The incoming frontal system will bring more snow to the north coast ranges.  Freezing levels will be near 1200 metres for the south coast this morning and near 300 metres for the north coast.  Ridgetop winds (~1500m) westerly 40 to 60 km/h for the south coast and westerly 20 km/h for the north coast (~2000m).  

Pockets of snow will fall over the interior, primarily near Nakusp as the environment is generally unstable. Freezing levels near 600 metres for the southern and central interior and near valley bottom for the North Rockies. Strong northwesterly/westerly ridgetop winds are expected. 

Mainly cloudy with some scattered flurries. Ridgetop winds north 20 km/h. Morning temperature -9ºC.

A cold front located near Waterton Lakes National Park will quickly dip south of the American border in the morning. Northeasterly upslope flow combined with instability behind the cold front will keep skies cloudy with flurries along east-facing slopes across the Rockies. The heaviest snow will fall south of Ghost River bringing 5 to 10 cm. Areas further north will see scattered flurries with trace amounts of 2 to 4 cm.

In Kakwa and Jasper National Park, light northwest ridgetop winds near 20 km/h will switch to southwest 20 km/h in the afternoon. Elsewhere, northwest winds of 30 to 40 km/h will switch to southwest 30 to 40 km/h as a low develops over southeastern British Columbia (BC) late in the day. Freezing levels at valley bottom except for areas south of Crowsnest Pass, where they will rise to 1400 m. Alpine temperatures peaking in the -6°C to -12°C range except for areas south of Crowsnest Pass, where they will be closer to -2°C.

Freezing levels will hover near 1000-1500 metres for the south coast and near 500 metres for the north coast. Precipitation continues this afternoon. Snowfall will be highly variable with 5 to 15 cm over the Northwest Coastal Ranges except locally higher amounts closer to the coasts (Kasiks and Mt. Madden). Further south, due to the rising thicknesses, precipitation type will play a role with Insular ranges reaching up to 1500 m while the south coast mainland varies between 1000-1500m.  5 to 15 cm over the Northshore and near 5 cm over the Sea to Sky and South Coast Inland Ranges by end of the day. The real kicker for the South Coast will be for tonight as the low center slides over the interior and tracks toward the Okanagan. As freezing levels gradually fall, precipitation intensity will certainly ramp up. Ridgetop winds westerly 40 to 60 km/h for the south coast and westerly 20 km/h for the north coast.  

Snow will ramp up over the interior ranges this afternoon as the coastal low tracks inland. By end of day (4PM), most interior ranges could see up to 5 cm. The primary concern is for more snow tonight as the surface low digs south. Heavy snow stretching from the Cariboos down to the border will occur, with anywhere from 10 to 25 cm by Tuesday morning. Freezing levels near 1000 metres for the southern and central interior this afternoon and near the valley bottom for the North Rockies. Strong northwesterly/westerly ridgetop winds are expected for the southern interior. For the northern Rockies, winds will shift to northeasterly this evening as the arctic air makes its presence from the back edge of the low.

A ridge of high pressure will build, bringing clearing skies in the evening. Ridgetop winds will increase to north 30 km/h with gusts to 50. Temperature near -10ºC this afternoon.

Through the evening, a substantial push of moisture from BC will envelop the entire Rockies as a low pressure system begins to develop over Montana. This will spread 10 to 20 cm of snow to most areas overnight, with snow-to-liquid ratios anywhere between 10:1 and 20:1. The heaviest snow with this system will fall in areas south of Peter Lougheed Provincial Park, bringing up to 25 cm.

Southwest ridgetop winds will flip to east 20 km/h except in Kakwa, where winds will strengthen to east at 40 to 50 km/h. All previously elevated freezing levels fall to valley bottom for the remainder of the week. Alpine temperatures will promptly drop into the -12°C to -20°C range by Tuesday morning except for areas south of Crowsnest Pass, where they will be slightly warmer between -6°C and -12°C.

Forecast for Tuesday Morning at 4 AM PST:

Snow will continue over the South Coast ranges but decrease in intensity as the bulk of precipitation slumps south. Over the North Coast except skies to clear out and cold temperatures to engulf the region. Freezing levels will fall over the South Coast to 600 m, but we await the back edge and outflow winds this afternoon for them to plummet to valley bottom.

Moderate northeasterly ridgetop winds over Northwest Coastal Ranges. Westerly winds up to 40 km/h over the North Shore this morning, winds will temporarily ease by noon.

On Tuesday morning, the frontal system will continue to spread snow to the southern half of BC. Regions south of Blue River will be hardest hit with snowfall for today. Monashee, Selkirk, Purcell, and Lizard Ranges should see widespread 5 to 15 cm with 20 cm likely over prone ridgetops. The backedge of the frontal band will begin over Blue River this morning and shift southward throughout the day. Northerly and northeasterly winds will set up along the backedge leading to blowing snow concerns. Strong northeasterly winds above the treeline over the North Rockies this morning.

