Public Information Statement
Issued by NWS Flagstaff, AZ

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PUBLIC INFORMATION STATEMENT
NATIONAL WEATHER SERVICE FLAGSTAFF AZ
1200 AM MST WED MAR 19 2014

THE NATIONAL WEATHER SERVICE (NWS) HAS DECLARED MARCH 16 THROUGH
MARCH 22 AS FLOOD SAFETY AWARENESS WEEK. THE NATIONAL WEATHER
SERVICE IN FLAGSTAFF WILL FEATURE INFORMATION ABOUT A DIFFERENT
FLOOD TOPIC EACH DAY DURING THE AWARENESS WEEK.


TODAY`S 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. SNOWMELT...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.

SNOWMELT: FLOODING DUE TO SNOWMELT 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
OVERTOPPING 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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