Atmospheric rivers are flowing towards BC’s coast, making for a very wet long weekend.
Metro Vancouverites should brace for a very wet Remembrance Day long weekend.
Environmental Canadian meteorologist Armel Castellan tells VIA that a “parade of storms” will drench the Lower Mainland with precipitation starting Friday evening, November 8, and continuing until the middle of next week.
The first storm in the cycle is the remnants of an atmospheric river hitting the north coast. He explains that 15 to 25 mm of rain could fall in areas on the North Shore, with precipitation rates of four to five millimeters per hour.
While rain should taper off Saturday night, a second storm should bring moisture to British Columbia’s southern coast beginning Sunday afternoon.
“It has the potential to receive more rainfall precisely because it is more robust when it reaches the coast,” he notes, adding that rates of seven to 10 mm of rain per hour are expected, especially at higher elevations.
The storm is technically an atmospheric river, but is not expected to produce the same quantities as the historically wet provincial Election Day. Metro Vancouverites captured images and videos of extensive flooding and damage on October 19, including extensive power outages and road closures.
Castellan says locals can expect more than 100mm of rain within 24 hours, but the rain is expected to ease on Monday. Rain from the storm would need to last 48 hours or more or require significantly higher hourly rates to reach previous amounts.
Some parts of the Lower Mainland received more than 200 mm of rain during the wet weather event. However, the storm’s narrow track was immediately completely over Metro Vancouver.
The weather forecast for Metro Vancouver includes a parade of storms
Atmospheric rivers are “narrow bands of heavy precipitation” that track north and south, meaning they only have to change course slightly and can miss a region entirely.
“They are about 100 to 200 km wide, compared to storms that extend over half or even two-thirds of the province,” Castellan notes.
A third storm will also impact the Lower Mainland starting Tuesday and early Wednesday, although the amount of rain is difficult to estimate.
Castellan says there is a potential of 15mm to more than 90mm, depending on where exactly the atmospheric river flows. As the beam moves north, Metro Vancouver could see more than 100mm. A southerly tracking storm could result in significantly lower quantities.
If the third storm produces more rainfall, there is a chance of greater damage. Being the third event in a ‘real parade of storms’, rain will fall on fully saturated ground.
“You’re dealing with the straw that breaks the camel’s back,” Castellan says, clarifying that these conditions increase the risk of mudslides and other disasters.
The event has a subtropical origin but is moving quickly, meaning it is unlikely to park over the region and drench it for several days. Still, the storms will come one day apart without providing recovery time between systems.
Travelers using BC’s highways should also pay attention to Environment Canada’s BC Traveler Forecast updates. The Sea to Sky Highway will receive a heavier plume of rain starting Friday night and snow will fall on Kootenay Pass early Saturday.
Stay informed with hyper-local forecasts around the world 50 neighborhoods in the Lower Mainland with VIA’s Weatherhood.