Flood Potential Outlook
Issued by NWS Portland, OR

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WATER SUPPLY OUTLOOK
NATIONAL WEATHER SERVICE PORTLAND OR
1140 AM PST SAT APRIL 12 2014

...OREGON WATER SUPPLY AND SPRING FLOOD POTENTIAL OUTLOOK AS OF
APRIL 12TH 2014...

THE OREGON WATER SUPPLY FOR THE SPRING AND SUMMER IS FORECAST TO BE
BELOW-NORMAL FOR MOST OF OREGON...ESPECIALLY SOUTHERN AND EAST-
CENTRAL BASINS. NEAR-NORMAL WATER SUPPLY IS FORECAST FOR BASINS IN
APPROXIMATELY THE NORTHERN THIRD OF THE STATE. WATER SUPPLY
FORECASTS ARE BASED ON CURRENT SNOWPACK CONDITIONS AND OBSERVED
PRECIPITATION THUS FAR THIS WINTER. THE POTENTIAL FOR SPRING
SNOWMELT FLOODING IS NEAR-AVERAGE IN NORTHEAST OREGON AND BELOW-
AVERAGE ELSEWHERE IN OREGON. SPRINGTIME /MAY-JUNE/ FLOODING IS
TYPICALLY LIMITED TO BASINS EAST OF THE CASCADES AND IS USUALLY
CAUSED BY A COMBINATION OF RAINFALL AND SNOWMELT.

MARCH PRECIPITATION WAS ABOVE-NORMAL FOR MOST OREGON BASINS. THIS
WAS THE SECOND WET MONTH IN A ROW AFTER A VERY DRY START TO THE
WATER YEAR /OCTOBER THROUGH JANUARY/. MOST OF THE PRECIPITATION IN
MARCH FELL AS RAIN...AND SNOWPACK REMAINS VERY LOW AT MOST MOUNTAIN
MONITORING SITES. MANY SOUTHERN OREGON SNOTEL SITES ARE AT OR NEAR
RECORD LOW LEVELS FOR SNOW WATER EQUIVALENT.

DESPITE THE WET CONDITIONS OF THE PAST TWO MONTHS...DROUGHT IMPACTS
ARE LIKELY FOR MANY BASINS IN SOUTHERN AND CENTRAL OREGON. FEDERAL
AND STATE DROUGHT DECLARATIONS ARE ALREADY IN EFFECT FOR SEVERAL
OREGON COUNTIES. MOST OF THE SOUTHERN HALF OF THE STATE IS IN A D2
/SEVERE DROUGHT/ DESIGNATION...WHILE MOST OF THE NORTHERN HALF AND A
PART OF SOUTHWEST IS D1 /MODERATE DROUGHT/. VISIT DROUGHT.GOV FOR
IMAGES AND DETAILS OF CURRENT AND PREDICTED DROUGHT CONDITIONS.

WATER SUPPLY FORECASTS ARE UPDATED ON A DAILY BASIS AT
WWW.NWRFC.NOAA.GOV (MOST OF OREGON) AND WWW.CNRFC.NOAA.GOV (KLAMATH
BASIN). PRECIPITATION FOR THE REMAINDER OF SPRING WILL LIKELY NOT BE
ENOUGH TO BRING SIGNIFICANT CHANGE TO WATER SUPPLY
CONDITIONS...ESPECIALLY FOR SOUTHERN OREGON.

REFER TO THE SECTIONS BELOW AND THE LINKS PROVIDED FOR DETAILS
REGARDING SNOWPACK...PRECIPITATION...RESERVOIR CONDITIONS AND WATER
SUPPLY FORECASTS.

NOAA`S CLIMATE PREDICTION CENTER SEASONAL OUTLOOKS FOR APRIL THROUGH
JUNE CALL FOR AN ENHANCED LIKELIHOOD OF BELOW-NORMAL PRECIPITATION
AND ABOVE-NORMAL TEMPERATURES FOR MUCH OF OREGON. ENSO-NEUTRAL
CONDITIONS IN THE TROPICAL PACIFIC ARE EXPECTED TO CONTINUE THROUGH
THE SPRING. FOR MORE INFORMATION ON SEASONAL OUTLOOKS...VISIT
WWW.CPC.NCEP.NOAA.GOV.

THE NEXT UPDATE OF THIS OUTLOOK WILL BE ISSUED BY MAY 12TH.

============================================================
SNOWPACK ACROSS OREGON

SNOWPACK AS OF EARLY APRIL WAS BELOW-NORMAL IN ALL BASINS EXCEPT FOR
SOME FAR-NORTHEAST BASINS WHERE SEASONAL TOTALS ARE NEAR-NORMAL.
SEASONAL SNOWPACK IN THE SOUTHERN OREGON CASCADES AND SOUTHEAST
MOUNTAINS REMAINS ESPECIALLY LOW...RANGING FROM 25 TO 50 PERCENT OF
AVERAGE. SEVERAL SNOTEL STATIONS IN SOUTH-CENTRAL OREGON ARE AT OR
NEAR RECORD LOWS FOR SNOW-WATER EQUIVALENT...EVEN WITH A LATE MARCH
STORM THAT PROVIDED A SMALL BOOST IN SNOWPACK FOR MUCH OF THE STATE.
PEAK SEASONAL SNOWPACK TYPICALLY OCCURS BETWEEN LATE MARCH AND MID
APRIL.

