A flash flood warning ( SAME code: FFW) is a

severe weather Severe weather is any dangerous meteorological phenomenon with the potential to cause damage, serious social disruption, or loss of human life. These vary depending on the latitude, altitude, topography, and atmospheric conditions. High ...

warning product of the

National Weather Service The National Weather Service (NWS) is an Government agency, agency of the Federal government of the United States, United States federal government that is tasked with providing weather forecasts, warnings of hazardous weather, and other weathe ...

that is issued by national

weather forecasting Weather forecasting or weather prediction is the application of science and technology forecasting, to predict the conditions of the Earth's atmosphere, atmosphere for a given location and time. People have attempted to predict the weather info ...

agencies throughout the world to alert the public that a

flash flood A flash flood is a rapid flooding of low-lying areas: washes, rivers, dry lakes and depressions. It may be caused by heavy rain associated with a severe thunderstorm, hurricane, or tropical storm, or by meltwater from ice and snow. Flash f ...

is imminent or occurring in the warned area. A flash flood is a sudden, violent

flood A flood is an overflow of water (list of non-water floods, or rarely other fluids) that submerges land that is usually dry. In the sense of "flowing water", the word may also be applied to the inflow of the tide. Floods are of significant con ...

after a heavy

rain Rain is a form of precipitation where water drop (liquid), droplets that have condensation, condensed from Water vapor#In Earth's atmosphere, atmospheric water vapor fall under gravity. Rain is a major component of the water cycle and is res ...

, 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

. One is a

flash flood watch A flash flood watch ( SAME code: FFA; also referred as a "green box" by meteorologists) is severe weather watch product of the National Weather Service that is issued when conditions are favorable for flash flooding in flood-prone areas, usually ...

, 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 A weather radar, also called weather surveillance radar (WSR) and Doppler weather radar, is a type of radar used to locate precipitation (meteorology), precipitation, calculate its motion, and estimate its type (rain, snow, hail etc.). Modern w ...

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

Flash flood emergency

In addition, there is an enhanced version of flash flood warning, referred to as a flash flood emergency (or as termed by the

Albany, New York Albany ( ) is the List of capitals in the United States, capital city of the U.S. state of New York (state), New York. It is located on the west bank of the Hudson River, about south of its confluence with the Mohawk River. Albany is the oldes ...

office as a flash flood warning emergency), which indicates a severe flooding situation, often, but not always in densely populated areas, similar to the procedure for declaring a

tornado emergency A tornado emergency is an enhanced version of a tornado warning, which is used by the National Weather Service (NWS) in the United States during imminent, significant tornado occurrences. Although it is not a new warning type from the NWS, issue ...

. According to the National Weather Service, examples of situations that warrant the inclusion of flash flood emergency language in flash flood warnings may include, but are not necessarily limited to: * Emergency manager(s) of the affected county(ies) or the state emergency management association declare a state of emergency and have confirmed that rapidly rising floodwaters are placing or will place people in life-threatening situations The state of emergency for the affected areas may have been previously relayed by the emergency manager(s) or the state emergency management association through the local NWS forecast office in a Non-Weather emergency message. These might include a Civil Emergency Message (CEM), an Evacuation Immediate (EVI), or a Local Area Emergency (LAE). * Water has rapidly risen or will rapidly rise to levels where people who are ordinarily in safe locations during previous flash flood events are now placed in life-threatening situations. For example, people in homes that might see waters rapidly rise up to their front yards or steps during typical flash flood situations would experience waters that are several feet above floor level, such that rescue is necessary and/or their entire home is threatened. * Multiple swift water rescue teams have been or are being deployed in response to flash flooding of an exceptional magnitude. * Stream gages, where available, indicate floodwaters have risen rapidly to at least major levels, or if gages are not available, floodwaters have risen to levels rarely, if ever, seen. * Total failure of a major high hazard dam that would have a catastrophic impact on the downstream communities. The National Weather Service also notes that in situations where a robust emergency management structure does not exist orexternal communications are not possible, a local forecast office may include flash flood emergency language in a flash flood warning without pre-coordinating with emergency managers when the above or similar criteria are met.

Notable events where flash flood emergencies were issued

On August 27, 2017, as

Hurricane Harvey Hurricane Harvey was a devastating tropical cyclone that made landfall in Texas and Louisiana in August 2017, causing catastrophic flooding and more than 100 deaths. It is tied with 2005's Hurricane Katrina as the costliest tropical cy ...

