Chance of Snow: Winter Storm Types and Snowfall Intensity

You can tell how hazardous snowfall will be by what it is called

Young sisters look at snowfall outside
Noel Hendrickson / Getty Images

The terms "winter storms" and "snowstorms" may mean roughly the same thing, but mention a word like "blizzard," and it conveys so much more that just "a storm with snow." Here's a look at the flurry of winter weather terms you may hear in your forecast, and what each means. 

Blizzards

Blizzards are dangerous winter storms whose blowing snow and high winds lead to low visibility and "white out" conditions.

While heavy snowfall often occurs with blizzards it isn't needed. In fact, if strong winds pick up snow that's already fallen this would be considered as a blizzard (a "ground blizzard" to be exact.) In order to be considered a blizzard, a snowstorm must have: heavy snow OR blowing snow, winds of 35 mph or more, and a visibility of 1/4 mile or less, all lasting for at least 3 hours.

Ice Storms

Another type of dangerous winter storm is the ice storm. Because the weight of ice (freezing rain and sleet) can down trees and power lines, it doesn't take much of it to paralyze a city. Accumulations of just 0.25 inches to 0.5 inches are considered to be significant, with accumulations over 0.5 inches considered as "crippling." (Just 0.5 inches of ice on power lines can add up to 500 pounds of extra weight!) Ice storms are also extremely dangerous to motorists and pedestrians. Bridges, and overpasses are especially dangerous when traveling since they freeze before other surfaces.

Lake Effect Snow

Lake effect snow occurs when cold, dry air moves across a large warm body of water (such as one of the Great Lakes) and picks up moisture and heat. Lake effect snow is known for producing heavy bursts of snow showers known as snow squalls, which drop several inches of snowfall per hour.

Nor'easters

Named for their winds which blow from the northeast, nor'easters are low pressure systems that bring heavy rain and snow to the East Coast of North America. Although a true nor'easter can occur any time of the year, they're most fierce in the winter and spring and can often be so strong that they trigger blizzards and thundersnow.

How hard is it snowing?

Like rainfall, there are a number of terms used to describe snowfall depending on how fast or intensely it is falling. These include:

  • Snow Flurries: Flurries are defined as light snow falling for a short duration. They can also be tiny snowflakes falling for longer periods of time. The most accumulation that can be expected is a light dusting of snow.
  • Snow Showers: When snow is falling at varying intensities for brief periods of time, we call it snow showers. Some accumulation is possible, but not guaranteed.
  • Snow Squalls: Often, brief but intense snow showers will be accompanied by strong, gusty winds. These are referred to as snow squalls. Accumulation may be significant.
  • Blowing Snow: Blowing snow is another winter hazard. High wind speeds can blow falling snow into almost horizontal bands. In addition, lighter snows on the ground may be picked up and redistributed by the wind causing reduced visibility, "white out" conditions, and snow drifts.

     

    Edited by Tiffany Means

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    Oblack, Rachelle. "Chance of Snow: Winter Storm Types and Snowfall Intensity." ThoughtCo, Dec. 19, 2016, thoughtco.com/winter-storm-types-and-intensity-3444548. Oblack, Rachelle. (2016, December 19). Chance of Snow: Winter Storm Types and Snowfall Intensity. Retrieved from https://www.thoughtco.com/winter-storm-types-and-intensity-3444548 Oblack, Rachelle. "Chance of Snow: Winter Storm Types and Snowfall Intensity." ThoughtCo. https://www.thoughtco.com/winter-storm-types-and-intensity-3444548 (accessed November 24, 2017).