REFER TO THE FOLLOWING LINKS FOR MORE DETAILS ON SNOW CONDITIONS.

NOAA`S NATIONAL WEATHER SERVICE - NORTHWEST RIVER FORECAST CENTER
WWW.NWRFC.NOAA.GOV/SNOW/

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

============================================================
PRECIPITATION ACROSS OREGON

SEASONAL PRECIPITATION TOTALS ARE BELOW-NORMAL ACROSS OREGON FOR THE
FIRST FIVE MONTHS OF THE 2014 WATER YEAR...RANGING FROM 40 TO 70
PERCENT FOR THE SOUTHERN HALF OF THE STATE AND 60 TO 90 PERCENT FOR
THE NORTHERN HALF. WHILE LOW...THESE NUMBERS ARE A SIGNIFICANT
IMPROVEMENT FROM LATE JANUARY. SEASONAL TOTALS IN TERMS OF PERCENT
OF AVERAGE HAVE IMPROVED 15 TO 30 PERCENT OVER THE LAST TWO MONTHS.

VISIT THE FOLLOWING LINK FOR MORE DETAILS ON PRECIPITATION TOTALS.

NOAA`S NATIONAL WEATHER SERVICE - NORTHWEST RIVER FORECAST CENTER
WWW.NWRFC.NOAA.GOV/WATER_SUPPLY/WY_SUMMARY/WY_SUMMARY.PHP

============================================================
MAJOR IRRIGATION RESERVOIRS

AT THE CLOSE OF MARCH...1.6 MILLION ACRE-FEET OF WATER WAS STORED IN
26 MAJOR IRRIGATION RESERVOIRS IN OREGON. THE CURRENT STORAGE
REPRESENTS 71 PERCENT OF AVERAGE...AND IS ONLY 50 PERCENT OF STORAGE
CAPACITY. THE CURRENT STORAGE IS 118 PERCENT OF STORAGE FOR THIS
SAME TIME LAST YEAR. OF PARTICULAR NOTE...OWYHEE RESERVOIR...THE
LARGEST IRRIGATION RESERVOIR IN OREGON...ONLY HAS 24 PERCENT OF
CAPACITY. RESERVOIR DATA IS PROVIDED COURTESY OF THE NATURAL
RESOURCES CONSERVATION SERVICE.

VISIT THE FOLLOWING LINK FOR MORE INFORMATION:
WWW.WCC.NRCS.USDA.GOV/WSF/WSF-RESERVOIR.HTML

============================================================
CURRENT AND FORECAST STREAMFLOW

OBSERVED STREAMFLOW FOR MARCH WAS ABOVE-NORMAL IN OREGON...WITH
MINOR FLOODING ALONG A FEW RIVERS IN WESTERN OREGON. THE HIGH FLOWS
HELPED TO BOOST RESERVOIR STORAGE IN MANY BASINS. FOR MORE DETAILS
ON OBSERVED STREAMFLOW...VISIT WATERWATCH.USGS.GOV.

FORECAST STREAMFLOW VOLUMES FOR THE SPRING AND SUMMER RANGE FROM 30
TO 70 PERCENT OF AVERAGE FOR BASINS IN SOUTHERN AND EAST-CENTRAL
OREGON...AND 70 TO 110 PERCENT OF AVERAGE FOR NORTHERN OREGON
BASINS...HIGHEST IN NORTHEAST OREGON. FORECASTS FOR BASINS IN SOUTH-
CENTRAL OREGON...INCLUDING THE KLAMATH AND SILVIES BASINS...ARE
PARTICULARLY LOW...30 TO 50 PERCENT OF AVERAGE.

THE FORECAST FOR THE COLUMBIA RIVER AT THE DALLES...WHICH IS A GOOD
INDEX OF CONDITIONS IN THE COLUMBIA BASIN...IS 97% OF AVERAGE FOR
THE APRIL-SEPTEMBER PERIOD.

VISIT THE FOLLOWING LINKS FOR MORE DETAILS ON BASIN-SCALE WATER
SUPPLY FORECASTS:

NOAA`S NATIONAL WEATHER SERVICE - NORTHWEST RIVER FORECAST CENTER
WWW.NWRFC.NOAA.GOV/WS/

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

============================================================
SPRING FLOOD POTENTIAL

THE POTENTIAL FOR SPRING /MAY-JUNE/ SNOWMELT FLOODING IS HIGHEST IN
NORTHEAST OREGON...WHERE THE SNOWPACK IS NEAR-NORMAL IN THE WALLOWA
AND BLUE MOUNTAINS. HOWEVER...EVEN IN THIS AREA...THE POTENTIAL IS
NOT EXCEPTIONAL. ELSEWHERE IN OREGON...THE POTENTIAL FOR SPRING
FLOODING IS LOW.

VISIT THE FOLLOWING LINK FOR MORE DETAILS ON SPRING FLOOD POTENTIAL
AND EXPECTED PEAK FLOW.

WWW.NWRFC.NOAA.GOV/PEAK/

BRYANT
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