Some Call It The Greatest Thing That's Ever Happened. I call it Winter.

I had a dream last night.

Mount Washington on Vancouver Island, along with Mount Cain were able to open up, thanks to mother nature flicking the 'on switch' with regards to the conveyor belt (AKA the Jet Stream), ready to deliver the goods to the slopes once we get through the coldest week of February since 1989

In 8-12 days time, you'll be skiing the slopes on Mt. Washington (or Mt. Cain for that matter).

Why am I so confident?

After checking the normally highly accurate and prized European weekly ensemble forecasts, along with Canadian and American forecast models there's a high confidence of a return to that ever elusive zonal flow for the second half of February. 

This one model forecast looks very plausible for at least the amounts in the mountains, and shows snowfall amounts being measured by the foot on the North Shore and Vancouver Island Mountain ranges. Maybe for extra measure, print this photo and place it under your mattress. Amounts for the lowlands are suspect though

This one model forecast looks very plausible for at least the amounts in the mountains, and shows snowfall amounts being measured by the foot on the North Shore and Vancouver Island Mountain ranges. Maybe for extra measure, print this photo and place it under your mattress. Amounts for the lowlands are suspect though

Ski resorts, now would be the time to start the preparations to call in extra staff for resorts not running at operational normals right now. Below, is a graph of the range of temperatures one can expect at about 1500 metres, with temperatures below 0 for at least the next 14 days. 

Yahoo!

This graph is a type of ensemble plot, that shows the range of values we can expect at 1500 metres elevation for the next couple of weeks. If you're a skier, I won't judge if you just had to wipe the drool away

This graph is a type of ensemble plot, that shows the range of values we can expect at 1500 metres elevation for the next couple of weeks. If you're a skier, I won't judge if you just had to wipe the drool away

Tentative forecast amounts: 

As I've said several times, mountain snow/weather conditions are extremely difficult to predict even 72 hours before impending storms, but a VERY general 50-100 cm through till February 18th can be anticipated on most slopes around southern BC.  Enough to save the ski season for Vancouver Island, and hopefully set the stage for skiing well into March and April.

Fingers crossed. Not to mention give us enough of a water supply to last through the summer.

Vancouver Island Strait-effect Snow Potential

Something that's caught my attention is the potential for some localized strait-effect snow squalls this week for portions of eastern Vancouver Island. 

Back in early December the Comox area was hit with strait-effect snow with very heavy snow in a short amount of time:

First a brief introduction of strait-effect snow for those who want to learn a little bit more about the process:

1) As cold continental air flows out of the myriad of channels and inlets along the coast, it travels across the warm ocean waters of Georgia Strait. As the cold air flows across the water, it is heated through a process called conduction.

2) The large temperature difference between the water and air creates a steep lapse rate, becoming conditionally or absolutely unstable 

3) Other atmospheric processes such as the latent heat of condensation and the latent heat of freezing create this positive buoyancy in the atmosphere

4) Once the cloud formations and disturbance reaches Vancouver Island topographic effects become significant especially with steep elevation changes along the coastline of Vancouver Island. This gives that extra bit of friction and convergence to give the necessary lift for a significant, localized heavy snowfall often several kilometres inland.

These squalls can create havoc for forecasters and the public because there isn't much advanced notice with these types of mesoscale events. A beautiful blue sky day, can turn into an impressive localized blizzard in a very short time. Also, these ferocious squalls can have snowfall rates in excess of 5 cm/hr, so the potential for a disruptive snowfall is very much elevated!

Typically, when forecasters look for strait-effect snow they follow a check-list for conditions needed -- more conditions met, the more likely lake/strait-effect snow will be.

Normally, low wind shear, a large temperature gradient, and warmer ocean temperatures (ice free of course) are the main ones, but secondary factors like wind speed and the length of time the winds are over the open waters also play a bit of a factor as well.

The direction of the wind is critical, because it influences the fetch (length of wind over open water).

For Vancouver Island, an east or south-east wind direction would maximize fetch, and the distance over the warm waters over Georgia Strait (about 7-8C in Winter). 

Right now, Tuesday looks like the best opportunity for this, but the current 4 km WRF GFS isn't picking up any precipitation at all, as the resolution might be too coarse, so I'll wait some higher resolution modelling is out to do some further analysis of this.

So... If you live between Comox and Duncan BC tomorrow, be on the lookout for squalls forming over Georgia Strait, especially tomorrow.

Use the hashtag #BCstorm to notify the forecasters that these events are ongoing as well.

#50shadesofVan