Explaining flood alerts issued by National Weather Service

Knowing the differences in these flood-related terms could save your life

Flooding is one of the top weather-related killers in the U.S. each year.

Knowing the differences between all the flood-related alerts that are issued by the National Weather Service can help keep you safe in the event waters start to rise.

Remember: Turn around. Don’t drown. It is never safe to drive through floodwaters.

Here are the terms you should know.

Flood vs. flash flood

A flood happens when an existing body of water, such as a lake, a river, a stream or a creek, overflows onto dry land. The term can even include drainage ditches. Floods do not usually have rushing water and are usually longer-term events.

A flash flood occurs when heavy rain falls in a very short period, causing rapid rises in water levels in a particular area. They are usually characterized by rushing water that sweeps away things such as debris, vehicles and even people. Flash floods are usually short-term events and can dissipate nearly as fast as they began.

Watch, warning, emergency

The NWS can issue a watch or warning for either type of flood event. An emergency is reserved for a flash flood.


A flood watch or flash flood watch is issued when government meteorologists believe conditions are favorable or will become favorable for these types of events to occur. This type of alert is usually issued for a large area and is the NWS’ way of telling you to be prepared for flooding.


A flood warning or flash flood warning means that a flood or flash flood is happening and you need to take action. These warnings are usually issued for a specific area.

For flood warnings, you need to keep a close eye on water levels in your area and move to higher ground if those levels start to increase. This is especially true for people who live in flood-prone areas.

For flash flood warnings, you should immediately seek shelter on higher ground.


This is the most dire of all the flood alerts that can be issued by the NWS. They are rarely issued and are reserved for flash floods.

A flash flood emergency means there is a severe threat to human life from a flash flood and catastrophic damage is happening or will happen soon. You should move to higher ground immediately.