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Ice Storm



Discussion

The National Weather Service defines an ice storm as freezing rain that produces ice accretion of one-fourth inch or more that can cause damage to trees and power lines. Ice thresholds will be different in some locations. The National Weather Service in Caribou, ME, for example, uses a threshold of one-half inch or more, at least as of the year 2021. Advisory and warning thresholds for any type of wintery precipitation can differ depending upon the part of the country you live in. From a layman's perspective, major sleet accumulations on the ground, such as several tenths of an inch or more, may also be called an ice storm, especially if even a small amount of freezing rain is involved. The National Weather Service will usually issue a Winter Storm Warning in that situation.

References

National Weather Service Glossary definition of an ice storm

Warning Criteria of National Weather Service Caribou, ME