Flash flood warning

A flash flood warning (SAME code: FFW) is issued when 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. In this case, there would be heavy rain in areas upstream of the warned location.^[1]

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.^[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]

• 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^[5]), which indicates a severe flooding situation in densely populated areas, similar to the procedure for declaring a tornado emergency.

Example of a flash flood warning and emergency

Warning

	Flash flood warning Tennessee An example of a flash flood warning in Tennessee.
Problems playing this file? See media help.

FLASH FLOOD WARNING
MOC025-061-117-177-270815-
/O.NEW.KEAX.FF.W.0041.160827T0214Z-160827T0815Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

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

THE NATIONAL WEATHER SERVICE IN PLEASANT HILL HAS ISSUED A

* FLASH FLOOD WARNING FOR...
  LIVINGSTON COUNTY IN NORTH CENTRAL MISSOURI...
  DAVIESS COUNTY IN NORTH CENTRAL MISSOURI...
  NORTHERN RAY COUNTY IN WEST CENTRAL MISSOURI...
  CALDWELL COUNTY IN NORTH CENTRAL MISSOURI...

* UNTIL 315 AM CDT SATURDAY

* AT 913 PM CDT...DOPPLER RADAR INDICATED THUNDERSTORMS PRODUCING
  HEAVY RAIN ACROSS THE WARNED AREA. UP TO TWO INCHES OF RAIN HAVE
  ALREADY FALLEN AND ADDITIONAL HEAVY RAIN IS LIKELY THIS EVENING
  AND OVERNIGHT. FLASH FLOODING IS EXPECTED TO BEGIN SHORTLY.

* SOME LOCATIONS THAT WILL EXPERIENCE FLOODING INCLUDE...
  CAMERON...CHILLICOTHE...LAWSON...HAMILTON...GALLATIN...BRAYMER...
  POLO...JAMESPORT...BRECKENRIDGE...KINGSTON...PATTONSBURG...UTICA...
  COWGILL...EXCELSIOR ESTATES...KIDDER...WINSTON...CHULA...
  ALTAMONT...HOMESTEAD AND LUDLOW.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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 4004 9377 3996 9376 3997 9349 3963 9346
      3961 9350 3961 9375 3952 9376 3936 9421
      4005 9421

$$

GITRO

Emergency

	Flash flood emergency Tennessee An example of a flash flood emergency in Tennessee.
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Flash Flood Emergency In Initial Bulletin

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

897
WGUS71 KILN 290010
FFSILN

FLASH FLOOD STATEMENT
NATIONAL WEATHER SERVICE WILMINGTON OH
810 PM EDT SUN AUG 28 2016

KYC015-037-117-OHC061-290230-
/O.CON.KILN.FF.W.0044.000000T0000Z-160829T0230Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
KENTON KY-CAMPBELL KY-BOONE KY-HAMILTON OH-
810 PM EDT SUN AUG 28 2016

...THIS IS A FLASH FLOOD EMERGENCY FOR KENTON...NORTHERN CAMPBELL...
CENTRAL BOONE AND EASTERN HAMILTON COUNTIES...

...A FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 1030 PM EDT...

AT 807 PM EDT...RADAR INDICATED THAT EXTREMELY HEAVY RAIN HAD FALLEN
ACROSS SOUTHERN HAMILTON...NORTHERN KENTON AND NORTHERN CAMPBELL
COUNTIES. DOPPLER RADAR ESTIMATES INDICATE THAT 3 TO 5 INCHES OF
RAIN HAVE FALLEN SINCE 6 PM. HEAVY RAIN CONTINUES TO FALL WITH
ANOTHER 2 INCHES POSSIBLE. FLASH FLOODING IS OCCURRING AND WILL
CONTINUE THROUGH 1000 PM.

SOME LOCATIONS THAT WILL EXPERIENCE FLOODING INCLUDE...
CINCINNATI...COVINGTON...FLORENCE...INDEPENDENCE...NORWOOD...
FOREST PARK...ERLANGER...FORT THOMAS...NEWPORT...SHARONVILLE...
BLUE ASH...SPRINGDALE...READING...MONTGOMERY...NORTH COLLEGE HILL...
MADEIRA...EDGEWOOD...ALEXANDRIA...ELSMERE AND WYOMING.

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.

TO REPORT FLASH FLOODING...GO TO OUR WEBSITE AT WEATHER.GOV/ILN AND
SUBMIT YOUR REPORT VIA SOCIAL MEDIA...WHEN YOU CAN DO SO SAFELY.

&&

LAT...LON 3930 8452 3928 8431 3889 8435 3891 8475

$$

See also

Severe weather terminology (United States)

References