Increasing clouds in the morning. Ridgetop winds north 30 km/h. Tuesday morning temperature -18ºC.

A low pressure system over Montana in the morning will continue to bring cloudy skies and snow to the Rockies. The heaviest snow will fall south of Crowsnest Pass giving 5 to 10 cm, and up to 15 cm in Waterton Lakes National Park (WLNP). Elsewhere, expect trace amounts of 2 to 4 cm. Snow will taper off through the day in Kakwa, becoming partly cloudy by the afternoon with about 40 percent cloud cover. 

East ridgetop winds of 30 to 40 km/h. Very cold alpine temperatures in the -15°C to -20°C range.

Forecast for Tuesday Afternoon at 4 PM PST:

Sunny and cold over the North Coastal ranges. Further south, outflow winds will develop late afternoon through Whistler, and reach the North Shore late evening. Higher terrain prone to outflow winds will occur, with Sasquatch for example reaching northeasterly ridgetop winds 40 to 50 km/h. Alongside outflow winds, scattered flurries bringing accumulating snowfall are possible, especially over the Sea to Sky Ranges.

As the low center continues to shift towards the border, snowfall will ease with the exception of heavier flurries (with snow squall characteristics) over Nakusp down to Castlegar. This convective line of flurries may shift west/east in its path; whichever way it shifts it will certainly produce accumulating snowfall. 

Easterly ridgetop winds will develop in the afternoon as an arctic airmass descends from the north. Strong northeasterly ridgetop winds will continue for the North Rockies.

Partly cloudy. Ridgetop winds north 25 km/h. Tuesday afternoon temperature near -10ºC.

As a surface ridge builds over Alberta, snow will taper off from Jasper National Park to the American border through the night. South Rockies and WLNP can expect to see another 2 to 4 cm. Skies will become partly cloudy similar to Kakwa by Wednesday morning, with about 40 to 60 percent cloud cover. Scattered flurries will linger with this cloud, giving minimal accumulations.

East ridgetop winds of 30 to 40 km/h continue. Frigid alpine temperatures will drop into the -25°C to -30°C range and are expected to stay this cold until later this week. Risk of frostbite. 

On Wednesday, the arctic airmass will continue to move southward.  Strong outflow winds will develop near the mainland inlets and frigid temperatures are anticipated in the alpine. 

On Thursday, the upper ridge axis will be displaced from the Pacific High through to the Yukon. As this axis slumps south, any remnant cloud cover over the South Coast Ranges will clear out leaving behind decent winds and frigid temperatures.

On Wednesday, the arctic airmass will continue to descend from the north. Frigid temperatures are anticipated in the interior mountain ranges. Dry conditions are forecast with the exception of cloud cover south of the Cariboos and scattered flurries near Nakusp.

On Thursday, conditions will clear up south of the Cariboos with cold temperatures at the alpine.

The ridge of high pressure will rebuild over the region Wednesday, with clear skies and winds north becoming northeast 15 km/h. Wednesday morning temperature -20ºC increasing to -12ºC in the afternoon. On Thursday, an approaching frontal system will bring increasing clouds with snow beginning in the evening. Winds will become southwest 30 km/h Thursday afternoon. Thursday morning temperature -22ºC increasing to -10ºC in the afternoon

On Wednesday, an arctic airmass descending from the north will bring colder and drier conditions for the remainder of the week. Partly cloudy skies with lingering light flurries for all regions. Light to moderate east ridgetop winds with the possibility of strong gusts through valley gaps. Frigid alpine temperatures in the -20°C to -30°C range.

On Thursday, we will finally see a clearing trend across the Rockies. Light to moderate east ridgetop winds will switch to light from the west by Friday morning. Frigid alpine temperatures persist.

Heavy Snow Followed by Arctic Air

Ken D, Ken C, and Kristina K

A lean, mean, fighting machine (frontal system) over the Gulf of Alaska will crash into the BC coast this morning bringing widespread precipitation to the province today and tomorrow. Snow and strong ridgetop winds will be associated with this system. Please keep appraised of weather watches and warnings produced by Environment and Climate Change Canada. 

The weather system will be pushed south by an incoming arctic airmass on Tuesday night. The arctic airmass will continue to descend from the north on Wednesday with the entire province becoming clear and cold on Thursday. Mercury will fall with temperatures hitting values of 5 to 10 degrees below seasonal from Tuesday night until the weekend.

The 500 mb animation depicted above shows a surface low heading towards the BC north coast this morning. As it continues to track inland, it will gradually continue to strengthen and dig south forcing the broad high pressure off the coasts of California to flatten and shift south. This will allow the low to reign free over BC and spread heavy precipitation to both the coastal and interior ranges. 

In behind an arctic airmass will arrive Tuesday night as northerly flow sets up ahead of an upper ridge over the Gulf of Alaska. Anticipate cold temperatures for BC from then on until the weekend.