Flood Potential Outlook
Issued by NWS Reno, NV

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NVZ001>041-CAZ070>073-CAZ519>527-100000-

WATER SUPPLY AND SPRING FLOOD OUTLOOK
NATIONAL WEATHER SERVICE RENO NV
1050 AM PST SAT APR 4 2015

...WATER SUPPLY OUTLOOK FOR NEVADA AND EASTERN CALIFORNIA AS OF
APRIL 4 2015...

...WELL BELOW AVERAGE STREAM FLOW IS EXPECTED THIS SPRING AND
SUMMER...

ISSUED JOINTLY BY THE NATIONAL WEATHER SERVICE AND NATURAL RESOURCES
CONSERVATION SERVICE...

1/SUMMARY...WATER SUPPLY OUTLOOK...
PRECIPITATION HAS BEEN BELOW TO WELL BELOW NORMAL FOR MUCH OF NEVADA
AND EASTERN CALIFORNIA SINCE OCTOBER 2014. THE ONLY AREAS THAT HAVE
SEEN ABOVE NORMAL PRECIPITATION IN THAT TIME ARE LOCATED ACROSS
NORTHEAST CALIFORNIA...FAR NORTHWEST NEVADA...SOUTHERN INYO COUNTY
AND NORTHERN AND PARTS OF FAR EASTERN AND NORTHWEST SAN BERNARDINO
COUNTY IN EASTERN CALIFORNIA.

AFTER A SERIES OF WET STORMS IN DECEMBER LEFT A NEAR TO SLIGHTLY
ABOVE AVERAGE SNOW PACK IN EASTERN NEVADA...BUT BELOW NORMAL SNOW PACK
FOR WESTERN NEVADA AND THE EASTERN SIERRA...THE MONTH OF JANUARY WAS
WELL BELOW NORMAL IN TERMS OF PRECIPITATION AND HAD LONG STRETCHES
OF WELL ABOVE NORMAL TEMPERATURES. THIS COMBINATION OF NO
PRECIPITATION AND MILD TEMPERATURES WORKED TO DRASTICALLY DECREASE
THE SNOW PACK IN WESTERN NEVADA WHILE EASTERN NEVADA SAW DECREASES
AS WELL...JUST NOT AS SEVERE. THE DECREASED PRECIPITATION AND MILD
TEMPERATURES ALSO HELPED TO INTENSIFY DROUGHT CONDITIONS ACROSS
WESTERN NEVADA.

A SERIES OF WET...WARM STORMS MOVED THROUGH EASTERN CALIFORNIA AND
WESTERN NEVADA IN THE FIRST HALF OF FEBRUARY. THESE STORMS BOOSTED
PRECIPITATION OVER THE REGION...BUT HIGH SNOW LEVELS LIMITED
INCREASES TO THE SNOWPACK. THE WARM...WET NATURE OF THESE STORMS DID
PRODUCE RUNOFF AND INCREASED STORAGE ON AREA RESERVOIRS. A COLDER
STORM IN LATE FEBRUARY BROUGHT SNOW TO WESTERN NEVADA AND THE SIERRA
ALONG WITH SNOW AND RAIN TO SOUTHERN NEVADA...TEMPORARILY INCREASING
THE SNOWPACK. HOWEVER...THE BENEFITS OF THIS STORM LARGELY BYPASSED
EASTERN NEVADA.

ONE BRIGHT SPOT...THESE STORMS RESULTED IN AN INCREASE IN SOIL
MOISTURE ACROSS THE SIERRA AND WESTERN NEVADA. THE TRUCKEE RIVER
BASIN RECORDED ITS HIGHEST MARCH 1ST SOIL MOISTURE BASED ON TEN
YEARS OF DATA. SOIL MOISTURE WAS NEAR OR ABOVE AVERAGE FOR ALL AREAS
EXCEPT EASTERN NEVADA.

