Flood Potential Outlook
Issued by NWS Boise, ID

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029-031-033-035-037-039-041-043-045-047-049-051-053-055-057-059-061-
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WATER SUPPLY OUTLOOK
NATIONAL WEATHER SERVICE BOISE IDAHO
309 PM MDT FRI APR 8 2016

...IDAHO SPRING FLOOD AND WATER RESOURCES OUTLOOK...

THE POTENTIAL FOR SPRING FLOODING DUE TO SNOWMELT ACROSS IDAHO IS
AVERAGE TO BELOW AVERAGE. LOW ELEVATION SNOW AND MUCH OF THE MID
ELEVATION SNOWPACK HAS ALREADY MELTED. HOWEVER...ABUNDANT HIGH
ELEVATION SNOWPACK REMAINS ACROSS THE STATE.

THE PRIMARY FACTORS IN THE DEVELOPMENT OF SPRING FLOODING ARE THE
OCCURRENCE OF PERSISTENT ABOVE NORMAL TEMPERATURES...AND RAIN ON
SNOW PRECIPITATION EVENTS. EVEN FOR AREAS THAT HAVE LOW
SNOWPACK...SPRING FLOODING IS POSSIBLE UNDER THE RIGHT SCENARIO.
ADDITIONALLY...BURN SCARS CAN HAVE A SIGNIFICANT IMPACT ON LOCAL
FLOOD POTENTIAL DURING SPRING SNOWMELT.

NATIONAL WEATHER SERVICE APRIL THROUGH SEPTEMBER WATER SUPPLY
FORECASTS VARY FROM 90 TO 110 PERCENT OF AVERAGE FOR THE PANHANDLE
REGION...THE CLEARWATER BASIN...SALMON RIVER BASINS AND WEST CENTRAL
BASINS. FORECASTS FOR THE WOOD AND LOST RIVER BASINS RANGE FROM 100
TO 130 PERCENT OF AVERAGE. SOUTHSIDE SNAKE RIVER BASIN FORECASTS ARE
GENERALLY 110 TO 135 PERCENT OF AVERAGE. FORECASTS FOR EASTERN IDAHO
AND THE MAINSTEM SNAKE RIVER IN SOUTHERN IDAHO RANGE FROM 70 TO 95
PERCENT OF AVERAGE FOR THE APRIL THROUGH SEPTEMBER PERIOD. THESE
FORECASTS MAY CHANGE SLIGHTLY BASED ON SPRING RAINFALL PATTERNS.

PRECIPITATION...

AS OF APRIL 8...WATER YEAR PRECIPITATION WAS NORMAL OR ABOVE NORMAL
FOR MOST OF IDAHO. PERCENTAGES WERE THE HIGHEST ALONG THE SOUTHERN
BORDER...WHERE MOST OF OWYHEE COUNTY...SOUTHWEST TWIN FALLS COUNTY
...ONEIDA COUNTY AND MUCH OF BANNOCK AND WESTERN CARIBOU COUNTIES
RECEIVED 130 TO 150 PERCENT OF NORMAL. LOWEST PERCENTAGES IN THE
STATE WERE MOSTLY OVER NORTHEAST IDAHO...WHERE A PORTION OF FREMONT
COUNTY AND POCKETS OF THE LOST RIVER BASINS RECEIVED ONLY 70 TO 90
PERCENT OF NORMAL PRECIPITATION.

SNOWPACK...

APRIL 1...SNOWPACK ACROSS IDAHO WAS NEAR NORMAL OR ABOVE NORMAL FOR
ALMOST ALL BASINS. WITH THE EXCEPTION OF THE OWYHEE BASIN WHICH WAS
AT 67 PERCENT OF NORMAL...HIGHEST PERCENTAGES WERE ACROSS SOUTHSIDE
SNAKE RIVER BASINS...THE SALMON RIVER AND WEST CENTRAL BASINS...AND
WOOD AND LOST RIVER BASINS WITH 98 TO 124 PERCENT OF NORMAL.
ELSEWHERE...APRIL 1 BASIN SNOWPACK WAS GENERALLY 95 TO 105 PERCENT
OF NORMAL.

RESERVOIRS...

