Flood Potential Outlook
Issued by NWS Denver/Boulder, CO

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WATER SUPPLY OUTLOOK
NATIONAL WEATHER SERVICE DENVER CO
656 PM MDT THU APR 3 2014

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

THIS OUTLOOK IS FOR THE DENVER/BOULDER SERVICE AREA. IT INCLUDES THE
UPPER COLORADO AND NORTH PLATTE RIVER BASINS IN NORTH CENTRAL
COLORADO AND SOUTH PLATTE BASIN EXTENDING ACROSS NORTHEAST COLORADO.

.SPRING SNOWMELT FLOOD OUTLOOK
...IN THE NORTH CENTRAL MOUNTAINS AND NORTHERN COLORADO FRONT RANGE
THE SPRING FLOOD RISK IS ELEVATED EXCEPT THE FLOOD POTENTIAL IS HIGH
IN AREAS SEVERELY IMPACTED BY THE SEPTEMBER 2013 FLOODS.
...ON THE NORTHEAST PLAINS THE FLOOD RISK IS NEAR NORMAL EXCEPT THE
RISK OF FLOODING IS SOMEWHAT ELEVATED ALONG AREA RIVER AND STREAMS
IN SOUTHWEST WELD COUNTY.

THE FLOOD POTENTIAL DUE TO SNOWMELT IS ELEVATED. MUCH ABOVE AVERAGE
APRIL-JULY RUNOFF VOLUMES ARE EXPECTED. MORE SIGNIFICANT FLOODING
WILL OCCUR THIS SPRING IF RAIN FALLS ON THE SNOW...RAPID WARMING
OCCURS AND IF THERE IS MORE SNOW BETWEEN NOW AND THE MELT. THE
THREAT OF SPRING SNOWMELT FLOODING WILL DECREASE WITH GRADUAL OR
INTERMITTENT FREEZING AND THAWING...BELOW AVERAGE PRECIPITATION AND
DRY WINDS.

THERE ARE ADDITIONAL FLOOD CONCERNS THIS SPRING PRIMARILY IN THE
FRONT RANGE FOOTHILLS EXTENDING INTO THE URBAN CORRIDOR OF
BOULDER...LARIMER...SOUTHWEST WELD AND EXTREME NORTHERN JEFFERSON
COUNTIES. AS A RESULT OF LAST SEPTEMBER`S RAIN AND FLOODING...THE
RISK OF FLOODING AND FLASH FLOODING IS HIGHER. A SMALL AMOUNT OF
WATER COULD START MOVING LARGE QUANTITIES OF SEDIMENT IN AFFECTED
STREAMS. THERE ARE REDUCED CREEK AND RIVER CAPACITIES DUE TO THE
INCREASED SEDIMENTATION...ROCKY DEBRIS AND STREAM BANK EROSION.
DEBRIS FLOWS AND LANDSLIDES MAY CAUSE ACCESS ISSUES AND OBSTRUCT
CREEK FLOWS. WOODY DEBRIS ALONG STREAMS COULD POTENTIALLY CAUSE
DEBRIS DAMS AND SUBSEQUENT FLOODING. ALTERED LOCATIONS AND
CONDITIONS OF RIVERS AND CREEKS MAY IMPACT STRUCTURES AND
INFRASTRUCTURES AT RISK. SOME RESERVOIRS IN THESE AREAS ARE AT OR
NEAR CAPACITY AND WILL SPILL EARLIER THAN USUAL CAUSING ADDITIONAL
FLOW DURING THE RUNOFF AND THUNDERSTORM SEASON.

.SNOWPACK...MOUNTAIN SNOWPACK IN NORTH CENTRAL COLORADO REMAINED
WELL ABOVE AVERAGE IN EARLY APRIL. NEAR RECORD SNOWPACK CONTINUED AT
SEVERAL LOCATIONS NEAR THE CONTINENTAL DIVIDE. THE MOUNTAIN SNOWPACK
WAS 140 PERCENT OF NORMAL IN THE NORTH PLATTE BASIN...135 PERCENT OF
NORMAL IN THE SOUTH PLATTE BASIN AND 125 PERCENT OF NORMAL IN THE
UPPER COLORADO RIVER BASIN ON APRIL 3RD. LIQUID WATER IN THE SNOTEL
MOUNTAIN SNOWPACK GENERALLY RANGED FROM 5 TO 53 INCHES. THE BASIN
SNOWPACK WAS 123 PERCENT OF THE AVERAGE SEASONAL PEAK SNOWPACK IN
THE UPPER COLORADO AND SOUTH PLATTE BASINS AND 137 PERCENT OF THE
AVERAGE PEAK IN THE NORTH PLATTE BASIN. THE NORMAL PEAK SNOWPACK
DATES ARE APRIL 10TH AND 11TH FOR THE UPPER COLORADO AND NORTH
PLATTE RIVER BASINS AND APRIL 26TH FOR THE SOUTH PLATTE BASIN.

