What is a Blizzard?
A blizzard is a severe winter storm characterized by strong winds, heavy snowfall, and low visibility. According to the National Weather Service, a blizzard is defined as a storm with large amounts of snow or blowing snow, winds greater than 35 mph, and visibility of less than ï¿½ mile for at least three hours. There are also what are known as ground blizzards, which are characterized by the same conditions, but with no falling snow. Instead, the blizzard conditions are created by the blowing around or drifting of snow that has already fallen.
Blizzard conditions typically develop on the northwest side of a powerful storm system. The storm system produces copious amounts of snow, while strong winds are created by the difference in pressure between the low pressure of the storm and the high pressure beyond the storm. Blizzard conditions can be extremely dangerous, as the blowing snow can cause whiteout conditions, making it difficult to see and navigate. Roadways can also be partially or fully blocked by snowdrifts, which are piles of snow formed by the wind. In addition, cold temperatures during a blizzard can lead to frostbite or hypothermia, which can persist even after the storm has ended.
What Causes a Blizzard?
There are three main factors that contribute to the formation of a large snowstorm or blizzard: cold air, moisture, and rising moist air.
- Cold air: For snow to fall to the ground, the temperature must be below freezing both in the clouds where snowflakes form and at ground level. If the air near the ground is too warm, the snow will melt and turn into rain or freezing rain.
- Moisture: Moisture in the air, also known as water vapor, is necessary to form clouds and precipitation. Wind moving over a body of water, such as a lake or the ocean, can pick up moisture from the surface and put it into the air. This is how lake effect snowstorms and nor'easters get so much moisture. However, cold air is not able to hold much water vapor, so very cold air does not produce much snow.
- Rising moist air: Moist air needs to rise over very cold air in order to form clouds and snow. This can happen when winds bring cold air towards the equator from the poles and warm, moist air towards the poles from the equator, resulting in a front and snow formation. Warm air can also rise to form clouds and blizzard snows as it flows up a mountainside.
- To be classified as a blizzard, a storm must meet certain, more severe, conditions. The storm must last for at least three hours and produce a significant amount of falling snow.
- Additionally, the winds must be over 35 mph, causing a large volume of snow to blow around in the air and near the ground, reducing visibility. Meteorologists will declare blizzard conditions if the snow limits visibility to the point where it is difficult to see an object more than ï¿½ mile away.
The Great Blizzard of 1888
One of the most famous recorded blizzards is the Great Blizzard of 1888, which occurred between March 11 and 14. This blizzard impacted an area stretching from Maine to Maryland in the United States. The storm brought about 55 inches of snow, paralyzing the growing cities of New England and New York City. Approximately one in four people in the United States lived in one of the New England states at the time, making the blizzard particularly devastating. The storm is estimated to have caused around 400 deaths.
Written by princy