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Aflash flood warning (SAME code: FFW) is asevere weather warning product of theNational Weather Service that is issued by nationalweather forecasting agencies throughout the world to alert the public that aflash flood is imminent or occurring in the warned area. A flash flood is a sudden, violentflood after a heavyrain, 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.[1][failed verification]
There are two types of alerts for flash floods which are issued by theNational Weather Service. One is aflash flood watch, which means that conditions are favorable for flash flooding, and the other is aflash flood warning, meaning that a flash flood is occurring or one will occur imminently and is usually issued when there are strongweather radar echoes for an area that is prone to flash flooding.[2]Flash floods can also occur because of a dam or levee failure,[3] 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:[4]
In addition, some NWS Weather Forecast Offices have instituted an enhanced flash flood warning, referred to as aflash flood emergency (or as termed by theAlbany, New York office as aflash flood warning emergency[5]), which indicates a severe flooding situation in densely populated areas, similar to the procedure for declaring atornado emergency.
On August 27, 2017, asHurricane Harvey brought torrential rain to southeast Texas, the NWS issued a "Flash Flood Emergency for Catastrophic Life Threatening Flooding."[6]
On September 10, 2017, the NWS issued a Flash Flood Emergency for life-threatening storm surge because ofHurricane Irma in southwestern Florida at the eye landfall.[7][8]
On February 6, 2020, the NWS issued a Flash Flood Emergency forTazewell County, Virginia due to a major storm moving through the area which caused theClinch River to rise to its highest crest in 40 years.[9]
On May 20, 2020, the NWS issued a Flash Flood Emergency for theTittabawassee River inMidland County, Michigan due to multiple dam failures causing the river to overflow and reach its highest crest since 1986.[10]
On July 6, 2020, the NWS issued a Flash Flood Emergency forTacony Creek andFrankford Creek, the former situated alongMontgomery County andNorth Philadelphia,Pennsylvania, and the latter along Philadelphia'sFrankford neighborhood.[11]
On September 2, 2021, the NWS issued a first ever Flash Flood Emergency forNew York City,Philadelphia,Fairfield andNew Haven Counties inConnecticut,[12] and most of CentralNew Jersey a region that stretches over 200 miles, as the remnants ofHurricane Ida transitioned and intensified into apost 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.[13]
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. Astatement was later posted on Twitter.
On September 27, 2024, a Flash Flood Emergency was issued forMetro Atlanta asHurricane Helene brought catastrophic flooding to the area.[14]
On October 9, 2024, a Flash Flood Emergency was issued for several counties in the Tampa Bay and Big Bend areas of Florida asHurricane Milton posed life-threatening flooding to a large portion of the West Coast.
This warning was issued following a dam failure along theMinnesota-Wisconsin border.
Flash Flood WarningMNC115-WIC013-031-192330-/O.NEW.KDLH.FF.W.0012.180618T2329Z-180619T2330Z//00000.U.DM.000000T0000Z.000000T0000Z.000000T0000Z.OO/BULLETIN - EAS ACTIVATION REQUESTEDFlash Flood WarningNational Weather Service Duluth MN1203 PM CDT SUN JUN 18 2018The National Weather Service in Eastern Duluth MN has issued a* Flash Flood Warning for... A Dam Failure in... East central Pine County in east central Minnesota... Northwestern Douglas County in northwestern Wisconsin... North central Burnett County in northwestern Wisconsin...* Until 543 PM CDT* At 1201 PM CDT, local law enforcement reported the Radigan Flowage Dam west of Dairyland has failed, causing flash flooding downstream on the Tamarack River south of the Dam as it flows towards the Saint Croix River.* Locations impacted include... Town Rd T west of Dairyland. Swedish Highway at the Tamarack River. Highway T west of Cozy Corner. Markville Road east of Markville.PRECAUTIONARY/PREPAREDNESS ACTIONS...Turn around, don`t drown when encountering flooded roads. Most flooddeaths occur in vehicles.Move to higher ground now. Act quickly to protect your life.Please report flooding to your local law enforcement agency when youcan do so safely.&&LAT...LON 4623 9218 4616 9226 4611 9228 4607 9229 4605 9234 4612 9234 4617 9230 4622 9225$$LE
This warning was issued for heavy rainfall.[15]
PAC051-102345-/O.NEW.KPBZ.FF.W.0017.200710T2142Z-200710T2345Z//00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
BULLETIN - EAS ACTIVATION REQUESTEDFlash Flood WarningNational Weather Service Pittsburgh PA542 PM EDT Fri Jul 10 2020
The National Weather Service in Northern Pittsburgh has issued a
Central Fayette County in southwestern Pennsylvania...
heavy rain across the warned area. Between 1 and 2.5 inches of rain have fallen. Flash flooding is ongoing or expected to begin shortly.
HAZARD...Flash flooding caused by thunderstorms.
SOURCE...Doppler radar.
IMPACT...Flooding of small creeks and streams, urban areas, highways, streets and underpasses as well as other drainage and low lying areas.
Uniontown, South Connellsville, Dunbar, Vanderbilt and Dawson.
