Why Freezing Rain Could Be The Most Deadly

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W​inter Storm Blair is set to wring out a stripe of snow and ice across the Midwest, Ohio Valley, Appalachians and mid-Atlantic. While the storm's snow will be the focus of many headlines, its freezing rain could also have significant impacts.

So what exactly is freezing rain?

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Simply put, it's rain that freezes on contact with the ground, trees, cars and other surfaces when the ground is at or below freezing.

This is analogous to water dripping in the back of an overcooled refrigerator and freezing when it hits the shelf. That ice builds up on the shelf until either the fridge warms up or you chip away at it to remove it.

(​MORE: Why Snowfall Forecasts Sometimes Change)

Freezing rain does not bounce when it hits the ground like sleet, and it does not run off as warm rain does.

Due to its resemblance to ordinary rain, its onset may catch some off-guard until it begins to accumulate as ice.

Here are five reasons why freezing rain is the worst precipitation type:

1. It Could Be A Silent, Invisible Killer

Early in a freezing rain event, bridges, roads and metal surfaces become coated with a clear, thin layer of ice that leaves untreated roads, especially bridges and overpasses, slippery. This ice is often referred to as "black ice" because it is nearly invisible to drivers. Perhaps ice is one of those things that is slightly better in surplus since we can actually see it.

(MORE: Black Ice Explained)

Ice created by freezing rain can also be hidden by snow or sleet that falls after freezing rain transitions to one of those precipitation types. This makes the ice nearly impossible to see with extremely poor traction under the blanket of snow.

2. It Weighs Down Everything And Leads To Tree Damage And Power Outages

It's harder for snow to accumulate on bare trees and power lines without falling or blowing off, but ice can easily accumulate on those surfaces. With the extra weight of the ice, power lines and tree branches can snap, leaving people without power and blocking roads.

Just a half-inch of accumulation on power lines can add 500 pounds of extra weight.

Wind only adds stress to trees and power lines, forcing them to snap even easier.

(​MORE: Your Preparation Guide Ahead Of Winter Storms)

3. It Generally Occurs On The Southern Periphery Of Winter Storms 

Because there must be warm air to produce freezing rain, it generally falls farther south than snow. Freezing rain sometimes marks the southern edge of wintry precipitation in weather systems. That southern edge can dip into areas not used to dealing with wintry weather, such as the South.

Freezing rain can also occur in valleys where cold air can get dammed or stuck. Because cold air sinks below warm air, it sometimes can get stuck in pools or forced into lower elevations by wind such as cold air damming situations that occur a few times each winter in the Southeast east of the Appalachians. When rain or drizzle glides across these areas, it falls into the colder air below and freezes on contact. This occurs most frequently in the valleys of the Northeast.

Arguably, conditions in either snow or plain rain are easier to deal with as a motorist than the fine line between the two.

(​MORE: 'Frost Flowers' And 5 Other Interesting Winter Phenomena)

4. When Icicles Fall, They Can Be Deadly And Damaging

Most of us like the sight of the icicles or an icy curtain on buildings, but watch out when they fall. Due to their spearlike shape, they can pierce whatever they hit on the way down to the ground. Like snow, when ice comes down from office buildings, it can be damaging to cars and anything else that lies below.

(​WATCH: Ice Daggers Close Bridge)

5. It Cannot Be Plowed And It Does Not Run Off

Although roads can be salted or sanded, this doesn't always remove the ice. Snow plows usually cannot remove ice unless it is thicker and easier to break up.

Unlike rain, freezing rain does not generally run off until it is warm enough to melt.

Often, the only way to get rid of ice is to wait for it to melt or to melt it with salt. And road salt becomes less effective when it is colder than 20 degrees. That can lead to icy roads that linger for days if a strong arctic outbreak follows an ice storm.