The National Weather Service (National Oceanic and Atmospheric Administration) has gone to great lengths to help the public understand the difference between types of “watches” and “warnings”.  The differences can be subtle, but knowing the difference can save a life.

Here is a good summary to keep handy:

A Winter Storm Watch is issued when there is the potential for significant and hazardous winter weather,  such as blizzard conditions, heavy snow, freezing rain and/or sleet. within 48 hours. It does not mean that significant and hazardous winter weather will occur…it only means it is possible.
A Winter Storm Warning is issued when a significant combination of hazardous winter weather is occurring or imminent and 5 to 7 inches or more of snow/sleet is expected within the next 12 to 24 hours.  OR, enough ice accumulation is expected to cause damage to trees or powerlines.

Ice Storm Warning
¼ inch or more of ice accumulation is expected.

A Winter Weather Advisory will be issued for any amount of freezing rain, or when 2 to 4 inches of snow (alone or in combination with sleet and freezing rain), is expected to cause a significant inconvenience, but not serious enough to warrant a warning.   Advisories are more urgent than a “watch,” but still not as urgent as a “warning.”
A Wind Chill Advisory is issued when wind chills of  -10 to -24F are expected in our area for an extended period of time..
A Wind Chill Warning is issued when wind chills of -25F or lower are expected for an extended period of time. Frostbite can occur within 30 minutes under these conditions.
– Typically issued a day or two before an expected blizzard. This means conditions would eventually deteriorate and an actual blizzard would occur. When a blizzard watch is issued, this would be a good time to make plans and get prepared for incoming winter weather that may leave you sitting in one place for a lengthy period of time.
A Blizzard Warning means that the following conditions are occurring or expected within the next 12 to 18 hours:  1) Snow and/or blowing snow reducing visibility to 1/4 mile or less for 3 hours or longer and Sustained winds of 35 mph or greater or frequent gusts to 35 mph or greater.  There is no temperature requirement that must be met to achieve blizzard conditions
This would be your final chance to have your survival kits stocked and ready in preparation for the storm.
Remember that a WARNING is worse (higher level) than a WATCH.

You can find their expanded definitions here:

The National Weather Service (National Oceanic and Atmospheric Administration)