Flood Potential Outlook
Issued by NWS Denver/Boulder, CO

Home | Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11
000
FGUS75 KBOU 220048
ESFBOU
COC001-005-013-014-019-031-035-039-047-049-057-059-069-073-075-087-
093-095-115-117-121-123-200000-

WATER SUPPLY OUTLOOK
NATIONAL WEATHER SERVICE DENVER CO
645 PM MST FRI MAR 21 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 IN AREAS SEVERELY IMPACTED
BY THE SEPTEMBER 2013 FLOODS WHERE THE FLOOD POTENTIAL IS HIGH.
...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 ABOVE AVERAGE. ROUGHLY 15
PERCENT OF THE SNOW ACCUMULATION SEASON REMAINS AND CONDITIONS COULD
CHANGE BEFORE THE RUNOFF BEGINS. 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 DEREASE 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 DUE TO THE DESTRUCTIVE SEPTEMBER 2013 FLOODS. AS A RESULT
OF LAST SEPTEMBER`S RAIN AND FLOODING...THE RISK OF FLOODING AND
FLASH FLOODING IS HIGHER THIS YEAR. 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.

.MOUNTAIN SNOWPACK... SNOWPACK REMAINS ABOVE AVERAGE IN LATE MARCH.
NEAR RECORD SNOWPACK CONTINUED AT SEVERAL LOCATIONS NEAR THE
CONTINENTAL DIVIDE. ON MARCH 21ST THE BASIN SNOWPACK WAS ALREADY 114
TO 122 PERCENT OF THE AVERAGE SEASONAL PEAK SNOWPACK EVEN THOUGH THE
NORMAL PEAK DATE TYPICALLY DOES NOT OCCUR UNTIL LATE APRIL.  THE
HIGH COUNTRY SNOWPACK WAS 137 PERCENT OF AVERAGE IN BOTH THE NORTH
AND SOUTH PLATTE RIVER BASINS EAST OF THE DIVIDE. THIS IS THE THIRD
HIGHEST MARCH 21ST SNOWPACK IN THE SOUTH PLATTE BASIN IN THE PAST 35
YEARS FOLLOWING THE YEARS 1986 AND 1996. THIS YEAR IS TIED WITH 1997
AS THE FOURTH HIGHEST MARCH 21ST SNOWPACK IN THE NORTH PLATTE AND
LARAMIE RIVER BASINS BEHIND 1986...1996 AND 2011. THE SNOWPACK WEST
OF THE DIVIDE IN UPPER COLORADO RIVER BASIN WAS 129 PERCENT OF
AVERAGE WHICH IS THE NINTH HIGHEST MARCH 21ST SNOWPACK IN THE
COLORADO RIVER HEADWATERS SINCE 1980. LIQUID WATER IN THE SNOTEL
MOUNTAIN SNOWPACK GENERALLY RANGED FROM 5 TO 37 INCHES. AT LOWER
ELEVATIONS EAST OF THE DIVIDE THERE WAS LITTLE TO NO SNOW.

.RESERVOIRS... THE SOUTH PLATTE BASIN STORAGE WAS 112 PERCENT OF
AVERAGE AND AROUND 83 PERCENT OF CAPACITY ON MARCH 1ST. THE COMBINED
RESERVOIR STORAGE IN THE UPPER COLORADO RIVER BASIN WAS 97 PERCENT
OF AVERAGE AND 64 PERCENT OF CAPACITY.

.RIVER CONDITIONS AND THE WATER TABLE... 48 PERCENT OF THE U.S.
GEOLOGICAL SURVEY STREAM GAGES WITH A LONG HISTORICAL RECORD ARE
REPORTING ABOVE NORMAL TO HIGH FLOWS IN NORTH CENTRAL COLORADO. 38
PERCENT OF THE GAGES HAVE NEAR NORMAL FLOWS AND 13 PERCENT HAVE
BELOW TO BELOW AVERAGE FLOWS. GROUNDWATER REMAINS HIGH IN THE MANY
AREAS OF NORTH CENTRAL COLORADO. THIS CAN CAUSE LANDSLIDE ISSUES AND
MORE OF THE SNOWMELT TO RUNOFF THEREBY CREATING HIGHER STREAMFLOWS.

.DROUGHT CONDITIONS...CONDITIONS ARE ABNORMALLY DRY IN THE FAR
NORTHEAST PLAINS...WITH SEVERE DROUGHT PERSISTENT IN SOUTHERN
LINCOLN COUNTY.

.CLIMATE SUMMARY...A PROGRESSIVE WEATHER PATTERN BROUGHT 150 TO OVER
300 PERCENT OF THE AVERAGE PRECIPITATION IN THE NORTH CENTRAL
MOUNTAINS AND ON THE PLAINS NORTH OF INTERSTATE 70 IN THE PAST 30
DAYS. IN CONTRAST PRECIPITATION RANGED FROM ONLY 25 TO 75 PERCENT OF
AVERAGE IN SECTIONS OF DOUGLAS...ELBERT...JEFFERSON...LINCOLN AND
PARK COUNTIES. TEMPERATURES THE PAST MONTH RANGED FROM 2 TO 8
DEGREES ABOVE AVERAGE IN THE NORTH PLATTE AND UPPER COLORADO RIVER
BASINS IN THE MOUNTAINS TO 2 TO 10 DEGREES BELOW AVERAGE IN THE
LOWER SOUTH PLATTE BASIN ON THE NORTHEAST PLAINS.

.PRECIPITATION/TEMPERATURE OUTLOOK...ANOTHER TWO DISTURBANCES WILL
BRING PRECIPITATION TO NORTHERN COLORADO THROUGH MARCH 31ST.  THE
OUTLOOK FOR NORTHERN COLORADO FOR MARCH 29 TO APRIL 5 SHOWS EQUAL
CHANCES OF BELOW...NORMAL..OR ABOVE NORMAL PRECIPITATION AND
TEMPERATURE.

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 NEXT WEEK. THE NEXT WATER SUPPLY OUTLOOK WILL BE ISSUED THE
SECOND WEEK OF APRIL.

$$
RTG/TH



USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.