Flash flood warning

A Flash Flood Warning 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. 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 your location. [NOAA - http://www.nws.noaa.gov/om/brochures/ffbro.htm]

Flash Flood Alerts

There are two types of alerts for flash floods which are released by the National Weather Service. One is a flash flood watch, which means a flash flood could occur in the area. And the other is a flash flood warning, which means a flash flood is occurring or one will occur. A flash flood warning is issued when there are strong weather radar echoes for an area that is prone to flash flooding. [Stormwarn - http://www.stormwarn.com/rants/flash_flood_warnings.html] If a flash flood warning is issued, evacuate quickly and move to higher ground. Do not try to drive through the flooded areas! If your vehicle does stall, get out immediately and move to higher ground! [American Red Cross - http://www.redcross.org/services/prepare/0,1082,0_240_,00.html]

Some things to be aware of when in a flash flood prone area:
* be aware of any signs of heavy rain
* if you see or hear rapid rising water get to high ground
* do not attempt to cross the flowing water [NOAA - http://www.noaa.gov/floods.html]

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.

In addition, some NWS offices have instituted an enhanced Flash Flood Warning called a Flash Flood Emergency, which indicates a severe flooding situation.

Example of a Flash Flood Warning and Emergency

Warning

FLASH FLOOD WARNINGKSC003-302230-

BULLETIN - EAS ACTIVATION REQUESTEDFLASH FLOOD WARNINGNATIONAL WEATHER SERVICE TOPEKA KS1129 AM CDT SAT JUN 30 2007

THE NATIONAL WEATHER SERVICE IN TOPEKA HAS ISSUED A

* FLASH FLOOD WARNING FOR... ANDERSON COUNTY IN EAST CENTRAL KANSAS...

* UNTIL 530 PM CDT SATURDAY

* AT 1129 AM CDT...THE PUBLIC REPORTED WATER FLOWING OVER A COUPLEOF PAVED ROADS NEAR WESTPHALIA. ANDERSON COUNTY EMERGENCYMANAGEMENT ALSO INDICATED THAT SEVERAL PAVED ROADS HAD WATER RISINGAND APPROACHING ROADWAYS. DOPPLER RADAR INDICATED THAT ANOTHER BANDOF HEAVY RAINFALL WAS DEVELOPING AND TRAINING OVER ANDERSON COUNTYPRODUCING RAINFALL RATES UP TO ONE INCH PER HOUR. ENHANCED RAINFALLRATES WILL LIKELY BE ENOUGH TO BRING WATER OVER SEVERAL PAVED ROADSIN THE COUNTY

* LOCATIONS IMPACTED INCLUDE... HARRIS... GREELEY... GARNETT... WESTPHALIA...

RUNOFF FROM THIS STORM WILL CAUSE FLASH FLOODING OF CREEKS ANDSTREAMS...HIGHWAYS AND UNDERPASSES. ADDITIONALLY ROADS AND FARMLANDSALONG THE BANKS OF CREEKS AND STREAMS AND LOW LYING AREAS ARE SUBJECTTO FLASH FLOODING.

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

TO REPORT FLOODING...HAVE THE NEAREST LAW ENFORCEMENT AGENCY RELAYYOUR REPORT TO THE NATIONAL WEATHER SERVICE FORECAST OFFICE INTOPEKA.

STAY TUNED TO NOAA WEATHER RADIO OR LOCAL MEDIA OUTLETS FOR THELATEST INFORMATION CONCERNING THE SEVERE WEATHER.

LAT...LON 3803 9551 3803 9507 3839 9506 3838 9550

$$

Emergency

FLASH FLOOD STATEMENTNATIONAL WEATHER SERVICE TOPEKA KS210 PM CDT SAT JUN 30 2007

KSC003-302230-ANDERSON-210 PM CDT SAT JUN 30 2007

...A FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 530 PM CDT FORANDERSON COUNTY...

.A FLASH FLOOD EMERGENCY FOR ANDERSON COUNTY...

AT 200 PM CDT...TRAINED WEATHER SPOTTERS AND PUBLIC REPORTEDWIDESPREAD FLOODING OVER ANDERSON COUNTY. KNOWN WATER RESCUES AREONGOING WEST OF GARNETT. EMERGENCY CREWS ARE UNABLE TO FIND A ROUTEFROM WESTPHALIA TO GARNETT. NUMEROUS PAVED AND GRAVEL ROADS HAVEBEEN REPORTED TO BE UNDER WATER ACROSS THE COUNTY....SEVERAL AREAS 1TO 2 FEET DEEP. MEASURED STORM TOTAL PRECIPITATION AMOUNTS RANGEFROM 14 TO 16 INCHES OF RAINFALL DURING THE PAST THREE DAYS. WITHONGOING RAINFALL AMOUNTS ON THE ORDER OF 1 TO 2 INCHES PERHOUR...ANY ADDITIONAL RAINFALL WILL CONTINUE TO AGGRAVATE THEFLOODING SITUATION.

LOCATIONS IMPACTED INCLUDE...WESTPHALIA...COLONY...HARRIS...GREELEY AND GARNETT.

RUNOFF FROM THIS STORM WILL CAUSE FLASH FLOODING OF CREEKS ANDSTREAMS...HIGHWAYS AND UNDERPASSES. ADDITIONALLY ROADS AND FARMLANDSALONG THE BANKS OF CREEKS AND STREAMS AND LOW LYING AREAS ARE LIKELYTO CONTINUE OR QUICKLY BEGIN TO FLASH FLOOD. DO NOT DRIVE INTO AREASWHERE THE WATER COVERS THE ROAD.

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

LAT...LON 3803 9551 3803 9507 3839 9506 3838 9550

$$

BLAIR / CAVANAUGH

ee also

Severe weather terminology (United States)

References