Ice storm, decoded. Rain that freezes the second it lands.
An ice storm does not look dramatic at first. No blizzard whiteout, no howling wind — just rain falling on a cold day, and then everything it touches turns to glass. This page is the short version of how that happens, how little ice it takes to bring down a power line, and the one decision that matters most when an ice storm is forecast: stay off the roads.
WHAT IT ACTUALLY IS.
Rain falling through a cold sandwich.
An ice storm is a prolonged period of freezing rain that coats trees, power lines, sidewalks, and roads in a layer of glaze ice. It forms when a shallow layer of subfreezing air sits at the surface beneath a warmer layer aloft, so snow falling from above melts into rain in the warm layer and then freezes the instant it touches a cold surface below. The result is not snow on the ground but ice on everything, and it keeps building as long as the rain keeps falling.
HOW LITTLE ICE IT TAKES.
A quarter inch is already a problem.
A quarter inch of ice can add hundreds of pounds to a single span of power line, which is why limbs snap and lines come down long before the ice looks deep. A half inch or more can cause widespread outages that last days, because crews cannot safely repair lines while ice is still accumulating and roads are impassable. That is why an Ice Storm Warning is issued when significant ice accumulation is expected: the warning is not about how cold it feels, but about how much weight is about to land on everything overhead.
WHAT TO DO ABOUT IT.
Stay off the roads, charge everything, wait it out.
Travel during an ice storm is extremely hazardous because roads, bridges, and sidewalks ice over all at once, and a car cannot grip glaze ice no matter how careful the driver is, so the safest action is simply to stay off the roads until crews have treated them. Before the storm, charge phones and backup batteries, keep flashlights and blankets handy, and bring pets inside, since an outage in freezing weather is a cold problem, not just a dark one. Brzzy's forecast, live radar, and severe weather alerts turn the same kind of ground truth into a plain-language answer before the ice arrives: stay home, charge up, or go now while the roads are still just wet.
What is an ice storm?
An ice storm is a prolonged period of freezing rain that coats trees, power lines, sidewalks, and roads in a layer of glaze ice. It is the event, not the precipitation type: freezing rain is what falls, an ice storm is what happens when it keeps falling for hours.
How does an ice storm form?
It forms when a shallow layer of subfreezing air sits at the surface beneath a warmer layer aloft. Snow falling from above melts into rain in the warm layer, then freezes the instant it touches a cold surface below, building a coating of glaze ice as long as the rain continues.
What is the difference between an ice storm, freezing rain, and sleet?
Freezing rain is liquid rain that freezes on contact with a cold surface. Sleet is ice pellets that form when rain refreezes before reaching the ground and bounce on impact. An ice storm is a prolonged freezing-rain event that coats everything in glaze ice; sleet, by contrast, does not coat surfaces and rarely causes the same damage.
How much ice does it take to cause damage?
A quarter inch of ice can add hundreds of pounds to a span of power line, enough to snap limbs and bring lines down. A half inch or more can cause widespread outages lasting days. An Ice Storm Warning is issued when significant ice accumulation is expected.
Does Brzzy warn me about ice storms?
Brzzy shows your local forecast with hourly updates, live radar, severe weather alerts, GIF forecasts, and activity ratings that weigh the sky for your plans. Brzzy is free to download on iPhone.
More from Brzzy: Full weather glossary, Freezing rain, Sleet
