Flash Flood Warning
Encyclopedia
A Flash Flood Warning is issued when a flash flood
Flash flood
A flash flood is a rapid flooding of geomorphic low-lying areas—washes, rivers, dry lakes and basins. It may be caused by heavy rain associated with a storm, hurricane, or tropical storm or meltwater from ice or snow flowing over ice sheets or snowfields...

 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.

Flash Flood Alerts

There are two types of alerts for flash floods which are released by the National Weather Service
National Weather Service
The National Weather Service , once known as the Weather Bureau, is one of the six scientific agencies that make up the National Oceanic and Atmospheric Administration of the United States government...

. One is a Flash flood watch
Flash flood watch
A Flash flood watch is issued by the National Weather Service when conditions are favorable for flash flooding in flood-prone areas where grounds are already saturated from recent rains....

, which means a flash flood could occur in the area. And the other is a Flash Flood Warning, which means a flash flood
Flash flood
A flash flood is a rapid flooding of geomorphic low-lying areas—washes, rivers, dry lakes and basins. It may be caused by heavy rain associated with a storm, hurricane, or tropical storm or meltwater from ice or snow flowing over ice sheets or snowfields...

 is occurring or one will occur. A Flash Flood Warning is issued when there are strong weather radar
Weather radar
Weather radar, also called weather surveillance radar and Doppler weather radar, is a type of radar used to locate precipitation, calculate its motion, estimate its type . Modern weather radars are mostly pulse-Doppler radars, capable of detecting the motion of rain droplets in addition to the...

echoes for an area that is prone to flash flooding. 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!

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


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.

Warning





FLASH FLOOD WARNING
KSC003-302230-

BULLETIN - EAS ACTIVATION REQUESTED
FLASH FLOOD WARNING
NATIONAL WEATHER SERVICE TOPEKA KS
1129 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 COUPLE

OF PAVED ROADS NEAR WESTPHALIA. ANDERSON COUNTY EMERGENCY
MANAGEMENT ALSO INDICATED THAT SEVERAL PAVED ROADS HAD WATER RISING
AND APPROACHING ROADWAYS. DOPPLER RADAR INDICATED THAT ANOTHER BAND
OF HEAVY RAINFALL WAS DEVELOPING AND TRAINING OVER ANDERSON COUNTY
PRODUCING RAINFALL RATES UP TO ONE INCH PER HOUR. ENHANCED RAINFALL
RATES WILL LIKELY BE ENOUGH TO BRING WATER OVER SEVERAL PAVED ROADS
IN THE COUNTY
  • LOCATIONS IMPACTED INCLUDE...

HARRIS...
GREELEY...
GARNETT...
WESTPHALIA...

RUNOFF FROM THIS STORM WILL CAUSE FLASH FLOODING OF CREEKS AND
STREAMS...HIGHWAYS AND UNDERPASSES. ADDITIONALLY ROADS AND FARMLANDS
ALONG THE BANKS OF CREEKS AND STREAMS AND LOW LYING AREAS ARE SUBJECT
TO 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 PRECAUTIONS
TO PROTECT LIFE AND PROPERTY.

TO REPORT FLOODING...HAVE THE NEAREST LAW ENFORCEMENT AGENCY RELAY
YOUR REPORT TO THE NATIONAL WEATHER SERVICE FORECAST OFFICE IN
TOPEKA.

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

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

$$


Emergency





FLASH FLOOD STATEMENT
NATIONAL WEATHER SERVICE TOPEKA KS
210 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 FOR
ANDERSON COUNTY...

.A FLASH FLOOD EMERGENCY FOR ANDERSON COUNTY...

AT 200 PM CDT...TRAINED WEATHER SPOTTERS AND PUBLIC REPORTED
WIDESPREAD FLOODING OVER ANDERSON COUNTY. KNOWN WATER RESCUES ARE
ONGOING WEST OF GARNETT. EMERGENCY CREWS ARE UNABLE TO FIND A ROUTE
FROM WESTPHALIA TO GARNETT. NUMEROUS PAVED AND GRAVEL ROADS HAVE
BEEN REPORTED TO BE UNDER WATER ACROSS THE COUNTY....SEVERAL AREAS 1
TO 2 FEET DEEP. MEASURED STORM TOTAL PRECIPITATION AMOUNTS RANGE
FROM 14 TO 16 INCHES OF RAINFALL DURING THE PAST THREE DAYS. WITH
ONGOING RAINFALL AMOUNTS ON THE ORDER OF 1 TO 2 INCHES PER
HOUR...ANY ADDITIONAL RAINFALL WILL CONTINUE TO AGGRAVATE THE
FLOODING SITUATION.

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

RUNOFF FROM THIS STORM WILL CAUSE FLASH FLOODING OF CREEKS AND
STREAMS...HIGHWAYS AND UNDERPASSES. ADDITIONALLY ROADS AND FARMLANDS
ALONG THE BANKS OF CREEKS AND STREAMS AND LOW LYING AREAS ARE LIKELY
TO CONTINUE OR QUICKLY BEGIN TO FLASH FLOOD. DO NOT DRIVE INTO AREAS
WHERE 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 PRECAUTIONS
TO PROTECT LIFE AND PROPERTY.

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

$$

BLAIR / CAVANAUGH

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