HYDROLOGIC OUTLOOK
NATIONAL WEATHER SERVICE RENO NV
235 PM PST FRI JAN 9 2009
...WATER SUPPLY OUTLOOK FOR NEVADA AND THE EASTERN SIERRA NEVADA...
ISSUED JOINTLY BY THE NATIONAL WEATHER SERVICE AND NATURAL RESOURCES
CONSERVATION SERVICE...
1/ SUMMARY...WATER SUPPLY...
THE WINTER SNOWPACK ACCUMULATION SEASON IS OFF TO A FITFUL START.
ONLY TWO BASINS IN NORTHEAST NEVADA HAD AVERAGE SNOWPACK ON JANUARY
1...WHILE THE REMAINDER OF NEVADA AND THE EASTERN SIERRA HAD
BELOW TO WELL BELOW AVERAGE CONDITIONS. AFTER TWO DRY YEARS...MANY
RESERVOIRS ARE SEVERELY DRAWN DOWN AND WILL BE UNABLE TO PROVIDE
CARRY OVER WATER TO HELP MEET DEMANDS NEXT SUMMER. THE NEXT COUPLE
OF WEEKS ARE FORECAST TO BE DRY WITH SOME INDICATION OF THE STORM
DOOR OPENING BACK UP BY THE END OF THE MONTH. DEFICITS THIS EARLY
IN THE SEASON ARE EASY TO OVERCOME WITH JUST ONE OR TWO BIG
STORMS...BUT THE LATER IT GETS THE MORE DIFFICULT IT BECOMES TO
STAGE A COMEBACK. AT THIS EARLY STAGE...STREAMFLOWS ARE EXPECTED TO
BE BELOW TO WELL BELOW AVERAGE...WITH THE EXCEPTION OF THE LOWER
COLORADO RIVER BASIN. THIS IS DUE TO DRY SOIL CONDITIONS GOING INTO
WINTER AND LOW SNOWPACK AT THE FIRST OF THE YEAR.
2/ SNOWPACK...
AS 2009 BEGAN...ONLY A COUPLE OF BASINS IN NORTHEAST NEVADA HAD
NEAR AVERAGE SNOWPACK...WHILE THE REST OF THE REGION HAD BELOW TO
MUCH BELOW AVERAGE SNOWPACK. MOST OF THE STORMS THAT MOVED ACROSS
THE REGION IN DECEMBER WERE QUICK AND COLD...LEAVING BEHIND LIGHT
FLUFFY POWDER LOW IN WATER CONTENT. THE FIRST PART OF JANUARY HAS
BEEN RELATIVELY DRY AND NO STRONG STORMS ARE FORECAST TO HIT THE
REGION OVER THE NEXT TWO WEEKS. AS OF JANUARY 1...THE HIGHEST
SNOWPACK WAS ON THE SNAKE RIVER BASIN AT 104 PERCENT OF AVERAGE.
THE CLOVER VALLEY AND FRANKLIN RIVER BASIN WAS LOWEST AT 42 PERCENT.
LAST YEAR THIS YEAR
BASIN PERCENT OF AVERAGE PERCENT OF AVERAGE
LAKE TAHOE ................................. 53 ................ 85
TRUCKEE RIVER .............................. 53 ................ 83
CARSON RIVER ............................... 57 ................ 84
WALKER RIVER ............................... 45 ................. 75
NORTHERN GREAT ............................. 65 ................ 83
UPPER HUMBOLDT RIVER ....................... 81 ................ 78
LOWER HUMBOLDT RIVER ....................... 71 ................ 65
CLOVER VALLEY & FRANKLIN RIVER ............. 62 ................ 42
SNAKE RIVER ................................ 72 ................ 104
OWYHEE RIVER ............................... 58 ................ 103
EASTERN NEVADA ............................. 77 ................ 92
3/ PRECIPITATION...
