A Blowing Snow Advisory in Canada means strong winds are expected to lift loose snow from the ground, reducing visibility and creating hazardous travel conditions.
Blowing snow can occur during active snowfall or after the snow has stopped. When strong winds move loose snow across roads and through the air, visibility can quickly decrease and previously cleared roads may become covered again.
Environment and Climate Change Canada issues advisories for certain weather conditions that may cause inconvenience or concern but do not reach the level of a warning.
This guide explains what a Blowing Snow Advisory means in Canada, why one is issued, how serious blowing snow can become, potential impacts and what to do when an advisory affects your area.
What Is a Blowing Snow Advisory?
A Blowing Snow Advisory is a weather alert issued when blowing snow is expected to reduce visibility and create hazardous conditions.
Blowing snow occurs when strong winds lift loose snow from the ground and carry it through the air.
The airborne snow can make it difficult for drivers and other travellers to see roads, vehicles and potential hazards.
Blowing snow can occur while snow is falling, but new snowfall is not necessary.
Strong winds may lift snow already on the ground several hours or even days after a snowfall has ended.
This means hazardous winter driving conditions can develop even when there is no new snow in the forecast.
Environment and Climate Change Canada includes Blowing Snow Advisories among the official types of weather alerts in Canada.
Why Is a Blowing Snow Advisory Issued?
A Blowing Snow Advisory is issued to alert people when blowing snow is expected to reduce visibility and create hazardous travel conditions.
The advisory gives people time to monitor changing weather conditions, check road information and reconsider unnecessary travel.
Several factors can contribute to the development of blowing snow.
Strong Winds
Wind is one of the primary causes of blowing snow.
Strong winds can lift loose snow from the ground and carry it through the air.
As wind speeds increase, larger amounts of snow may become airborne and visibility can deteriorate.
Loose Snow
Fresh, dry snow is particularly vulnerable to being lifted by strong winds.
Even after snowfall ends, loose snow remaining on the ground can continue to create blowing snow conditions.
Reduced Visibility
Airborne snow can make it difficult for drivers to see roads, vehicles and other hazards.
Visibility may change significantly over short distances.
Drivers may travel through relatively clear conditions before suddenly encountering an area of significantly reduced visibility.
Open and Exposed Areas
Blowing snow can be particularly hazardous on highways, rural roads and other open areas.
Without trees, buildings and other obstacles to reduce wind speeds, snow can move more easily across the landscape.
Drifting Snow
Wind can move snow across roads and cause it to accumulate in drifts.
Previously cleared roads may become partially or completely covered again.
Snow drifts can make some roads difficult or dangerous to use.
The Government of Canada provides additional information about severe winter weather and the winter hazards that can affect Canadians.
How Serious Is a Blowing Snow Advisory?
A Blowing Snow Advisory should be taken seriously because visibility and road conditions can deteriorate quickly.
Possible impacts may include:
- Reduced visibility
- Snow-covered roads
- Drifting snow
- Difficult driving conditions
- Transportation delays
- Traffic collisions
- Vehicles becoming stranded
- Rapidly changing road conditions
- Difficult travel in rural areas
- Disruptions to outdoor activities
The seriousness of a blowing snow event depends on wind speeds, snow conditions, visibility, duration and location.
Conditions may vary significantly over relatively short distances.
One area may experience relatively good visibility while nearby roads are affected by significant blowing and drifting snow.
Environment and Climate Change Canada uses Weather Impact Guides to assess how hazardous weather may affect daily life, travel, utilities and services, land and structures, human health and community recovery.
What Causes Blowing Snow?
Blowing snow occurs when strong winds lift loose snow from the ground and carry it through the air.
Several weather and environmental conditions can influence the development and seriousness of blowing snow.
Wind Speed
Stronger winds can lift and transport larger amounts of snow.
The direction and duration of the wind can also influence where blowing and drifting snow develop.
Snow Conditions
Fresh, dry and powdery snow is generally easier for the wind to lift than wet or compacted snow.
For this reason, blowing snow may be particularly common after a recent snowfall followed by increasing winds.
Cold Temperatures
Cold temperatures can help snow remain dry and loose.
Dry snow can be more easily lifted and carried by strong winds.
Open Terrain
Open fields, highways and rural areas may experience significant blowing snow because there are fewer obstacles to slow the wind.
Trees, buildings and other structures can sometimes reduce wind speeds, although snow may accumulate in drifts around these obstacles.
Recent Snowfall
Blowing snow can develop after a winter storm or snowfall event has ended.
