What are ice storms and why are they dangerous?
Ice storms can be very dangerous, and heavy accumulations of ice can topple power and telephone lines, television towers and trees.
FILE: How historic ice storm affects tourism in popular Michigan island
Jason St. Onge, fire chief of the City of Mackinac Island, spoke about the ways Mackinac Island was affected by the historic ice storm that hit the area in late March. He also shared how much the storm damage will impact the island's travel season.
Winter weather brings a wide range of conditions, from mild inconveniences to severe threats, and with it comes the added hazard of ice storms.
But what exactly is an ice storm?
An ice storm occurs when freezing rain coats roads, trees and other exposed outdoor surfaces with a layer of ice, creating hazardous conditions.
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During freezing rain, damaging ice accretions can make conditions extremely dangerous.
MEMPHIS, TN - FEBRUARY 03: A large tree that fell due to ice accumulation blocks off North Cooper Street on February 3, 2022 in Memphis, Tennessee. The massive storm, working its way across the Midwest, continues to blast states with snow, sleet, and freezing rain in some areas.
(Brad Vest / Getty Images)
Ice accretion is different than snow accumulation, in the sense that significant ice accretions are a quarter of an inch or greater, and when compared to snow, several inches to a foot could be considered significant.
According to the Midwestern Regional Climate Center (MRCC), heavy accumulations of ice can topple power and telephone lines, television towers and trees. Highways can also become extremely dangerous and sometimes even impossible to travel on.
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Bridges and overpasses can become dangerous because they freeze before other surfaces.
So why does freezing rain occur? According to the MRCC, when rain forms in a relatively warm layer of air and falls through a shallow layer of subfreezing air, the rain is "supercooled," or still liquid as it falls through the cold layer near Earth’s surface.
When these "supercooled" raindrops strike the ground or objects below freezing, they freeze instantly, forming a layer of ice commonly called glaze.
![Freezing rain]()
Image 1 of 4FILE - Frozen branches of a tree is seen as freezing rain hits in New York City, United States on February 25, 2022. (Tayfun Coskun/Anadolu Agency )
![Nebraska Freezing Rain]()
Image 2 of 4Freezing rain in North Platte, Nebraska on Jan. 2, 2023. (National Weather Service, North Platte, NE)
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Image 3 of 4Ice coats trees outside the office of the National Weather Service in Moon, Pennsylvania, as freezing rain moves through the area. (NWS Pittsburgh)
![Oregon Freezing Rain]()
Image 4 of 4FILE - Bush coated with ice on a cold morning in at the Sunriver Nature Center in Sunriver near Bend, Oregon. (Wolfgang Kaehler/LightRocket)
The MRCC breaks down the severity of an ice storm based on the following factors, noting that urban areas tend to suffer more economic and physical damage than rural areas:
• How much rain falls and how much ice accumulates.
• The strength of the wind.
• Whether the storm hits an urban or rural area.
FILE: Emergency crews responded to reports of an 18-car pileup due to black ice early Monday morning in Fort Montgomery, New York.
(Fort Montgomery Fire Department/Facebook / FOX Weather)
Other hazards from ice storms could include black ice, which is difficult to see and can typically lead to severe accidents.
During ice storms, it’s important to be extra cautious on roads and around icy surfaces.