HYDROLOGIC OUTLOOK 
NATIONAL WEATHER SERVICE RENO NV
335 PM PDT TUE APRIL 8 2006
...WATER SUPPLY AND SPRING FLOOD POTENTIAL OUTLOOK FOR NEVADA AND THE
EASTERN SIERRA NEVADA...
ISSUED JOINTLY BY THE NATIONAL WEATHER SERVICE AND NATURAL RESOURCES
CONSERVATION SERVICE... 
1/ SUMMARY...WATER SUPPLY...
MARCH PRECIPITATION WAS DISAPPOINTING IN MUCH OF NEVADA AND THE 
EASTERN SIERRA.  MANY AREAS RECEIVED A QUARTER OR LESS OF NORMAL 
MARCH PRECIPITATION.  THE SIERRA NEVADA...EASTERN NEVADA AND 
SOUTHERN NEVADA WERE ON THE LOSING END OF THE DRY SPELL.  THOUGH 
SOMEWHAT WETTER...CENTRAL AND NORTHEAST NEVADA STILL RECEIVED WELL 
BELOW AVERAGE PRECIPITATION AMOUNTS FOR THE MONTH.  TAKE OUT SOME 
MELT OF THE EXISTING SNOWPACK AND MANY BASINS DROPPED BELOW AVERAGE 
AS OF APRIL 1...THOUGH THE HUMBOLDT SYSTEM AND NORTHEAST NEVADA 
MAINTAINED ABOVE AVERAGE READINGS.  THE SIERRA NEVADA BASINS ALL HAD 
BELOW AVERAGE SNOWPACK...ALTHOUGH THE WALKER BASIN AT 96 PERCENT OF 
AVERAGE WAS CLOSE.  THIS HAS RESULTED IN AVERAGE TO BELOW AVERAGE 
FORECASTS FOR WESTERN NEVADA AND THE EASTERN SIERRA AND AVERAGE TO 
ABOVE AVERAGE FORECASTS FOR THE REMAINDER OF NEVADA.  WHILE WATER 
SUPPLY THIS YEAR IS NOTHING TO GET TERRIBLY EXCITED ABOUT...MEETING 
THE WATER NEEDS OF OUR STATE SHOULD BE EASIER TO DO THIS YEAR THAN 
IT WAS LAST YEAR. 
SUMMARY...SPRING FLOOD POTENTIAL...
MOST OF THE NORTHERN TWO THIRDS OF NEVADA AND THE EASTERN SIERRA HAS 
HAD AVERAGE TO BELOW AVERAGE PRECIPITATION AND SNOWPACK...ALONG WITH 
DRY SOILS AND BELOW AVERAGE RESERVOIR STORAGE CONDITIONS.  SO... 
FLOOD POTENTIAL FROM SPRING SNOWMELT IS NEAR TO BELOW AVERAGE FOR 
THIS AREA.  FLOOD POTENTIAL IS BELOW AVERAGE FOR THE SOUTHERN 
THIRD OF NEVADA.   
2/ SNOWPACK...
APRIL 1 SNOWPACK IN NEVADA AND THE EASTERN SIERRA WAS QUITE 
VARIABLE.  A FAIRLY DRY MARCH AND SOME EARLY MELT OF THE EXISTING 
SNOWPACK CAUSED SNOWPACK VALUES TO DROP QUITE A BIT SINCE MARCH 1.  
THE LOWER HUMBOLDT RIVER BASIN HAD THE HIGHEST VALUE AT 120 PERCENT 
OF AVERAGE...WHILE THE LOWER COLORADO RIVER BASIN WAS LOWEST AT 81 
PERCENT.
                                      PERCENT OF AVERAGE SNOWPACK         
BASIN                                APR 1 2007         APR 1 2008
LAKE TAHOE............................  43 ................  89
TRUCKEE RIVER ........................  50 ................  86
CARSON RIVER .........................  37 ................  82
WALKER RIVER .........................  41 ................  96
NORTHERN GREAT .......................  47 ................ 102
UPPER HUMBOLDT RIVER .................  51 ................ 105
LOWER HUMBOLDT RIVER .................  38 ................ 120
CLOVER VALLEY & FRANKLIN RIVER .......  44 ................ 110
SNAKE RIVER ..........................  49 ................ 108
OWYHEE RIVER .........................  39 ................ 115
EASTERN NEVADA .......................  52 ................  98
LOWER COLORADO RIVER.................   19 ................  81
3/ PRECIPITATION... 