Fresh snow remaining on the ground may be lifted by increasing winds and create hazardous conditions without additional precipitation.
Blowing Snow Advisory vs Snowfall Warning
A Blowing Snow Advisory and Snowfall Warning communicate different winter weather hazards.
A Blowing Snow Advisory focuses on snow being lifted and carried by strong winds.
The primary hazards are reduced visibility, drifting snow and difficult travel.
A Snowfall Warning focuses primarily on significant falling snow that is expected to create hazardous conditions and potentially significant impacts.
A snowfall event may also produce blowing snow, particularly when strong winds develop.
Learn more about what a Snowfall Warning means in Canada.
Blowing Snow Advisory vs Snow Squall Warning
A Blowing Snow Advisory and Snow Squall Warning can both involve reduced visibility and hazardous travel conditions, but the weather events are different.
A Blowing Snow Advisory focuses on loose snow being lifted from the ground by strong winds.
A Snow Squall Warning is associated with intense, localized bands of snow that can cause sudden reductions in visibility and rapidly accumulating snow.
Snow squalls can cause weather and road conditions to deteriorate extremely quickly.
Learn more about what a Snow Squall Warning means in Canada.
Blowing Snow Advisory vs Blizzard Warning
A Blowing Snow Advisory and Blizzard Warning can both involve strong winds, blowing snow and reduced visibility.
The main difference is the severity of the conditions.
A Blowing Snow Advisory indicates hazardous conditions caused by blowing snow and reduced visibility.
A Blizzard Warning indicates more severe conditions involving strong winds combined with falling or blowing snow that create widespread, severely reduced visibility.
Blizzard conditions can make travel extremely dangerous or impossible.
Learn more about what a Blizzard Warning means in Canada.
Blowing Snow Advisory vs Winter Storm Warning
A Blowing Snow Advisory focuses specifically on blowing snow and reduced visibility.
A Winter Storm Warning may involve a combination of severe winter weather hazards.
Depending on the storm, conditions may include heavy snow, freezing rain, strong winds and blowing snow.
Blowing snow may therefore be one of several hazards occurring during a winter storm.
Learn more about what a Winter Storm Warning means in Canada.
Can a Blowing Snow Advisory Become a Warning?
A Blowing Snow Advisory does not necessarily become a specific Blowing Snow Warning if weather conditions become more serious.
Instead, a different warning may be issued when conditions meet the criteria for another winter weather hazard.
For example, worsening wind and visibility conditions could result in a Blizzard Warning when the appropriate criteria are expected to be met.
Other winter weather warnings may be issued depending on the conditions and expected impacts.
People in affected areas should continue monitoring current weather information rather than relying only on an earlier advisory.
Always read the complete alert because updated information may include changes to expected conditions, timing, affected locations, potential impacts and recommended actions.
What Can Happen During a Blowing Snow Advisory?
The impacts of a Blowing Snow Advisory depend on the severity and duration of the weather conditions.
Visibility Can Decrease Quickly
Blowing snow can cause visibility to change rapidly.
Drivers may move from relatively clear conditions into areas where it becomes difficult to see the road or nearby vehicles.
Roads Can Become Snow-Covered
Wind can move snow back onto roads after they have been cleared.
This can create slippery surfaces and difficult driving conditions.
Snow Drifts Can Develop
Snow carried by strong winds may accumulate in drifts.
Large drifts can partially block roads or make some routes difficult to use.
Travel Can Become Dangerous
Reduced visibility and snow-covered roads can increase the risk of collisions and vehicles becoming stranded.
Travel conditions may be particularly hazardous on highways and rural roads.
Transportation Can Be Delayed
Blowing snow may cause delays or cancellations for road and other transportation services.
Conditions may continue to affect travel after the wind begins to decrease while roads are cleared.
What Should You Do During a Blowing Snow Advisory?
The appropriate response depends on local conditions and the information included in the advisory.
Read the Complete Advisory
Read the complete alert to understand the expected conditions, timing, affected locations, potential impacts and recommended actions.
Check Conditions Before Travelling
Review current weather and road information before leaving.
Conditions can vary significantly between locations.
Consider Delaying Unnecessary Travel
If poor visibility and dangerous road conditions are expected, consider delaying unnecessary trips.
Conditions may deteriorate quickly after travel begins.
Reduce Your Speed
If you encounter blowing snow while driving, reduce your speed and allow additional distance between your vehicle and others.
Driving too quickly for conditions can increase the risk of losing control or being unable to stop safely.
