Mountain Weather Forecast

The winds and lowered freezing levels over the Thanksgiving weekend were just a trial run. Today, a new potent low pressure system crosses Vancouver Island this morning and fizzles out near Blue River tonight. A subsequent new lee low forms near or just south of Calgary and continues marching eastward along the Saskatchewan-USA border by Wednesday morning.

Fierce winds batter communities all over Vancouver Island and the southern mainland coast. Please see ECCC's Weather Alerts page for the latest Warnings and Special Weather Statements in your area. Strong southeasterly winds will abruptly transition to widespread, fierce westerlies as the low pressure system transits through Vancouver Island. Very strong winds aloft have the potential to mix down to the surface (see Day 1 tab for details), increasing the risk of damage to shingles, tossing loose items, breaking tree branches and power outages.

Meanwhile, white stuff is falling throughout the interior as freezing levels bottom out this morning. Valley bottom communities will see a few centimeters of accumulation, making roads slick and challenging for those caught off guard by this first low-level snow fall. Freezing levels will attempt to rise this afternoon but high elevation transportation corridors may or may not see the transition to rain this afternoon. As such, significant snowfall is expected throughout the day; a good news story for eager skiers and riders sharpening their edges ahead of the winter season!

As the lee low forms over southern Alberta, strong westerly gap winds form along the southern Rockies this evening and persist into Wednesday morning. Aloft, northeasterly winds will drive upslope flow along the eastern slopes of the Rockies giving snow to the mountains and mountain towns.

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The 500mb animation shows a tight geopotential height gradient (black lines) stretching across the Pacific and through southern BC. This is indicative of a very strong westerly jet that in turn supports the swift movement of the low from Vancouver Island across the province today. A healthy dose of precipitation will fall over the southern coast (yellow shading) but the main story is the wind event unfolding. Moderate to heavy snowfall over the interior mountain highways (smaller yellow shading bull's eyes) continues this morning and throughout the day. Thickness values attempt to rise this afternoon leading one to believe precipitation may changeover to rain, even at higher elevations, but diabatic cooling from high precipitation rates will compete to keep snow levels low.

On Wednesday, an upper ridge just off the coast of California pokes its head northwards. This changes the upper level flow from westerly to northwesterly over BC. Flurries on northwestern aspects of the Coast Mountains, Cariboos, Columbias, and Monashees continue.

A new frontal system rides up and over the ridge on Thursday bringing ample precipitation to Prince Rupert, Kitimat, and the central and northern interior Thursday night. Freezing levels will be much higher for this storm as denoted by the northward bulge of orange, dashed thickness lines.