MARCH WAS GENERALLY DRY IN NEVADA AND THE EASTERN SIERRA.  IT WAS 
ESPECIALLY DRY IN THE SIERRA NEVADA...EASTERN NEVADA AND SOUTHERN 
NEVADA.  MARCH PRECIPITATION WAS HIGHEST IN THE SNAKE RIVER BASIN AT 
87 PERCENT OF AVERAGE AND LOWEST IN THE LOWER COLORADO RIVER BASIN 
AT 12 PERCENT.  WATER YEAR PRECIPITATION (SINCE OCTOBER 1 2007) WAS 
HIGHEST IN THE CLOVER VALLEY AND FRANKLIN RIVER BASIN AT 111 PERCENT 
OF AVERAGE AND LOWEST IN THE LOWER COLORADO RIVER BASIN AT 73 PERCENT.
                               PERCENT OF AVERAGE PRECIPITATION
BASIN                          MARCH 2008        2008 WATER YEAR
                                                 THRU APR 1 2008
UPPER PIT RIVER ..................  30 ................  78
UPPER FEATHER RIVER ..............  24 ................  69
LAKE TAHOE .......................  27 ................  80
TRUCKEE RIVER ....................  28 ................  83
CARSON RIVER .....................  23 ................  73
WALKER RIVER .....................  22 ................  98
NORTHERN GREAT ...................  69 ................  97
UPPER HUMBOLDT RIVER .............  71 ................ 103
LOWER HUMBOLDT RIVER .............  59 ................  99
CLOVER VALLEY AND FRANKLIN RIVER .  74 ................ 111
SNAKE RIVER ......................  87 ................ 105
OWYHEE RIVER .....................  75 ................ 100
EASTERN NEVADA ...................  22 ................  79
LOWER COLORADO RIVER .............  12 ................  73
4/ RESERVOIRS...
END OF MARCH RESERVOIR STORAGE IN NEVADA AND THE EASTERN SIERRA WAS 
GENERALLY POOR.  ONLY THE TRUCKEE RIVER BASIN WAS NEAR AVERAGE.  
RESERVOIR STORAGE WAS  HIGHEST IN THE TRUCKEE RIVER BASIN AT 94 
PERCENT OF AVERAGE...WHILE THE WALKER RIVER BASIN WAS LOWEST AT 50 
PERCENT.
BASIN                        PERCENT OF          PERCENT OF 
                         RESERVOIR CAPACITY    AVERAGE STORAGE
                                    AS OF APRIL 1 2008
MIDDLE FORK FEATHER RIVER......  57 ................  75
LAKE TAHOE ....................  35 ................  66
TRUCKEE RIVER .................  56 ................  94
CARSON RIVER ..................  41 ................  55
WALKER RIVER ..................  34 ................  50
LOWER HUMBOLDT RIVER ..........  33 ................  58
OWYHEE RIVER ..................  43 ................  67
LOWER COLORADO RIVER ..........  52 ................  61
5/ STREAMFLOW...
STREAMFLOW FORECASTS FOR NEVADA AND THE EASTERN SIERRA ARE EXPECTED 
TO VARY FROM BELOW TO ABOVE AVERAGE.  STREAMFLOW FORECASTS ARE 
HIGHEST FOR THE LOWER COLORADO RIVER BASIN AT 120 PERCENT OF AVERAGE 
AND LOWEST FOR THE CARSON RIVER BASIN AT 75 PERCENT.
NOTE...FORECASTS BELOW ARE FOR THE MOST PROBABLE OUTCOME...THE BEST 
ESTIMATE THAT CAN BE PRODUCED GIVEN CURRENT CONDITIONS.  SO...THERE 
IS A 50 PERCENT CHANCE THAT ACTUAL STREAMFLOW VOLUME WILL BE LESS 
THAN THESE FORECAST VALUES ...AND A 50 PERCENT CHANCE THAT THEY WILL 
EXCEED THEM.  FORECASTS ARE BASED ON THE OUTCOME OF SIMILAR PAST 
SITUATIONS.                           
                                           PERCENT OF AVERAGE FLOW
                                            MOST PROBABLE FORECAST 
BASIN                              /50 PERCENT CHANCE OF EXCEEDANCE/ 
PIT RIVER .........................................  86 
FEATHER RIVER .....................................  76 
LAKE TAHOE ........................................  78 
TRUCKEE RIVER .....................................  80 
CARSON RIVER ......................................  75 
WALKER RIVER ......................................  88 
NORTHERN GREAT .................................... 109 
UPPER HUMBOLDT RIVER .............................. 101 
LOWER HUMBOLDT RIVER .............................. 103 
CLOVER VALLEY AND FRANKLIN RIVER .................. 116 
SNAKE RIVER .......................................  98 
OWYHEE RIVER ...................................... 105 
EASTERN NEVADA .................................... 110 
LOWER COLORADO RIVER .............................. 120
6/ SPRING FLOOD POTENTIAL OUTLOOK...
