Spring Flood and Water Resource Outlook 2

PROBABILISTIC HYDROLOGIC OUTLOOK 
NATIONAL WEATHER SERVICE NORTH PLATTE NE
835 AM CST THU FEB 16 2012 /735 AM MST THU FEB 16 2012/

...SPRING FLOOD AND WATER RESOURCE OUTLOOK...

THIS SPRING FLOOD AND WATER RESOURCE OUTLOOK IS FOR THE NORTH PLATTE
HYDROLOGIC SERVICE AREA...WHICH COVERS WESTERN AND NORTH CENTRAL
NEBRASKA. THE RIVER BASINS INCLUDE...THE NORTH AND SOUTH PLATTE
RIVERS AND THE PLATTE RIVER IN THE EASTERN PANHANDLE AND WESTERN
NEBRASKA...FRENCHMAN CREEK IN SOUTHWEST NEBRASKA...THE LOUP AND
DISMAL RIVERS IN THE SANDHILLS OF NEBRASKA...AND PORTIONS OF THE
ELKHORN AND NIOBRARA BASINS IN NORTH CENTRAL NEBRASKA.

FLOOD OUTLOOK SUMMARY...

THERE IS AN ABOVE NORMAL CHANCE FOR FLOODING ALONG THE NORTH PLATTE
RIVER DOWNSTREAM OF LAKE MCCONAUGHY WHILE POINTS ALONG THE REMAINDER
OF THE RIVERS AND STREAMS ACROSS WESTERN AND NORTH CENTRAL NEBRASKA
HAVE AN AVERAGE CHANCE FOR FLOODING DUE TO SNOWMELT AND ICE JAMS.

SNOW COVER...

AN AVERAGE OF 1 TO 2 INCHES OF SNOWPACK REMAINS ACROSS CENTRAL AND
SOUTHWEST NEBRASKA. LITTLE IF ANY SNOW COVER EXISTS IN NORTH CENTRAL
AND NORTHWEST NEBRASKA.

SOIL CONDITIONS...

ACCORDING TO THE U.S. DROUGHT MONITOR...SOIL MOISTURE CONDITIONS
ACROSS WESTERN AND NORTH CENTRAL NEBRASKA ARE NEAR NORMAL.

MOUNTAIN SNOWPACK...

AS OF MID FEBRUARY...THE UPPER NORTH PLATTE RIVER BASIN IN WYOMING
WAS NEAR 75 PERCENT OF NORMAL...WHILE THE LOWER NORTH PLATTE BASIN
IN COLORADO AND WYOMING WAS NEAR 90 PERCENT OF NORMAL.

SNOWPACK IN THE SOUTH PLATTE RIVER BASIN WAS AROUND 85 PERCENT OF
NORMAL AS OF MID FEBRUARY.

RIVER AND STREAMFLOW CONDITIONS...

RIVER AND STREAM LEVELS ACROSS MUCH OF WESTERN AND NORTH CENTRAL
NEBRASKA WERE RUNNING NEAR OR SLIGHTLY ABOVE NORMAL. RIVERS ARE
MOSTLY ICE FREE AND ICE JAMMING IS NOT EXPECTED ALONG THE NORTH AND
SOUTH PLATTE RIVERS...THE NIOBRARA RIVER....OR THE LOUP AND ELKHORN
RIVER SYSTEMS. HOWEVER...A RETURN OF COLDER TEMPERATURES COULD AGAIN
CAUSE ICE JAM CONCERNS.