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 Hurricane Irma was an extremely powerful and devastating tropical cyclone that was the first Category 5 hurricane to strike the Leeward Islands on record, followed by Hurricane Maria, Maria two weeks later. At the time, it was considered ...

in southwestern Florida at the eye landfall. On February 6, 2020, the NWS issued a Flash Flood Emergency for

Tazewell County, Virginia Tazewell County () is a county located in the southwestern portion of the Commonwealth of Virginia. As of the 2020 census, the population was 40,429. Its county seat is Tazewell. Tazewell County is part of the Bluefield, WV-VA Micropoli ...

due to a major storm moving through the area which caused the

Clinch River The Clinch River is a river that flows southwest for more than through the Great Appalachian Valley in the U.S. states of Virginia and Tennessee, gathering various tributaries, including the Powell River, before joining the Tennessee River in ...

to rise to its highest crest in 40 years. On May 20, 2020, the NWS issued a Flash Flood Emergency for the

Tittabawassee River The Tittabawassee River ( ) flows in a generally southeasterly direction through the Lower Peninsula of the U.S. state of Michigan. The river begins at Secord Lake in Clement Township, at the confluence of the East Branch and the Middle Branch ...

Midland County, Michigan Midland County is a county located in the U.S. state of Michigan. As of the 2020 census, the population was 83,494. The county seat is Midland. The county's name is due to its closeness to the geographical Lower Peninsula's geographical cent ...

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 Frankford Creek is a minor tributary of the Delaware River in southeast Pennsylvania. It derived its name from today's Frankford, Philadelphia neighborhood. The stream originates as Tookany Creek at Hill Crest in Cheltenham Township and meander ...

, the former situated along Montgomery County and

North Philadelphia North Philadelphia, nicknamed North Philly, is a section of Philadelphia, Pennsylvania. It is immediately north of Center City, Philadelphia, Center City. Though the full extent of the region is somewhat vague, "North Philadelphia" is regarded as ...

Pennsylvania Pennsylvania, officially the Commonwealth of Pennsylvania, is a U.S. state, state spanning the Mid-Atlantic (United States), Mid-Atlantic, Northeastern United States, Northeastern, Appalachian, and Great Lakes region, Great Lakes regions o ...

, 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 New York, often called New York City (NYC), is the most populous city in the United States, located at the southern tip of New York State on one of the world's largest natural harbors. The city comprises five boroughs, each coextensive w ...

Philadelphia Philadelphia ( ), colloquially referred to as Philly, is the List of municipalities in Pennsylvania, most populous city in the U.S. state of Pennsylvania and the List of United States cities by population, sixth-most populous city in the Unit ...

, Fairfield and

New Haven New Haven is a city of the U.S. state of Connecticut. It is located on New Haven Harbor on the northern shore of Long Island Sound. With a population of 135,081 as determined by the 2020 U.S. census, New Haven is the third largest city in Co ...

Counties in

Connecticut Connecticut ( ) is a U.S. state, state in the New England region of the Northeastern United States. It borders Rhode Island to the east, Massachusetts to the north, New York (state), New York to the west, and Long Island Sound to the south. ...

, and most of Central

New Jersey New Jersey is a U.S. state, state located in both the Mid-Atlantic States, Mid-Atlantic and Northeastern United States, Northeastern regions of the United States. Located at the geographic hub of the urban area, heavily urbanized Northeas ...

a region that stretches over 200 miles, as the remnants of

Hurricane Ida Hurricane Ida was a deadly and extremely destructive tropical cyclone in 2021 that became the second-most damaging and intense hurricane to make landfall in the U.S. state of Louisiana on record, behind Hurricane Katrina in 2005. In terms of m ...

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.
statement
was later posted on Twitter. On September 27, 2024, a Flash Flood Emergency was issued for

Metro Atlanta Metro Atlanta, designated by the United States Office of Management and Budget as the Atlanta–Sandy Springs–Roswell metropolitan statistical area, is the most populous metropolitan statistical area in the U.S. state of Georgia and the sixt ...

Hurricane Helene Hurricane Helene ( ) was a deadly and devastating tropical cyclone that caused widespread catastrophic damage and numerous fatalities across the Southeastern United States in late September 2024. It was the strongest hurricane on record to ...

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 Hurricane Milton was an extremely powerful and destructive tropical cyclone which in 2024 became the most intense Atlantic hurricane ever recorded over the Gulf of Mexico, tying with Hurricane Rita in 2005. Milton made landfall on the west coa ...

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 Minnesota ( ) is a U.S. state, state in the Upper Midwestern region of the United States. It is bordered by the Canadian provinces of Manitoba and Ontario to the north and east and by the U.S. states of Wisconsin to the east, Iowa to the so ...

Wisconsin Wisconsin ( ) is a U.S. state, state in the Great Lakes region, Great Lakes region of the Upper Midwest of the United States. It borders Minnesota to the west, Iowa to the southwest, Illinois to the south, Lake Michigan to the east, Michig ...

border.

