▶️ Little Did I Know: Explaining freezing rain — with beer

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It was the question that was on every Central Oregonian’s lips last week. How can it be so dang cold out there and still be raining? Once again, this is where getting a meteorology degree helps.
I spent the first give years of my meteorology career forecasting the weather for the Great State of Alaska. And I know what you’re thinking. How hard can that be? All you have to say is “It’s gonna be cold!”

And you’d be wrong. 

At one-fifth the size of continental United States, Alaska has at least six major distinctive climates, not to mention the millions of micro climates. You could be talking 50-below windchill in one area, driving rains in another and peaceful sunshine and warmth in another. 

But you’d also be right. To live in Alaska is to become intimately involved with cold weather. And of all the types of winter weather I saw in my tenure in Alaska — massive blizzards, scorching sun and driving rain — my least favorite type of weather  was freezing rain.

It was also the only one I ever saw that caused school to be canceled in Alaska. Yes, the same type of weather that caused school districts in Central Oregon to be canceled last week and coated every house, power line, and highway with a sheet of ice. 

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But considering how many times I’ve been asked in the last week how it can be below freezing on the ground and yet raining in the sky, I decided it was time to break down what is actually happening using something close to home — beer. 

The reason most people don’t understand how it could be below freezing on the ground and raining up above is because, under normal circumstances, it gets colder as you go higher in elevation. But cold air is actually more dense than warm air. It has a tendency to sink, while warm air is lighter and has a tendency to rise.

Here’s the beer example. In a drink called a black and tan, a lighter colored but denser beer — like a lager — is poured in first. Then a darker, but less dense beer, is poured over the top. It leaves us with one tasty visual for getting us closer to freezing rain.

What we actually have in the glass is very similar to when we get an inversion in Central Oregon. That was something we had in the days right before the freezing rain came — it was cold and foggy and yet sunny and warmer up at the mountain.

Now, imagine another cold layer came in over the warmer air and began to snow. That snow would fall through the warmer air and turn into rain. The rain then falls into the colder layer, hits the ground that is below freezing and freezes on contact. 

In many freezing rain scenarios, the surface is below freezing, but the roads and sidewalks are dry. In our case, when the freezing rain started, it not only fell into a layer below freezing, but onto a surface that was already covered in frozen precipitation. 

But what kind of “Little Did I Know” would this be if I didn’t share one mostly unknown but massive detail related to freezing rain?

One of Canada’s biggest natural disasters was caused by freezing rain. In this case, nearly four inches of ice accumulated. One cubic foot of ice weights over 57 pounds — five times more than the wettest, heaviest snow. That weight on the power grid caused over 1,000 transmission towers to collapse. It led to 4 million people without power, 34 fatalities and the largest deployment of military personnel in that country since the Korean war. 

In our area, the freezing rain mainly led to slips, slides, accidents and a lot of people just staying home and enjoying a low density or high density beverage of their choice. 

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