055
FGUS75 KBOI 012005 CCA
ESFBOI
IDC001-003-005-007-009-011-013-015-017-019-021-023-025-027-029-031-
033-035-037-039-041-043-045-047-049-051-053-055-057-059-061-063-065-
067-069-071-073-075-077-079-081-083-085-087-020600-
WATER SUPPLY OUTLOOK
NATIONAL WEATHER SERVICE BOISE ID
105 PM MST FRI MAR 1 2024
..IDAHO SPRING FLOOD AND WATER RESOURCES OUTLOOK
SPRING FLOOD POTENTIAL...
THE RISK FOR SPRING FLOODING DUE TO SNOWMELT IS NORMAL TO ABOVE
NORMAL FOR MOST OF SOUTHERN IDAHO. AREAS SOUTH OF THE SNAKE RIVER
PLAIN WHERE SNOWPACK IS WELL ABOVE NORMAL HAVE THE GREATEST RISK OF
SPRING FLOODING, INCLUDING THE PORTNEUF, BLACKFOOT AND BEAR RIVER
BASINS. THE SPRING FLOOD RISK FOR THE BOISE RIVER BASIN, WOOD RIVER
AND LOST RIVER BASINS, HENRY'S FORK, AND TETON BASINS IS NEAR
NORMAL. ELSEWHERE ACROSS THE CENTRAL MOUNTAINS AND NORTHERN IDAHO
THE SPRING FLOOD RISK IS GENERALLY LOW, ESPECIALLY ACROSS THE
CLEARWATER, PALOUSE, AND NORTHERN PANHANDLE REGION WHERE SNOWPACK IS
WELL BELOW NORMAL AND SUBSTANTIAL WATER YEAR PRECIPITATION AND SOIL
MOISTURE DEFICITS RESIDE.
IDAHO'S SNOWPACK AS A WHOLE TYPICALLY CONTINUES BUILDING THROUGH
MARCH AND PEAKS IN EARLY APRIL, LEAVING SEVERAL WEEKS AHEAD OF US
FOR ADDITIONAL SNOW ACCUMULATION AND POTENTIAL CHANGES TO THE SPRING
FLOOD RISK.
THE PRIMARY FACTORS IN THE DEVELOPMENT OF SPRING FLOODING ARE THE
OCCURRENCE OF PERSISTENT ABOVE NORMAL TEMPERATURES, AND RAIN ON SNOW
PRECIPITATION EVENTS. EVEN IF MAINSTEM RIVERS DO NOT REACH FLOOD
STAGE, SMALLER CREEKS AND STREAMS CAN STILL OVERFLOW THEIR BANKS.
UNDER THE RIGHT SCENARIO, SPRING FLOODING IS POSSIBLE EVEN FOR AREAS
THAT HAVE LOW SNOWPACK. ADDITIONALLY, WILDFIRE BURN SCARS CAN HAVE A
SIGNIFICANT IMPACT ON LOCAL FLOOD POTENTIAL DURING SPRING SNOWMELT.
TEMPERATURE AND PRECIPITATION SUMMARY...
NORMAL TO ABOVE NORMAL TEMPERATURES DOMINATED THE FIRST THREE MONTHS
OF THE 2024 WATER YEAR, ESPECIALLY IN DECEMBER WHERE TEMPERATURE
ANOMALIES WERE 3 TO 6 DEGREES ABOVE NORMAL. A COLD ARCTIC OUTBREAK
IN EARLY JANUARY BROUGHT A PERIOD OF WELL BELOW NORMAL TEMPERATURES
TO THE STATE RESULTING IN JANUARY TEMPERATURE ANOMALIES BEING
SLIGHTLY BELOW NORMAL ACROSS NORTHERN IDAHO AND ONLY SLIGHTLY ABOVE
NORMAL ACROSS CENTRAL AND SOUTHERN IDAHO. FEBRUARY TEMPERATURES HAVE
GENERALLY BEEN 1 TO 3 DEGREES ABOVE NORMAL ACROSS THE STATE.
