What Is a Snowdrift?
A snowdrift is an accumulation of snow created by wind. As loose snow is carried across the ground, it can collect in certain areas and form piles or banks that are much deeper than the surrounding snow.
Snowdrifts commonly form beside roads, buildings, fences, trees and other obstacles that change the flow of the wind. They can also develop across open areas where wind moves snow from one location to another.
Large snowdrifts can block roads, driveways and entrances even when relatively little new snow is falling. On roads, drifting snow can also create sudden areas of deeper snow that are difficult for drivers to see.
Related Conditions
| Condition | Description |
|---|---|
| Blowing Snow | Loose snow lifted and carried through the air by wind. |
| Ground Blizzard | Blizzard conditions caused mainly by loose snow being lifted from the ground by strong winds. |
| Whiteout | A condition where snow and poor visibility make the horizon and surrounding features difficult to see. |
| Wind Crust | A hard layer that can form on the snow surface after wind redistributes and compacts snow. |
| Snow Cornice | An overhanging mass of wind-deposited snow that commonly forms along ridges and steep terrain. |
Related Alerts
| Alert | Description |
|---|---|
| Blowing Snow Advisory | Issued when blowing snow is expected to significantly reduce visibility. |
| Blizzard Warning | Warns of strong winds and blowing snow producing severely reduced visibility. |
| Winter Storm Warning | Issued when a significant combination of hazardous winter weather is expected. |
| Snowfall Warning | Issued when significant snowfall is expected to meet warning criteria for an area. |
| Snow Squall Warning | Warns of snow squalls that can cause sudden poor visibility and hazardous travel. |
What Causes Snowdrifts?
Snowdrifts form when wind picks up loose snow and moves it across the ground. This can happen while snow is falling or after a snowfall has ended if there is enough loose snow available.
As the wind carries the snow, anything that slows or changes the airflow can cause some of it to settle. Buildings, fences, trees, roadside barriers and other obstacles can all create areas where snow begins to collect.
Once snow starts building up, the drift itself can change the airflow and cause even more snow to accumulate. This is why a snowdrift can become much deeper than the average snow depth around it.
Dry, powdery snow is generally easier for wind to move than wet, heavy snow. Strong winds combined with loose surface snow can also produce blowing snow and significantly reduce visibility.
When strong winds lift enough previously fallen snow to create widespread severe visibility problems, conditions can develop into a ground blizzard even if little or no new snow is falling.
FAQ
Blowing snow is snow being carried through the air by wind. A snowdrift is the accumulation that forms when wind-blown snow is deposited on the ground.
Snowdrifts often form around buildings, fences, trees, roadside barriers and other obstacles. They can also develop across roads and open areas where changes in wind cause snow to collect.
Yes. Wind can pick up loose snow that is already on the ground and create new snowdrifts hours or even days after snowfall has ended.
Wind continually moves snow from exposed areas and deposits it where airflow slows. This can concentrate snow in one location and create a drift much deeper than the surrounding snow.
Large snowdrifts can block roads, entrances and driveways. On roads, unexpected areas of deep snow can also make driving difficult or cause vehicles to become stuck.
Yes. Wind can carry snow across open roads and deposit it on the roadway, particularly in exposed rural areas.
Normal accumulation mainly comes from snow falling directly onto a surface. Snowdrifts form when wind redistributes that snow and concentrates it in particular locations.