More rounds of rain threaten already flood-vulnerable areas of B.C.

·3 min read
More rounds of rain threaten already flood-vulnerable areas of B.C.
More rounds of rain threaten already flood-vulnerable areas of B.C.

British Columbia is still dealing with the aftermath of last week's damaging atmospheric river, with still more rain ahead for the province. The first round began drenching the North and Central coasts on Wednesday, and people in the Lower Mainland will dealing with the rain through Thursday. Some areas, including those worst-hit by last week's downpours, could see 100-200 mm of rain by Friday, likely delaying the recovery process – worsened by dropping freezing levels that will allow rain to hit snowy mountain passes, exacerbating the flooding. For a closer look at timing and impacts, see below.

THURSDAY-FRIDAY: FIRST OF TWO ATMOSPHERIC RIVERS PUSHES IN

The first round of heavy rain was already aimed squarely at more northern parts of B.C., creeping southward through the day on Wednesday and pushing into the South Coast on Thursday, with impacts expected to last through Thursday.

The upshot is that unlike last week's Category 4 atmospheric river that caused catastrophic damage, this latest dose of Pacific moisture will feature lower totals, and be slightly shorter-lived. However, there will still be plenty of rain by the end of the week, with the Lower Mainland in the 40-80 mm range and considerably higher for parts of Vancouver Island and areas further north. Rainfall warnings are in effect.

BC rain (2)
BC rain (2)

Though this system will be tamer and less intense than the event over November 13-15, it's still a serious concern for people in the region, chiefly because the sheer amount of rain that fell last week has left most areas thoroughly waterlogged, with little chance for the soil to absorb the runoff.

As such, much of the incoming rains will end up once again in the region's rivers – at a time when most of those at or near coastal areas are still running high, with widespread high streamflow advisories in effect.

Additionally, freezing levels will soar above 2,000 metres Thursday, with many high-elevation areas already having several centimetres of accumulated snow.

snowoutlook
snowoutlook

That's still more moisture ready to pour into the system as snowmelt, compounding flood risk.

"This may worsen recent flooding and impact vulnerable landscapes and infrastructure," Environment and Climate Change Canada warns.

LOOK AHEAD: SECOND ATMOSPHERIC RIVER INBOUND FOR THE WEEKEND, POTENTIAL FOR MORE WET WEATHER

Beyond the first event, the next system is set to move in Saturday evening and continue through Sunday, but the current forecast is for the heaviest rain to be situated over central B.C. and western Vancouver island once again.

With these new accumulations, parts of the North Coast and western Vancouver Island will have picked up more than 200 mm over the course of the two systems, with more than 100 mm for parts of the Lower Mainland.

BC long range
BC long range

That won't be the end of it, either, as another system is expected early next week. Seven-day rainfall totals of 75-125 mm are anticipated for much of the Lower Mainland, with 125-250+ mm for alpine regions and the west coast of Vancouver Island.

Mild temperatures are forecast late week and on the weekend for the South Coast.

CANADA GETTING ITS OWN ATMOSPHERIC RIVER RATING SCALE

Click here to view the video

Check back as we continue to monitor this week's rainy systems.

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