.RESERVOIRS... THE SOUTH PLATTE BASIN STORAGE REMAINED SLIGHTLY
ABOVE AVERAGE AND THE UPPER COLORADO RIVER STORAGE WAS A BIT BELOW
AVERAGE AT THE END OF MARCH. THE COMBINED RESERVOIR STORAGE WAS
AROUND 87 PERCENT OF CAPACITY IN THE SOUTH PLATTE BASIN AND 58
PERCENT OF CAPACITY IN THE UPPER COLORADO RIVER BASIN.

.RIVER CONDITIONS AND SOIL MOISTURE...52 PERCENT OF THE U.S.
GEOLOGICAL SURVEY STREAM GAGES WITH A LONG HISTORICAL RECORD IN
NORTH CENTRAL COLORADO ARE REPORTING ABOVE TO MUCH ABOVE NORMAL
FLOWS. 39 PERCENT OF THE GAGES HAVE NEAR NORMAL FLOWS AND ONLY 9
PERCENT HAVE BELOW AVERAGE FLOWS.

VOLUME FORECASTS HAVE INCREASED IN THE UPPER COLORADO RIVER BASIN
THIS SPRING AND SUMMER. FOLLOWING ARE THE STREAMFLOW FORECASTS FOR
SELECTED LOCATIONS IN GRAND AND SUMMIT COUNTIES:
                                    MOST PROBABLY FORECAST
                                      VOLUME      PERCENT
STREAM AND STATION         PERIOD     1000 AF      OF AVG
__________________         ______     _______     _______
COLORADO RIVER
 LAKE GRANBY               APR-JUL     310         141

WILLOW CREEK
 WILLOW CREEK RES          APR-JUL      59         126

FRASER RIVER
 WINTER PARK               APR-JUL      28         144

WILLIAMS FORK RIVER
 WILLIAMS FORK RES         APR-JUL     135         141

BLUE RIVER
 DILLON RES                APR-JUL     250         153
 GREEN MTN RES             APR-JUL     400         147

MUDDY CREEK
 WOLFORD MTN RES BLW       APR-JUL      90         167

COLORADO RIVER
 KREMMLING                 APR-JUL     1260        147

THESE FORECASTS REFLECT NATURAL FLOW ONLY.  ACTUAL OBSERVED FLOW
WILL LIKELY BE AFFECTED BY UPSTREAM WATER MANAGEMENT.

.DROUGHT CONDITIONS AND SOIL MOISTURE...CONDITIONS ARE ABNORMALLY
DRY IN THE FAR NORTHEAST PLAINS...WITH SEVERE DROUGHT PERSISTENT IN
SOUTHERN LINCOLN COUNTY. IN CONTRAST...THE SOIL MOISTURE IN THE
NORTH CENTRAL COLORADO MOUNTAINS IS ABOVE AVERAGE.

.CLIMATE SUMMARY...THERE WAS A FAIRLY ACTIVE ZONAL UPPER AIR FLOW
PATTERN OVER COLORADO IN MARCH. MARCH PRECIPITATION GENERALLY RANGED
FROM 100 TO 200 PERCENT OF THE AVERAGE NORTH OF INTERSTATE 70 AND
WEST OF HIGHWAY 71. PRECIPITATION WAS GENERALLY ONLY 25 TO 75
PERCENT OF AVERAGE IN SECTIONS OF DOUGLAS...ELBERT...JEFFERSON...
LINCOLN...PHILLIPS...PARK AND SEDGWICK COUNTIES. TEMPERATURES THE
PAST MONTH WERE NEAR AVERAGE TO FOUR DEGREES BELOW AVERAGE IN MANY
AREAS OF NORTHERN COLORADO.

.PRECIPITATION/TEMPERATURE OUTLOOK...THE 8 TO 14 DAY OUTLOOK HAS
ABOVE AVERAGE PRECIPITATION AND TEMPERATURES. THE EXCEPTION IS THE
FAR NORTHEAST CORNER OF COLORADO WHERE NORMAL PRECIPITATION AND
TEMPERATURES ARE EXPECTED. THE 30 AND 90 DAY OUTLOOKS GENERALLY CALL
FOR EQUAL CHANCES OF ABOVE...NEAR OR BELOW AVERAGE PRECIPITATION AND
TEMPERATURES. ENSO-NEUTRAL CONDITIONS ARE EXPECTED TO CONTINUE
THROUGH THIS SPRING. THERE IS A 50 PERCENT CHANCE OF EL NINO
DEVELOPING DURING THIS SUMMER OR FALL.

VISIT OUR WEB SITE AT WEATHER.GOV/DENVER FOR MORE HYDROLOGIC
INFORMATION INCLUDING GRAPHS OF PROBABILISTIC RIVER OUTLOOKS.

THE NEXT ROUTINE LONG-RANGE PROBABILISTIC RIVER OUTLOOK WILL BE
ISSUED TOWARD THE END OF THIS MONTH.

$$
TH



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