Be Prepared for Changing Visibility
Visibility may improve and deteriorate repeatedly during a blowing snow event.
Remain alert for rapidly changing road and weather conditions.
Follow Road Closures
Do not travel on closed roads.
Follow instructions and travel recommendations from local authorities.
Monitor Current Weather Information
Continue checking weather information while the advisory remains in effect.
Environment and Climate Change Canada provides official weather radar and satellite services that can help people monitor approaching weather conditions.
The Government of Canada also provides information about preparing for winter storms.
Can You Drive During a Blowing Snow Advisory?
Driving during a Blowing Snow Advisory may be hazardous.
Reduced visibility, drifting snow and snow-covered roads can make travel difficult.
Conditions may also change quickly.
A road may initially appear clear before visibility decreases or blowing snow begins to cover the surface.
Before travelling, check current weather and road conditions.
Consider delaying unnecessary trips when poor visibility and dangerous driving conditions are expected.
If you encounter blowing snow while driving, reduce your speed, increase the distance between vehicles and follow road closures and instructions from authorities.
What Is the Difference Between Blowing Snow and Drifting Snow?
Blowing snow and drifting snow are related but describe different conditions.
Blowing snow refers to snow that is lifted from the ground and carried through the air by wind.
The airborne snow can reduce visibility.
Drifting snow refers to snow that is moved by the wind and deposited in piles or drifts.
Drifts may develop across roads, around buildings and near other obstacles.
A blowing snow event may produce both reduced visibility and significant snow drifts.
Can Blowing Snow Happen Without Falling Snow?
Yes.
Blowing snow can occur even when no new snow is falling.
Strong winds can lift loose snow that is already on the ground and carry it through the air.
For this reason, hazardous blowing snow conditions may develop after a snowfall or winter storm has ended.
How Long Does a Blowing Snow Advisory Last?
There is no standard duration for a Blowing Snow Advisory.
The length of the advisory depends on wind speeds, snow conditions, visibility, weather patterns and expected impacts.
Some blowing snow events may last for several hours.
Others may continue for a longer period when strong winds and loose snow remain present.
Travel disruptions may also continue after the advisory ends while roads are cleared and conditions improve.
Where Is Blowing Snow Most Common in Canada?
Blowing snow can occur in many parts of Canada.
Open and exposed areas may be particularly vulnerable because there are fewer obstacles to reduce wind speeds.
The Prairies frequently experience conditions that can produce blowing and drifting snow because of open terrain, strong winds and winter snowfall.
Blowing snow can also affect highways, rural areas and exposed locations in other parts of the country.
Local geography, snowfall, temperature and wind conditions influence the likelihood and seriousness of blowing snow events.
How Can You Check Current Blowing Snow Advisories?
Current Blowing Snow Advisories and other weather alerts can be checked through Environment and Climate Change Canada’s official weather services.
The official Weather Information map allows users to check current forecasts and weather alerts across Canada.
The Government of Canada’s WeatherCAN application also provides official forecasts, alerts and customizable notifications.
Frequently Asked Questions About Blowing Snow Advisories
A Blowing Snow Advisory means blowing snow is expected to reduce visibility and create hazardous travel conditions.
A Blowing Snow Advisory can indicate dangerous travel conditions caused by reduced visibility, drifting snow and snow-covered roads.
Strong winds lifting loose snow from the ground can create blowing snow conditions and significantly reduce visibility.
Yes. Strong winds can lift existing snow from the ground even when no new snow is falling.
A Blowing Snow Advisory indicates hazardous conditions caused by blowing snow. A Blizzard Warning indicates more severe conditions involving strong winds and falling or blowing snow that create widespread, severely reduced visibility.
A Blowing Snow Advisory does not necessarily become a specific Blowing Snow Warning. If conditions become more serious, another appropriate winter weather warning may be issued.
Sources
- https://www.canada.ca/en/services/environment/weather/severeweather/weather-alerts.html
- https://www.canada.ca/en/environment-climate-change/services/seasonal-weather-hazards/severe-winter.html
- https://www.canada.ca/en/services/environment/weather/severeweather/weather-alerts/weather-impact-guides.html
- https://www.canada.ca/en/services/environment/weather/radar-satellites.html
- https://www.canada.ca/en/services/policing/emergencies/preparedness/get-prepared/hazards-emergencies/winter-storms/how-prepare.html
- https://www.canada.ca/en/environment-climate-change/services/weather-general-tools-resources/weather-webmapping.html
- https://www.canada.ca/en/environment-climate-change/services/weather-general-tools-resources/weathercan.html