Flash flood warning
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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.[not in citation given]
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.
Example of a flash flood warning and emergency
An example of a flash flood warning in Tennessee.
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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
An example of a flash flood emergency in Tennessee.
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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
- "New Orleans Levee Breach Flash Flood Warning".
- "NOAAWatch Home". Retrieved 17 January 2014.
- NWGeek on YouTube. "NWS Albany Flash Flood Warning Emergency EAS - Newfane, VT". NWRGeek. NWRGeek Productions. Retrieved 1 August 2012.