NOUS42 KCHS 071100
PNSCHS

GAZ087-088-099>101-114>119-137>141-081100-

PUBLIC INFORMATION STATEMENT
NATIONAL WEATHER SERVICE CHARLESTON SC
600 AM EST THU FEB 7 2013

...GEORGIA SEVERE WEATHER AWARENESS WEEK CONTINUES THROUGH FRIDAY...

TODAY WE WILL DISCUSS THE DANGERS OF FLASH FLOODING. 

FLASH FLOODS AND FLOODS ARE ADDITIONAL HAZARDS ASSOCIATED WITH
THUNDERSTORMS. FLASH FLOODING IS THE NUMBER ONE KILLER IN 
THUNDERSTORMS...KILLING AROUND 90 PEOPLE ANNUALLY. MOST FLASH FLOOD 
DEATHS OCCUR WHEN PEOPLE BECOME TRAPPED IN AUTOMOBILES AT NIGHT.

FLASH FLOODING OCCURS WHEN STREAMS...SMALL RIVERS AND URBAN AREAS 
CANNOT HANDLE LARGE AMOUNTS OF RAINFALL IN A SHORT PERIOD OF
TIME...USUALLY LESS THAN SIX HOURS.

IF SIGNIFICANT FLASH FLOODING BECOMES POSSIBLE...USUALLY
ASSOCIATED WITH A TROPICAL CYCLONE OR OTHER WIDESPREAD HEAVY RAIN 
EVENT...THE NATIONAL WEATHER SERVICE WILL ISSUE A FLASH FLOOD
WATCH FOR A DURATION OF SEVERAL HOURS...SOMETIMES SPANNING PERIODS
OF ONE TO TWO DAYS. IF FLASH FLOODING OCCURS OR IS IMMINENT...THE
NATIONAL WEATHER SERVICE WILL ISSUE A FLASH FLOOD WARNING FOR THE
AFFECTED AREA. A FLASH FLOOD WARNING MEANS THAT FLOODING THREATENS
LIFE AND PROPERTY. WARNINGS ARE TYPICALLY ISSUED FOR PERIODS OF
ONE TO THREE HOURS BUT CAN BE ISSUED FOR LONGER PERIODS IF
NECESSARY.

RIVER FLOODING OCCURS AFTER HEAVY RAINFALL HAS FALLEN OVER A RIVER
BASIN. THIS TYPE OF FLOODING DEVELOPS OVER A LONGER PERIOD OF TIME
THAN FLASH FLOODING AND USUALLY ONLY AFFECTS PEOPLE...PROPERTY
AND CROPS THAT ARE NEAR THE BANKS OR WITHIN THE FLOOD PLAIN OF THE
RIVER. WHEN NECESSARY...THE NATIONAL WEATHER SERVICE WILL ISSUE
RIVER FLOOD WARNINGS FOR SPECIFIC LOCATIONS ALONG A GIVEN RIVER.
THE NATIONAL WEATHER SERVICE CATEGORIZES RIVER FLOODING AS
MINOR...MODERATE OR MAJOR BASED ON PREDETERMINED RIVER LEVELS
AT THESE SPECIFIC POINTS.

URBAN FLOODING OCCURS IN CITIES AND TOWNS WHERE DRAINAGE IS
INADEQUATE TO HANDLE THE RUNOFF DURING PERIODS OF HEAVY RAIN. 
AS COVERAGE OF PAVED SURFACES EXPANDS IN URBAN AREAS...THE LAND
ABSORBS LESS RAINFALL AND RUNOFF INTENSIFIES. DURING PERIODS OF
URBAN FLOODING...STREETS CAN BECOME IMPASSABLE AS WATER
ACCUMULATES AT POORLY DRAINED INTERSECTIONS AND LOW SPOTS. URBAN
FLOODING CAN BE ENHANCED ALONG THE SOUTH CAROLINA COAST...
PARTICULARLY IN DOWNTOWN CHARLESTON...WHEN HEAVY RAINFALL OCCURS
AROUND THE TIME OF HIGH TIDE.

WHEN DRIVING...ESPECIALLY AT NIGHT...NEVER CROSS A FLOODED ROADWAY
SINCE IT WILL BE IMPOSSIBLE TO KNOW HOW DEEP THE WATER IS. A TORRENT
OF WATER 18 INCHES DEEP EXERTS ENOUGH FORCE TO SWEEP AN AUTOMOBILE
AWAY. SEEK AN ALTERNATE ROUTE. ALWAYS REMEMBER TO TURN
AROUND...DON/T DROWN.

KNOW THE FLOOD RISK IN AREAS WHERE YOU LIVE...DRIVE AND WORK. BE 
PREPARED TO MOVE TO SAFETY QUICKLY IF A WARNING IS ISSUED FOR YOUR
AREA OR IF YOU OBSERVE RAPIDLY RISING WATER. 

TOMORROW WE WILL DISCUSS SEVERE WEATHER SAFETY. 

CHECK OUT ADDITIONAL SEVERE WEATHER AWARENESS WEEK INFORMATION ON 
OUR WEB PAGE AT WWW/ERH.NOAA.GOV/CHS/...AS WELL ON FACEBOOK AT 
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHARLESTONSC.GOV. YOU CAN 
ALSO FOLLOW @NWSCHARLESTONSC ON TWITTER.  

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