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| Winter Storm |
strong, strong blows of snow and surface winds. A blizzard is also a storm in
which a large amount of snow falls. Snow is less dense than liquid water, by a
factor of about 10 at temperatures slightly below freezing, and even more at
colder temperatures.
Winter storms sometimes result in snowy days, where weather conditions make
travel and exposure to cold air too risky for routine daily activities. A
winter storm is a weather event in which the precipitation is mainly snow,
hail, or freezing rain. Often accompanied by strong winds and temperatures
below freezing, winter storms can be dangerous. But how do winter storms form?
Winter Storm Formation
Blizzards occur when warm, wet air meets cold air. These warm and wet air
masses and cold air masses can reach a diameter of 1000 km or more.
Winter storms begin with moist air rising into the atmosphere, like other
types of storms. Rising air is common on cold fronts, where warm air is lifted
above cold air and is required for cloud formation and precipitation. Rising
air can also occur when air moves up a large hill or mountain. A source of
moisture, such as air blowing across a large lake or ocean, is required for
cloud formation and precipitation. The final ingredient, and what makes winter
storms different from other storms, is cold air. Below freezing temperatures
near the ground and up to the clouds will cause precipitation to fall as
either snow or ice. However, very cold air cannot hold much moisture and
therefore will not produce much snow. This explains why some of the coldest
places on Earth, like Antarctica.
Winter Storm Type
A blizzard is a type of winter storm. A blizzard is a blizzard with strong
winds, and a lake-effect storm is a blizzard that forms near the Great Lakes.
Hailstorms can bring freezing rain or hail and snow. Read below to learn more
about the different types of winter storms.
- Snowstorm
Storms in which precipitation falls as snow are called blizzards. In winter,
most of the precipitation forms as snow in clouds because the temperature at
the height of the storm is cold enough to make snowflakes. Snowflakes are
collections of frozen ice crystals that form when water vapor condenses into
water droplets and freezes. These ice crystals stick together as they fall to
the ground, forming snowflakes. If the air temperature stays at or below 0℃
between the cloud and the ground, precipitation will fall as snow. If the air
near the earth’s surface is above freezing temperature, the precipitation will
melt to form rain or freezing rain.
A blizzard in which there is no accumulation beyond light snow dust is called
a blizzard. A brief blizzard with snow falling of varying intensity and some
accumulation is called a snowfall . If a snowfall is accompanied by strong
gusts of wind and the accumulation of a lot of snow, it is called a blizzard.
Blizzards are considered a type of severe blizzard and are described in more
detail below.
- Snowstorm
A blizzard is a severe blizzard that is determined by the strength of the wind
rather than the amount of snow it carries. With wind speeds at or above 35mph,
blizzards create blown snow conditions, where snow on the ground is carried
away by the wind, causing reduced visibility and snow accumulation. Blizzards
last for three hours or more and often cause the accumulation of large amounts
of snow, either as new snowfall or as a redistribution of previously fallen
snow as blowing snow.
- Lake Effect Storm
Most blizzards are formed by a low-pressure system that lifts moist air into
the atmosphere, but lake-effect storms are formed by the abundance of water
vapor from the Great Lakes. When cold, dry air from the north passes through
the Great Lakes area, it picks up large amounts of water, which falls back to
the ground as heavy snowstorms in areas south and east of the lake.
- Ice storm
An ice storm is a winter storm that has accumulated at least 0.25 inches
(6.35mm) of ice on all outer surfaces. Ice forms a slippery layer on the
ground which can make driving and walking conditions dangerous and can cause
branches and power lines to break under the weight of the ice. There are
different types of icy winter weather, which are determined by the temperature
of the air masses in the storm. Hail forms when snowflakes that fall to the
surface first pass through a layer of air that is above freezing, causing the
snowflake to partially melt, and then passes through a layer of air that is
below freezing, causing the snowflake to re-form. -frozen into ice pellets.
Similar to the formation of hail, frozen rain forms when precipitation (either
rain or snow) passes through a layer of warmer air, allowing it to become
rain, and then through a layer of much colder air. But this time, the rain
couldn’t refreeze as it fell through a shallow layer of frozen air near the
surface. Rain becomes extremely cold through this process and freezes
instantly upon contact with a cold surface.
Winter Weather Safety
Winter storms often create conditions in which outdoor exposure and travel are
dangerous due to cold temperatures, wind, snow, or ice. Check the weather
forecast for information on winter storms in your area and watch the weather
before going outdoors during the winter months. The National Weather Service
issues weather warnings for areas that must prepare for blizzards, blizzards,
wind chill, lake effect storms, and ice storms based on three levels:
- Winter Weather Alert: take action!
It is very likely that a winter storm will have an impact on your area. Be
prepared for heavy snow or ice, strong winds, and freezing temperatures that
will make travel and outdoor exposure dangerous.
- Winter Weather Monitoring: be prepared!
Conditions are favorable for winter storms in your area, and there is the
potential for severe winter weather. If a winter storm hits your area, be
prepared for heavy snow or ice, strong winds, and freezing temperatures that
can make travel and outdoor exposure dangerous.
- Winter Weather Alert: beware!
Winter weather conditions are expected but will not be severe enough to meet
warning levels. Be careful when traveling and avoid prolonged outdoor contact.
Check the National Weather Service to learn about current weather warnings in
the US or the National Weather Service’s Winter Weather page to learn more
about winter weather safety.
