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NCZ087-096-097-099>101-SCZ017-023-024-032>034-039-046-241000-

PUBLIC INFORMATION STATEMENT 
NATIONAL WEATHER SERVICE WILMINGTON NC
600 AM EST WED MAR 23 2005 
 
THE NATIONAL WEATHER SERVICE HAS DECLARED MARCH 21 THROUGH 26 FLOOD 
SAFETY AWARENESS WEEK. THE NATIONAL WEATHER SERVICE IN WILMINGTON 
WILL FEATURE A DIFFERENT EDUCATIONAL TOPIC EACH DAY DURING THE 
AWARENESS WEEK. TODAY'S TOPIC: TROPICAL CYCLONE INLAND FLOODING.

WHEN IT COMES TO TROPICAL CYCLONES, A GENERIC TERM FOR A HURRICANE, 
TYPHOON, OR TROPICAL STORM, WIND SPEEDS DO NOT TELL THE WHOLE STORY. 
INTENSE RAINFALL, NOT DIRECTLY RELATED TO THE WIND SPEED OF A 
TROPICAL CYCLONE, OFTEN CAUSES MORE DAMAGE. SINCE THE 1970S, INLAND 
FLOODING HAS BEEN RESPONSIBLE FOR MORE THAN HALF OF THE DEATHS 
ASSOCIATED WITH TROPICAL CYCLONES IN THE UNITED STATES. TYPICALLY, 
GREATER RAINFALL AMOUNTS AND FLOODING ARE ASSOCIATED WITH TROPICAL 
CYCLONES THAT HAVE A SLOW FORWARD SPEED OR STALL OVER AN AREA. 

WHAT DO I NEED TO KNOW ABOUT INLAND FLOODING FROM TROPICAL CYCLONES? 
INLAND FRESHWATER FLOODS ACCOUNTED FOR MORE THAN HALF OF U.S. 
TROPICAL CYCLONE DEATHS OVER THE PAST 30 YEARS. 

RAINFALL IS TYPICALLY HEAVIER WITH SLOWER MOVING STORMS AS SLOWER 
MOVING TROPICAL CYCLONES ALLOW HEAVY RAIN TO PERSIST OVER A 
LOCATION. 

WHAT TYPES OF INLAND FLOODING ARE CAUSED BY TROPICAL CYCLONES? 
FLASH FLOODING OCCURS IN CREEKS, STREAMS, AND URBAN AREAS WITHIN A 
FEW MINUTES OR HOURS OF EXCESSIVE RAINFALL.  STREETS CAN BECOME 
SWIFT MOVING RIVERS AND UNDERPASSES CAN BECOME DEATH TRAPS.
 
RIVER FLOODING ALSO RESULTS FROM HEAVY RAINS ASSOCIATED WITH 
DECAYING HURRICANES OR TROPICAL STORMS.  HOWEVER...THE FLOODING 
OCCURS OVER A MUCH LONGER TIME SCALE, SOMETIMES LASTING A WEEK OR 
MORE. 

HOW DO I KNOW HOW SEVERE A RIVER FLOOD WILL BE? 
WITHIN RIVER FLOOD WARNING PRODUCTS, THE NWS CONVEYS THE MAGNITUDE 
OF OBSERVED OR FORECAST FLOODING USING FLOOD SEVERITY CATEGORIES. 
THESE FLOOD SEVERITY CATEGORIES INCLUDE MINOR FLOODING, MODERATE 
FLOODING, AND MAJOR FLOODING. EACH CATEGORY HAS A DEFINITION BASED 
ON PROPERTY DAMAGE AND PUBLIC THREAT.
 
MINOR FLOODING: MINIMAL OR NO PROPERTY DAMAGE, BUT POSSIBLY SOME 
PUBLIC THREAT OR INCONVENIENCE.
 
MODERATE FLOODING: SOME INUNDATION OF STRUCTURES AND ROADS NEAR 
STREAMS. SOME EVACUATIONS OF PEOPLE AND...OR TRANSFER OF PROPERTY TO 
HIGHER ELEVATIONS ARE NECESSARY. 

MAJOR FLOODING: EXTENSIVE INUNDATION OF STRUCTURES AND ROADS. 
SIGNIFICANT EVACUATIONS OF PEOPLE AND...OR TRANSFER OF PROPERTY TO 
HIGHER ELEVATIONS.
 
THE IMPACTS OF FLOODS VARY LOCALLY.  FOR EACH NWS RIVER FORECAST 
LOCATION, FLOOD STAGE AND THE STAGE ASSOCIATED WITH EACH OF THE NWS 
FLOOD SEVERITY CATEGORIES ARE ESTABLISHED IN COOPERATION WITH LOCAL 
PUBLIC OFFICIALS.  INCREASING RIVER LEVELS ABOVE FLOOD STAGE 
CONSTITUTE MINOR, MODERATE, AND MAJOR FLOODING.  IMPACTS VARY FROM 
ONE RIVER LOCATION TO ANOTHER BECAUSE A CERTAIN RIVER STAGE (HEIGHT) 
IN ONE LOCATION MAY HAVE AN ENTIRELY DIFFERENT IMPACT THAN THE SAME 
LEVEL ABOVE FLOOD STAGE AT ANOTHER LOCATION. 

$$

RAN