What is the difference between a Watch and a Warning?

I’ve seen numerous analogies for this, but the first one I remember came from Brad Panovich, the veteran meteorolgist at the NBC station in Charlotte — who compared it to baking cupcakes. No matter what the weather hazard (tornado, winter storm, etc.), a Watch means conditions in the atmosphere are rapidly coming together to make that event more likely. The hazard is not here yet, but the meteoroligcal community is legitimately concerned, and it’s time to start thinking about a plan of action.

A Warning means the hazard is upon us. Different warnings have different time scales. Severe Thunderstorm and Tornado Warnings typically give you a few dozen minutes of notice, as they are very small compared to the size of the atmopshere. On the other end, hurricanes and winter storms are larger and slower, so those warnings are typically 24 hours in advance.

As a lower-tierd alert, an Advisory is sometimes issued, when the hazard is expected to be more of a nuisance than a threat to life and property.

All of these have specific definitions at the National Weather Service.