast Centre has put the South Coast, including Howe Sound, the Sea to Sky corridor and the North Shore Mountains, under a Flood Warning. Coastal residents have also been warned of a storm surge that could raise sea levels, Vancouver Is Awesome reported.

A series of storms, not a single one

A series of storms was set to reach B.C.'s coast over the coming week, with the first systems moving in on Thursday night, according to forecasts reported by NORTHLINE. Global BC meteorologist Mark Madryga said well-defined frontal systems would sweep through all coastal areas.

West and central Vancouver Island were under an orange, high-impact rainfall warning from the morning of Nov. 10 through Thursday morning, Environment and Climate Change Canada (ECCC) said. The agency also expected another weather system to approach the Island on Friday, Nov. 13.

B.C. Hydro has warned that more storm systems are on the way, the Vancouver Sun reported. On Saturday, tens of thousands of people across B.C. were without power after strong winds and heavy storms, according to Vancouver Is Awesome.

ECCC has also flagged what it called a potentially stronger storm following on Saturday evening. That message came in its wind warning for the Coquihalla Highway and Okanagan Connector, so it speaks most directly to travellers heading into the Interior.

What a Flood Warning means

The River Forecast Centre upgraded a Flood Watch to a Flood Warning for the South Coast, Pemberton Valley and Kingcome River. The two terms are not interchangeable. Under provincial definitions, a Flood Watch means river levels are rising and will approach or may exceed the bank. A Flood Warning means river levels have exceeded the riverbank or will soon, and flooding may occur near the affected rivers.

The centre's advice is blunt. Keep away from unstable riverbanks, and never drive across flooded roads, bridges or river crossings.

The effects are already being felt. A shelter-in-place advisory was issued near Squamish after flooding from heavy rain, Global News BC reported. The rain has also triggered evacuation orders and alerts, flood warnings and the shutdown of a water treatment plant.

From 50 mm in the city to 160 mm on the Sea to Sky

ECCC's rainfall warnings show how steeply the totals climb as you move from the city toward the mountains.

The Sea to Sky Highway between Squamish and Whistler was under an orange, high-impact warning, with 120 to 160 mm forecast. A yellow warning for West Vancouver and North Vancouver called for 60 to 100 mm, possibly near 120 mm in the mountains. Central Metro Vancouver, including the City of Vancouver, Burnaby and New Westminster, was forecast up to 50 mm, according to ECCC's rain warnings.

Later, ECCC said rainfall may reach up to 80 mm at higher elevations on the North Shore and near southern Howe Sound. Anyone planning to drive the Sea to Sky or hike in the North Shore mountains is dealing with the upper end of those ranges, not the city figure.

Wind, ferries and a forecast with rain on it every day

Wind caused the most visible disruption to travel on Friday. ECCC's wind warning for parts of Metro Vancouver had gusts up to 70 km/h into the afternoon before weakening. BC Ferries cancelled four morning sailings between Horseshoe Bay and Departure Bay and six between Tsawwassen and Swartz Bay, citing high winds and wave height in the Strait of Georgia. The company said it refunds fees or fares when a sailing is cancelled.

ECCC's Vancouver forecast, issued at 4 p.m. on Thursday, Nov. 12, laid out the days that followed:

• Friday, Nov. 13: Mainly cloudy with a 60 per cent chance of afternoon showers. East winds of 30 km/h, gusting to 50. High of 15 C.
• Saturday, Nov. 14: Cloudy, with a 60 per cent chance of showers and windy conditions. High of 14 C.
• Sunday, Nov. 15: Rain, with a high of 13 C.

At Vancouver International Airport at 3 a.m. Friday, it was cloudy and 12.3 C.

For anyone with a ferry booking, the cancellations are a reminder to check sailing status before leaving the house. Closer to home, the practical rule is the River Forecast Centre's: if a road is flooded, turn around. The next confirmed point on the calendar is Sunday, when the forecast calls for rain again.