UPDATED 10AM: Snow is coming just a matter of how much.

UPDATE 10AM: re read the post. Things are starting sooner, and accumulations not quite as severe. I will update again if anything else major changes.

All sources have come into agreement. There will be snow this weekend, and there may be a lot in some places.

The biggest question that remains is how much snow will stick, or when will it start sticking. That depends on the ground temperatures. This mornings special weather statement says it well (click the Watches and Warnings link above the forecast to get to it in full).

I’ve bolded the part below:

Statements

Inland Vancouver Island
4:49 AM PST Friday 21 February 2014
Special weather statement for
Inland Vancouver Island continued

Complex weather pattern this weekend.

Environment Canada is monitoring a weather system that is forecast to reach the South Coast this weekend. Similar to recent storms that have affected the Lower Mainland, it has the potential to generate snow near sea level for portions of the South Coast. While it is likely that precipitation will fall in the form of wet snow, it is uncertain whether surface temperatures will be sufficiently cold for snow to accumulate.

Current indications are that precipitation from this system will begin early Saturday morning and continue Sunday. Snowfall accumulations on Saturday may reach 5 cm near sea level and near 10 cm at higher elevations.

The public, especially those with travel plans this weekend, are advised to stay tuned to the latest forecasts and warnings from Environment Canada at WWW.WEATHER.GC.CA.

The public is advised to monitor future forecasts and warnings as warnings may be required or extended.

Please monitor the latest forecasts and warnings from Environment Canada at www.weatheroffice.gc.ca.

So how can we tell if and when the ground will be cold enough? Well, if it was falling right now, after a night at or below freezing, we’d likely have no trouble at all. If, however, we have a warm day Friday and it clouds over overnight, trapping a lot of that warmth, then less of the surface will cool to the atmosphere it could take a while longer for the ground to get cooled by the snow or rain.

There is a forecast model for that though! It’s a product that simulates Infrared Energy leaving the surface and ends up looking like a shot of the clouds during the nighttime.

We can see by 1AM tonight, the area should be relatively clear.
Update: because the new model run has this coming faster. We are going to be partly cloudy Friday, and then mostly cloudy by tonight. So not as much chance for cooling, which may decrease the likelihood of snow sticking, especially on the East Coast I think.

By 4AM clouds are starting to appear with the rain/snow system, but the East Coast is more clear. So there is some possibility they could get some additional cooling before the clouds and snow arrive. However, it is going to come after sunrise, so unless it is foggy, there will be opportunity for the sun to warm the ground and keep the beginnings from sticking.

So when will the snow and or rain begin? Current models say around or before 11AM 5AM for North, West and Alberni Island regions.

By 1PM 10AM Saturday, the threat of snow spreads throughout the Island from Courtenay to Victoria. I would aim to be off the roads before this time. Earlier obviously on Sutton Pass.

Finally, what are the predictions for accumulations?! Again, these are worst case scenarios if the ground is cool enough to allow the snow to stick early.
From Friday 4PM through to Sunday 4PM
Alberni: 5-10 cm (2-3″)
Courtenay: 10-15 cm (6″)
Parksville: 5-10 cm (2-3″)
Nanaimo: 10-15 cm (6″)
Duncan: 10-15 cm (6″)
Victoria: 5-10 cm (2-3″)

Plan accordingly! Let’s hope everyone stays safe, we can watch the Olympics in the morning and play in the snow in the afternoon!

Go Canada!

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Alberniweather Blog (Chris)

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