Winter weather watch, warning and advisory: What’s the difference?

Metro Atlanta was under a winter weather advisory early Tuesday. JOHN SPINK / JSPINK@AJC.COM

How are winter storms monitored and forecast?

Have you ever wondered how the National Weather Service can tell a major winter storm is brewing and will impact your area in the coming days or hours? How can meteorologists tell if a storm is intensifying and where it will bring the most snow?

» Atlanta weather: Forecast, news and updates

It's a highly sophisticated process. It all starts with observing the current situation. The National Weather Service operates a widespread network of observing systems such as geostationary satellites.

Doppler radars, and automated surface observing systems that constantly monitor the current state-of-the-art numerical computer models to provide a glimpse of what will happen next - ranging from hours to days.

The models are then analyzed by NWS meteorologists who use their experience and expertise to write and disseminate forecasts.

Want to learn more about the technologies? Visit the following web page:

A winter weather advisory for accumulating snow and ice will be in effect from through 7 p.m. Saturday for metro Atlanta, Channel 2 Action News reports. JOHN SPINK / JSPINK@AJC.COM

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Winter Weather Watches, Warnings and Advisories: What do they all mean?

The National Weather Service uses specific winter weather terms to ensure that people know what to expect in the coming days and hours.

Winter Storm Watch means severe winter conditions, such as heavy snow and/or ice, may affect your area, but its occurrence, location and timing are still uncertain. A winter storm watch is issued to provide 12 to 36 hours notice of the possibility of severe winter weather. A winter storm watch is intended to provide enough lead time so those who need to set plans in motion can do so.

A watch is upgraded to a Winter Storm Warning when 4 or more inches of snow or sleet is expected in the next 12 hours, or 6 or more inches in 24 hours, or 1/4 inch or more of ice accretion is expected.

A Winter Weather Advisory informs you that winter weather conditions are expected to cause significant inconveniences that may be hazardous. If caution is exercised, advisory situations should not become life-threatening.

A Blizzard Warning means that snow and strong winds will combine to produce a blinding snow (near zero visibility), deep drifts, and life-threatening wind chill. Be sure to listen carefully to the radio, television, and NOAA Weather Radio for the latest winter storm watches, warnings, and advisories.

For additional information on this story, visit the Winter Weather Awareness web page at:

WINDY WALK--NEW YORK, NY - JANUARY 23: A woman walks in strong winds and heavy snow fall in Central Park on January 23, 2016 in New York City. A major Nor'easter is hitting much of the East Coast and parts of the South as forecasts warn of up to two feet of snow in some areas. (Photo by Astrid Riecken/Getty Images) *** BESTPIX ***

Credit: Astrid Riecken

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Credit: Astrid Riecken

Why is predicting the exact amount of snowfall so challenging?

Snow forecasts continue to improve, but they remain a challenging task for meteorologists. Heavy snow often falls in small bands that are hard to discern on larger scale computer models. In addition, extremely small temperature differences define the boundary line between rain and snow.

Will the approaching storm bring heavy snowfall to your area?

Each winter, meteorologists at the Storm Prediction Center in Norman, Okla., monitor weather data from across the nation for developing bands of heavy snow and freezing precipitation, as well as lightning, within weather systems. Their ability to provide additional information about developing situations enhances winter storm warnings and helps National Weather Service field offices, private industry and local governments improve preparedness. For instance, a prediction of eight inches of snow carries much greater consequences for a city's rush hour than four inches. Want to learn more about the Storm Prediction Center's operations? For additional information visit the Storm Prediction Center web page at

A worker of a hardware store walks past a pallet of ice melt while restocking a display of snow shovels in Winston-Salem, N.C., Wednesday, Jan. 20, 2016. Forecasters warned residents of North Carolina on Wednesday to brace for what it calls a significant winter storm that could dump snow, sleet and ice and make driving hazardous. (AP Photo/Skip Foreman)

Credit: Skip Foreman

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Credit: Skip Foreman

Are you prepared for winter weather?

Winter weather too often catches people unprepared. Researchers say that 70 percent of the fatalities related to ice and snow occur in automobiles, and about 25 percent of all winter-related fatalities are people that are caught off guard, out in the storm.

What winter weather preparations are being made in your area, and what are the appropriate steps to take that will ensure your winter weather safety?

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What is wind chill?

One of the gravest dangers of winter weather is wind chill. The wind chill is based on the rate of heat loss from exposed skin by combined effects of wind and cold. As the wind increases, heat is carried away from the body at an accelerated rate, driving down the body temperature. Animals are also effected by wind chill. Check out the NWS chill chart

» Frostbite: How to recognize and treat this dangerous condition

Getting the latest winter weather information

There is no better way to keep ahead of a winter storm than with NOAA Weather Radio (NWR), a small receiver device that can be purchased at many electronic stores.

As the "Voice of the National Weather Service," it provides continuous broadcasts of the latest weather information from local National Weather Service offices. The NWR network has more than 425 stations, covering all 50 states, adjacent coastal waters, Puerto Rico, the U.S. Virgin Islands, and U.S. Pacific Territories. Weather radios come in many sizes, with a variety of functions and costs.

The NWR network has been further advanced by the implementation of Specific Area Message Encoding technology. SAME allows the user to receive warnings only for their specific location. SAME receivers are a live-saving tool, providing audible alert tones for any weather warnings. A NOAA Weather Radio is a useful and potentially life-saving gift idea this holiday season.

NOAA's Snow and Ice Center

The National Snow and Ice Data Center serves as the national information center that supports research in glaciers and freezing weather phenomenon.

Hard at work when the storm hits?

While most of us stay home from work or school during severe winter weather, National Weather Service meteorologists are hard at work. Twenty-four hours a day, 365 days a year, NWS meteorologists staff local offices across the country to make sure the latest forecasts, watches and warnings get out to emergency managers, the media, and the public. What's it like at a forecast office? Don't wait for a major winter storm; contact your local office and ask to spend the day with them, and observe the exciting, day-to-day process of forecasting the snow before it hits.