Flood Potential Outlook
Issued by NWS Reno, NV

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4
000
FGUS75 KREV 100029
ESFREV
NVZ001>041-CAZ070>073-CAZ519>527-150000-

WATER SUPPLY OUTLOOK
NATIONAL WEATHER SERVICE RENO NV
530 PM PDT MONDAY MAY 9 2016

...WATER SUPPLY OUTLOOK FOR NEVADA AND EASTERN CALIFORNIA AS OF
MAY 9 2016...

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

1/SUMMARY...WATER SUPPLY OUTLOOK...

PRECIPITATION HAS BEEN NEAR TO ABOVE NORMAL FOR MOST OF MOUNTAINOUS
NEVADA AND EASTERN CALIFORNIA SINCE THE BEGINNING OF THE WATER YEAR
ON OCTOBER 1, 2015. AREAS WITH THE HIGHEST WATER YEAR TO DATE
PRECIPITATION ARE EASTERN AND NORTHEASTERN NEVADA. APRIL
PRECIPITATION WAS NEAR OR ABOVE AVERAGE IN WESTERN NEVADA AND
EASTERN CALIFORNIA WITH THE EXCEPTION OF THE NORTHERN GREAT BASIN
AREA OF NORTHWESTERN NEVADA.

SNOWMELT IN THE FIRST HALF OF APRIL WAS MORE RAPID THAN NORMAL IN
MOST BASINS. FORTUNATELY, SOME ADDITIONAL SNOW ACCUMULATION,
COMBINED WITH COOLER TEMPERATURES LATER IN THE MONTH, HELPED REDUCE
SNOWMELT AND MAINTAIN NEAR AVERAGE CONDITIONS AS OF THE BEGINNING OF
MAY. STREAMFLOWS ARE NEAR NORMAL FOR MUCH OF THE AREA, AND AN
EXTREMELY EARLY SNOWPACK MELTOUT NOW SEEMS UNLIKELY.

WHILE NOT THE DROUGHT CRUSHING WINTER MANY HAD HOPED FOR, NEAR
NORMAL SNOWPACKS, STREAMFLOW AND RUNOFF FORECASTS  ARE HELPING TO
IMPROVE DROUGHT CONDITIONS SIGNIFICANTLY IN MOST AREAS.


2/SNOWPACK...

SNOWPACK AVERAGES, AS OF MAY 1ST, ARE NEAR NORMAL, RANGING FROM 66%
ON THE OWYHEE BASIN TO A HIGH OF 126% FOR EASTERN NEVADA. AS OF MID
APRIL MANY BASINS SEEMED TO BE ON THEIR WAY TO EARLY MELTOUT, BUT A
TRANSITION TO COOLER AND WETTER CONDITIONS FOR THE LAST THIRD OF THE
MONTH HELPED MAINTAIN LATE SEASON SNOWPACKS CLOSE TO NORMAL FOR MOST
BASINS. ONLY THE NORTHERN GREAT BASIN AND OWYHEE ARE SIGNIFICANTLY
BELOW NORMAL, AND ONLY THE OWYHEE SEEMS TO BE ON PACE FOR MUCH
EARLIER THAN NORMAL MELTOUT.

WITH THE WARM TEMPERATURES OF SPRING IT IS EASY TO FORGET THAT AT
HIGH ELEVATIONS WITH SHADY ASPECTS VERY SIGNIFICANT SNOWPACK STILL
REMAINS TO MELT. MANY SNOTEL SITES ABOVE 8000 FEET OF ELEVATION HAVE
MORE THAN HALF OF THEIR MAXIMUM SNOW ACCUMULATION REMAINING. A FEW
SITES LIKE LEAVITT LAKE IN MONO COUNTY ARE STILL AT, OR VERY NEAR,
THEIR SEASONAL MAXIMUM ACCUMULATION. AS OF MAY 9TH OVER 56 OF SNOW
WATER EQUIVALENT WAS REPORTED AT LEAVITT LAKE.