MARCH WAS ANOTHER DRY AND VERY WARM MONTH. THIS DRY AND WARM WEATHER
ACTED TO DECREASE AN ALREADY BELOW AVERAGE SNOW PACK EVEN MORE. MANY
SNOTEL SITES ACROSS NORTHERN AND WESTERN NEVADA AND THE EASTERN
SIERRA OF CALIFORNIA REPORTED THEIR RECORD LOWEST SNOW WATER
EQUIVALENT READINGS SINCE SNOTEL MEASUREMENTS BEGAN IN THE EARLY
1980S. ADDITIONALLY...A FEW LONG TERM HIGH ELEVATION SNOW COURSE
SITES ALSO REPORTED NEAR RECORD LOW SNOW WATER EQUIVALENT READINGS.

THE COMBINATION OF BELOW AVERAGE PRECIPITATION IN MOST AREAS AND
HIGH SNOW LEVELS IN THE STORMS THAT DID MOVE THROUGH THE AREA...
LEAVING RECORD LOW SNOW PACK IN THE REGION...HAS RESULTED IN A
FORECAST OF WELL BELOW AVERAGE RUNOFF THIS SPRING AND EARLY SUMMER.

2/SNOWPACK...
SNOWPACK AS OF APRIL 1ST IN THE SIERRA NEVADA REACHED NEAR HISTORIC
LOWS AS MEASURED BY SNOTEL SITES AND SNOW COURSES. MANY INDIVIDUAL
SITES HAD THEIR LOWEST OR SECOND LOWEST REPORTED SNOW WATER
EQUIVALENT READINGS DURING THEIR PERIODS OF RECORD. THE LAKE TAHOE
BASIN SNOWPACK WAS ONLY 2 PERCENT OF AVERAGE...DOWN FROM 23 PERCENT
IN EARLY MARCH. THE CARSON RIVER BASIN SNOWPACK SAT AT ONLY 4
PERCENT OF AVERAGE...DOWN FROM 36 PERCENT.

THE SNOWPACK ACROSS NORTHERN AND EASTERN NEVADA IS ALSO WELL BELOW
NORMAL. THE SNAKE RIVER BASIN REPORTED THE BEST SNOWPACK WITH 47
PERCENT OF AVERAGE.

MANY BASINS SAW DECLINES OF 20 PERCENT OR MORE WITH THE STEEPEST
DROP IN THE CLOVER VALLEY AND FRANKLIN RIVER BASIN AT 45 PERCENT.
THE CARSON RIVER BASIN SAW A DECLINE OF 32 PERCENT.

                                 APR 1 2015
BASIN               PERCENT OF AVERAGE
LAKE TAHOE ........................   2
TRUCKEE RIVER .....................  14
CARSON RIVER ......................   4
WALKER RIVER ......................  20
NORTHERN GREAT ....................  23
UPPER HUMBOLDT RIVER ..............  15
LOWER HUMBOLDT RIVER ..............  18
CLOVER VALLEY & FRANKLIN RIVER ....  32
SNAKE RIVER .......................  47
OWYHEE RIVER ......................  23
EASTERN NEVADA ....................  16
LOWER COLORADO RIVER ..............  NA

3/PRECIPITATION...
HEAVY PRECIPITATION IN EARLY FEBRUARY BOOSTED AVERAGES ACROSS THE
WESTERN PART OF NEVADA AND THE EASTERN SIERRA OF CALIFORNIA...BUT
MUCH OF NORTHERN AND EASTERN NEVADA MISSED THE BULK OF THIS
PRECIPITATION AND THEIR BASIN AVERAGES FELL THROUGH THE MONTH OF
FEBRUARY.

THEN ALONG CAME MARCH AND BROUGHT WITH IT ONE OF THE DRIEST WINTER
MONTHS ON RECORD. MANY AREAS REPORTED EITHER THEIR RECORD DRIEST
MONTH OR RANKED IN THE LOWEST 10 PERCENT IN TERMS OF PRECIPITATION
FOR THE MONTH OF MARCH. THE CLOVER VALLEY AND FRANKLIN RIVER BASIN
WAS THE ONLY BASIN TO REPORT BETTER THAN 50 PERCENT OF AVERAGE FOR
THE MONTH...BUT IT WAS ONLY AT 53 PERCENT. THE EASTERN SIERRA BASINS
HAD BY FAR THE LOWEST TOTALS WITH RESPECT TO AVERAGE AT LESS THAN 15
PERCENT FOR ALL FOUR.

