Public Information Statement
Issued by NWS Aberdeen, SD

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NOUS43 KABR 190920
PNSABR
MNZ039-046-SDZ003>011-015>023-033>037-045-048-051-200000-

PUBLIC INFORMATION STATEMENT
NATIONAL WEATHER SERVICE ABERDEEN SD
420 AM CDT WED MAR 19 2014 /320 AM MDT WED MAR 19 2014/

THE NATIONAL WEATHER SERVICE (NWS) HAS DECLARED MARCH 17 THROUGH MARCH
21 AS FLOOD SAFETY AWARENESS WEEK. THE NATIONAL WEATHER SERVICE IN
ABERDEEN SD WILL FEATURE INFORMATION ABOUT A DIFFERENT FLOOD TOPIC EACH
DAY DURING THE AWARENESS WEEK.

TODAYS TOPIC: FLOODS HAZARDS

A FLOOD IS DEFINED AS ANY HIGH FLOW...OVERFLOW...OR INUNDATION OF WATER
THAT CAUSES OR THREATENS DAMAGE.  FLOODING CAN OCCUR WITH PROLONGED
RAINFALL OVER SEVERAL DAYS...INTENSE RAINFALL OVER A SHORT PERIOD OF
TIME...OR WHEN WATER FROM AN EXISTING SOURCE MOVES TOO QUICKLY (I.E.
SNOW MELT...DAM BREAK...ETC.). BRIEF DESCRIPTIONS OF THE VARIOUS TYPES OF
FLOODING YOU MAY EXPERIENCE ARE FOUND BELOW.  MORE INFORMATION ABOUT THESE
FLOOD HAZARDS CAN BE FOUND ON THE NWS FLOOD SAFETY WEBSITE AT
WWW.FLOODSAFETY.NOAA.GOV.

FLASH FLOODING: FLASH FLOODING IS 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...BEGINNING WITHIN SIX HOURS OF
THE CAUSATIVE EVENT (I.E. INTENSE RAINFALL...DAM FAILURE...ICE JAM).

RIVER FLOODING: RIVER FLOODING OCCURS WHEN RIVERS RISE AND OVERFLOW THEIR
BANKS...INUNDATING AREAS THAT ARE NORMALLY DRY.

TROPICAL SYSTEMS AND COASTAL FLOODING: AT ANY TIME OF YEAR...A STORM FROM
OVER THE OCEAN CAN BRING HEAVY PRECIPITATION TO THE U.S. COASTS. WHETHER
SUCH A STORM IS TROPICAL OR NOT...PROLONGED PERIODS OF HEAVY PRECIPITATION
CAN CAUSE FRESHWATER FLOODING IN COASTAL AREAS...AS WELL AS FURTHER INLAND
AS THE STORM MOVES ON SHORE. IN ADDITION TO THE FRESHWATER FLOOD THREAT
TROPICAL SYSTEMS AND NOR EASTERS CAN BRING THE THREAT OF STORM
SURGE RELATED COASTAL FLOODING.

BURN SCARS/DEBRIS FLOWS: WILDFIRES BURN AWAY THE VEGETATION OF AN AREA...
LEAVING BEHIND BARE GROUND THAT TENDS TO REPEL WATER. WHEN RAIN FALLS...IT
RUNS OFF A BURN SCAR TOWARDS A LOW LYING AREA...SOMETIMES CARRYING
BRANCHES...SOIL AND OTHER DEBRIS ALONG WITH IT. WITHOUT VEGETATION TO HOLD
THE SOIL IN PLACE...FLOODING CAN PRODUCE MUD AND DEBRIS FLOWS.

SNOW MELT: FLOODING DUE TO SNOW MELT MOST OFTEN OCCURS IN THE SPRING WHEN
WARMING TEMPERATURES QUICKLY MELT THE SNOW. THE WATER RUNS OFF THE STILL
PARTIALLY FROZEN OR ALREADY SATURATED GROUND INTO NEARBY STREAMS AND
RIVERS...CAUSING THEM TO RAPIDLY RISE AND SOMETIMES OVERFLOW THEIR BANKS.

ICE AND DEBRIS JAMS: A BACKUP OF WATER INTO SURROUNDING AREAS CAN OCCUR
WHEN A RIVER OR STREAM IS BLOCKED BY A BUILD-UP OF ICE OR OTHER DEBRIS.

DRY WASH: WHEN HEAVY RAIN FALLS OVER DRY LAND...THE WATER RUSHES TOWARDS
LOW-LYING AREAS...WHICH MAY INCLUDE DRIED UP CANYON OR STREAM BEDS. THIS
CAN QUICKLY TURN A DRY CHANNEL INTO A RAGING RIVER.

DAM BREAK AND LEVEE FAILURE: A BREAK OR FAILURE CAN OCCUR WITH LITTLE TO
NO WARNING. MOST OFTEN THEY ARE CAUSED BY WATER OVER TOPPING THE
STRUCTURE...EXCESSIVE SEEPAGE THROUGH THE SURROUNDING GROUND...OR A
STRUCTURAL FAILURE.

UNDERSTANDING THE DIFFERENT FLOOD HAZARDS AND KNOWING THE ACTIONS TO TAKE
BEFORE...DURING...AND AFTERWARDS CAN HELP YOU PROTECT YOUR LIFE...THE
LIVES OF YOUR LOVED ONES...AND YOUR PROPERTY.  PREPARE NOW BY VISITING
WWW.FLOODSAFETY.NOAA.GOV

JOIN US TOMORROW FOR INFORMATION ON FLOOD RELATED SERVICES PROVIDED BY THE
NATIONAL WEATHER SERVICE.

$$








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