Here's Why Snow Squalls are Dangerous and Why the National Weather Service Now Warns For Them

Chris Dolce and Jonathan Erdman
Published: November 13, 2019

A relatively new type of winter alert called a snow squall warning issued by the National Weather Service highlights the danger motorists face from a sudden, intense round of snow.

Snow squalls are bursts of heavy snow, but they're very brief, typically lasting less than an hour.

Because of its rapid movement, accumulations from a snow squall are light. Snow squalls can occur in situations where there is no major large-scale winter storm in progress.

But that doesn't mean snow squalls aren't hazardous.

Let's say you're driving in good winter driving conditions, with the pavement dry.

You notice some distance ahead a white haze. There is no winter storm warning in effect, so you're not concerned about a big snowstorm. You keep driving expecting some snow flurries ahead. No big deal, right?

Within just a few minutes, it all changes. The snow squall arrives.

Strong winds and snow create a whiteout. You can barely see the vehicles in front of you, and a thin film of snow makes the road increasingly slippery.

Time series every 6-8 min from 2:59 pm to 3:20 pm of a snow squall in Hollidaysburg, Pennsylvania, Jan. 12, 2016.
(Wunderground.com)

You hope the vehicles ahead of you don't stop suddenly, or there isn't an accident blocking lanes in front of you, since your visibility is low.

Scary, right?

Within minutes after the whiteout sets in, the snow squall moves on.

The sudden reduced visibility and slippery roads can lead to multi-vehicle, chain-reaction accidents.

An 85-vehicle chain-reaction wreck in whiteout conditions north of Akron, Ohio, Tuesday, only resulted in five minor injuries. Other recent pileups in Pennsylvania in 2016 and 2017 claimed lives.

Vehicles pile up at the site of a fatal crash near Fredericksburg, Pennsylvania on Feb. 13, 2016. The pileup left tractor-trailers, box trucks and cars tangled together across several lanes of traffic and into the snow-covered median. (James Robinson/PennLive.com via AP)
(James Robinson/PennLive.com via AP)

"Annual highway fatalities from these events can exceed fatalities due to tornadoes in many years," the NWS said in its product description for the new snow squall warning.

(MORE: Weather-Related Car Accidents Far More Deadly Than Tornadoes, Hurricanes, Floods

The Snow Squall Warning

For this reason, the National Weather Service now issues snow squall warnings.

In general, snow squall warnings will be of short duration and specify a localized area similar to what you would see with a tornado, severe thunderstorm or flash flooding warning. Snow squalls often resemble a line of severe thunderstorms sweeping through quickly.

Here is an example of one such warning issued on Nov. 12, 2019, in northern Michigan.

An example of a National Weather Service snow squall warning from Nov. 12, 2019 in northern Michigan.
(NOAA/NWS)

As with all other warnings the NWS issues, they are targeted at state and local officials, media, the general public and others.

"There are a few rare winter events each year that don't fit the mold of a winter storm warning or winter weather advisory and was determined to be a gap in our services," said Tim Halbach, acting meteorologist-in-charge at the National Weather Service near Milwaukee in an email to weather.com.

Here's what you should do if a snow squall warning is issued in your area, according to the National Weather Service:

-Delay your trip until the snow squall passes. Put simply, there is no safe place on the road in a snow squall.

-If you must travel, turn on your headlights, slow down, leave more distance between you and the vehicle in front of you and avoid slamming on your brakes, which could lead to a loss of control on a slippery road.

-If you become stopped on the road or involved in an accident, only if it is safe to do so, exit your vehicle and move as far away from the road as possible. Do not stand along or near the road, as approaching vehicles may not be able to see you and may have lost control of their vehicles.

Halbach said the NWS has future plans for snow squall warnings to trigger a Wireless Emergency Alert on your smartphone, similar to a tornado or severe thunderstorm warning. In the meantime, these alerts will be available on NOAA weather radio, weather.gov as well as local media and private vendors.

The Weather Company’s primary journalistic mission is to report on breaking weather news, the environment and the importance of science to our lives. This story does not necessarily represent the position of our parent company, IBM.


The Weather Company’s primary journalistic mission is to report on breaking weather news, the environment and the importance of science to our lives. This story does not necessarily represent the position of our parent company, IBM.