The National Weather Service (NWS) has launched a new ice accumulation forecast webpage to help residents and utilities better understand potential impacts during freezing rain events this winter. The tool provides detailed maps and forecasts showing expected ice build-up, similar to NOAA’s existing rainfall and snowfall accumulation pages.
The display provides:
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Most likely expected ice accumulation
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Minimum and maximum expected amounts
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Probability of exceedance maps
These values allow users to visualize the range of potential impacts, from light icing to heavier accumulations. For example, a forecast range of ¼ to ½ inch of ice shows the spectrum from the least expected to the heaviest possible ice. Typically, the “most likely” value falls in the middle of this range.
The probability of exceedance feature allows users to select a specific accumulation, like 0.50 inches, and see the percent chance it will be exceeded at a particular location. This helps gauge the risk of heavier icing and potential power outages, which often occur somewhere between ½ inch and 1 inch of ice.
While the display does not provide more accurate models than previous forecasts, it presents ice accumulation data in a clearer, more detailed format, with high resolution so users can see variations over short distances. Ice amounts can differ by over ½ inch within just 10 miles, reflecting the localized nature of ice storms.
The NWS expects this new tool to be especially useful for preparing for winter storms, assessing risks to electric grids, and helping communities plan for potential power outages caused by ice accumulation.
For more information and to view the ice forecast maps, visit the NOAA Weather Prediction Center.
(Photo captions: Ice- and debris-covered trees on Curtisville Road in Oscoda County, Mich., and a vehicle buried in ice-covered branches near downtown Gaylord on April 1, 2025.)
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