By Cory Phare
About as much fun as it sounds. Sometimes, snowflakes melt while passing through a warmer layer of air, then get “super cooled” by another thin layer of freezing air just above the surface. The result? Spine-chillingly cold rain that you really don’t want trickling down the back of your jacket, and which instantly refreezes on contact with very cold ground.
When falling snow meets winds hurtling at over 35mph, this is the unhappy result. Blizzards often feature heavy snowfall and severe cold, but their real danger comes from low visibility. For drivers, particularly, they are very bad news. (Note: Sometimes, strong winds lift up snow that has already fallen to create a ground blizzard, which means you get smacked full in the face by freezing snow. Bonus!)
Nobody’s idea of a good time. When enough freezing rain hits enough frozen ground, leaving at least a quarter inch of treacherous ice on exposed surfaces, then you’re in ice storm territory. Driving and even walking become next to impossible. Tree branches, power lines and flimsy roofs can all give way under the weight of the ice. It’s not pleasant.
In a word: Ouch. Hail happens when thunderstorm updrafts carry raindrops so high they freeze into ice. Then they drop again. Hard. Hailstones are usually pea or marble-sized, but can come down as big as grapefruits – at which point they pose a serious risk to people caught in the open. Colorado has more hail storms than almost anywhere else in the United States. If you’ve ever seen the totaled cars and wrecked roofs they leave behind, you’ll already know it’s a good idea to find cover, fast.
The grand-daddy of them all. A fierce combination of heavy, blowing snow and dangerous wind chills, winter storm conditions can be life-threatening if someone is left exposed to them. Get inside, quick!
Keah Schuenemann, Ph.D., is in the Earth and Atmospheric Science Department at MSU Denver.
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