What Do Winter Weather Advisories and Warnings Mean to You?

January 29, 2011; 6:48 PM ET
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The National Weather Service will issue a warning or advisory when lives or property are threatened by building weather conditions. There are various advisories and warnings issued throughout the winter season, but do people really know what they mean?

The NWS will issue a warning when a hazardous weather or hydrologic event is occurring, imminent, or has a high probability of occurring. An advisory highlights special weather conditions that may cause significant inconvenience.

An advisory is considered less serious compared to a warning, but caution should still be exercised.

A Winter Weather Advisory can be issued when a low pressure system produces a combination of winter weather that produces a hazard but does not meet warning criteria. The combination of winter weather can include, snow, freezing rain, sleet, etc.

A Winter Weather Advisory for Snow is used to express the risks of travel caused by snow-covered roads and low visibilities. Drive with caution.

Extreme conditions make for a dangerous drive. Check with AccuWeather.com for the latest storm updates. Photo courtesy of Photos.com

Heavy snow may be cited in a winter weather advisory, signifying severe winter conditions are anticipated or are already taking place. These conditions will produce significant amounts of snow making travel dangerous, so commuters are urged to only travel in the event of an emergency.

Windy conditions affect how people or animals feel the cold when skin is exposed outside. The wind chill temperature takes the wind and the temperature into account to describe how cold it actually feels. A Wind Chill Advisory is a used when the wind chill is harmful, and could be life-threatening. This advisory is set for a specific area.

Typically, wind chill advisories are used when the wind chill temperature is expected to fall between 15 below zero F and 24 below zero F.

Freezing rain has a reputation for causing numerous travel complications such as, icy roadways, fallen tree limbs, and downed power lines. A Freezing Rain Advisory refers to a forecast where substantial accumulation is expected.

Strong winds can pick up snow and move it around, creating low visibility for travelers. This is known as snow blowing. The amount of wind will determine if blowing snow is a high threat. If it is, a Blowing Snow Advisory will be issued.

Several NWS winter warnings are used to alert people of serve winter conditions.

When a Winter Storm Warning is in effect, a winter storm is either forecast or already taking place, meaning heavy snow or large ice accumulation are forecast or imminent. Typically, snow exceeding 6 inches, significant ice accumulation, dangerous wind chills, or any combination would prompt a warning to be issued.

In flat locations, such as the Plains or South, snow accumulation of 4 inches in a 12-hour period or 6 inches or more in a 24-hour period are grounds for a warning. Mountainous areas less than or equal to 7,000 feet qualify for a warning when 6 inches in 12 hours or 10 inches in 24 hours of snow is forecast.

For elevations higher then 7,000 feet, 8 inches in 12 hours or 12 inches in 24 hours would qualify for a winter storm warning. However, specific criteria for the amount of accumulation is determined from place to place and can vary.

Photo courtesy of Photos.com

According to the NWS, an accumulation of more then a quarter of an inch of ice in an area would usually cause an

Ice Storm Warning.

A Blizzard Warning is issued when storms have steady or frequent winds of 35 mph or higher, and considerable amounts of falling or blowing snow that will limit visibility to 1/4 of a mile or less. These conditions are expected to last a minimum of three hours.

The advisories and warnings are issued to inform people of extreme weather conditions. Being knowledgeable on these various terms can help you make educated travel decisions, and promote general safety as winter weather is in full drive.

Because of the specific criteria used to determine the need for advisories or warnings and the localization of many weather conditions, it is important to check with AccuWeather.com for your local weather updates.

AccuWeather.com can help determine the weather conditions close to home, and the conditions across the globe.

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