Snowmageddon: let the hype begin...

Yesterday, Vancouver International Airport broke a long-standing record for November 12th by reaching 14.6°C, breaking the old record from way back in 1953. 

Although it's been impressively mild the past couple of days, Whistler Mountain is opening early on Saturday, November 16th. Blackcomb Mountain is still scheduled to open on Thursday, November 28th (American Thanksgiving).

This is a whole 13 days earlier than was anticipated. But why? The mountain hasn't seen loads of natural snow this fall, but the past week or two has seen temperatures drastically decrease in the alpine, allowing ample time for the creation of artificial snow. This, paired with some natural snowfall has pushed opening weekend ahead of schedule.

Whistler-Blackcomb is home to over 150 snow cannons which greatly enhances the natural snowfall especially in the autumn before the major snows strike, which you can learn a little bit more about with this brief video from 2012.

Before we get to the juicy details of our forecast that hints at some modified arctic air sliding into the south coast for a couple days this weekend, there's some benign weather to get through.

A ridge building offshore will give us some northwest flow aloft over the next couple days, and then a disturbance will slide down from northern BC.

This NW flow will eventually drive down a much stronger trough from the northern latitudes into southwestern British Columbia.

But, it's 'modified' arctic air. What does that mean exactly?

Normally during wintertime, our atmospheric flow is from the west following typical jet stream patterns, but during an arctic outbreak that flow typically switches direction.

The Rocky Mountains act as barriers to the coldest, most frigid air encompassing the continent during these outbreaks. You know, the -30°C kind of air --- bone chilling prairie air.

In the case that the cold air is deep enough to spill over the Rocky Mountains, the Coastal Range works to hold back the cool air, but it's not a perfect shield. The air that spills over and descends the Rocky Mountains warms and compresses as it pools and settles in the interior of BC.

Once both of these two defense systems have failed, cool air has the potential to "leak" through a couple prominent mountain passes and valleys, such as the Fraser River Gap, which can bring outflow conditions to the Bellingham/Victoria area.

This can even create the possibility for strait effect snow for cities on eastern Vancouver Island such as Nanaimo and also the Victoria area which is often the case a couple times a year. 

The most common cause for our snowstorms is when the dense cool air pools at the surface, while a moist, warm pacific front moves over the cooler, shallower layer of air. The precipitation initially falls as snow, before eventually creating the slushy mess we all know and love in Vancouver.

This weekend will not be this case, but you wouldn't be able to discern the difference judging from the hype on social media.

Here's a small sample:

The Capital Weather Gang (The Washington Post), did a fantastic article about unnecessary hype for these winter events, especially when it's about a long range forecast (>48hours). 

Another compelling and relevant article is this one, which gives a couple brilliant quotes that summarizes the state of social media and the hyping of these events.

"But, when there are potential high impact weather stories, it’s easy to get carried away and post sensational, hype-filled narrative, especially given the draw for recognition (“likes” and shares) as being “first” in getting the word out."

We live in a world where a headline like the one below wouldn't get nearly as many shares/likes/re-tweets as something much more hyperbolic and hype-filled.

"VERY LOW PROBABILITY OF ACCUMULATING SNOW IN METRO VANCOUVER..."

The Forecast

The NW flow and modified arctic air will create some impressive height drops in the atmosphere. For example, the point in the atmosphere where half the weight of the atmosphere is above and half below (500 hpa level), is forecasted to fall up to 280 meters, indicating the arrival of the cool, dry air.

Friday, during the day, they'll be steadier rains with a low pressure system moving south into eastern Washington before the arrival of the arctic front.

Expect it to be a bit windy for Friday night and Saturday as a polar high sets up over BC along with the substantial height drop. Outflow winds are possible around the Fraser Gap and small craft warnings/gale warnings are also likely over BC waters.

Cold air will be in place, but they'll be an noticeable drop in the moisture content preventing any flurries. We're likely to moderate our temperatures by early next week, so the cool air won't be in place for any extended period of time.

NAEFS latest ensemble run showing mean low temperatures near freezing for YVR, but little in the way of precipitation

NAEFS latest ensemble run showing mean low temperatures near freezing for YVR, but little in the way of precipitation

Checking NOAA's (National Oceanic and Atmospheric Administration) SREF  (Short-Range Ensemble Forecasts), which update every 6 hours are useful for determining the probability of a specific precipitation type:

Green: Probability of Rain Blue: Probability of Snow  

Green: Probability of Rain Blue: Probability of Snow

 

Not looking too good snow fans...

The SREF is going for a measly 1% chance for the precipitation to be falling as snow during the foreseeable future.

Places where this percentage will drastically increase is in the Fraser Valley or anywhere above 300 m (Burnaby Mountain), which could see the precipitation briefly change over to snow Saturday morning, before the bulk of the colder air reaches us.

 

#50shadesofVan

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Did you know?

When you think of Canada's snowiest cities, a couple usual cities normally come to mind.

Montreal, Toronto, Edmonton, and Ottawa...

But what about all-time single day snowfalls among Canada's major cities?

A city that gets on the podium in 3rd place may shock you...

Victoria, British Columbia

Yes, Victoria has the third highest single day snowfall for ALL major cities across Canada at 64.5 cm with over 80 cm accumulating within 48 hours in December 1996.

The army was called in to help with clean-up.