EARLY APRIL RESERVOIR STORAGE ACROSS IDAHO WAS IN GOOD SHAPE OVERALL
AND MANY RESERVOIRS ARE EXPECTED TO FILL. EVEN FOR THOSE THAT MAY
NOT FILL...WATER SUPPLIES ARE GENERALLY EXPECTED TO BE ADEQUATE.
GOOD INFLOWS ON THE OWYHEE SYSTEM IN MARCH DOUBLED THE ACTIVE LAKE
STORAGE COMPARED ITS HIGHEST POINT LAST YEAR. PRECIPITATION...
SNOWMELT AND IRRIGATION DEMAND WILL DRIVE RESERVOIR OPERATIONS OVER
THE NEXT FEW MONTHS. WET SPRING WEATHER OR EXTENDED PERIODS OF
WARMTH RESULTING IN RAPID SNOWMELT COULD RESULT IN SIGNIFICANT
INCREASES IN RESERVOIR OUTFLOWS AND RIVER LEVELS.

DROUGHT...

AUTUMN RAINS FOLLOWED BY A GOOD WINTER AND EARLY SPRING SNOWPACK
HAVE EASED DROUGHT CONCERNS ACROSS IDAHO. JUST A FEW POCKETS OF
ABNORMALLY DRY CONDITIONS REMAINING ACROSS THE STATE ACCORDING TO
THE U.S. DROUGHT MONITOR. WEATHER AND PRECIPITATION THE REMAINDER OF
THIS SPRING WILL DETERMINE WHETHER OR NOT CONDITIONS CONTINUE TO
IMPROVE BEFORE HEADING INTO THE WARM AND DRY SEASON.

LONG RANGE OUTLOOK...

THE OUTLOOK FOR APRIL...MAY AND JUNE FAVORS ABOVE NORMAL
TEMPERATURES ACROSS IDAHO. THE PRECIPITATION OUTLOOK LEANS SLIGHTLY
TOWARD BELOW NORMAL PRECIPITATION FOR THE PANHANDLE REGION...AND FOR
ABOVE NORMAL PRECIPITATION FOR SOUTHERN IDAHO. FOR CENTRAL
IDAHO...THE ODDS ARE NOT SHIFTED IN EITHER DIRECTION.

REFER TO THE LINKS PROVIDED BELOW FOR THE LATEST INFORMATION ON
WATER RESOURCES.

WATER SUPPLY VOLUME FORECASTS...
NATIONAL WEATHER SERVICE-NORTHWEST
RIVER FORECAST CENTER HTTP://WWW.NWRFC.NOAA.GOV/WS/

NATIONAL WEATHER SERVICE-COLORADO BASIN RIVER FORECAST CENTER
WWW.CBRFC.NOAA.GOV/

USDA-NATURAL RESOURCES CONSERVATION SERVICE
WWW.NRCS.USDA.GOV/WPS/PORTAL/NRCS/MAIN/ID/SNOW/

SNOWPACK INFORMATION...
NATIONAL WEATHER SERVICE-NORTHWEST RIVER
FORECAST CENTER WWW.NWRFC.NOAA.GOV/SNOW/

NATIONAL WEATHER SERVICE-NATIONAL OPERATIONAL HYDROLOGIC REMOTE
SENSING CENTER
WWW.NOHRSC.NOAA.GOV/

USDA-NATURAL RESOURCES CONSERVATION SERVICE
WWW.ID.NRCS.USDA.GOV/WPS/PORTAL/NRCS/MAIN/ID/SNOW

RESERVOIR STORAGE...
BUREAU OF RECLAMATION RESERVOIR STORAGE
WWW.USBR.GOV/PN/HYDROMET/SELECT.HTML

USDA-NATURAL RESOURCES CONSERVATION SERVICE
WWW.WCC.NRCS.USDA.GOV/BASIN.HTML

DROUGHT CONDITIONS...
U.S. DROUGHT PORTAL
WWW.DROUGHT.GOV

U.S. DROUGHT MONITOR
WWW.DROUGHTMONITOR.UNL.EDU/

PEAK FLOW FORECASTS...
NORTHWEST RIVER FORECAST CENTER PEAK FLOW
WWW.NWRFC.NOAA.GOV/PEAK/

COLORADO BASIN RIVER FORECAST CENTER PEAK FLOW
WWW.CBRFC.NOAA.GOV/RMAP/PEAK/PEAKLIST.PHP

TEMPERATURE AND PRECIPITATION OUTLOOK...
CLIMATE PREDICTION CENTER
WWW.CPC.NCEP.NOAA.GOV/

$$

LINDQUIST



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