THE VERY DRY MONTH OF MARCH RESULTED IN PUSHING THE WATER YEAR
AVERAGES LOWER FOR ALL BASINS AS WELL. THE CLOVER FRANKLIN RIVER
BASIN IS THE ONLY BASIN REPORTING BETTER THAN 80 PERCENT OF AVERAGE
FOR THE WATER YEAR AT 84 PERCENT. THE CARSON RIVER AND WALKER RIVER
BASINS ARE BOTH LESS THAN 50 PERCENT OF AVERAGE FOR THE WATER
YEAR...47 PERCENT AND 45 PERCENT...RESPECTIVELY.

                                                  WATER YEAR 2015
                                    MAR 2015    /THROUGH 3/31/2015/
BASIN                              PCT OF AVE        PCT OF AVE
LAKE TAHOE .........................   13  ...........   52
TRUCKEE RIVER ......................   12  ...........   53
CARSON RIVER .......................   12  ...........   47
WALKER RIVER .......................   12  ...........   45
NORTHERN GREAT .....................   39  ...........   78
UPPER HUMBOLDT RIVER ...............   30  ...........   66
LOWER HUMBOLDT RIVER ...............   32  ...........   70
CLOVER VALLEY AND FRANKLIN RIVER ...   53  ...........   84
SNAKE RIVER ........................   41  ...........   75
OWYHEE RIVER .......................   41  ...........   78
EASTERN NEVADA .....................   27  ...........   50
LOWER COLORADO RIVER ...............   NA  ...........   NA

4/RESERVOIRS...
VERY WARM TEMPERATURES DURING THE MONTH OF MARCH PRODUCED EARLY
SEASON RUNOFF THAT PROVIDED INFLOWS INTO RESERVOIRS IN THE
TRUCKEE...CARSON AND WALKER BASINS. HOWEVER...THIS INFLOW WAS OFFSET
SLIGHTLY BY EVAPORATION AND DECREED OUTFLOWS ON THE TRUCKEE BASIN.

OVERALL RESERVOIR STORAGE REMAINS WELL BELOW CAPACITY AND AVERAGE
FOR LATE MARCH AND EARLY APRIL. AT THE END OF MARCH...STORAGE IN
EASTERN CALIFORNIA AND NORTHERN NEVADA RESERVOIRS VARIED FROM A HIGH
OF 44 PERCENT OF AVERAGE ON TRUCKEE RIVER BASIN TO A LOW OF 10
PERCENT OF AVERAGE ON THE LOWER HUMBOLDT BASIN. THE BIGGEST GAIN WAS
ON THE CARSON RIVER BASIN WHERE STORAGE IN LAHONTAN RESERVOIR
INCREASED FROM 25 PERCENT OF AVERAGE TO 29 PERCENT OF AVERAGE DUE TO
RUNOFF FROM EARLY SEASON SNOW MELT. IN SOUTHERN NEVADA THE LOWER
COLORADO BASIN HAD A STORAGE OF 55 PERCENT OF AVERAGE. MOST BASINS
SAW DECLINES WITH RESPECT TO AVERAGE STORAGE AS THE AVERAGES BEGIN
TO INCREASE THIS TIME OF YEAR.

EFFECTIVE STORAGE ON LAKE TAHOE REMAINED AT 0 PERCENT DUE TO THE
LAKE`S FALLING BELOW ITS NATURAL RIM IN LATE FALL. THE LEVEL OF LAKE
TAHOE ON APRIL 1ST WAS 6222.82 FEET...WHICH EQUATES TO A STORAGE
DEFICIT OF 21,826 ACRE-FEET AS NO WATER CAN FLOW OUT OF THE LAKE
BELOW ITS NATURAL RIM OF 6223.0 FEET.

BASIN                        PERCENT OF CAPACITY   PERCENT OF AVERAGE
LAKE TAHOE ........................   0 ................   0
TRUCKEE RIVER .....................  28 ................  44
CARSON RIVER ......................  20 ................  29
WALKER RIVER ......................  16 ................  27
LOWER HUMBOLDT RIVER ..............   5 ................  10
OWYHEE RIVER ......................  20 ................  36
LOWER COLORADO RIVER ..............  43 ................  55

5/STREAMFLOW...
APRIL THROUGH JULY STREAMFLOW FORECASTS FOR ALL OF NEVADA AND EASTERN
CALIFORNIA AS OF APRIL 1ST ARE FORECAST TO BE MUCH BELOW AVERAGE.
ALL LOCATIONS SAW SHARP DECLINES IN STREAMFLOW FORECASTS FROM MARCH
1ST TO APRIL 1ST.