AS OF EARLY APRIL...SNOWPACK AND PRECIPITATION FOR THE SEASON TO 
DATE RANGED FROM SOMEWHAT ABOVE TO SOMEWHAT BELOW AVERAGE THROUGHOUT 
MOST OF NEVADA AND THE EASTERN SIERRA.  RESERVOIR STORAGE REMAINED 
BELOW AVERAGE.  SOILS BENEATH SNOWPACK WERE RELATIVELY DRY IN MOST 
AREAS DUE TO THE DRIER THAN NORMAL FALL...SO A SIGNIFICANT PORTION 
OF SPRING SNOWMELT WILL GO INTO WETTING SOILS BEFORE RUNOFF BEGINS.  
THE APRIL 1ST 2008 U.S. DROUGHT MONITOR PLACED MOST OF NEVADA AND 
THE EASTERN SIERRA IN THE ABNORMALLY DRY TO MODERATE DROUGHT 
CATEGORY.  HOWEVER...PORTIONS OF NORTHWEST AND CENTRAL NEVADA 
REMAINED IN SEVERE DROUGHT.  
CONSEQUENTLY...FLOOD POTENTIAL FROM SPRING SNOWMELT IS NEAR TO BELOW 
AVERAGE FOR THE NORTHERN TWO-THIRDS OF NEVADA AND THE EASTERN SIERRA 
AT THIS TIME.  FLOOD POTENTIAL IS BELOW AVERAGE FOR THE SOUTHERN 
THIRD OF NEVADA.   
UNDER NORMAL SNOWMELT CONDITIONS...RUNOFF SHOULD BE EASILY 
CONTROLLED...ESPECIALLY ON THE TAHOE AND TRUCKEE BASINS AND OTHERS 
WHICH HAVE PLENTY OF FLOOD CONTROL STORAGE AVAILABLE IN RESERVOIRS.  
HOWEVER...HEAVY RAINFALL OR SEVERAL DAYS OF WELL ABOVE AVERAGE 
TEMPERATURES DURING THE MELT SEASON COULD RESULT IN LOCALIZED 
FLOODING ANYWHERE IN THE REGION UNTIL THE SNOWMELT SEASON ENDS.  
MAXIMUM SPRING SNOWMELT ON RIVERS AND STREAMS IN NEVADA AND THE 
EASTERN SIERRA TYPICALLY OCCURS IN MAY OR EARLY JUNE.  ALTHOUGH 
SPRING SNOWMELT FLOODING ON MAINSTEM RIVERS USUALLY ONLY OCCURS 
DURING THE SPRING MONTHS IN NEVADA AND THE EASTERN SIERRA... 
URBAN...SMALL STREAM AND FLASH FLOODING IS A POSSIBILITY DURING 
HEAVY RAIN ANY TIME OF YEAR. 
7/ LONG RANGE WEATHER OUTLOOK FOR NEVADA AND THE EASTERN 
SIERRA...FOR APRIL...PRECIPITATION IS EXPECTED TO BE NEAR AVERAGE 
NORTH OF A LINE FROM MONO LAKE CA TO PIOCHE NV...AND BELOW AVERAGE 
SOUTH OF THIS LINE  TEMPERATURES ARE EXPECTED TO BE NEAR AVERAGE FOR 
THE ENTIRE AREA IN APRIL.
THE LONG RANGE OUTLOOK FOR THE MONTHS OF MAY THROUGH JULY IS FOR 
ABOVE NORMAL TEMPERATURES OVER THE ENTIRE REGION.  PRECIPITATION IS 
EXPECTED TO BE NEAR AVERAGE THROUGHOUT THE AREA...EXCEPT IN THE 
EXTREME NORTH...WHICH IS EXPECTED TO BE BELOW AVERAGE.  
8/ FOR MORE DETAILED WATER SUPPLY AND STREAMFLOW FORECAST 
INFORMATION FOR THE EASTERN SIERRA AND NEVADA...PLEASE REFER TO THE 
FOLLOWING WEB SITES...
NWS WESTERN WATER SUPPLY FORECASTS... 
http://www.cbrfc.noaa.gov/westernwater/map.php?map=wsup
NWS CALIFORNIA NEVADA RIVER FORECAST CENTER...
http://www.cnrfc.noaa.gov/
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 MONITOR...
http://www.drought.unl.edu/dm/monitor.html