Weather Blog

Frequently asked questions about the big storm

Frequently asked questions about the big storm
A cyclist makes his way over the crest of the Denny Way bridge over Interstate 5.
Here's a quick "FAQ" about the incoming storm:

What does a "blizzard" mean?

A blizzard means there has to be heavy snow falling and sustained winds of 35 mph. That is occurring with this storm along the northwestern tip of Washington, where strong winds are racing out to sea near the mouth of the Strait of Juan de Fuca, and heavy snow is falling as wind runs into the Olympics.

We are also getting blizzard conditions in the mountains, where 1-2 feet of snow are expected in addition to wind gusts of 70-75 mph.

What causes freezing rain?

Although not that common in Western Washington, freezing rain is one of the most dangerous types of winter-time weather around, as it can turn road and sidewalks into a sheen of ice in a very short time.

Freezing rain is caused when you have a warm mass of air in the middle altitudes between the ground and the cloud deck, followed by a mass of freezing air near the surface.

When the precipitation falls from the cloud, it will generally be snow. As it encounters the warm air, it will melt into the usual rain. But right before it reaches the ground, it enters the below-freezing air and quickly turns into super cooled droplets that freeze on impact to whatever it lands on. That can turn streets into skating rinks in no time and coat trees and power lines with ice, weighting them down and potentially toppling them over. Ice storms are usually met with widespread power outage.

What's the difference between Hail, Sleet and Freezing rain?

You've seen what freezing rain is above. Sleet is what happens when the warm layer is thin and the cold layer near the ground is much thicker. In this case the snow starts to melt, but doesn't fully, and then refreezes but has enough time to refreeze back into an ice pellet before it reaches the ground.

Sleet isn't as dangerous as freezing rain since it just bounces off whatever it hits, but a pile of sleet can be a little slippery.

Hail is created in the clouds -- caused by strong updrafts that blow rain back up into the higher elevations, where the raindrop freezes into ice, then gets to heavy for the updraft to keep it in the cloud and it falls to the ground.

Why not as much snow in the windy areas?

This storm is a bit inverse than typical snows, where we tend to see heavier snow totals as you go east into the foothills. That's usually because the foothills have higher elevations, which gets them a couple degrees cooler and when we're on the bubble of freezing, as we are with most snow events here, it's enough to switch them to snow. Also, when we have a west wind, that air runs up the side of the mountains, squeezing out moisture and bringing snow there.

But! This is no ordinary storm. For one, it's cold everywhere, so elevation is not a factor. But more importantly, we have a strong east wind this time, blowing in a very cold, dry air mass from Eastern Washington. What's more, as that wind comes down the western slopes of the Cascades, it sinks and dries out further.

That's creating a dry slot of air right along the Cascades -- in essence, it's a "snow eating" wind.

On the flip side, that east wind is smashing into the eastern slopes of the Olympic Mountains meaning far greater snow totals along the Hood Canal and US 101 area where snow totals could reach 12-24"

Feel free to e-mail me any other storm related questions, and I might add them here.