# Flash flood warning

A flash flood warning (SAME code: FFW) is a severe weather warning product of the National Weather Service that is issued by national weather forecasting agencies throughout the world to alert the public that a flash flood is imminent or occurring in the warned area. A flash flood is a sudden, violent flood after a heavy rain, or occasionally after a dam break. Rainfall intensity and duration, topography, soil conditions, and ground cover contribute to flash flooding.
Most flash floods occur when there is a heavy amount of precipitation falling in an area and that water is then channeled through streams or narrow gullies. Flash floods may take minutes or hours to develop. It is possible to experience a flash flood without witnessing any rain.

## Flash flood alerts

There are two types of alerts for flash floods which are issued by the National Weather Service. One is a flash flood watch, which means that conditions are favorable for flash flooding, and the other is a flash flood warning, meaning that a flash flood is occurring or one will occur imminently and is usually issued when there are strong weather radar echoes for an area that is prone to flash flooding. Flash floods can also occur because of a dam or levee failure, or because of a sudden release of water held by an ice jam.
Residents are usually urged to do the following when flash flooding is imminent:
* Be aware of any signs of heavy rain
* Move to higher ground if rapidly rising water is seen or heard
* Not attempt to cross the flowing water
In addition, some NWS Weather Forecast Offices have instituted an enhanced flash flood warning, referred to as a flash flood emergency (or as termed by the Albany, New York office as a flash flood warning emergency), which indicates a severe flooding situation in densely populated areas, similar to the procedure for declaring a tornado emergency.
On August 27, 2017, as Hurricane Harvey brought torrential rain to southeast Texas, the NWS issued a "Flash Flood Emergency for Catastrophic Life Threatening Flooding."
On September 10, 2017, the NWS issued a Flash Flood Emergency for life-threatening storm surge because of Hurricane Irma in southwestern Florida at the eye landfall.
On February 6, 2020, the NWS issued a Flash Flood Emergency for Tazewell County, Virginia due to a major storm moving through the area which caused the Clinch River to rise to its highest crest in 40 years.
On May 20, 2020, the NWS issued a Flash Flood Emergency for the Tittabawassee River in Midland County, Michigan due to multiple dam failures causing the river to overflow and reach its highest crest since 1986.
On July 6, 2020, the NWS issued a Flash Flood Emergency for Tacony Creek and Frankford Creek, the former situated along Montgomery County and North Philadelphia, Pennsylvania, and the latter along Philadelphia's Frankford neighborhood.
On September 2, 2021, the NWS issued a first ever Flash Flood Emergency for New York City, Philadelphia, Fairfield and New Haven Counties in Connecticut, and most of Central New Jersey a region that stretches over 200 miles, as the remnants of Hurricane Ida transitioned and intensified into a post tropical cyclone causing torrential rains. Some areas reported up to 10 inches of rain in less than an hour. Although the region was forecasted to experience heavy rains, this event is considered unprecedented as such a warning has never been issued to the area. The region had already experienced above average precipitation for most of the Summer due to previous storm systems and tropical storms affecting the area.
On July 28, 2022, the NWS issued several Flash Flood Emergencies in eastern Kentucky for catastrophic and deadly flooding.
On March 27, 2023, the NWS issued a Flash Flood Emergency for a dam break on the Head's Creek Reservoir in Spaulding County, Georgia. A statement was later posted on Twitter.
On September 27, 2024, a Flash Flood Emergency was issued for Metro Atlanta as Hurricane Helene brought catastrophic flooding to the area.
On October 9, 2024, a Flash Flood Emergency was issued for several counties in the Tampa Bay and Big Bend areas of Florida as Hurricane Milton posed life-threatening flooding to a large portion of the West Coast.

## Example of a flash flood warning and emergency
### Warning

This warning was issued following a dam failure along the Minnesota-Wisconsin border.
This warning was issued for heavy rainfall.

### Emergency
#### Flash flood emergency in initial bulletin

This warning, containing both the "Flash Flood Emergency" wording and the Particularly Dangerous Situation wording, was issued in the wake of the devastating flooding that took place in western North Carolina due to the effects of Hurricane Helene.

#### Flash flood emergency in follow-up statement

This particular Flash flood emergency also includes the enhanced wording "Particularly Dangerous Situation".