SPRING SNOWMELT RUNOFF INTO THE NORTH AND SOUTH PLATTE RIVER BASINS
FROM THE MOUNTAINS OF COLORADO AND WYOMING IS FORECAST TO BE BELOW
NORMAL THIS YEAR. THEREFORE...RELEASES FROM RESERVOIRS ALONG THE
NORTH PLATTE RIVER IN WYOMING ARE NOT EXPECTED TO CAUSE FLOODING AT
LOCATIONS UPSTREAM OF LAKE MCCONAUGHY. WATER IS PLANNED TO BE
RELEASED FROM KINGSLEY DAM AT LAKE MCCONAUGHY BEGINNING THE 22ND OF
FEBRUARY AND CONTINUING THROUGH MUCH OF MARCH. THESE RELEASES ARE
EXPECTED TO CAUSE THE RIVER LEVELS DOWNSTREAM OF LAKE MCCONAUGHY TO
RISE...HOWEVER SHOULD STAY BELOW FLOOD STAGE. LOOKING FURTHER INTO
THE SEASON...IT IS LIKELY THAT RELEASES FROM LAKE MCCONAUGHY WILL BE
INCREASED TO THE POINT WHERE MINOR TO MODERATE FLOODING IS POSSIBLE
AT NORTH PLATTE.

WEATHER OUTLOOKS...

A WEAKENING LA NINA IS CURRENTLY IN PROGRESS...WITH AN EXPECTED
TRANSITION TO ENSO NEUTRAL CONDITIONS DURING MARCH THROUGH MAY.

ACCORDING TO THE CLIMATE PREDICTION CENTER...THE 8 TO 14 DAY OUTLOOK
INDICATES TEMPERATURES WILL BE BELOW NORMAL...WITH NEAR NORMAL
PRECIPITATION OVER WESTERN AND NORTH CENTRAL NEBRASKA.

THE THREE MONTH OUTLOOK FOR FEBRUARY...MARCH AND APRIL INDICATES
TEMPERATURES TO BE NEAR OR SLIGHTLY ABOVE NORMAL AND PRECIPITATION
TO BE NEAR OR SLIGHTLY BELOW NORMAL.

NUMERICAL RIVER OUTLOOKS...

THE OUTLOOK FOR THE SITES BELOW IS VALID FROM FEB 15 2012 THROUGH
MAY 18 2012.

THE FOLLOWING TABLE GIVES THE CHANCE OF REACHING FLOOD STAGE AT THE
GAGES DURING THE VALID PERIOD. THESE VALUES DO NOT REFLECT THE
FLOODING POTENTIAL DUE TO ICE JAMS.

RIVER APPROXIMATE CHANCE OF
LOCATION FS (FT) REACHING FLOOD STAGE
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PLATTE RIVER NEAR BRADY 7.5 FT 21%
STINKING WATER CREEK NEAR PALISADE 10.0 FT < 10%
ELKHORN RIVER NEAR EWING 9.0 FT < 10%
NIOBRARA RIVER NEAR SPARKS 6.0 FT < 10%

IN THE TABLE BELOW...THE 90 THROUGH 10 PERCENT COLUMNS INDICATE THE
CHANCE THE RIVER COULD RISE ABOVE THE LISTED STAGE LEVELS IN THE
NEXT 90 DAYS. FOR EXAMPLE: THE PLATTE RIVER NEAR BRADY HAS A FLOOD
STAGE OF 7.5 FEET. THERE IS A 20 PERCENT CHANCE THAT THE RIVER WILL
RISE ABOVE 7.7 FEET IN THE NEXT 90 DAYS.

LOCATION FS(FT) 90% 80% 70% 60% 50% 40% 30% 20% 10%

-------- ------ --- --- --- --- --- --- --- --- ---

PLATTE RIVER AT BRADY CH 1
7.5 4.5 4.6 4.8 5.0 5.4 5.8 6.4 7.7 9.2
STINKING WATER CREEK AT PALISADE 2NW
10.0 2.2 2.2 2.2 2.2 2.9 3.2 3.6 4.9 9.3
ELKHORN RIVER AT EWING 1N
9.0 3.4 3.5 3.7 3.9 4.2 4.3 4.6 4.9 5.5
NIOBRARA RIVER AT SPARKS 7SW
6.0 2.8 3.0 3.0 3.1 3.1 3.1 3.2 3.2 3.4

THE OUTLOOK FOR THE SITES BELOW IS VALID FOR THE REMAINDER OF THE
WATER YEAR...FROM FEB 16 2012 THROUGH SEP 30 2012.

