What Is a Snow Squall?
A snow squall is a sudden period of heavy snow that can cause visibility and road conditions to deteriorate within minutes. They are often narrow and localized, so conditions can be very different over relatively short distances.
Snow squalls are especially dangerous for drivers. Heavy falling snow, gusty winds and blowing snow can make it difficult to see the road or vehicles ahead. Roads can also become snow-covered quickly.
Some snow squalls pass through an area quickly, while others can continue or repeatedly affect the same location and produce significant snowfall.
Related Conditions
| Condition | Description |
|---|---|
| Heavy Snowfall | Snowfall that produces significant accumulation over a relatively short period. |
| Lake-Effect Snow | Snow that develops when cold air moves across relatively warmer, open lake water. |
| Snowband | A narrow band of concentrated snowfall that can produce much heavier snow than nearby areas. |
| Blowing Snow | Loose snow lifted and carried by the wind, often reducing visibility. |
| Whiteout | A condition where snow and poor visibility make the horizon and surrounding features difficult to see. |
Related Alerts
| Alert | Description |
|---|---|
| Snow Squall Warning | Warns that snow squalls are occurring or expected and may create dangerous travel conditions. |
| Snowfall Warning | Issued when significant snowfall is expected to meet warning criteria for an area. |
| Blowing Snow Advisory | Issued when blowing snow is expected to significantly reduce visibility. |
| Winter Storm Warning | Issued when a significant combination of hazardous winter weather is expected. |
| Blizzard Warning | Warns of strong winds and blowing snow producing very poor visibility for an extended period. |
What Causes a Snow Squall?
Snow squalls develop when cold, unstable air contains enough moisture to produce a narrow area of heavy snow. Rising air cools, allowing ice crystals to develop in clouds and eventually fall as snow.
In Canada, many snow squalls form near large bodies of water. When cold air moves across relatively warmer, open lake water, it picks up heat and moisture. The moist air rises and cools, allowing clouds and lake-effect snow to develop downwind.
The Great Lakes make this type of snow squall particularly common in parts of Ontario. Narrow snowbands can form over the lakes and move inland, producing intense snowfall in one community while another nearby receives much less.
Snow squalls can also develop along strong cold fronts. In these cases, a narrow line of heavy snow and gusty winds can move quickly across an area and cause visibility to drop with little warning.
Wind also plays an important role. Stronger winds can carry falling and loose snow through the air, creating blowing snow and making already poor visibility even worse.
Meteorologists use radar, satellite observations, wind patterns and weather models to identify where snow squalls may develop and track where they are moving. Our guide to how meteorologists predict snow explains how snowfall forecasts are made.
FAQ
A snow squall can last from several minutes to a few hours at one location. Lake-effect snowbands can last longer or repeatedly move over the same area.
Yes. Snow squalls can cause visibility and road conditions to deteriorate very quickly, making them particularly dangerous for drivers.
Heavy snowfall describes snow falling heavily or producing significant accumulation. A snow squall is usually more localized and can cause a sudden change in visibility and road conditions.
A snow squall is generally a localized period or band of intense snowfall. A blizzard is defined by strong winds and severely reduced visibility lasting for a specified period, and falling snow is not always required.
Yes. Heavy falling snow and blowing snow can reduce visibility enough to create whiteout conditions.
Yes. Snow squalls can also develop along strong cold fronts, where rapidly rising air produces a narrow band of heavy snow and gusty winds.