A flash flood warning ( SAME code: FFW) is an hazardous weather statement issued by national

weather forecasting Weather forecasting 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 informally for millennia a ...

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 or snow flowing o ...

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

flood A flood is an overflow of water ( 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 an area of study of the discipline hydrol ...

after a heavy

rain Rain is water droplets that have condensed from atmospheric water vapor and then fall under gravity. Rain is a major component of the water cycle and is responsible for depositing most of the fresh water on the Earth. It provides water f ...

, 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 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 ...

. 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 Weather radar, also called weather surveillance radar (WSR) and Doppler weather radar, is a type of radar used to locate precipitation, calculate its motion, and estimate its type (rain, snow, hail etc.). Modern weather radars are mostly puls ...

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 Albany ( ) is the capital of the U.S. state of New York, also the seat and largest city of Albany County. Albany is on the west bank of the Hudson River, about south of its confluence with the Mohawk River, and about north of New York City ...

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 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 in highly populated areas. Although it is not a new warning ...

. On August 27, 2017, as

Hurricane Harvey Hurricane Harvey was a devastating Category 4 hurricane that made landfall on 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 t ...

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 Cape Verde hurricane that caused widespread destruction across its path in September 2017. Irma was the first Category 5 hurricane to strike the Leeward Islands on record, followed by Maria two ...

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 U.S. state 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 Micropolitan S ...

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 Ki ...

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. From ...

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 center ...

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 Frankford Creek is a minor tributary of the Delaware River in southeast Pennsylvania. It derived its name from the nearby town of Frankford, Philadelphia County. The stream originates as Tookany Creek at Hill Crest in Cheltenham Township and mean ...

and

Frankford Creek Frankford Creek is a minor tributary of the Delaware River in southeast Pennsylvania. It derived its name from the nearby town of Frankford, Philadelphia County. The stream originates as Tookany Creek at Hill Crest in Cheltenham Township and mean ...

, 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. Though the full extent of the region is somewhat vague, "North Philadelphia" is regarded as everything north of either ...

Pennsylvania Pennsylvania (; ( Pennsylvania Dutch: )), officially the Commonwealth of Pennsylvania, is a state spanning the Mid-Atlantic, Northeastern, Appalachian, and Great Lakes regions of the United States. It borders Delaware to its southeast, ...

, 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 or NYC, is the List of United States cities by population, most populous city in the United States. With a 2020 population of 8,804,190 distributed over , New York City is also the L ...

Philadelphia Philadelphia, often called Philly, is the largest city in the Commonwealth of Pennsylvania, the sixth-largest city in the U.S., the second-largest city in both the Northeast megalopolis and Mid-Atlantic regions after New York City. Sinc ...

, Fairfield and

New Haven New Haven is a city in the U.S. state of Connecticut. It is located on New Haven Harbor on the northern shore of Long Island Sound in New Haven County, Connecticut and is part of the New York City metropolitan area. With a population of 134,02 ...

Counties in

Connecticut Connecticut () is the southernmost state in the New England region of the Northeastern United States. It is bordered by Rhode Island to the east, Massachusetts to the north, New York to the west, and Long Island Sound to the south. Its cap ...

, and most of Central

New Jersey New Jersey is a state in the Mid-Atlantic and Northeastern regions of the United States. It is bordered on the north and east by the state of New York; on the east, southeast, and south by the Atlantic Ocean; on the west by the Delaware ...

a region that stretches over 200 miles, as the remnants of Hurricane Ida transitioned and intensified into a

post tropical cyclone Post or POST commonly refers to: *Mail, the postal system, especially in Commonwealth of Nations countries **An Post, the Irish national postal service **Canada Post, Canadian postal service **Deutsche Post, German postal service ** Iraqi Post, Ir ...

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.

Example of a flash flood warning and emergency

Warning

This warning was issued following a dam failure along the

Minnesota Minnesota () is a state in the upper midwestern region of the United States. It is the 12th largest U.S. state in area and the 22nd most populous, with over 5.75 million residents. Minnesota is home to western prairies, now given over to ...

Wisconsin Wisconsin () is a state in the upper Midwestern United States. Wisconsin is the 25th-largest state by total area and the 20th-most populous. It is bordered by Minnesota to the west, Iowa to the southwest, Illinois to the south, Lake M ...

