Severe Weather 101
Winter Weather Basics
A winter storm is an event in which the main types of precipitation are snow, sleet or freezing rain.
- Why can winter storms be so dangerous?
Most deaths from winter storms are not directly related to the storm itself.
- People die in traffic accidents on icy roads.
- People die of heart attacks while shoveling snow.
- People die of hypothermia from prolonged exposure to cold.
Everyone is potentially at risk during winter storms. The actual threat to you depends on your specific situation. Recent observations show that:
- Of injuries related to ice and snow:
- About 70% occur in automobiles.
- About 25% are people caught out in the storm.
- Majority are males over 40 years old.
- Of injuries related to exposure to cold:
- 50% are people over 60 years old.
- Over 75% are males.
- About 20% occur in the home.
- How do winter storms form?
Just like any other storm at other times of the year, the right combination of ingredients is necessary for a winter storm to develop.
Three basic ingredients are necessary to make a winter storm:
- Cold air. Below freezing temperatures in the clouds and near the ground are necessary to make snow and/or ice.
- Lift. Something to raise the moist air to form the clouds and cause precipitation. An example of lift is warm air colliding with cold air and being forced to rise over the cold dome. The boundary between the warm and cold air masses is called a front. Another example of lift is air flowing up a mountainside.
- Moisture. To form clouds and precipitation. Air blowing across a body of water, such as a large lake or the ocean, is an excellent source of moisture.
What we do: NSSL researchers studied winter thunderstorms and found that there is some evidence that snowfall is heavier during reports of thunder and lightning at the same place and time. They also learned that these winter thunderstorms, although rare, occur most often in the central United States, Great Lakes, the east coast of the U.S. and Canada, and northern Canada during the winter and spring.