APRIL 1ST STREAMFLOW FORECASTS FROM THE NRCS WERE HIGHEST ON THE
SNAKE RIVER BASIN...SALMON FALLS CREEK NEAR SAN JACINTO...AT 36
PERCENT OF AVERAGE. THE LOWEST FORECASTS WERE FOR THE NORTHERN GREAT
BASIN NEAR MCDERMITT...MCDERMITT CREEK...AND THE LOWER HUMBOLDT
RIVER AT IMLAY. THE FORECAST WAS FOR 3 PERCENT OF AVERAGE AT BOTH OF
THESE LOCATIONS. THE VIRGIN RIVER AT LITTLEFIELD IN THE LOWER
COLORADO BASIN IS FORECAST TO BE 21 PERCENT OF AVERAGE.

BELOW ARE FORECASTS FOR SELECTED RIVER POINTS ACROSS NEVADA AND
EASTERN CALIFORNIA. SOME CONTAIN BOTH THE NRCS FORECAST AND NWS
FORECAST PROVIDED BY THE ENSEMBLE STREAMFLOW PREDICTION SYSTEM AT
THE CALIFORNIA-NEVADA RIVER FORECAST CENTER. THE FORECASTS MAY
DIFFER SLIGHTLY BASED ON FORECAST METHODOLOGY.

                      PERCENT OF AVERAGE APRIL TO JULY STREAMFLOW
                        MOST PROBABLE FORECAST AS OF APR 1 2015
                          (50 PERCENT CHANCE OF EXCEEDANCE)
BASIN                                 NRCS    NWS
LAKE TAHOE RISE ...................... 15 ... -5  .. 0.2 FOOT RISE (NRCS)
TRUCKEE RIVER ........................ 19 ... 25  .. FARAD
CARSON RIVER .........................  8 ...  7  .. CARSON CITY
WEST WALKER RIVER .................... 15 ... 33
EAST WALKER RIVER .................... 12 ... 15
NORTHERN GREAT .......................  3 ... NA  .. MCDERMITT
UPPER HUMBOLDT RIVER ................. 18 ... 22  .. PALISADE
LOWER HUMBOLDT RIVER .................  3 ...  3  .. IMLAY
CLOVER VALLEY AND FRANKLIN RIVER ..... 29 ... NA
SNAKE RIVER .......................... 36 ... 17@
OWYHEE RIVER ......................... 10 ... 13@
EASTERN NEVADA .......................  7 ... NA  .. ELY
LOWER COLORADO RIVER ................. 21 ... 16* .. LITTLEFIELD
SUSAN RIVER........................... NA ... 17  .. SUSANVILLE
MIDDLE FORK FEATHER RIVER............. NA ...  1  .. PORTOLA

NA - FORECAST EITHER NOT AVAILABLE OR NOT PRODUCED FOR THIS LOCATION
     AT THE TIME OF THE REPORT
*  - VIRGIN RIVER NWS FORECAST PROVIDED BY CBRFC IN SALT LAKE CITY
@  - SNAKE AND OWYHEE RIVER NWS FORECASTS PRODUCED BY NWRFC IN
     PORTLAND

