What is the difference between a winter storm watch and a winter storm warning?

Dear Tom,

What is the difference between a winter storm watch and a winter storm warning?
Joe Gilleran, Palatine
Dear Joe,
The National weather Service issues a winter storm watch when it believes the potential exists for a significant and hazardous winter weather occurrence within 48 hours. It does not mean significant and hazardous winter weather will occur; it means it is possible. Significant and hazardous winter weather is defined as five inches or more of snow/sleet within a 12-hour period or seven inches or more within 24 hours and/or enough ice accumulation to damage trees or power lines and/or a life-threatening or damaging combination of snow and/or ice accumulation with significant wind.
A winter storm warning is issued when a significant combination of hazardous winter weather (defined above) either is occurring or is imminent.

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