What the Different Types of Winter Storm Warnings Mean
Keep yourself safe this winter by learning the subtle differences between winter storm advisories, warnings and watches.
Fortunately, this can be avoided — at least somewhat — if you pay attention to the winter storm advisories, watches and warnings issued by the National Weather Service (NWS).
These notices are typically communicated to the general public through national and local news media. Meteorologists receive frequent weather updates from the NWS and discuss the advisories, watches and warnings during their newscast’s weather segments. Some share details on their personal or station social media accounts as well. The point: To keep citizens informed so they can take any necessary action.
Likewise, the NWS reports winter storm information on social media and on the National Oceanic and Atmospheric Administration’s fee-based “weather radio” app, which provides updates based on your location.
Winter Storm Terms to Know
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While there are many types of NWS winter warnings and alerts, the main ones are winter storm advisories, warnings and watches, says Colby Newman, a meteorologist with the NWS office in Portland, Oregon. Blizzard warnings are sometimes issued as well.
The NWS issues these notifications whenever it expects weather will significantly impact the community, Newman explains. However, variations exist based on multiple factors, including the region you live in and the time of day the wintry weather is expected to hit.
In some places, it takes a lot of snow to trigger even a storm watch. In others, a watch might be issued even if an inch is expected — especially if it is likely that one inch will disrupt travel, says Newman. So it’s important to understand how watches, advisories and warnings differ, so you can take action when necessary.
What is a Winter Storm Watch?
A winter storm watch is the least concerning of these four winter storm alerts. In general, winter storm watches are issued between 12 and 48 hours in advance of an anticipated storm and indicate that meteorologists are about 50 percent confident that the storm will hit, says Newman. Don’t let this low probability keep you from being prepared, though. Instead, consider it your prep time.
“If you need to buy a shovel, this would be good time to do that,” he says.
What is a Winter Storm Advisory?
A winter storm advisory is more serious than a watch. Newman says the term can be ambiguous, but in general, advisories are issued when the weather event is expected to arrive within 12 to 24 hours.
“(It means the storm) is supposed to cause significant inconvenience,” he explains. While conditions can turn hazardous under a winter storm advisory, Newman says, they are not expected to be life threatening.
What is a Winter Storm Warning?
A winter storm warning is a significant upgrade to an advisory.
“This (is indicative of) one of the biggest weather events of the season,” Newman says.
If a winter storm warning is issued in your area, a storm is imminent. Again, the amount of snow triggering a warning is not set in stone, so don’t assume a forecast of just two inches of snow shouldn’t be taken seriously. Instead, commit to keeping yourself and others safe by staying off the roads.
It wouldn’t hurt to have some extra supplies (like candles and batteries) available in case the power goes out. The Federal Emergency Management Agency (FEMA) also has some great tips on what to do if a winter storm warning is issued in your area.
What is a Blizzard Warning?
A full-on blizzard warning is the worst-case scenario, and it doesn’t have much (if anything) to do with snowfall. Instead, it means gusts of at least 35 mph are expected, along with low visibility (under 1/4-mile).
Snow can play a role. But often, the snow already on the ground is blowing around in these high winds, triggering the warning. Under these conditions, driving and walking are extremely dangerous, and trees and power lines are likely to fall. What should you do? Find shelter right away.
What If There Is No Warning?
Finally, be aware that while these alerts will always be issued when needed, the absence of them doesn’t mean it’s safe to drop your guard. During winter months, it is always best to be prepared for icy roads and frigid air, Newman says.
“Just because there is not a winter weather advisory, it doesn’t mean there is no snow, or that road conditions have gone back to where they (were) in the summer,” he says.