6/ DROUGHT STATUS...
AS OF MARCH 31 2015...THE UNITED STATES DROUGHT MONITOR CLASSIFIED
MUCH OF WESTERN NEVADA...INCLUDING CHURCHILL...PERSHING...STOREY...
CARSON CITY...DOUGLAS...MINERAL...WESTERN LANDER AND SOUTHERN WASHOE
COUNTIES IN NEVADA AS IN EXCEPTIONAL DROUGHT /LEVEL 4 OF 4 LEVELS OF
DROUGHT/. IN CALIFORNIA...MUCH OF LASSEN...PARTS OF PLUMAS...
SIERRA...NEVADA...PLACER...EL DORADO COUNTIES...ALL OF ALPINE AND
MONO COUNTIES AND SMALL PARTS OF NORTHERN AND WESTERN INYO COUNTY WERE
CLASSIFIED IN EXCEPTIONAL DROUGHT. MUCH OF THE REMAINDER OF EASTERN
CALIFORNIA AND WESTERN NEVADA WAS CLASSIFIED AS IN EXTREME DROUGHT
/LEVEL 3 OF 4 LEVELS OF DROUGHT/. IN EASTERN AND SOUTHERN NEVADA...
PARTS OF ELKO...EUREKA AND NYE COUNTIES WERE CLASSIFIED AS HAVING
EXTREME DROUGHT WHILE THE REMAINDER OF EASTERN AND SOUTHERN NEVADA
WAS CLASSIFIED AS HAVING MODERATE TO SEVERE DROUGHT. FAR SOUTHEAST
INYO COUNTY AND MUCH OF SAN BERNARDINO COUNTY WERE ALSO NOTED AS
HAVING MODERATE TO SEVERE DROUGHT...EXCEPT AREAS ALONG THE COLORADO
RIVER WHICH WERE CLASSIFIED AS ABNORMALLY DRY.

POSSIBLE IMPACTS FROM DROUGHT IN NEVADA AND EASTERN CALIFORNIA
INCLUDE...

HIGH FIRE DANGER THIS COMING SPRING AND SUMMER...AS TEMPERATURES
WARM AND FUELS DRY.

POSSIBLE WATER SUPPLY DEFICITS...RESERVOIR STORAGE REMAINS LOW AND
WATER SUPPLY COULD BECOME AN ISSUE THROUGHOUT THE REGION THIS SPRING
AND SUMMER IF SIGNIFICANT PRECIPITATION DOES NOT OCCUR OVER THE NEXT
FEW WEEKS. WATER SUPPLY CONCERNS WOULD BE HIGHEST ON BASINS WITHOUT
RESERVOIR STORAGE.

7/ LONG RANGE WEATHER OUTLOOK FOR NEVADA AND EASTERN CALIFORNIA. THE
OUTLOOK FOR APRIL IS FOR ABOVE NORMAL TEMPERATURES ACROSS SOUTHERN
NEVADA AND EASTERN CALIFORNIA SOUTH OF HIGHWAY 50. MUCH OF EASTERN
AND NORTHERN NEVADA...ALONG WITH NORTHEAST CALIFORNIA ARE SHOWN AS
HAVING EQUAL CHANCES OF ABOVE...BELOW AND NEAR NORMAL TEMPERATURES.
ALL OF NEVADA AND EASTERN CALIFORNIA HAVE EQUAL CHANCES OF
ABOVE...BELOW OR NEAR NORMAL PRECIPITATION.

THE OUTLOOK FOR THE MONTHS OF MAY THROUGH JULY IS FOR EQUAL CHANCES
OF ABOVE...BELOW AND NEAR NORMAL PRECIPITATION ACROSS ALL OF NEVADA
AND EASTERN CALIFORNIA. TEMPERATURES DURING THIS PERIOD ARE EXPECTED
TO BE ABOVE NORMAL FOR THE ENTIRE REGION.

8/ FOR MORE DETAILED WATER SUPPLY AND STREAMFLOW FORECAST
INFORMATION FOR NEVADA AND EASTERN CALIFORNIA...PLEASE REFER TO THE
FOLLOWING WEB SITES /NOTE...ALL LETTERS IN WEB SITE ADDRESSES ARE
LOWER CASE/...

NWS CALIFORNIA NEVADA RIVER FORECAST CENTER...
HTTP://WWW.CNRFC.NOAA.GOV/WATER_SUPPLY.PHP

NEVADA NATURAL RESOURCES CONSERVATION SERVICE...
HTTP://WWW.NV.NRCS.USDA.GOV/SNOW/

CALIFORNIA DEPT. OF WATER RESOURCES...
HTTP://CDEC.WATER.CA.GOV/

NWS CLIMATE PREDICTION CENTER LONG RANGE OUTLOOK MAPS...
HTTP://WWW.CPC.NCEP.NOAA.GOV/PRODUCTS/FORECASTS/

U.S. DROUGHT PORTAL...INCLUDING U.S. DROUGHT MONITOR...
HTTP://DROUGHT.GOV/

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