Flash  Flood Safety 

Background Information: A "Flash Flood" is a flood that occurs suddenly during or shortly following (usually within 6 hours) heavy rains or from a sudden release of water (as in a dam break).  Small streams and creeks usually react the fastest to heavy rains and rise several feet in hours or even minutes, Flash floods also can be caused by ice jams.  Antecedent conditions such as how much rain has fallen recently, soil type, and terrain effects are important factors in determining the threat of flash flooding.

 Nationally, flooding and flash flooding is the number one weather-related killer, averaging 150 deaths per year.  Nearly half of these deaths occur in automobiles, Flash floods can move at tremendous speeds, tearing out trees and moving boulders.  The debris moves with the flood wave and sometimes destroys buildings and bridges in its path.  Debris may cause a temporary dam and when broken, a wall of water moves downstream, Walls of water can reach 10 to 20 feet.

Watch/Warning

Definition: A Flash Flood WATCH is issued for a portion of a state or states if there is the potential of-r flash flooding to occur, generally within the next 3 to 12 hours.  The Watch is issued by your local National Weather Service (NWS) Forecast Office, The NWS River Forecast Centers provide local NWS Weather Forecast Offices with "flash flood guidance" values, which estimate the amount of rainfall needed within various time intervals in order to create flash flooding.  These are derived from a numerical model, which takes into account the amount of expected rainfall, rainfall from previous days, snow melt, soil type, etc.,

 A Flash Flood WARNING is issued for a county or portion of a county when flash flooding is either occurring or is imminent.  This is based on direct observations of the flooding, rain gauge observations or estimates of rainfall (by radar or satellite) which exceed flash flood guidance values.  As with Flash Flood Watches, the warnings are issued by the local National Weather Service Forecast Office with warning jurisdiction for that county.

 How (if) warning is received:

 All Flash Flood Watches and Warnings are tone-alarmed by the National Weather Service on NOAA Weather Radios, (An alarm will sound if you have a receiver with an alarm feature.) Follow-up statements will be issued, with the latest information on the storms and flooding.

 The Weather Channel (on Cable TV) is another source for learning of Watches and      Warnings, Broadcasters will highlight where Watches are in effect, Warnings will scroll across the screen, which turns red-but have to be monitoring it carefully in order to notice this.

 Television and radio stations will broadcast Watch and Warning information.

 Depending on which part of the country you are in, some radio and television stations may activate the Emergency Broadcast System (EBS) for Flash Flood Warnings.

 All National Weather Service products are available on a printer via the satellite-feed GTE Federal Systems "Weather Wire."

What to expect: Heavy rains may be occurring all day -- or thunderstorms may be either stationary or traversing the same areas time after time.  The rain may have let up, but the school bus driver is caught by surprise when a small stream is out of its banks and flowing across a road, The water may have appeared shallow, but the road beneath it may already have been undermined, The bus could be swept rapidly away as the flash flood waters rise.  The result could be that the bus overturns and people drown,

 There are other scenarios, such as a "wall of water" which comes crashing down the stream, as mentioned in the "Background" section above.

 Procedures if a Watch is issued:

 KEEP AN EYE ON THE WEATHER AND LISTEN TO THE WEATHER RADIO OR LOCAL RADIO AND TV STATIONS FOR THE LATEST WEATHER INFORMATION.

 REVIEW SAFETY MEASURES, SINCE FLASH FLOODING CAN OCCUR SUDDENLY AND WITHOUT ANY WARNING.

 Procedures if a Warning is issued:

 GET OUT OF AREAS SUBJECT TO FLOODING.  This includes dips, low spots, canyons, washes, areas along streams and creeks.  This also includes urban areas where storm drains become clogged with debris and rain, unable to be soaked up by the paved ground, Some underpasses can be extremely dangerous,

 DO NOT ENTER FLOOD WATERS DO NOT ATTEMPT TO CROSS FLOWING WATER IN A CAR, BUS, OR TRUCK!!!  Almost half of all flood deaths occur in automobiles, Water depths can be very deceptive, A foot of water may be all that it takes to drag a car into deeper waters or flip it over!  Many cars stall once entering the water.  Electrical systems in the car may fail, causing power windows and doors to not operate, trapping the victim inside as the water continues to rise.

 If the vehicle stalls, abandon it immediately and seek higher ground.

 Procedures if a flash flood happens without warning:-

 Flash Flooding can occur with little or no official warning.  Thus, you should be paying close attention to your environment and trying to recognize signs that it may already have occurred, This means:

 ·     LISTENING FOR SOUNDS OF ROARING WATER.

·     NOTICING THAT HEAVY RAINFALL IS CONTINUING.

·     LISTENING FOR REPORTS THAT RAIN IS FALLING AT "AN INCH PER HOUR" OR MORE.

 Safety spots during event:

 ·     HIGHER GROUND

·     NOT IN A VEHICLE THAT IS NEAR FLOOD WATERS

 Safety rules/spots after event:

 DO NOT TOUCH ELECTRICAL EQUIPMENT IN WET AREAS UNTIL IT HAS BEEN

DRIED AND TESTED,

 DO NOT TOUCH FRESH FOOD THAT HAS COME IN CONTACT WITH FLOOD WATERS (also see safety procedures listed below)

 Safety procedures after event:

 FOR THE SAFETY OF OTHERS DOWNSTREAM, QUICKLY REPORT THE FLASH FLOOD AND ANY DAMAGE TO THE NATIONAL WEATHER SERVICE (YOU SHOULD HAVE THE NUMBER HANDY) -- OR TO LOCAL EMERGENCY OFFICIALS AND ASK THEM TO RELAY THE INFORMATION TO THE NATIONAL WEATHER SERVICE,

 IF A FLASH FLOOD HAS STRUCK THE SCHOOL, TURN OFF THE GAS AT THE MAIN SWITCH.

 IF ELECTRICAL WIRES ARE DOWN, TURN OFF POWER AT THE MAIN SWITCH.

 INSTRUCT PEOPLE NOT TO TOUCH LOOSE ELECTRICAL WIRES OR BROKEN UTILITY LINES.

 BOIL DRINKING WATER BEFORE USING UNTIL THE WATER HAS BEEN TESTED FOR PURITY.

 Safety rationale: Fast-moving water is extremely powerful and damaging.  Even a small amount of water can be enough to sweep cars away.

 Common misperceptions:

 1. You should not drive through what looks like shallow, non-threatening waters or drive around police barricades, Water moving at only 2 mph has the power to sweep cars off a road or bridge!