2013 Flood Safety Awareness Week - Types of Floods

PUBLIC INFORMATION STATEMENT
NATIONAL WEATHER SERVICE JACKSONVILLE FL
1200 AM EDT TUE MAR 19 2013

...DAY 2 OF 2013 NATIONAL FLOOD SAFETY AWARENESS WEEK...

THE NATIONAL WEATHER SERVICE HAS DECLARED MARCH 18 THROUGH MARCH 22
AS FLOOD SAFETY AWARENESS WEEK. THE NATIONAL WEATHER SERVICE IN
JACKSONVILLE WILL FEATURE A DIFFERENT EDUCATIONAL TOPIC EACH DAY
DURING THE AWARENESS WEEK.

TODAY'S TOPIC: TYPES OF FLOODS.

IT FLOODS SOMEWHERE IN THE UNITED STATES OR ITS TERRITORIES NEARLY
EVERY DAY OF THE YEAR. FLOODING ALSO CAUSES MORE DAMAGE IN THE UNITED
STATES THAN ANY OTHER WEATHER RELATED EVENT...WITH AN AVERAGE OF
EIGHT BILLION DOLLARS A YEAR IN DAMAGES AND AN AVERAGE OF NINETY-FIVE
FATALITIES PER YEAR IN THE PAST THIRTY YEARS. FLOODING CAN OCCUR IN
ANY OF THE FIFTY STATES OR U.S. TERRITORIES AT ANYTIME OF THE YEAR...
SOMETIMES RAPIDLY. BEING PREPARED IN ADVANCE AND KNOWING A FEW FLOOD
SAFETY TIPS WILL HELP YOU AND YOUR FAMILY SURVIVE A FLOOD IF IT
HAPPENS IN YOUR AREA.

A FLOOD IS DEFINED AS ANY HIGH FLOW...OVERFLOW...OR INUNDATION BY
WATER WHICH CAUSES OR THREATENS DAMAGE. THIS USUALLY OCCURS WITH
PROLONGED RAINFALL OVER SEVERAL DAYS...INTENSE RAINFALL OVER A SHORT
PERIOD OF TIME...OR WHEN AN ICE OR DEBRIS JAM CAUSES A RIVER OR
STREAM TO OVERFLOW AND FLOOD THE SURROUNDING AREA. OTHER FACTORS THAT
CAN CAUSE OR WORSEN FLOODING ARE MELTING SNOW IN THE WINTER AND EARLY
SPRING...THUNDERSTORMS IN THE SPRING AND SUMMER...AND TROPICAL
CYCLONES IN THE SUMMER AND FALL.

FLASH FLOODING...
A FLASH FLOOD IS DEFINED AS A RAPID AND EXTREME FLOW OF HIGH WATER
INTO A NORMALLY DRY AREA...OR A RAPID WATER LEVEL RISE IN A STREAM OR
CREEK ABOVE A PREDETERMINED FLOOD LEVEL. ONGOING FLOODING CAN
INTENSIFY TO FLASH FLOODING IN CASES WHERE INTENSE RAINFALL RESULTS
IN A RAPID SURGE OF RISING FLOOD WATERS. COMMONLY IT OCCURS WITHIN
SIX HOURS OF A HEAVY RAIN EVENT. HOWEVER FLASH FLOODS CAN ALSO OCCUR
WITHIN HOURS OR EVEN MINUTES IF A DAM OR LEVEE FAILS...FOLLOWING A
SUDDEN RELEASE OF WATER HELD BY AN ICE OR DEBRIS JAM...OR RAPID
PONDING OF WATER CAUSED BY TORRENTIAL RAINFALL. FLASH FLOODS CAN EVEN
OCCUR IN AREAS AWAY FROM THE CAUSATIVE EVENT. FOR EXAMPLE...AN
OTHERWISE DRY ARROYO OR CANYON CAN FILL QUICKLY FROM AN UPSTREAM RAIN
EVENT. FLASH FLOODS CAN CATCH PEOPLE OFF GUARD AND UNPREPARED. YOU
MAY ONLY HAVE A FEW MINUTES WARNING THAT THESE DEADLY...SUDDEN FLOODS
ARE COMING. IF YOU LIVE IN AREAS PRONE TO FLASH FLOODS PLAN NOW TO
PROTECT YOUR FAMILY AND PROPERTY.

RIVER FLOODING...
WITH RIVER FLOODING...THE NWS USES DIFFERENT CATEGORIES TO CONVEY THE
EXPECTED FLOOD SEVERITY. THESE CATEGORIES ARE: MINOR FLOODING...
MODERATE FLOODING...AND MAJOR FLOODING. EACH CATEGORY HAS A
DEFINITION BASED ON PROPERTY DAMAGE AND PUBLIC THREAT AND ARE CLOSELY
COORDINATED BY THE NWS OFFICE IN JACKSONVILLE...THE SOUTHEAST RIVER
FORECAST CENTER...OR SERFC...AND OTHER EMERGENCY AND PUBLIC
OFFICIALS. HERE ARE THE OFFICIAL DEFINITIONS OF THE NWS FLOOD
CATEGORIES:
 
MINOR FLOODING USUALLY HAS MINIMAL OR NO PROPERTY DAMAGE... BUT THERE
COULD BE SOME LEVEL OF PUBLIC THREAT OR INCONVENIENCE. MANY TIMES YOU
WILL HEAR THIS REFERRED TO AS NUISANCE FLOODING.

MODERATE FLOODING GENERALLY HAS SOME INUNDATION OF STRUCTURES AND
ROADS NEAR STREAMS AND RIVERS. SOME EVACUATIONS OF PEOPLE AND
TRANSFER OF PROPERTY TO HIGHER ELEVATIONS CAN BECOME NECESSARY WITH
MODERATE FLOODING.

