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, lift and moisture.

• 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.

How do blizzards form?
A blizzard is a long-lasting snowstorm with very strong winds and intense snowfall. You need three things to have a blizzard; cold air at the surface, lots of moisture, and lift. Warm air must rise over cold air.

What is thundersnow?
Thundersnow is when thunder and lighting occur during a snowstorm. This occurs most often in late winter or early spring. To get thundersnow, you need a mass of cold air on top of warm air, plus moist air closer to the ground. Thundersnow starts out like a summer thunderstorm. The sun heats the ground and pushes masses of warm, moist air upward, creating unstable air columns. As it rises, the moisture condenses to form clouds, which are jostled by internal turbulence. The “tricky part” for making thundersnow is creating that atmospheric instability in the wintertime. For thundersnow to occur, the air layer closer to the ground has to be warmer than the layers above, but still cold enough to create snow. During thundersnow events, heavy snowfall is to be expected. In some cases, two inches per hour is possible.

What is sleet?
Sleet is just rain drops that freeze into ice pellets before reaching the ground. Sleet usually bounces when hitting a surface and does not stick to objects. However, it can accumulate like snow and cause a hazard to motorists.

What is freezing rain?
Freezing rain is just rain that falls onto a surface with a temperature below freezing. This causes it to freeze to surfaces, such as trees, cars, and roads, forming a coating or glaze of ice. Even small accumulations of ice can cause a significant hazard.

What is graupel?
Graupel (a.k.a. soft hail or snow pellets) are soft small pellets of ice created when supercooled water droplets coat a snowflake.

What is an ice storm?
An ice storm is a type of winter storm caused by freezing rain. The U.S. National Weather Service defines an ice storm as a storm which results in the accumulation of at least 0.25-inch of ice on exposed surfaces.

How do ice storms form?
Ice storms form when a layer of warm air is between two layers of cold air. Frozen precipitation melts while falling into the warm air layer, and then proceeds to refreeze in the cold layer above the ground. This creates freezing rain or a glaze of ice.

What is frost?
Frost is white ice crystals that form on a surface, like the ground or leaves of a plant. Frost is created when the air temperature drops below freezing and the water vapor in the air freezes into ice crystals.

What is a frost quake?
Frost quakes are non-tectonic seismic events, meaning they are not caused by the shifting of the Earth’s tectonic plates. Also known as cryoseisms, frost quakes are caused by a sudden rapid freezing of ground and bedrock, usually when temperatures go from above freezing to below zero. As moisture absorbed in the rock and soil freezes, it expands. This puts a great amount of stress on the areas around it. Eventually, the stress is too much and the soil and rock will crack in an “explosive” manner, creating a loud sound and even shaking the ground surface. Since temperatures are coldest in the overnight hours, most people experience frost quakes in the middle of the night.

How is lake-effect snow formed?
As the cold air flows over the warm lake water, the relatively warm water heats the air’s bottom layer as lake moisture evaporates into the cold air. Since warm air is lighter or less dense than cold air, the heated air rises and begins to cool. As the air cools, the moisture that evaporated into it condenses and forms clouds and snow begins falling from the cloud if the air is humid enough. (Graphic Credit: USA TODAY.)

Cold air moves over warm water and is warmed from below. Moisture evaporates in the air. Warm moist air rises downwind of lakes and forms heavy snow.

What is a Nor’easter?
Nor’easters can occur in the eastern United States any time between October and April, when moisture and cold air are plentiful. A Nor’easter is named for the winds that blow in from the northeast and drive the storm up the east coast along the Gulf Stream, a band of warm water that lies off the Atlantic coast. They are known for dumping heavy amounts of rain and snow, producing hurricane-force winds, and creating high surfs that cause severe beach erosion and coastal flooding.

What is an Alberta Clipper?
An Alberta clipper is an area of low pressure that generally forms over Alberta, Canada, east of the Rocky Mountains. They develop east of the Rockies because air flowing eastward over the mountains creates favorable conditions. Once an Alberta Clipper forms it usually moves very rapidly to the southeast across the USA’s northern Plains and then to the east off the mid-Atlantic Coast. Clippers usually cause only light precipitation with very few producing major snowstorms. However, if conditions are favorable, some Alberta clippers can rapidly intensify off the East Coast once the storm taps the relatively warm moist air over the Atlantic Ocean. The storms that rapidly intensify sometimes spread heavy snow over New England and southeastern Canada. Generally, the main weather features associated with Alberta clippers are some light snow and a reinforcement of cold air over the USA.

What is an avalanche?
An avalanche is a moving mass of snow that may contain ice, soil, rocks, and uprooted trees. The height of a mountain, the steepness of its slope, and the type of snow lying on it all help determine the likelihood of an avalanche. Avalanches begin when an unstable mass of snow breaks away from a mountainside and moves downhill. The growing river of snow picks up speed as it rushes down the mountain. Avalanches have been known to reach speeds of 245 miles an hour (394 kilometers per hour)—about four times as fast as the speediest downhill skier.

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.

What is Wind Chill?
The wind chill is the temperature your body feels when the air temperature is combined with the wind speed. The higher the wind speed the faster exposed areas of your body lose heat and the colder you feel.

Click here to use a wind chill calculator!

What is frostbite?
Frostbite is damage to the skin due to prolonged exposure to cold temperatures, usually below 32° F.

WINTER STORM OUTLOOK – Issued prior to a Winter Storm Watch. The Outlook is given when forecasters believe winter storm conditions are possible and are usually issued 3 to 5 days in advance of a winter storm.

