Blowing snow and blizzards

B. Geerts and E. Linacre


Blowing snow is frequently reported in the Great Plains of the US and Canada, often after the passage of a cold front. For instance, blizzard conditions were reported in North Dakota on 15 January 1997 as a result of blowing snow, which can be seen in Fig 1. Under these conditions blowing snow was not limited to a few meters above the ground. The rolls or billows of blowing snow were deep enough to cast shadows in the satellite image (Fig 1). They were aligned parallel to the surface winds (northerly at 15-25 m/s), and were induced by thermal and/or mechanical mixing (1).

Fig 1. Visible GOES 8 image of North Dakota at 21:45 UTC (3:45 pm local time, about 1:20 min before local sunset) on 15/01/'97. Counties are outlined in red, and station identifiers in yellow (1). (click on picture for details)

The Sun may be partly or completely obscured by the blowing snow on otherwise clear days (Fig 2). Blowing snow can bare the land of snow in some places and accumulate in huge snowdrifts elsewhere, especially behind obstacles such as hedges (Fig 3).

Fig 2. View towards the Sun under blowing snow.

Fig 3. A snowdrift.

Canadian studies (2) show that wet snow is blown by surface winds of more than about 10 m/s (ranging between 7 - 14 m/s), whilst dry snow is blown by over 7.7 m/s (4 - 11 m/s). There is an ill-defined non-linear increase of these speeds with rising temperature.



  1. See here.
  2. Li, L. and J.W. Pomeroy. 1997. Estimates of threshold wind speeds for snow transport using meteorological data. J. Appl. Meteor. 36, 205-13.

A blizzard is defined as follows, in Canada -

Some places in Canada have 5 or more such blizzards per winter, on average. The frequency of such conditions declines exponentially with duration, i.e. a blizzard lasting several days is extremely rare even where 4-hour blizzards are numerous.

The National Weather Service of the United States defines a blizzard as:

So while it may be true that blizzards are more extreme events in the US, and they tend to be briefer there than in Canada, the difference is at least partly explained by the definitions themselves.