First, understand the terms. The National Weather Service issues alerts when dangerous weather conditions can potentially affect an area, or are in immediate danger of affecting an area.
A watch is used when there is a risk of hazardous weather (thunderstorm, tornado or flooding). When a watch is issued, keep an eye on the weather. Be ready to enact your plan if it becomes necessary to do so.
A warning is issued when hazardous weather (thunderstorm, tornado or flooding) is occurring, is imminent, or has a very high probability of occurring. A warning is used for conditions posing a threat to life or property. When a thunderstorm or tornado warning is issued, take cover on the lowest level of your home, in an interior room. If your home is in danger of flooding, move to higher ground immediately.