Winter storm watch in Metro Detroit upgraded to storm warning: Here’s what blizzard, winter storm warnings mean

Understanding severe winter weather labels

This Tuesday, Nov. 27, 2019 photo provided by the Mammoth Mountain Ski Area shows a Caterpillar snow plow clearing a road at Mammoth Mountain Ski Area resort in Mammoth Mountain, Calif. (Peter Morning/Mammoth Mountain Ski Area via AP) (Peter Morning)

A winter storm is approaching Michigan just before Christmas, and meteorologists say any slight changes could affect the severity of the storm and its particular conditions.

A winter storm watch was issued Wednesday for Southeast Michigan beginning late Thursday, Dec. 22. That watch was upgraded Wednesday afternoon to a winter storm warning that will last from 7 p.m. Thursday through 4 a.m. Saturday.

It is possible the storm warning will be upgraded once again to a blizzard warning.

There are different types of advisories to watch out for when strong or severe weather is approaching that will help you know what to expect. Here, we’re defining winter weather terms to know, including a winter storm watch, winter storm warning, blizzard, blizzard warning and winter weather advisory.

What is a winter storm?

A winter storm occurs when there is heavy snow in combination with blowing snow, cold temperatures, wind, rain, freezing rain and/or sleet. It is still a dangerous storm and can be life threatening.

During a winter storm, the NWS says at least 8 inches of snow or more falls within 12 or more hours, or at least 6 inches or more falls between 6-9 hours.

Winter storm watch

A winter storm watch is an advisory that is issued due to potentially severe winter weather that could occur within 48 hours. The key word in this type of advisory is “watch,” as hazardous or severe weather is not necessarily imminent, but it is possible.

The NWS defines significant and hazardous weather as a combination of:

  • 5 inches or more of snow and/or sleet within a 12-hour period, or 7 inches or more of snow and/or sleet within a 24-hour period; and/or
  • Enough ice accumulation to cause damage to trees or power lines; and/or
  • A life threatening or damaging combination of snow and/or ice accumulation with wind.

Winter storm warning

A winter storm warning is issued when a “significant combination of hazardous winter weather is occurring or imminent,” the NWS says.

Again, such weather is defined as a combination of:

  • 5 inches or more of snow and/or sleet within a 12-hour period, or 7 inches or more of snow and/or sleet within a 24-hour period; and/or
  • Enough ice accumulation to cause damage to trees or power lines; and/or
  • A life threatening or damaging combination of snow and/or ice accumulation with wind.

Click here for tips from the Red Cross on staying safe during severe winter weather.

What is a blizzard?

A blizzard is a severe snowstorm in which there are strong winds and little-to-no visibility. This type of storm is more hazardous than a regular winter storm, and typically lasts for at least a few hours.

When is a blizzard warning issued?

According to the National Weather Service, a blizzard warning will be issued if the following conditions are “occurring or expected” within the next 12-18 hours:

  • Snow and/or blowing snow reducing visibility to a quarter mile or less for 3 hours or longer, and
  • Sustained winds of 35 mph or greater, or frequent gusts to 35 mph or greater.

Officials say there is “no temperature requirement that must be met to achieve blizzard conditions.”

During a blizzard, people are urged to stay indoors and avoid driving or being outside in order to stay safe.

Winter weather advisory

A winter weather advisory is issued when winter weather is approaching and expected to cause a “significant inconvenience,” but is not severe enough to require a warning to be issued.

During a winter weather advisory, expected precipitation includes any amount of freezing rain, or 2-4 inches of snowfall -- which could be on its own or in combination with sleet and freezing rain.

Click here to learn more about types of winter weather from the National Oceanic and Atmospheric Administration’s National Severe Storms Laboratory.


About the Author:

Cassidy Johncox is a senior digital news editor covering stories across the spectrum, with a special focus on politics and community issues.