What is a snow squall?

A snow squall is an intense, but limited-duration, period of moderate to heavy snowfall, accompanied by strong, gusty winds, and possible lightning. Snow squalls can produce various amounts of snow accumulations at ski resorts and can create hazardous conditions.  

The difference between a snow squall and other precipitation types such as lake effect snow or atmospheric rivers is that snow squalls are separated from the main area of precipitation. Snow squalls are often individual clouds or accompanied by groups of clouds. Individual snow squalls typically do not persist for more than one hour, but several snow squalls can track over an area for a day to several days. 

Winds can be very gusty during snow squalls, usually ranging from 20 to 50mph, which can create whiteout conditions. There have been reports of wind gust over 70mph during snow squalls as well. Temperatures usually drop during and behind a snow squall, similar to a cold front. 

Here are two radar loops of snow squalls from the Northeast (top) and Pacific Northwest (bottom)

Radar imagery (top) on March 27th, 2022 from the Northeast of a snow squall event that brought brief whiteout conditions and approximately 1-6 inches of snow. 

Radar imagery (bottom) on April 9th, 2022 from the Pacific Northwest of a snow squall event that brought approximately 1-10 inches of snow. 

What does this mean for my skiing and riding?

Snow squalls mean more snow! They usually drop 1-2 inches of snow in less than 1 hour, but can often produce more snow if several snow squalls track over an area (>6in). The snow ratios with snow squalls will vary depending on temperatures at the surface. The atmospheric dynamics do not allow for high snow-liquid ratios.

Credit: Erik Smith - Steamboat, CO

The greatest hazard from snow squalls is the whiteout and blizzard conditions due to gusty winds. Whiteout conditions can impact the travel commute to ski resorts and have caused deadly accidents before. Whiteout conditions can also be dangerous on the slopes due to limited visibility. 

When in doubt, pull over on the road or stop on the slope to remain safe. Snow squalls often last 30-60 minutes or less. Make sure to keep a tab on the OpenSnow radar for the latest locations and movement of snow squalls. 

Also, snow squalls are often accompanied by lightning, which is an added danger if you’re on the slopes. Lightning can cause lift delays and even temporarily shut down mountains. It is for your safety and allows some free refills on the mountain as well. 

How do they form?

Snow squalls are like mini thunderstorms due to wintertime atmospheric dynamics and can have lightning associated with them. They can occur day or night but are strongest during the afternoon or evening. This is due to daytime heating, which allows them to form and strengthen. 

Here are some great visuals and diagrams of snow squall information from the National Weather Service at State College, PA.

Classic views of the wall of snow accompanied by a snow squall and the visual appearance of a mini thunderstorm. Snow squalls often catch drivers by surprise because the sky goes from clear blue to heavy snow in a matter of minutes. 

A Snow Squall Warning is issued by the National Weather Service when hazardous travel is expected. If you are in a Snow Squall Warning, expect reduced visibility, icy roadways, and rapidly-changing conditions.

Snow squalls form from a variety of storm systems. They often occur ahead of a cold front and behind a cold front. The cold front provides lift in the atmosphere, which allows this type of storm to develop.

Depending on the track of the storm system and the air masses behind them, snow squalls can track over an area for less than 30 minutes to several hours or even a couple of days. They are similar to lake effect snow bands in that they can track over areas and give heavy snow accumulations if the wind direction remains favorable. 

When snow squalls track over mountains, there is orographic lift, often called upslope snow showers. Snow squalls strengthen due to enhanced lift as the clouds travel over mountains, temperatures cool, and more moisture or snow falls out of the storm. 

Where do they occur?

Anywhere! Snow squalls occur over all areas of the world and North America. Anywhere that snow falls, snow squalls are possible and will contribute a small portion to seasonal snowfall averages. The spring is most favorable for snow squalls due to longer days, more sun, and daytime heating that allows snow squalls to develop and strengthen. 

Thanks for reading this article and keep an eye out the next time you see a snow squall!

Zach Butler, OpenSnow Meteorologist