CAUTION MUST BE USED WHEN EVALUATING SNOWPACK PERCENTAGE OF NORMAL
LATE IN THE MELTOUT. RELATIVELY SMALL DIFFERENCES IN MELTOUT TIMING
COMBINED WITH SMALLER SNOWPACK WATER EQUIVALENT CAN RESULT IN LARGE
DIFFERENCES IN REPORTED PERCENTAGES. THE OWYHEE BASIN IS AN EXAMPLE
OF THIS, WHERE RAPID MELT IN EARLY APRIL BROUGHT FORMERLY ABOVE
NORMAL CONDITIONS TO MUCH BELOW NORMAL WITH THE MELT ONE TO THREE
WEEKS EARLIER THAN NORMAL.

                                 MAY 1 2016
BASIN                    PERCENT OF MEDIAN
LAKE TAHOE ........................   106
TRUCKEE RIVER .....................    96
CARSON RIVER ......................    95
WALKER RIVER ......................    92
NORTHERN GREAT BASIN...............    82
UPPER HUMBOLDT RIVER ..............   103
LOWER HUMBOLDT RIVER ..............   113
CLOVER VALLEY & FRANKLIN RIVER ....   119
SNAKE RIVER .......................   119
OWYHEE RIVER ......................    66
EASTERN NEVADA ....................   127
LOWER COLORADO RIVER ..............    NA

3/PRECIPITATION...

CURRENT WATER YEAR-TO-DATE PRECIPITATION AS OF MAY 1ST IS NEAR TO
ABOVE NORMAL THROUGHOUT NEVADA. BASINS DRAINING THE EAST SLOPE OF
THE SIERRA ARE NEAR AVERAGE AND CONDITIONS ARE SOMEWHAT WETTER TO
THE EAST WITH THE FAR EASTERN NEVADA AREA AT 137%. APRIL
PRECIPITATION WAS NEAR TO ABOVE AVERAGE THROUGHOUT THE REGION, WITH
EASTERN NEVADA AND THE WALKER BASINS BENEFITING FROM THE WETTEST
CONDITIONS AT 161% AN 149% RESPECTIVELY. ONLY THE NORTHERN GREAT
BASIN AREA HAD APRIL PRECIPITATION APPRECIABLE BELOW AVERAGE AT 74%.

                                                  WATER YEAR 2016
                                    APR 2016    /THROUGH 04/30/2016/
BASIN                              PCT OF AVE        PCT OF AVE
LAKE TAHOE .........................   118 ...........  116
TRUCKEE RIVER ......................   100 ...........  107
CARSON RIVER .......................    99 ...........  106
WALKER RIVER .......................   149 ...........  106
NORTHERN GREAT BASIN................    74 ...........  112
UPPER HUMBOLDT RIVER ...............   141 ...........  125
LOWER HUMBOLDT RIVER ...............   100 ...........  117
CLOVER VALLEY AND FRANKLIN RIVER ...   136 ...........  128
SNAKE RIVER ........................   147 ...........  132
OWYHEE RIVER .......................   130 ...........  118
EASTERN NEVADA .....................   161 ...........  137
LOWER COLORADO RIVER ...............    NA ...........   NA

4/RESERVOIRS...

MOST RESERVOIRS IN THE AREA MADE SIGNIFICANT GAINS IN STORAGE SINCE
LAST MONTH INCLUDING 64,000 ACRE-FEET IN LAKE TAHOE, WHICH IS NOW
ABOVE THE NATURAL RIM FOR THE FIRST TIME SINCE THE FALL OF 2014.
CURRENT TAHOE LEVELS ARE STILL WELL BELOW AVERAGE AND ARE ONLY
SUFFICIENT TO SUPPORT LOW FLOWS INTO THE TRUCKEE RIVER. STAMPEDE,
LAHONTAN AND RYE PATCH ALSO MADE SIGNIFICANT GAINS DURING APRIL.
CONDITIONS IN RYE PATCH ARE NOW SUPPORTING RELEASES FOR
DOWNSTREAM IRRIGATION, WHICH WAS NOT POSSIBLE DURING THE LAST TWO
SEASONS. THE UPPER WALKER RESERVOIRS WERE THE ONLY EXCEPTION TO
SIGNIFICANT APRIL GAINS, WITH MINIMAL CHANGES IN STORAGE OVER THE
MONTH DUE TO SEASONAL FILLING RESTRICTIONS. DESPITE THESE GAINS,
RESERVOIR STORAGE IS STILL MUCH BELOW AVERAGE.