OCTOBER PRECIPITATION WAS WELL ABOVE NORMAL ACROSS MOST OF THE SNAKE
RIVER PLAIN AND BASINS ALONG THE UTAH AND NEVADA BORDER. MEANWHILE,
NORTHERN AND CENTRAL IDAHO EXPERIENCED BELOW TO WELL BELOW NORMAL
PRECIPITATION IN OCTOBER WITH MUCH OF NORTHERN IDAHO RECEIVING LESS
THAN 50 PERCENT OF NORMAL. THIS PATTERN OF WET CONDITIONS ACROSS THE
SOUTHERN THIRD OF IDAHO AND PROGRESSIVELY DRIER CONDITIONS ACROSS
CENTRAL AND NORTHERN IDAHO GENERALLY PERSISTED THROUGH THE WATER
YEAR TO DATE, ALTHOUGH NORTHERN IDAHO HAS SEEN IMPROVED
PRECIPITATION DURING THE MONTH OF FEBRUARY.
SNOWPACK...
SOUTHSIDE SNAKE RIVER BASINS ALONG THE UTAH AND NEVADA BORDER ARE
HOLDING THE HIGHEST SNOWPACK PERCENTAGES AS OF MARCH 1, RANGING FROM
120 TO 146 PERCENT OF MEDIAN. PERCENTAGES DECREASE TO THE NORTH,
RANGING FROM 80 TO 100 PERCENT OF MEDIAN ACROSS THE CENTRAL
MOUNTAINS AND SNAKE RIVER HEADWATERS REGION. SNOWPACK PERCENTAGES
ARE ONLY AROUND 65 TO 77 PERCENT OF MEDIAN ACROSS THE NORTHERN THIRD
OF THE STATE WITH SOME SNOTEL LOCATIONS IN THE CLEARWATER, COEUR
D'ALENE, AND ST. JOE BASINS SITTING NEAR RECORD LOWS. IDAHO SNOWPACK
AS A WHOLE TYPICALLY BUILDS THROUGH MARCH AND PEAKS IN EARLY APRIL.
AS SPRING TEMPERATURES WARM THE SNOWPACK WILL RIPEN AND EVENTUALLY
REACH A STATE WHERE SNOWMELT DRIVEN RUNOFF SUBSTANTIALLY INCREASES.
RESERVOIRS...
THE MAJORITY OF RESERVOIRS ACROSS SOUTHERN IDAHO AND EASTERN OREGON
ARE HOLDING ABOVE AVERAGE STORAGE. WEATHER PATTERNS, IRRIGATION
DEMAND, AND FLOOD RISK MANAGEMENT WILL DRIVE RESERVOIR OPERATIONS
OVER THE NEXT SEVERAL MONTHS. WET SPRING WEATHER OR EXTENDED PERIODS
OF ABOVE NORMAL TEMPERATURES RESULTING IN RAPID SNOWMELT AND LARGE
RESERVOIR INFLOWS COULD RESULT IN SIGNIFICANT FLUCTUATIONS IN
RESERVOIR DISCHARGE AND DOWNSTREAM RIVER LEVELS.
OBSERVED STREAMFLOW...
OBSERVED RUNOFF VOLUMES FOR THE WATER YEAR AS A WHOLE HAVE GENERALLY
BEEN BELOW NORMAL ACROSS NORTHERN IDAHO AND MOSTLY NEAR NORMAL OR
ABOVE NORMAL FOR THE SOUTHERN HALF OF THE STATE. USGS STREAMFLOW
AVERAGES FOR THE MONTH OF FEBRUARY HAVE BEEN NORMAL TO ABOVE NORMAL
WITH THE EXCEPTION OF SOME LOWER FLOWS ON THE MAINSTEM SNAKE RIVER
IN SOUTHERN IDAHO.
DROUGHT...
