Flood Safety and Preparedness

What A 'Flash Flood Emergency' Means And Why This Alert Could Save Your Life

At a Glance

This is the highest-end alert the NWS issues for flash flooding.
They are issued when flooding poses an imminent, ongoing severe threat to life, and catastrophic damage.
More than two dozen such emergencies were issued in 2023 across the U.S.
Among those recent events included California snowmelt, the Ft. Lauderdale flood and severe flooding in Vermont.

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A flash flood emergency is a rare alert issued by the National Weather Service that should not only grab your attention, but also serve as a signal that you're likely in imminent danger.

First, what is a flash flood warning? You might have heard of flash flood warnings before. These are issued by the NWS when flash flooding is either already happening or expected to develop soon. According to the Iowa Environmental Mesonet, almost 3,700 of these warnings were issued by the NWS in 2023.

Typically, at least some streets and roads will be flooded in areas covered by a flash flood warning, which can be dangerous for motorists. Some of these warnings cover events in which a few low-lying properties have taken on some water.

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The distribution of flash flood warnings issued in the U.S. in 2023, parsed by each NWS forecast area.
(IEM/NWS)

But there's a higher-level flash flood alert. Given the large number of flash flood warnings issued, just over 20 years ago the NWS begun issuing a more dire alert, called a flash flood emergency, to highlight rare occasions when there is a major threat to life or potential for catastrophic damage.

When issued, these flash flood emergencies are embedded within existing flash flood warnings as a headline near the top of the warning.

The difference between a flash flood emergency and flash flood warning.
(NOAA/NWS)

What does an "emergency" mean? According to NWS guidelines, situations that may trigger a flash flood emergency include:

A local or state emergency manager has confirmed rapidly rising water is placing, or will place, people in a life-threatening situation.
Water is expected, or has already rapidly risen, to levels where people in typically safe locations during other flash flood events will be in danger. These include cases where water could encroach several feet above floor level in a home, requiring rescue and putting the entire home at risk.
A number of swift-water rescue teams have been deployed to a flash flood of unusual magnitude.
River and stream gauges indicate water has risen to at least major or rarely seen flood levels.
Complete failure of a large, high-hazard dam that would have catastrophic impact on downstream areas.

This is a similar concept to tornado emergencies, which are issued in cases where catastrophic damage and a severe threat to life is imminent or ongoing with a confirmed tornado.

What should I do if I'm in a flash flood emergency? This highest flash flood alert will trigger your smartphone to screech loudly, known as a wireless emergency alert.

If you're in a flash flood emergency:

Move to higher ground immediately.
Do not travel unless you're either escaping a flooded area or are ordered to evacuate by local officials.
Otherwise, avoid walking or driving through any flood water. You may not be able to tell how deep the water is and the road underneath could have been washed out. Even slow-moving water can knock you off your feet or float your vehicle, sweeping you away downstream.

How rare are these emergencies? According to the Iowa Environmental Mesonet, only 29 flash flood emergencies were issued across the country in 2023, comprising less than 1 percent of all NWS flash flood alerts.

Areas covered by the 29 NWS flash flood emergencies issued in 2023, from California to South Florida to New England.
(Data: IEM/NWS)

What are some recent flash flood emergency events? 2023 had its share of life-threatening flash floods.

In mid-March, heavy rain falling on massive southern Sierra snowpack triggered a flash flood emergency for Kernville, California, just one of several destructive flood events in the state from December 2022 through spring.

One month later, more than 20 inches of rain in less than 24 hours triggered historic flash flooding in Ft. Lauderdale, Florida.

And in mid-July, torrential rain triggered multiple flash flood emergencies in New York's Lower Hudson Valley and parts of Vermont where roads were washed out and homes inundated.

Each of those events caused at least $1 billion damage, according to estimates from NOAA.

Other smaller-scale flash flood emergencies in 2023 included flooding in Leominster, Massachusetts, on Sept. 11, and Georgetown, South Carolina on Dec. 17. Widespread road flooding, stranded vehicles and flooded homes occurred in both cases.

Floodwaters overtake vehicles in Weston, Vt., on Monday July 10, 2023. (Shauntay Morsey via Facebook) — Floodwaters overtake vehicles in Weston, Vermont, on Monday July 10, 2023.
(Shauntay Morsey via Facebook)

Flash flood emergencies are damaging, life-threatening flash flood events.

If one is issued for your area, take immediate action, as you would for a tornado warning. That quick action could save your life.

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Jonathan Erdman is a senior meteorologist at weather.com and has been covering national and international weather since 1996. His lifelong love of meteorology began with a close encounter with a tornado as a child in Wisconsin. He studied physics at the University of Wisconsin-Madison, then completed his Master's degree working with dual-polarization radar and lightning data at Colorado State University. Extreme and bizarre weather are his favorite topics. Reach out to him on X (formerly Twitter), Threads, Facebook and Bluesky.

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