Centre of low pressure early this morning situated over Haida Gwaii with frontal system extending southward. This is the first punch of significant weather this week. 

Extreme southerly mountain top winds ahead of this front will switch to strong to extreme southwesterly winds as the frontal system moves inland later today. 

5 cm of snowfall accumulation expected across northwest ranges, but up to 10 cm in upslope locations. Across south coast ranges expect up to 10 to 20 cm of snow. Freezing levels will be approximately 1100 to 1400 metres along the entire BC coastline today. 

Just light snow across many of the interior ranges from the North Rockies and right down to the US border. Looking at 2 to 5 cm of snowfall accumulation today, perhaps as much as 10 cm in ideal upslope locations.

Mountain top winds strong southerly and easing through the day to a more southwesterly direction.

Freezing levels at, or near valley bottom will slowly rise to sit between 1000 to 1500 metres this afternoon.

Periods of snow. Snowfall amount 10 cm. Strong southerly ridgetop winds.

Forecast for Tonight - 4 p.m to 4 a.m PST:

A bit of a default ridge to start this evening. However, a very impactful storm is bearing down on the BC coast in time for Christmas. Starting late overnight the robust frontal system will initially impact northwest - coast ranges.

Some pockets of light snow to start this evening. Freezing levels around 1000 to 1300 metres. Token amounts of snow along coastal ranges to start evening, but as next frontal system approaches by day break Wednesday look for snow amounts to ramp up over the north coast. 10 to 15 cm snow over north coastal regions and 5 to 10 cm over south coast regions tonight.

Mountain top winds switch from strong southwesterly to extreme southerly after midnight as next frontal system gets closer.

A bit of ridging over the interior before the large frontal system over the Pacific pushes in. We start the evening with light snow from the North Rockies to the USA border. Generally snowfall amounts can be expected to be on the order of 5 to 10 cm. Later overnight just light flurry activity.

Mountain top winds tonight are a strong southwesterly

Freezing levels start off this evening at between 1000 to 1500 metres and then drop to between valley bottom and 1000 metres later overnight. 

Flurries. Snowfall near 2 cm. Ridgetop winds southeast 20 km/h.

Forecast for Wednesday - 4 a.m to 4 p.m PST:

A Very active Christmas Day on the coast due to a very active and strong storm system

Mountain top winds will be extreme southerly and then will switch to extreme southwesterly Wednesday afternoon in behind the main frontal band.

Precipitation will start as moderate to heavy Wednesday morning and then ramp up to very heavy Wednesday afternoon in more favourable upslope locations along Vancouver Island, central and northern coast ranges. Total accumulation of snow over north coast ranges 10 to 20, possibly up to 25 cm. Over south coast ranges looking at generally 15 to 25 cm, but as high as 40 cm.

Freezing levels remain relatively level through Wednesday to sit between 1000 to 1500 metres.

A fairly quiet start to the interior ranges Wednesday morning. Some light snow and strong southwesterly winds over the Columbia ranges and spreading into the Lizard-Flathead and Purcells.

As the robust frontal system pushes in from the coast, the mountain top southerly winds become strong to severe. Snowfall rates pick up and spread to the Cariboo and North Rockies ranges. Total snowfall accumulations are still muted over interior compared to the coast and so some regions may see 2 to 4 cm, but likely not much more.

Freezing levels remain between 500 to 1000 metres for Christmas Day.

Periods of snow. Amount five centimetres. Moderate northeast outflow winds.

Past Wednesday on Boxing Day, models seem to diverge fairly significantly about what systems, if any will impact the BC coast. The GDPS solution tries to develop a strong low just west of Vancouver Island, while the NAM and ECMWF have a broad trough. 

Depending on what actually materializes will greatly determine how strong the mountain top winds for the coastal ranges are on Thursday.

On Friday still a bit troughy, but no storms expected. Potentially another storm system on tap for Saturday, but still very far out to peg any kind of confidence on that.

Freezing levels maintain between 1000 to 1500 metres both Thursday and Friday.

Ridge top winds diminish from strong southwesterly to moderate on Thursday. Some isolated flurry activity over the Cariboo, Columbia and Purcell ranges. Not much change on Friday.

Freezing levels sitting at between 700 to 1200 metres for Thursday and Friday over ranges from Columbia south.

Periods of snow on Thursday with light accumulations as another low moves onto the Alaskan Panhandle. Snow will end Friday morning as the low pushes inland. Moderate to strong southerly ridgetop winds will develop Thursday in advance of the low and will weaken Friday afternoon as the low moves inland and weakens. Temperatures remain mild for this time of year.

A Series of Significant Storms

Dave Wray

Series of low pressure systems still on course to impact coastal BC with significant weather this week.

Strong to extreme southerly component of winds are expected for the next 3 days along the coast starting through day today and continuing through Boxing Day.

A weak ridge over the interior of BC will be pushed east as the coastal frontal system pushes in today.

There are still some uncertainties for the exact timing, the strength, and the track of each successive low pressure system after Christmas Day.