LONG AND SHORT-TERM PRECIPITATION DEFICITS ALONG WITH ABOVE NORMAL
TEMPERATURES HAVE ALLOWED VARYING DEGREES OF DROUGHT TO PERSIST
ACROSS THE NORTHERN HALF OF THE STATE. TEMPERATURE AND
PRECIPITATION PATTERNS FOR THE REMAINDER OF THE WINTER AND THIS
SPRING WILL DETERMINE WHETHER OR NOT DROUGHT CONDITIONS IMPROVE OR
DETERIORATE.
WATER SUPPLY...
NATIONAL WEATHER SERVICE WATER SUPPLY FORECASTS FOR APRIL THROUGH
SEPTEMBER 2024 CALL FOR NEAR NORMAL TO WELL ABOVE NORMAL RUNOFF
VOLUMES FOR THE SOUTHERN THIRD OF IDAHO. MEANWHILE, FORECASTS FOR
THE CENTRAL MOUNTAINS INCLUDING THE BOISE BASIN, WOOD AND LOST RIVER
BASINS, AND SNAKE RIVER HEADWATERS REGION ARE GENERALLY FORECAST TO
90 TO 95 PERCENT OF NORMAL. FOR THE REST OF CENTRAL AND NORTHERN
IDAHO THE WATER SUPPLY FORECASTS ARE ABOUT 75 TO 85 PERCENT OR
NORMAL.
SEASONAL OUTLOOK...
THE OUTLOOK FOR THE MONTH OF MARCH INDICATES EQUAL CHANCES FOR
EITHER BELOW NORMAL, NORMAL, OR ABOVE NORMAL TEMPERATURES ACROSS
IDAHO. MEANWHILE, ABOVE NORMAL PRECIPITATION IS FAVORED FOR THE
SOUTHERN HALF OF THE STATE WITH EQUAL CHANCES OF EITHER BELOW
NORMAL, NORMAL, OR ABOVE NORMAL PRECIPITATION ACROSS NORTHERN IDAHO.
THE OUTLOOK FOR APRIL THROUGH JUNE FAVORS ABOVE NORMAL TEMPERATURES
ACROSS IDAHO. ODDS FAVOR BELOW NORMAL PRECIPITATION FOR THE
PANHANDLE REGION OF IDAHO DURING THE PERIOD. ACROSS SOUTHERN IDAHO
THERE ARE EQUAL CHANCES FOR EITHER BELOW, ABOVE, OR NORMAL
PRECIPITATION.
ON-LINE RESOURCES...
REFER TO THE LINKS PROVIDED BELOW FOR THE LATEST INFORMATION ON
WATER RESOURCES.
WATER SUPPLY VOLUME FORECASTS
NATIONAL WEATHER SERVICE-NORTHWEST RIVER FORECAST CENTER
WWW.NWRFC.NOAA.GOV/WS/
NATIONAL WEATHER SERVICE-COLORADO BASIN RIVER FORECAST CENTER
WWW.CBRFC.NOAA.GOV/
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.NRCS.USDA.GOV/WPS/PORTAL/NRCS/MAIN/ID/SNOW/
RESERVOIR STORAGE
BUREAU OF RECLAMATION WWW.USBR.GOV/PN/HYDROMET/SELECT.HTML
USDA-NATURAL RESOURCES CONSERVATION SERVICE
WWW.NRCS.USDA.GOV/WPS/PORTAL/NRCS/MAIN/ID/SNOW
DROUGHT CONDITIONS
U.S. DROUGHT PORTAL WWW.DROUGHT.GOV
PEAK FLOW FORECASTS
NORTHWEST RIVER FORECAST CENTER WWW.NWRFC.NOAA.GOV/PEAK/
COLORADO BASIN RIVER FORECAST CENTER
WWW.CBRFC.NOAA.GOV/RMAP/PEAK/PEAKLIST.PHP
TEMPERATURE AND PRECIPITATION OUTLOOK
CLIMATE PREDICTION CENTER WWW.CPC.NCEP.NOAA.GOV/
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