The Difference Between 'Blowing' and 'Drifting' Snow and the Hazards they Cause

Brian Donegan
Published: December 20,2016
Blowing and drifting snow are often misunderstood not only among the general public, but also meteorologists who use the terms in their forecasts. While they share many similarities, blowing and drifting snow can be very different.
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Despite their differences, they are both hazardous and can lead to serious problems for drivers and even air pilots. Below, we'll discuss the technicalities of blowing and drifting snow and then touch on their hazards.

Blowing Snow

Blowing snow is defined as snow lifted from the surface by the wind, at a height of 8 feet or more, that will reduce visibility.
While blowing snow is to be expected during a snowstorm with gusty winds, you may also see it in your local forecast after the snow has stopped falling, even if it's a sunny day. How could that be?

Sun and wind gusts make for limited visibility on Washington Street in Watertown, New York, Wednesday, Nov. 19, 2014.
(AP Photo/The Watertown Daily Times, Justin Sorensen)

If winds remain strong enough behind a snowstorm, that fresh powder can still be picked up by the wind, reducing visibility with each gust. Sometimes weather observing stations can even get confused and report "light snow" on a clear day.
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Blowing snow can lead to snow drifts, or banks of deep snow built up by the wind, which is a nice segue into our next topic.

Drifting Snow

Drifting snow, like blowing snow, is defined as snow lifted from the surface by the wind. The key difference is that the lifted snow remains below 8 feet. Once it rises to 8 feet or higher, it becomes blowing snow.
Drifting snow generally doesn't reduce visibility as much as blowing snow does, since it's not lifted as high into the air.
The blowing and drifting snow has to end up somewhere, which is how snow drifts form. If the winds are blowing in the same direction for several hours, the snow is also going to blow in that direction, allowing snow drifts to continuously grow larger.
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After the snowy winter of 2014-15 in New England, in which a record-setting 110.6 inches of snow was dumped on the city of Boston, snow drifts buried people's cars and topped the height of their front doors.

Those look more like snow mountains than snow drifts.

Hazards Caused By Blowing, Drifting Snow

The most common hazard caused by blowing and drifting snow is quickly reduced visibility while driving. The lowest visibility would occur when falling snow accompanies any blowing and drifting snow, but visibility is still reduced without the falling snow.
This may especially be the case when the sun is shining on areas of blowing and drifting snow, reflecting off the white snowflakes and making it even harder to see (see the photo from Watertown, New York, under the blowing snow section).
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In addition, any pilots trying to take off or land an aircraft may have a hard time doing so if blowing or drifting snow reduces visibility on the runway.
Although less common, snow drifts can technically be a fire hazard, in rare cases. This can happen during major lake-effect storms when heavy snow bands dump three or more inches of snow per hour over a given location for several consecutive hours. In the core of lake bands, winds can be very strong, leading to snow drifts six or more feet tall.
(MORE: The Science Behind Lake-Effect Snow)
If snow drifts grow higher than the windows and doors in your house, you may not be able to exit during an emergency. As the snow continuously gets blown against your home, it can be nearly impossible to get any doors open.
A prime example of this is shown in the photo below, after more than 7 feet of snow accumulated locally in the Buffalo Southtowns the week before Thanksgiving 2014.

This photo shows lake-effect snow in Lancaster, New York, on Nov. 18, 2014. (@MyersRocks/Twitter)

(MORE: Up to 88 Inches of Snow Buries Parts of Western New York, Including the Buffalo Southtowns)
When combined with falling snow, blowing and drifting snow can lead to near zero visibility at times. It is best to stay off the roads when this happens and wait until conditions improve before driving to your destination.
Mountain locations are rather susceptible to blowing and drifting snow, especially in the highest elevations of the mountain West.
The Plains states are also very prone to blowing and drifting snow, and they are sometimes referred to as "Blizzard Alley." A good example of this recently occurred in Montana. The sun was shining, but visibility was reduced significantly from blowing and drifting snow.

It's always best to check local forecasts on weather.com before traveling through areas susceptible to blowing and drifting snow, so you can avoid potential spots with reduced visibility.

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