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

Note that this warning contains the enhanced wording Particularly Dangerous Situation.


FLASH FLOOD WARNING
KSC091-209-MOC047-095-270645-
/O.NEW.KEAX.FF.W.0043.160827T0247Z-160827T0645Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
FLASH FLOOD WARNING
NATIONAL WEATHER SERVICE KANSAS CITY/PLEASANT HILL MO
947 PM CDT FRI AUG 26 2016

...FLASH FLOOD EMERGENCY FOR THE IMMEDIATE DOWNTOWN KANSAS CITY
AREA!...

THE NATIONAL WEATHER SERVICE IN PLEASANT HILL HAS ISSUED A

* FLASH FLOOD WARNING FOR...
  EASTERN WYANDOTTE COUNTY IN NORTHEASTERN KANSAS...
  NORTHEASTERN JOHNSON COUNTY IN EAST CENTRAL KANSAS...
  NORTHWESTERN JACKSON COUNTY IN WEST CENTRAL MISSOURI...
  SOUTHWESTERN CLAY COUNTY IN WEST CENTRAL MISSOURI...

* UNTIL 145 AM CDT
* AT 943 PM CDT...DOPPLER RADAR INDICATED HEAVY RAIN ACROSS THE
  WARNED AREA. LIFE THREATENING FLASH FLOODING IS ALREADY OCCURRING!

  THIS IS A FLASH FLOOD EMERGENCY FOR THE KANSAS CITY
METRO...PARTICULARLY THE DOWNTOWN KANSAS CITY AREA! THIS IS  A
PARTICULARLY DANGEROUS SITUATION. SEEK HIGHER GROUND NOW!

* SOME LOCATIONS THAT WILL EXPERIENCE FLOODING INCLUDE...
  KANSAS CITY...OVERLAND PARK...INDEPENDENCE...SHAWNEE...LENEXA...
  LEAWOOD...RAYTOWN...LIBERTY...GLADSTONE...PRAIRIE VILLAGE...
  MERRIAM...MISSION...EDWARDSVILLE...NORTH KANSAS CITY...FAIRWAY...
  MISSION HILLS...SUGAR CREEK...RIVERSIDE...WESTWOOD AND CLAYCOMO.

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 ESPECIALLY CAUTIOUS AT NIGHT WHEN IT IS HARDER TO RECOGNIZE THE
DANGERS OF FLOODING.

A FLASH FLOOD WARNING MEANS THAT FLOODING IS IMMINENT OR OCCURRING.
IF YOU ARE IN THE WARNED AREA MOVE TO HIGHER GROUND IMMEDIATELY.
RESIDENTS LIVING ALONG STREAMS AND CREEKS SHOULD TAKE IMMEDIATE
PRECAUTIONS TO PROTECT LIFE AND PROPERTY.

&&

LAT...LON 3917 9466 3915 9466 3916 9460 3919 9460
      3927 9435 3907 9428 3892 9477 3912 9481

$$

GITRO

Flash Flood Emergency In Follow-Up Statement

This particular Flash Flood Emergency also includes the enhanced wording " Particularly Dangerous Situation".


844
WGUS71 KBOX 282143
FFSBOX

Flash Flood Statement
National Weather Service Boston/Norton MA
543 PM EDT Sun Jun 28 2020

MAC005-017-021-023-027-282300-
/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 AND
SURROUNDING TOWNS...

...THE FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 700 PM EDT FOR
NORFOLK...EASTERN WORCESTER...SOUTH CENTRAL MIDDLESEX...WEST CENTRAL
PLYMOUTH AND NORTH CENTRAL BRISTOL COUNTIES...

At 537 PM EDT, law enforcement reported heavy rain falling including
the towns of Norwood and Dedham where up to 3.5 inches have already
fallen. Flash flooding is already occurring. Some evacuations may be
necessary. 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 and
life-threatening situation. Do not attempt to travel unless you are
fleeing 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 7108

FLASH FLOOD...OBSERVED
FLASH FLOOD DAMAGE THREAT...CATASTROPHIC
EXPECTED RAINFALL...1-2 INCHES IN 1 HOUR

$$

NOCERA

References

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