THE FOLLOWING TABLE GIVES THE CHANCE OF REACHING FLOOD STAGE AT THE
GAGES DURING THE VALID PERIOD. THESE VALUES DO NOT REFLECT THE
FLOODING POTENTIAL DUE TO ICE JAMS.


RIVER APPROXIMATE CHANCE OF
LOCATION FS (FT) REACHING FLOOD STAGE
--------------------------------------------------------------------

NORTH PLATTE RIVER NEAR LISCO 4.0 FT 19%
NORTH PLATTE RIVER NEAR LEWELLEN 7.5 FT 32%
NORTH PLATTE RIVER NEAR NORTH PLATTE 6.0 FT 97%
SOUTH PLATTE RIVER NEAR ROSCOE 9.0 FT 24%
SOUTH PLATTE RIVER AT NORTH PLATTE 13.0 FT < 10%

IN THE TABLE BELOW...THE 90 THROUGH 10 PERCENT COLUMNS INDICATE THE
CHANCE THE RIVER COULD RISE ABOVE THE LISTED STAGE LEVELS ENDING
SEPTEMBER 30 2012. FOR EXAMPLE: THE NORTH PLATTE RIVER NEAR LISCO
HAS A FLOOD STAGE OF 4 FEET. THERE IS A 20 PERCENT CHANCE THAT THE
RIVER WILL RISE ABOVE 3.8 FEET BY SEPTEMBER 30.

LOCATION FS(FT) 90% 80% 70% 60% 50% 40% 30% 20% 10%

-------- ------ --- --- --- --- --- --- --- --- ---

NORTH PLATTE RIVER AT LISCO 1S
4.0 2.2 2.3 2.4 2.7 2.7 2.9 3.2 3.8 4.6
NORTH PLATTE RIVER AT LEWELLEN
7.5 6.7 6.9 7.0 7.2 7.2 7.3 7.6 8.1 8.7
NORTH PLATTE RIVER AT NORTH PLATTE
6.0 6.3 6.3 6.4 6.5 6.5 6.6 6.6 6.7 7.7
SOUTH PLATTE RIVER AT ROSCOE 1SE
9.0 6.0 6.2 6.8 7.0 7.6 8.3 8.6 9.4 11.6
SOUTH PLATTE RIVER AT NORTH PLATTE
13.0 7.4 7.7 8.2 8.5 9.2 9.5 9.8 10.2 12.0

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THIS LONG-RANGE PROBABILISTIC OUTLOOK CONTAINS FORECAST VALUES THAT
ARE CALCULATED USING MULTIPLE SEASON SCENARIOS FROM 30 OR MORE YEARS
OF CLIMATOLOGICAL DATA INCLUDING CURRENT CONDITIONS OF THE
RIVER...SNOW COVER AND SOIL MOISTURE ALONG WITH THE 30 TO 90 DAY
LONG-RANGE OUTLOOKS OF TEMPERATURE AND PRECIPITATION. BY PROVIDING
THE COMPLETE RANGE OF PROBABILITIES...THE LEVEL OF RISK ASSOCIATED
WITH LONG-RANGE PLANNING DECISIONS CAN BE DETERMINED. THESE
PROBABILISTIC FORECASTS ARE PART OF THE NATIONAL WEATHER SERVICE
ADVANCED HYDROLOGIC PREDICTION SERVICES /AHPS/.

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THIS IS THE FIRST SPRING FLOOD AND WATER RESOURCE OUTLOOK FOR 2012.
LONG-RANGE PROBABILISTIC OUTLOOKS ARE TYPICALLY ISSUED NEAR THE END
OF THE MONTH THROUGHOUT THE YEAR. THE NEXT SCHEDULED OUTLOOK FOR
THESE SITES WILL BE ISSUED ON MARCH 01 2012.

FOR MORE WEATHER AND RIVER INFORMATION INCLUDING GRAPHS OF
PROBABILISTIC RIVER OUTLOOKS VISIT OUR WEB SITE AT:
HTTP://WATER.WEATHER.GOV/AHPS2/INDEX.PHP?WFO=LBF


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