Additional rainfall amounts up to 1 inch are possible in the warnedarea.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
Turn around, don't drown when encountering flooded roads. Most flooddeaths occur in vehicles.
&&
LAT...LON 4006 7967 3997 7982 3986 7972 3995 7955
FLASH FLOOD...RADAR INDICATED
$$
This warning, containing both the "Flash Flood Emergency" wording and theParticularly Dangerous Situation wording, was issued during the severe weather event of early April 2025 that impacted parts of the central and mid-southern United States.
Flash Flood WarningMOC035-050630-/O.NEW.KPAH.FF.W.0035.250405T0018Z-250405T0630Z//00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/BULLETIN - EAS ACTIVATION REQUESTEDFlash Flood WarningNational Weather Service Paducah KY718 PM CDT Fri Apr 4 2025...FLASH FLOOD EMERGENCY FOR VAN BUREN...The National Weather Service in Paducah has issued a* Flash Flood Warning for... Carter County in southeastern Missouri...* Until 130 AM CDT Saturday.* At 718 PM CDT, Emergency management reported thunderstorms producing heavy rain with water rescues ongoing in the Van Buren area. Up to 2 inches of rain have fallen. Additional rainfall amounts of 1 to 2 inches are possible in the warned area. Flash flooding is ongoing or expected to begin shortly. This is a FLASH FLOOD EMERGENCY for Van Buren. This is a PARTICULARLY DANGEROUS SITUATION. SEEK HIGHER GROUND NOW! HAZARD...Life threatening flash flooding. Thunderstorms producing flash flooding. SOURCE...Emergency management reported. IMPACT...This is a PARTICULARLY DANGEROUS SITUATION. SEEK HIGHER GROUND NOW! Life threatening flash flooding of low water crossings, small creeks and streams, urban areas, highways, streets and underpasses.* Some locations that will experience flash flooding include... Van Buren, Ellsinore, Hunter, Fremont and Grandin.PRECAUTIONARY/PREPAREDNESS ACTIONS...Move to higher ground now! This is an extremely dangerous andlife-threatening situation. Do not attempt to travel unless you arefleeing an area subject to flooding or under an evacuation order.Turn around, don`t drown when encountering flooded roads. Most flooddeaths occur in vehicles.&&LAT...LON 3705 9073 3700 9073 3700 9071 3697 9071 3697 9070 3693 9070 3693 9068 3688 9068 3688 9066 3681 9066 3683 9122 3709 9122 3708 9111 3710 9100 3710 9096 3705 9096FLASH FLOOD...OBSERVEDFLASH FLOOD DAMAGE THREAT...CATASTROPHIC$$SP
This particular Flash flood emergency also includes the enhanced wording "Particularly Dangerous Situation".
844WGUS71 KBOX 282143FFSBOXFlash Flood StatementNational Weather Service Boston/Norton MA543 PM EDT Sun Jun 28 2020MAC005-017-021-023-027-282300-/O.CON.KBOX.FF.W.0003.000000T0000Z-200628T2300Z//00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/Norfolk MA-Worcester MA-Middlesex MA-Plymouth MA-Bristol MA-543 PM EDT Sun Jun 28 2020...THIS IS A FLASH FLOOD EMERGENCY FOR THE TOWN OF NORWOOD ANDSURROUNDING TOWNS......THE FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 700 PM EDT FORNORFOLK...EASTERN WORCESTER...SOUTH CENTRAL MIDDLESEX...WEST CENTRALPLYMOUTH AND NORTH CENTRAL BRISTOL COUNTIES...At 537 PM EDT, law enforcement reported heavy rain falling includingthe towns of Norwood and Dedham where up to 3.5 inches have alreadyfallen. Flash flooding is already occurring. Some evacuations may benecessary. Listen to local officials.THIS IS A FLASH FLOOD EMERGENCY FOR NORWOOD AND SURROUNDING TOWNS!This is a PARTICULARLY DANGEROUS SITUATION. SEEK HIGHER GROUND NOW!HAZARD...Life threatening flash flooding. Heavy rain producing flash flooding.SOURCE...Law enforcement.IMPACT...This is a PARTICULARLY DANGEROUS SITUATION. SEEK HIGHER GROUND NOW! Life threatening flash flooding of low water crossings, small creeks and streams, urban areas, highways, streets and underpasses.Some locations that will experience flooding include...Brockton, Quincy, Randolph, Franklin, Norwood, Milford, Milton,Stoughton, Dedham, Walpole, Mansfield, Easton, Canton, Sharon,Foxborough, Bellingham, Abington, Westwood, Holliston and Medway.PRECAUTIONARY/PREPAREDNESS ACTIONS...Move to higher ground now. This is an extremely dangerous andlife-threatening situation. Do not attempt to travel unless you arefleeing an area subject to flooding or under an evacuation order.&&LAT...LON 4210 7096 4204 7114 4203 7151 4219 7152 4223 7114 4223 7113 4224 7108FLASH FLOOD...OBSERVEDFLASH FLOOD DAMAGE THREAT...CATASTROPHICEXPECTED RAINFALL...1-2 INCHES IN 1 HOUR$$NOCERA