Flash Flood Warning
MNC115-WIC013-031-192330-
/O.NEW.KDLH.FF.W.0012.180618T2329Z-180619T2330Z/
/00000.U.DM.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Duluth MN
1203 PM CDT SUN JUN 18 2018

The 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 flood
deaths occur in vehicles.

Move to higher ground now. Act quickly to protect your life.

Please report flooding to your local law enforcement agency when you
can 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.

PAC051-102345-
/O.NEW.KPBZ.FF.W.0017.200710T2142Z-200710T2345Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Pittsburgh PA
542 PM EDT Fri Jul 10 2020

The National Weather Service in Northern Pittsburgh has issued a

* Flash Flood Warning for...
Central Fayette County in southwestern Pennsylvania...

* Until 745 PM EDT.
* At 542 PM EDT, Doppler radar indicated thunderstorms producing 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.

* Some locations that will experience flash flooding include...
Uniontown, South Connellsville, Dunbar, Vanderbilt and Dawson.

Additional rainfall amounts up to 1 inch are possible in the warned area.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Turn around, don't drown when encountering flooded roads. Most flood
deaths occur in vehicles.

&&

LAT...LON 4006 7967 3997 7982 3986 7972 3995 7955

FLASH FLOOD...RADAR INDICATED

$$

Emergency

Flash flood emergency in initial bulletin

This warning, containing both the "Flash Flood Emergency" wording and the

Particularly Dangerous Situation A PDS tornado watch issued on December 14, 2022. In weather forecasting in the United States, "particularly dangerous situation" (PDS) is the wording used by the National Weather Service and the Storm Prediction Center to convey special urgency in ...

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 Warning
MOC035-050630-
/O.NEW.KPAH.FF.W.0035.250405T0018Z-250405T0630Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Paducah KY
718 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 and
life-threatening situation. Do not attempt to travel unless you are
fleeing an area subject to flooding or under an evacuation order.

Turn around, don`t drown when encountering flooded roads. Most flood
deaths 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 9096

FLASH FLOOD...OBSERVED
FLASH FLOOD DAMAGE THREAT...CATASTROPHIC

$$

SP

Flash flood emergency in follow-up statement

This particular Flash flood emergency also includes the enhanced wording "


387 
WGUS71 KRNK 161006
FFSRNK

Flash Flood Statement
National Weather Service Blacksburg VA
506 AM EST Sun Feb 16 2025

VAC185-161300-
/O.CON.KRNK.FF.W.0006.000000T0000Z-250216T1300Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Tazewell VA-
506 AM EST Sun Feb 16 2025

...FLASH FLOOD EMERGENCY FOR ENTIRE AREA...

...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 8 AM EST THIS MORNING 
FOR TAZEWELL COUNTY...

At 506 AM EST, emergency management and local law enforcement 
reported numerous road closures from flash flooding.  Between 1.5 
and 3 inches of rain have fallen. Additional rainfall amounts of 0.5 
to 1 inch are possible between now and 8:00 AM. This rainfall may 
result additional flooding.

This is a FLASH FLOOD EMERGENCY for Entire area. This is a 
PARTICULARLY DANGEROUS SITUATION. SEEK HIGHER GROUND NOW!

HAZARD...Life threatening flash flooding. Heavy rain producing
         flash flooding.

SOURCE...Emergency management and local law enforcement reported.

IMPACT...This is a PARTICULARLY DANGEROUS SITUATION. REMAIN ON
         HIGHER GROUND! 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...
  Richlands...                       Bluefield...
Tazewell...                        Cedar Bluff...
Burkes Garden...                   Pocahontas...
Cliffield...

This includes the following streams and drainages...
  Clinch River, Big Creek, Blue Spring Creek, Burkes Garden Creek, 
  Beech Fork and Bluestone River.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Move to higher ground now! This is an extremely dangerous and 
life-threatening situation. Do not attempt to travel unless you are 
fleeing an area subject to flooding or under an evacuation order.

Be aware of your surroundings and do not drive around road closure 
barriers.

Rainfall of more than five inches in similar storms has been 
associated with an increased risk of landslides and rockslides. If 
you live on a mountainside or in a cove at the base of a mountain, 
especially near a stream, be ready to leave in advance of the storm 
or as quickly as possible should rising water, moving earth, or 
rocks threaten. Consider postponing travel along mountain roads 
during periods of heavy rainfall.

&&

LAT...LON 3722 8128 3717 8126 3715 8133 3713 8127
      3709 8127 3704 8146 3701 8144 3699 8148
      3701 8147 3693 8168 3698 8171 3696 8178
      3714 8190 3724 8173 3720 8168 3721 8155
      3727 8142 3734 8136 3723 8123

FLASH FLOOD...OBSERVED
FLASH FLOOD DAMAGE THREAT...CATASTROPHIC

$$

11

References

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