BASIN                      PERCENT OF CAPACITY   PERCENT OF AVERAGE
LAKE TAHOE ........................   6 ................  11
TRUCKEE RIVER .....................  41 ................  61
CARSON RIVER ......................  33 ................  47
WALKER RIVER  ...................... 29 ................  43
LOWER HUMBOLDT RIVER ..............  21 ................  39
OWYHEE RIVER ......................  76 ................  52
LOWER COLORADO RIVER ..............  37 ................  48

5/STREAMFLOW...

OBSERVED STREAMFLOWS FOR 2016 WATER YEAR TO DATE ARE GENERALLY NEAR
TO ABOVE AVERAGE FOR THE REGION. THE LOWER HUMBOLDT AND EAST FORK OF
THE WALKER STAND OUT AS EXCEPTIONS AND ARE BOTH SIGNIFICANTLY BELOW
AVERAGE RUNOFF TO DATE.

STREAMFLOW FORECASTS FOR ALL OF NEVADA AND EASTERN CALIFORNIA AS OF
MAY 1ST ARE NEAR AVERAGE FOR APRIL TO JULY RUNOFF. WATER SUPPLY
CONDITIONS ARE FORECAST TO BE MUCH HIGHER THAN LAST YEAR, WITH
AVERAGE TO ABOVE AVERAGE CONDITIONS FOR MOST OF THE AREA. BELOW
AVERAGE CONDITIONS ARE EXPECTED ON THE EAST WALKER AS WELL AS
FARTHER SOUTH IN THE MONO BASIN. WHILE FORECASTS FROM THE NRCS AND
NWS HAVE CONVERGED SOMEWHAT FROM EARLIER IN THE SEASON, SIGNIFICANT
DIFFERENCES STILL EXIST AND ARE DRIVEN BY DIFFERING FORECAST
METHODOLOGIES.

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


               PERCENT OF AVERAGE APRIL TO JULY STREAMFLOW
                MOST PROBABLE FORECAST AS OF MAY 1 2016
                     (50 PERCENT CHANCE OF EXCEEDANCE)

BASIN                                NRCS     NWS
LAKE TAHOE INFLOW..................... 92 ...  98
TRUCKEE RIVER.........................104 ... 104  .. FARAD
CARSON RIVER .........................107 ...  98  .. CARSON CITY
WEST WALKER RIVER ....................100 ... 112
EAST WALKER RIVER .................... 91 ...  71
NORTHERN GREAT BASIN.................. 88 ...  NA  .. 4 SITE AVERAGE
UPPER HUMBOLDT RIVER .................127 ... 129  .. PALISADE
LOWER HUMBOLDT RIVER .................104 ... 101  .. IMLAY
CLOVER VALLEY AND FRANKLIN RIVER .....109 ...  NA
SNAKE RIVER...........................134 ... 109@ .. SALMON FALLS CK
OWYHEE RIVER .........................109 ...  71@
EASTERN NEVADA....................... 126 ...  NA  .. 4 SITE AVERAGE
LAKE POWELL INFLOW   ................. 77 ...  77*
SUSAN RIVER........................... NA ... 126  .. SUSANVILLE (WATER YEAR)
MIDDLE FORK FEATHER RIVER............. NA ...  NA  .. PORTOLA (WATER YEAR)