MAJOR FLOODING OCCURS WITH EXTENSIVE INUNDATION OF STRUCTURES AND
ROADS. SIGNIFICANT EVACUATIONS OF PEOPLE AND TRANSFER OF PROPERTY TO
HIGHER ELEVATIONS MAY BECOME NECESSARY.

AN ADDITIONAL CATEGORY OF FLOODING IS RECORD FLOODING. THIS IS
FLOODING WHICH EQUALS OR EXCEEDS THE HIGHEST STAGE OR DISCHARGE
OBSERVED AT A GIVEN SITE DURING THE PERIOD OF RECORD. THE HIGHEST
STAGE ON RECORD IS NOT NECESSARILY ABOVE THE OTHER THREE FLOOD
CATEGORIES...ESPECIALLY IF THE PERIOD OF RECORD IS SHORT.

ONE THING TO NOTE: FLOOD CATEGORIES DO NOT EXIST FOR ALL FORECAST
POINTS OR FLOOD LOCATIONS. THAT DOES NOT MEAN THEY DO NOT FLOOD!
CONTACT YOUR LOCAL NWS OFFICE MORE INFORMATION ON FLOOD CATEGORIES.

COASTAL FLOODING...
COASTAL FLOODING IS ANOTHER TYPE OF FLOOD. WHEN IT COMES TO TROPICAL
CYCLONES...THE GENERIC TERM FOR A HURRICANE...TYPHOON...OR TROPICAL
STORM...WIND SPEEDS DO NOT TELL THE WHOLE STORY. ALONG THE COAST...
STORM SURGE IS OFTEN THE GREATEST THREAT TO LIFE AND PROPERTY FROM A
TROPICAL CYCLONE. IN THE PAST, LARGE DEATH TOLLS HAVE RESULTED FROM
THE RISE OF THE OCEAN ASSOCIATED WITH MANY OF THE MAJOR HURRICANES
THAT HAVE MADE LANDFALL. HURRICANE KATRINA IN 2005 IS A PRIME EXAMPLE
OF THE DAMAGE AND DEVASTATION THAT CAN BE CAUSED BY STORM SURGE. AT
LEAST 1500 PEOPLE LOST THEIR LIVES DURING HURRICANE KATRINA AND MANY
OF THOSE DEATHS OCCURRED DIRECTLY...OR INDIRECTLY...AS A RESULT OF
STORM SURGE. BY KNOWING YOUR VULNERABILITY AND WHAT ACTIONS YOU
SHOULD TAKE...YOU CAN REDUCE THE EFFECTS OF A COASTAL FLOODING
DISASTER.

INLAND FLOODING...
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. THESE AREAS CAN BE RIGHT ALONG THE COAST...BUT
THEY MAY BE EVEN HUNDREDS OF MILES AWAY FROM WHERE THE STORM MADE
LANDFALL. TROPICAL STORM LEE IS A RECENT EXAMPLE OF INLAND FLOODING
SEVERAL HUNDREDS OF MILES AWAY FROM WHERE THE EYE OF THE STORM
ULTIMATELY LANDED. IN 2011...TROPICAL STORM LEE MADE LANDFALL ALONG
THE LOUISIANA COAST...BUT THE REMNANTS FROM THE STORM CAUSED HEAVY
RAINFALL AND HISTORIC FLOODING IN WASHINGTON DC...PENNSYLVANIA...AND
AS FAR AWAY AS NEW YORK. TEN FATALITIES...ALL IN PENNSYLVANIA...WERE
CONFIRMED AS FLOOD RELATED DURING THE FLOODING ASSOCIATED WITH
TROPICAL STORM LEE.

RAINFALL FROM TROPICAL CYCLONE REMNANTS CAN CAUSE FLOODING IF
CONDITIONS ARE RIGHT. FLASH FLOODING CAN OCCUR 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 CAN OCCUR FROM HEAVY RAINS ASSOCIATED
WITH DECAYING TROPICAL CYCLONES...AND IN EXTREME CASES...RIVER FLOODS
CAN LAST A WEEK OR MORE. JUST BECAUSE YOU DO NOT LIVE NEAR THE COAST
DOES NOT MEAN YOU WILL NOT BE IMPACTED BY TROPICAL CYCLONE FLOODING.

KNOWING THE DIFFERENT TYPES OF FLOODS...HOW TO PREPARE FOR THEM...AND
KNOWING THE ACTIONS TO TAKE DURING...AND AFTERWARDS CAN SAVE YOU
TIME...MONEY...AND EVEN YOUR LIFE. PREPARE NOW...AND BE A FORCE OF
NATURE!

JOIN US TOMORROW FOR INFORMATION ON TURN AROUND...DON’T DROWN.

&&

IMPORTANT FLOOD WEBSITES

NWS AHPS: HTTP://WATER.WEATHER.GOV/AHPS/

NATIONAL HURRICANE CENTER: HTTP://WWW.NHC.NOAA.GOV/

NWS MARINE AND COASTAL SERVICES:
HTTP://WWW.NWS.NOAA.GOV/OM/MARINE/MARINE.SHTML

NWS FLOOD SAFETY AWARENESS: HTTP://WWW.FLOODSAFETY.NOAA.GOV/

NWS: HTTP://WWW.WEATHER.GOV/

NWS WRN: HTTP://WWW.NWS.NOAA.GOV/COM/WEATHERREADYNATION/

BE A FORCE OF NATURE:
HTTP://WWW.NWS.NOAA.GOV/COM/WEATHERREADYNATION/FORCE.HTML

$$





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