Thursday, December 19, 2024

British Columbia’s endless storm chaos: what’s fuelling it?

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One million customers left in the dark. Ferries cancelled. Trees uprooted. Highways blocked. Over the past 41 days, British Columbia has endured three distinct but high-impact windstorms. Each storm brought its own twist, yet all raised the same question:

Why is B.C. facing this barrage of extreme weather, and will it continue through December?

Before I answer that, let’s take a look at what’s happened so far.

Three major storms in 41 days

November 4, 2024 – 290,000 customers without power

  • Victoria Gonzales recorded a 108 km/h wind gust.

  • A seemingly average-intensity storm intensified thanks to perfect dynamics and “lucky” afternoon timing.

November 19-20, 2024 – 390,000 customers without power

  • A remarkable bomb cyclone with 945 hPa pressure stalled west of 130°W, delivering hours of gale and storm-force winds to Vancouver Island.

  • Many highways were impassable for a time on Vancouver Island.

December 14, 2024 – 320,000 customers without power

  • A textbook 980 hPa storm tracked offshore, hooking inside 130°W toward Tofino. The pressure gradient aligned perfectly across the South Coast.

  • Landslide closed the Sea-to-Sky corridor north of Lions Bay.

BC Storms 2024 - timeline of events

BC Storms 2024 – timeline of events

But what makes these storms stand out isn’t just their impacts–it’s the science behind why they’ve been so impactful.

The science behind the storms

1. The ‘sweet spot’ storm tracks

Explainer: B.C. Three major lows in 41 daysExplainer: B.C. Three major lows in 41 days

Explainer: B.C. Three major lows in 41 days

Most Pacific storms track toward Haida Gwaii and northern Vancouver Island, delivering winds up to 50-70 km/h.

These recent storms, however, followed tracks and timing that funnelled winds into BC’s most vulnerable areas:

  • November 4: Modest pressure (995 hPa) but perfect dynamics brought stronger gusts aloft down to the surface.

  • November 19-20: Near-record pressure (945 hPa) made up for its offshore position.

  • December 14: A classic storm track aligned the strongest pressure gradient across the South Coast.

BC South Coast: October to December 2024 storms, rainfall totals, wind gustsBC South Coast: October to December 2024 storms, rainfall totals, wind gusts

BC South Coast: October to December 2024 storms, rainfall totals, wind gusts

RELATED: B.C. bomb cyclone to create the world’s largest wave pool

2. The Role of the Pacific Decadal Oscillation (PDO)

This sharp temperature contrast fuels storm formation by:

  • Enhancing the jet stream: The greater thermal gradient intensifies flow, steering more storms into B.C.

  • Fuelling storms with moisture: Warmer southern waters add latent heat and moisture, amplifying storms and potential atmospheric rivers.

  • TLDR: Storms thrive on temperature gradients—it’s the fuel that drives their formation and intensification

3. Waterlogged soils amplify damage

  • A severe atmospheric river from October 18-20 oversaturated B.C.’s soils. With weakened roots, trees became more vulnerable to wind gusts, increasing the severity of power outages.

A stormy precedent: Fall 2006

For those who remember the Fall of 2006, the parallels are striking.

Three major windstorms hit B.C. in quick succession:

  • November 15th, 2006

  • December 11th, 2006

  • December 14-15, 2006

BC Storms October-December 2006BC Storms October-December 2006

BC Storms October-December 2006

The resemblance is uncanny and begs the question if this pattern is set to continue to mirror the 2006 storm season.

Rest of December: Buckle up

The East Pacific Oscillation (EPO), a key metric for storminess in B.C., is forecast to remain negative through December 22nd. This favours a stormy 7-10-day stretch leading up to Christmas.

TLDR: The jet stream is active, the setup is primed, and British Columbia is far from being out of the woods

The Bottom Line

British Columbia’s storm season has hit early and hard. A perfect storm of factors—prime storm tracks, sea surface temperature gradients, and oversaturated soils—has amplified the impacts of each system.

The next question isn’t if more storms will hit, but how bad will they be.

WATCH BELOW: Storm causes power outages and landslides across southern B.C.

Click here to view the video

Header image credit: Lower Mainland Dist. @TranBC_LMD/X

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