Forecast for Today - 4 a.m. to 4 p.m. PST

The remnants of a frontal system are hanging back over the Island and South Coast ranges, spreading light to moderate precipitation. Freezing levels are approximately 1000 metres and winds have eased to light. Through the late morning and afternoon the precipitation eases significantly over the south coast as the frontal system continues to push out of the area.

Over the north coast a default ridge is in place initially, however, another system is spinning up over the Pacific and some moisture will gradually push into northwest ranges through today. Ahead of the front, winds are strong southerly to start and will become severe later this afternoon. 

Central and northern ranges remain mainly dry under a ridge of high pressure. From south Cariboo down to the USA border there is some light precipitation along the dissipating front. Freezing levels at valley bottom and mountain top winds generally light.

A frontal system moving across the northern Gulf of Alaska will spread snow to White Pass on Thursday.  Snowfall accumulations near 30 cm are expected. Light southerly winds will increase to strong southerlies this afternoon. This will result in some slight warming in the alpine.

Today, a cold front will produce 5-10 cm of snow across Jasper National Park and the Banff, Yoho, Kootenay regions. Other regions will receive only a trace to a few centimetres of snow. Ridgetop winds for south of Highwood Pass will remain strong from the southwest. Freezing levels will drop to near or at valley bottom for the range. The tight surface pressure gradient across the mountain range will weaken by morning,  with strong gap winds decreasing in the valleys east of the continental divide.

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

Over the north coastal ranges we see tonight that the front has stalled in its forward progression somewhat. Some moderate precipitation is making it into areas like Shames, but not propagating much inland. Right along and in front of the frontal band, the winds remain strong to severe southerly. Freezing levels remain between 500 to 1000 metres. 

Over the southern ranges, especially south coast, the weather dries out and some clearing occurs in the overnight period. On the Island, however, some lingering precipitation remains, albeit quite light. Mountain top winds pick up to moderate southerly over the Island by Friday morning. 

The last remnant of moisture over the Columbia ranges will move off into Alberta through the night. Mostly clear conditions by morning will prevail, however, that will lead to the formation of extensive valley cloud due to the abundant moisture in the atmosphere. Winds remain light at mountain top.

The frontal system will move inland tonight and the trailing cold front will move southward along the Alaska Panhandle. Snow will taper to a few flurries overnight and a further 10 to 20 cm could fall. Winds will veer to southwest but remain strong. 

Widespread snow will end overnight, but partly cloudy skies will remain, giving scattered flurries to the mountain range.  Trace accumulations will fall north of Kananaskis Country before morning, excluding Kakwa East. Ridgetop winds south of Jasper National Park will become strong from the west or southwest, while southwesterly ridgetop winds will become extreme south of Highwood pass. 

Forecast for Friday - 4 a.m. to 4 p.m. PST

Through the day on Friday we'll see a new low develop over the Yukon and move into the Northwest Territories. Trailing back from this low a cold front will move through the northwest ranges. Once can expect moderate to high amounts of precipitation along the front and in favourable upslope locations. Winds behind the front will be moderate west-northwesterly at mountain top. Snow level is approximately 1000 metres. 

The south coastal ranges will remain mainly dry through the day on Friday. The advancing frontal system by end of day on Friday is still only over the central coast. In fact, the frontal system is expected to stall there and not advance over the south coastal ranges due to a strong enough ridge of high pressure holding it back. 

The northern interior ranges start the day Friday mainly clear under the influence of a ridge. However, as the day progresses and the trailing cold front pushes south, that ridge budges and moves, allowing moisture to invade the north Rockies.  By later Friday, that front and accompanying moisture will also push into the Cariboo ranges. The precipitation is light to moderate during this event and winds in behind the cold front will be moderate west-northwesterly at mountain top.

A few flurries likely in the morning with little accumulation then mainly cloudy, as a ridge of high pressure begins to build. Winds will ease to light to moderate southwesterlies.

A low centre to the west of the South Klondike Highway will give a few flurries on Friday morning.. A  ridge of high pressure will give mainly cloudy skies and dry conditions  early Saturday before weakening. Temperatures drop slightly.

On Friday, west to southwest ridgetop winds will return to strong-extreme values. Isolated flurries produce trace amounts of snow for the mountains north of Waterton Lakes National Park. Overnight, a cold front pushes in from Northern BC , providing a trace to a couple of centimetres of snow in the Kakwa East and Jasper National Park regions. Freezing levels south of Highwood Pass rise to near or above ridgetop. 

On Saturday the remnants of a weak front remains over the central coast and slowly moves north up to the northwest ranges through the day. By Sunday conditions will dry out over the north. Meanwhile, over the south, a ridge keeps the weather mainly dry and moisture-free. By Sunday, light to moderate southerly mountain top winds develop.

Cariboo and north Rockies ranges will see small left over drabs of light precipitation on Friday, but nothing too major. Wind flow light at mountain top levels. Ridge over rest of interior ranges keeping conditions seasonal and dry. Sunday will see the ridge maintain its presence over the southern ranges with some cloud and isolated precipitation hitting the north Rockies later Sunday.

On Saturday, the ridge remains over the Yukon and mainly cloudy conditions are expected. Light southwesterlies will ease by the afternoon. 

Early Sunday morning, a front will approach from the southwest. About 5 to 10 cm of snow is expected before ending in the evening. Winds will rise to moderate southwesterlies. 

On Saturday, freezing levels south of Highwood Pass are maintained at or above ridgetop. Ridgetop winds north of Banff National Park (BNP) are strong from the west, while winds in BNP and south are generally extreme from the west before moderating late in the day and overnight. Trace amounts of snow will fall north of the Banff town site. Overnight Saturday, freezing levels for Kananaskis Country and south rise to the treeline.

On Sunday, freezing levels rise to near or above ridgetop south of Banff National Park. Ridgetop winds are light to moderate for the range.

Unsettled And Cooler

Dave Wray

Well, we're back at it with the onslaught of Pacific frontal systems rolling through the province which is quite typical for this time of year. The difference this time, however, is that these systems aren't overly strong with regards to wind, precipitation and temperature variations.  There really are no surprises in terms of expected records, or warnings the next several days. So, enjoy the mundane weather for a while!

As you can see on the upper level animation above an upper ridge is well in place over BC, with an upper trough well offshore digging deeply. This upper level set up stays in place much of today, but overnight tonight and into Friday the ridge begins to flatten out and move over the Prairies. This allows a weakened upper trough and associated precipitation the ability to make landfall on the north coast initially, and then slide to Vancouver Island by later Friday.