Know your flood terminology: What Flood Watches, Warnings and Emergencies really mean
Flash flooding is the deadliest weather-related hazard in the United States. According to NOAA data, an average of 127 people die from flooding each year, with nearly half of those fatalities involving vehicles.
Explaining Flood Alerts from the NWS
Flood alerts? The National Weather Service has been issuing flood alerts for years, here is how do you understand them and what do they mean.
Flooding is one of the deadliest weather hazards in the U.S. each year, and understanding flood alerts issued by National Weather Service meteorologists can be lifesaving.
These include Flood Watches, Flood Warnings, Flash Flood Warnings and the rare Flash Flood Emergency.
Each alert carries a different level of urgency and is meant to help protect lives and property.
According to NOAA data, an average of 127 people die from flooding each year, with nearly half of those deaths involving vehicles.
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Flood Watch: Prepare for the possibility of flooding
A Flood Watch can be issued by National Weather Service meteorologists hours or even days in advance of a potential flooding event.
While a watch does not guarantee flooding will occur, it signals a high likelihood based on forecasts, current conditions and recent rainfall accumulation.
These alerts typically cover large geographic areas and may remain in effect for several days, especially during prolonged weather systems like tropical cyclones or atmospheric rivers.
"The occurrence of flooding is neither certain nor imminent. Persons in the watch area are advised to check flood action plans, stay informed, and be prepared to take necessary actions if a warning is issued or flooding is observed. A Flash Flood Watch may also be issued for a potential dam break," the NWS stated.
Flood Watches are usually depicted in a dark green color on weather maps.
FILE - Flash Flood Watches, shaded in green, are issued by the National Weather Service. (FOX Weather)
FLOOD WATCH, WARNING AND EMERGENCY: HERE ARE THE DIFFERENCES THAT COULD SAVE YOUR LIFE
Flood Warning: Take action now
A Flood Warning or a Flash Flood Warning is issued when flooding is either imminent or occurring.
Heavy rainfall or flooded waterways can lead to the issuance of these alerts, which are usually only posted for a limited region.
Flash Flood Warnings are issued for events caused by heavy, sudden rainfall, while Flood Warnings are issued for events that occur more gradually, such as river rises.
The NWS issues more than 4,000 Flash Flood Warnings every year due to the dangers posed to lives and properties.
Buildings, driveways and other infrastructure can increase the amount of water runoff by reducing the amount of rain absorbed by the ground.
According to NWS forecasters, just 6 inches of fast-moving water can knock an adult off their feet and a foot of floodwater can carry a car away.
Flood Warnings are usually depicted in a light green color on weather maps.
Flash Flood Warning for Boston (FOX Weather)
Flash Flood Emergency: Rare with significant threats
A Flash Flood Emergency is the highest level of flood alert issued by the National Weather Service and is reserved only for life-threatening situations.
To warrant this designation, catastrophic flooding must be ongoing with the potential for devastating consequences.
The NWS began issuing Flash Flood Emergency alerts in 2003, and each year, only a few dozen are typically issued.
According to NOAA statistics, less than 1% of all flood alerts are classified as Flash Flood Emergencies.
A record 92 emergencies were issued in 2024, largely due to Hurricane Helene, which impacted communities from the Gulf Coast to the Ohio Valley.
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Flash Flood Emergencies issued by the National Weather Service since 2003. (FOX Weather)