November 28, 2010 in Idaho Voices

Blizzard can occur without snowstorm

Michelle Boss

When we think of a blizzard, we usually picture a landscape buried in snow, with howling winds, whiteout conditions, and frigid temperatures. We certainly got a taste of that last week.

Did you know it is possible to have a blizzard, however, when it’s not snowing? The meteorological term blizzard actually has more to do with reduced visibilities and wind, than it does with snowfall. There may be many instances when it is snowing heavily, but a “blizzard” is not occurring. Likewise, an arctic blast can result in blustery conditions that send wind chill readings below zero. That wouldn’t count as a blizzard either.

The definition of a blizzard is a storm in which there are sustained winds or frequent gusts of 35 mph or more and reduced visibilities of a quarter-mile or less due to blowing snow. The blowing snow does not have to come from active snow fall. Powdery snow already on the ground can get picked up by the wind and blown around. When conditions like that are forecast, the National Weather Service will issue a “blizzard warning.”

Along with last week’s treacherous travel conditions, also came another threat, the cold itself. Gusty winds sent wind chill readings well below zero, making it dangerous for folks to be outdoors doing anything, without proper warm winter clothing. The danger of frostbite becomes most significant in wind chills below minus 19 degrees, as exposed skin can suffer damage in less than 30 minutes. The wind chill is not an actual temperature that would register on a thermometer, but is an indication of how much cooler you would feel because heat is being whisked away from your body.

Objects such as car engines and water pipes would not be affected by wind chill other than perhaps to cool more rapidly, as the wind cannot cool an object below the actual air temperature. A wind chill is only defined for temperatures at or below 50 degrees Fahrenheit and for wind speeds above 3 mph. When wind chills of minus 20 or colder are expected, the National Weather Service will issue a “wind chill warning.”

Even without the wind, temperatures below zero are just difficult to deal with, especially this early in the season. When were some of the worst November cold snaps in history? In Coeur d’Alene, the coldest temperature ever recorded in November was minus 13 more than 100 years ago on Nov. 27, 1896. Spokane also saw bitter cold that year, but set a record in 1985 with a temperature of minus 21 measured on Nov. 23, 1985.

Michelle Boss can be reached at

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