Have you ever wondered how the National Weather Service can tell that a major winter storm is brewing and will affect 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?
How are winter storms monitored and forecast?
Doppler radars and automated surface observing systems 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.
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 that severe winter conditions, such as heavy snow and/or ice, may affect your area, but their 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 are expected in the next 12 hours or 6 or more inches in 24 hours, or a quarter-inch or more of ice accumulation is expected.
A winter weather advisory informs the public 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 chills. Listen carefully to the radio, television and NOAA weather radios for the latest winter storm watches, warnings and advisories.
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, Oklahoma, 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 8 inches of snow carries much greater consequences for a city's rush hour than 4 inches.
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