Snow Thursday – Then Concerning Melt + Rain + King Tide Christmas Eve and Christmas Atmospheric River.

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It’s COLD!

How cold did your thermometer get this morning! Alberniweather got to 8.9ºC. The Airport got to -13.7ºC (likely a record for the day).

Thursday start but mostly overnight.

I wanted to wait until this morning’s run of the model was complete so that we had the latest and hopefully most accurate update before things get started. There is a lot going on through the whole weekend and it unfortunately gets worse as we get through Christmas.

First, here is the *result* by Friday afternoon of the Thursday snow event:

The model above suggests 5-10cm (2-4in) but I think 15cm is possible in Port Alberni.

The map below shows the same result but highlights where snow is expected to fall the most.

Port Alberni, Nanaimo, Lake Cowichan and Chemainus look as though they will get the most. Parksville, Victoria and Duncan get very little.

Timing – Thursday afternoon hints – but mostly overnight

The first hints of the approaching weather should start to appear by mid to late afternoon on Thursday. Folks on the West Coast should see SE winds picking up throughout the day as the front approaches.

By the 4-7PM period the precipitation has begun to spread and pick up throughout the Island but focusing on snowfall first on the beach in Tofino and Ucluelet (green below) and spreading into Port Alberni and Port Renfrew.

NOTE: THE MODEL IS ASSUMING WE STAY BELOW FREEZING. This seems very likely given how strong a cold snap we are in today. However, with Southeasterly winds usually comes Pacific warmth. So don’t be surprised if this is not light and fluffy, but instead soggy or at least slushy. We live on the West Coast, we expect these things. 🙂

That said, according to the model *The Snow Intensifies Over the Water!* into the 7-10PM period. Look at it below! That’s a whole bunch of moist Pacific air running into an Arctic airmass! Green is snowfall, greys are rainfall.

The front moves fully onto Vancouver Island after midnight, below is the 1-4AM view. This should be where we see the most intense snowfall rates. Thankfully, not when people are driving.

Sutton Pass on Highway 4 will probably get the biggest totals and the West Coast might get just as much snow as Port Alberni.

Possibly turning to Rain or Freezing Rain Friday

In the 4-7AM period it looks like the warm Pacific wind starts to win the battle and we see a transition on the West Coast from snow to rain. This could get very messy! Watch for Freezing Rain.

Friday is a big question mark right now. We could see more snow, freezing rain, or straight rain. Or all three!

The model definitely expects right now that most precipitation will turn to rain over the Island by later Friday morning. However, this is very hard stuff for the model to predict. And local geography will play a big role.

I would expect it to keep snowing a little longer in Port Alberni and Lake Cowichan. But you might see the mountain passes switch to freezing rain, sleet and/or rain. It’s a mess. I would *not* recommend driving on Friday.

Christmas Eve Day – King Tides + Rain + Snowmelt Concerns

That big grey/black mass is rain. And a whole bunch of it.

It will hit the North Island early Saturday morning and bring both rain and SW wind to the rest of the Island for Christmas Eve Day. The main force of the rain lands with warm SW winds in the 10AM-1PM period.

It will be short lived. The rain should stop by sunset on Christmas Eve.

King Tide Flooding Concern

However, I am worried about the snow melt and rain combining with the seasonal high tides to produce flooding in some areas.

The highest tides are 3.8m on December 23rd at 11:36AM and December 24 at 12:25PM

If this forecast model is correct the peak tide lines up with the arrival and peak intensity of the storm and resulting/expected snowmelt. There will also be southwesterly winds so we could see a small amount of storm surge. No matter what, there could be a lot of pressure on low-lying areas and on Port Alberni’s sewage system.

The best outcome would be that it stays cold enough that the Saturday system does not fall all as rain, and/or the snow on the ground does not melt as fast but that won’t happen on Sunday.

Atmospheric River setup for Christmas Day

There will be no chance of snow by Christmas Day and we have what looks like the beginnings of an Atmospheric River setup on the south Vancouver Island region by the night of December 25th.

Expect heavy rain to begin first thing Christmas morning. If the snow isn’t melted by then already, it will be gone by noon.

The heavy rain will continue all day and into the night Sunday.

Again, with all of the snow on the Island over the past few weeks I have serious concerns about flooding from this Christmas Storm. It looks like the Cowichan and Fraser Valleys will bear the brunt of it but Port Alberni will also get a lot of rain.

The rain in Port Alberni and the South Island is not expected to stop until Monday afternoon/Boxing Day.

That’s it! Get out there and enjoy the beautiful sun and snow because it’s about to go away! :+)

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