NA - FORECAST EITHER NOT AVAILABLE OR NOT PRODUCED FOR THIS LOCATION
     AT THE TIME OF THE REPORT
*  - LAKE POWELL INFLOW 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 MAY 3, 2016, THE UNITED STATES DROUGHT
MONITOR CLASSIFIED 62% OF NEVADA IN MODERATE DROUGHT OR WORSE. THIS
IS 0.5 PERCENTAGE IMPROVEMENT FROM A MONTH AGO AND A 38% IMPROVEMENT
FROM A YEAR AGO. IN EASTERN NEVADA, INCLUDING PORTIONS OF ELKO,
WHITE PINE, LINCOLN, EUREKA AND NYE COUNTIES, CONDITIONS ARE LESS
SEVERE. EXTREME DROUGHT IS CLASSIFIED FOR 23% OF THE STATE INCLUDING
ALL OF STOREY, CARSON CITY, DOUGLAS, LYON, MINERAL, CHURCHILL, AND
PORTIONS OF WASHOE, PERSHING, LANDER, NYE AND ESMERALDA COUNTIES.
THIS IS A DECREASE OF 26% FROM LAST YEAR, AND NO PORTION OF NEVADA
IS CURRENTLY CLASSIFIED AS EXCEPTIONAL DROUGHT.

IN CALIFORNIA 90% OF THE STATE IS CLASSIFIED IN MODERATE DROUGHT OR
WORSE, ONLY EXCLUDING THE NORTHWESTERN PART OF THE STATE INCLUDING
COASTAL AREAS AND THE WESTERN HALF OF SISKIYOU COUNTY. THIS IS A
DECREASE OF 9% FROM LAST YEAR. EXTREME TO EXCEPTIONAL DROUGHT IS
INDICATED IN 49% OF THE STATE INCLUDING, BUT NOT LIMITED TO ALL OF
MONO COUNTY MOST OF ALPINE COUNTY, AND EASTERN PORTIONS OF PLUMAS,
SIERRA, NEVADA, PLACER, EL DORADO, AND LASSEN COUNTIES. MUCH OF
NORTHERN AND NORTHWESTERN AREAS SAW SIGNIFICANT IMPROVEMENT DUE TO
INTENSE EARLY MARCH STORMS AND RESERVOIR GAINS.

DESPITE NEAR AVERAGE OBSERVED AND FORECAST RUNOFF, WATER SUPPLY
DEFICITS ARE LIKELY TO CONTINUE FOR MUCH OF THE REGION DUE TO LOW
RESERVOIR STORAGE, DIMINISHED GROUND WATER LEVELS AND ASSOCIATED
IMPACTS TO FORESTS AND OTHER NATURAL RESOURCES.

7/ LONG RANGE WEATHER OUTLOOK FOR NEVADA AND EASTERN CALIFORNIA.

EARLY MAY PROVIDED ABOVE AVERAGE PRECIPITATION FOR MUCH OF EASTERN
CALIFORNIA AND WESTERN NEVADA, BUT WAS LESS FAVORABLE IN OTHER PARTS
OF NEVADA. MAY TEMPERATURES HAVE A SLIGHTLY INCREASED CHANCE OF
BEING ABOVE NORMAL IN NORTHERN CALIFORNIA AND NORTHWESTERN NEVADA.
LONG RANGE FORECASTS FOR MAY ALSO INDICATE SLIGHTLY INCREASED
PROBABILITY OF ABOVE AVERAGE PRECIPITATION FOR MOST OF REGION,
ESPECIALLY CENTRAL AND EASTERN NEVADA.

THE OUTLOOK FOR THE MONTHS OF JUNE THROUGH AUGUST IS FOR INCREASED
CHANCES OF ABOVE NORMAL TEMPERATURE THROUGHOUT THE REGION. SLIGHTLY
INCREASED CHANCES OF ABOVE NORMAL PRECIPITATION ARE PROJECTED FOR
NORTHERN NEVADA.

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.WATER.CA.GOV/

NEVADA NATURAL RESOURCES CONSERVATION SERVICE...
HTTP://WWW.NRCS.USDA.GOV/WPS/PORTAL/NRCS/MAIN/NV/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/

U.S. DROUGHT PORTAL...INCLUDING U.S. DROUGHT MONITOR...
HTTP://DROUGHTMONITOR.UNL.EDU/



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