Winter storm warnings are issued by the National Weather Service dozens of times each year, but the amount of snow that triggers this type of alert is determined by where you live.
A winter storm warning means a significant, high-impact winter weather event is imminent or ongoing: This could be in the form of snow or sometimes a mix of snow, sleet and freezing rain. Strong winds are also occasionally included in this type of warning.
Winter storm watches often precede the upgrade to a winter storm warning. However, depending on the situation, those watches are sometimes upgraded or changed to other alerts called blizzard warnings, ice storm warnings and winter weather advisories.
Winter storm warning criteria varies by geographic location: The threshold is higher in areas that are snowier compared to locations that experience winter weather more rarely. The easiest way to think of this is that a 2-inch snowfall is a higher-impact event in Atlanta than in Chicago or a mountain location in the West.
Here are some notables.
-The Gulf Coast and some parts of the Southwest have the lowest threshold, with an inch or more of snow prompting a warning.
-Many higher elevations in the West need at least a foot of snow in the forecast to require warnings. At least one spot located in the northern Utah mountains needs 18 inches.
-At least 6 inches of snow in a forecast prompts warnings along the Northeast Interstate 95 corridor, much of the upper Midwest and Northern and Central Plains, as well as several valley locations in the West. It’s an inch or two higher in snowier parts of the Great Lakes and northern New England.
-Most areas in the South located north of the Gulf Coast need anywhere from 2 to 4 inches for a warning to be posted.
-Much of the mid-Atlantic, Ohio Valley and mid-Mississippi Valley need 4 or 5 inches.