WINTER WEATHER ADVISORIES – Issued for accumulations of snow, freezing rain, freezing drizzle, and sleet which will cause significant inconveniences and, if caution is not exercised, could lead to life-threatening situations.

WINTER STORM WATCH – Alerts the public to the possibility of a blizzard, heavy snow, heavy freezing rain, or heavy sleet. Winter Storm Watches are usually issued 12 to 48 hours before the beginning of a winter storm.

WINTER STORM WARNING – Issued when hazardous winter weather in the form of heavy snow, heavy freezing rain, or heavy sleet is occurring. Winter Storm Warnings are usually issued 12 to 24 hours before the event is expected.

BLIZZARD WARNING – Issued for sustained or gusty winds of 35 mph or more, and falling or blowing snow creating visibilities at or below 1/4 mile. These conditions should persist for 3 hours.

FROST/FREEZE WARNING – Issued when below freezing temperatures are expected.

LAKE EFFECT SNOW ADVISORY – Issued when accumulation of lake effect snow will cause significant inconvenience.

LAKE EFFECT SNOW WARNING – Issued when heavy lake effect snow is occurring.

WIND CHILL ADVISORY – Issued when the wind chill temperature is forecast to be between -15°F to -24°F.

WIND CHILL WARNING – Issued when the wind chill temperature is forecast to be -25°F or lower.

DENSE FOG ADVISORY – Issued when fog will reduce visibility to ¼ mile or less over a widespread area.

SNOW FLURRIES – Light snow falling for short durations. No accumulation or light dusting is all that is expected.

SNOW SHOWERS – Snow falling at varying intensities for brief periods of time. Some accumulation is possible.

BLOWING SNOW – Wind-driven snow that reduces visibility and causes significant drifting. Blowing snow may be snow that is falling and/or loose snow on the ground picked up by the wind.

Click Here to see if there are any active warnings in your area.

BEFORE A WINTER STORM: Have a disaster plan and prepare a disaster supplies kit for your home and car. Include a first aid kit, emergency food supply, bottled water, battery-operated radio, flashlight, protective clothing, and blankets. Don’t forget, be aware of changing weather.

DURING A WINTER STORM: Stay indoors and dress warmly. Eat regularly, because food provides the body with energy for producing its own heat. Also, drink lots of water. If you must go outside, wear layered clothing, mittens and a hat. Watch for signs of hypothermia and frostbite. Remember to keep dry. Always change wet clothing to prevent the loss of body heat. If you must drive, carry a cell phone. Always, keep the gas tank full. Don’t forget, let someone know where you’re going, just in case your car gets stuck. If you’re car gets stuck, stay with it and wait for help unless help is visible within 100 yards. Use maps and car mats to stay warm.

AFTER A WINTER STORM: Avoid driving until conditions have improved. Avoid overexertion! Heart attacks from shoveling snow are the leading cause of deaths during the winter. Also, check on neighbors to make sure they’re okay.

In an average winter in the United States, about 100,000 avalanches will tumble down mountainsides. This is why you should always stay on a path and try not to ever venture in the backcountry. In the United States and Canada, crashing walls of white will tumble over about 300 people. Most will be skiers, snowboarders, or snowmobilers who set out to have fun. Many will be buried by snow. Most will survive, although some will not.

SAFETY FIRST:

• Never travel alone!
• Heed warning signs in avalanche-prone areas.
• Stay alert in backcountry areas.
• Travel single file, not side by side in the backcountry.

ALWAYS CARRY SAFETY EQUIPMENT:

• Make sure you have a long probe, small shovel and always carry an emergency avalanche rescue beacon that signals your location.

IF YOU GET CAUGHT:

• Try to get to the side of it.
• If you can’t, grab a tree as an anchor.

IF YOU GET SWEPT AWAY:

• “Swim” with the slide to stay as close to the surface as you can. I know this sounds weird, but this could save your life.

Lesson Plan: Here is a great lesson plan on learning about winter weather. In this activity, kids investigate aspects of winter weather, such as temperature and wind. They familiarize themselves with weather-related words. It’s a great activity for K-2nd graders.

Lesson Plan: Here is a great lesson plan on learning about winter weather. In this activity, kids learn how winter storms form and about the different types of fronts. It’s a great activity for 3rd-5th graders. Note: This is a PDF file, so you need to have Adobe Acrobat Reader.

Measuring Snow Experiment: Here is a great experiment that lets kids measure snow. They let the snow melt and then measure it again. It teaches kids that snow is very dense and is why it holds more space than water.

Melting Snow Experiment: Here is another experiment that teaches kids the difference between the freezing and melting process. It allows kids to take the temperature of a glass of snow. Then, watch the snow melt and observe how the temperature changed.

Examining Snowflakes Experiment: Here is a great experiment that lets kids see snowflakes up close. They can examine the snowflake’s six sides.

Make Dew And Frost Experiment: Here is a great experiment that lets kids make dew and frost. They can see how dew turns into frost in a matter of minutes.

Suck An Egg Into A Bottle Experiment: Here is an experiment that shows how pressure is created in our atmosphere by sucking an egg in a bottle. This is a very cool experiment!

Make Your Own Barometer I Experiment: Here is an experiment that allows the kids to make a barometer.

Make Your Own Barometer II Experiment: Here is an experiment that allows the kids to make a barometer.

Create Evaporation Experiment: Here is an experiment that shows kids how evaporation takes place.

Science Fair Project Ideas: Here is a complete list of science fair project ideas. Discover the science behind the weather that impacts us every day.