DECEMBER PRECIPITATION FOR NEVADA AND EASTERN CALIFORNIA WAS
GENERALLY ABOVE AVERAGE WITH THE EXCEPTION OF THE SIERRA NEVADA.
PRECIPITATION FOR THE 2009 WATER YEAR...WHICH BEGAN OCTOBER 1
2008...WAS VARIABLE ACROSS THE REGION. DECEMBER PRECIPITATION
WAS HIGHEST ON THE LOWER COLORADO RIVER BASIN AT 238 PERCENT OF
AVERAGE AND LOWEST ON THE WALKER RIVER BASIN AT 80 PERCENT. AS OF
JANUARY 1...2009 WATER YEAR PRECIPITATION WAS HIGHEST ON THE LOWER
COLORADO RIVER BASIN AT 133 PERCENT OF AVERAGE AND LOWEST ON THE
LAKE TAHOE BASIN AT 86 PERCENT.
DECEMBER WATER YEAR 2009
BASIN PERCENT OF AVERAGE PERCENT OF AVERAGE
LAKE TAHOE ................................. 98 ................ 86
TRUCKEE RIVER .............................. 100 ................ 89
CARSON RIVER ............................... 93 ................ 89
WALKER RIVER ............................... 80 ................ 89
NORTHERN GREAT ............................. 126 ................ 110
UPPER HUMBOLDT RIVER ....................... 129 ................ 116
LOWER HUMBOLDT RIVER ....................... 118 ................ 92
CLOVER VALLEY AND FRANKLIN RIVER ........... 119 ................ 109
SNAKE RIVER ................................ 161 ................ 126
OWYHEE RIVER ............................... 152 ................ 120
EASTERN NEVADA ............................. 101 ................ 94
LOWER COLORADO RIVER ....................... 238 ................ 133
THERE IS CURRENTLY A LARGE PRECIPITATION DEFICIT ACROSS MUCH OF THE REGION.
AS OF JANUARY 6...MUCH OF NORTHWESTERN AND EAST CENTRAL NEVADA...AS WELL AS
NORTHEAST CALIFORNIA WERE IN SEVERE DROUGHT CATEGORIES...AS CLASSIFIED BY THE
U.S. DROUGHT MONITOR. PORTIONS OF MODOC...LASSEN AND PLUMAS COUNTIES
CALIFORNIA WERE IN EXTREME DROUGHT. /THE DROUGHT MONITOR IS ONLINE AT
HTTP://WWW.DROUGHT.UNL.EDU/DM/MONITOR.HTML/
4/ RESERVOIRS...
RESERVOIR STORAGE AS OF NEW YEARS DAY IN NEVADA AND EASTERN CALIFORNIA WAS
IN POOR SHAPE. RESERVOIR STORAGE WAS HIGHEST IN THE TRUCKEE RIVER BASIN
AT 74 PERCENT OF AVERAGE...WHILE THE LAKE TAHOE BASIN WAS LOWEST AT 7 PERCENT
OF AVERAGE.
BASIN PERCENT OF CAPACITY PERCENT OF AVERAGE
LAKE TAHOE ................................. 3 ................ 7
TRUCKEE RIVER .............................. 40 ................ 74
CARSON RIVER ............................... 13 ................ 26
WALKER RIVER ............................... 21 ................ 52
LOWER HUMBOLDT RIVER ....................... 4 ................ 9
OWYHEE RIVER ............................... 35 ................ 66
LOWER COLORADO RIVER ....................... 50 ................ 60
5/ STREAMFLOW...
APRIL TO JULY STREAMFLOW FORECASTS FOR NEVADA AND EASTERN CALIFORNIA ARE
EXPECTED TO RANGE FROM AVERAGE TO WELL BELOW AVERAGE. STREAMFLOW FORECASTS
ARE HIGHEST FOR THE LOWER COLORADO RIVER BASIN AT 101 PERCENT OF AVERAGE
AND LOWEST FOR THE CARSON RIVER BASIN AT 59 PERCENT OF AVERAGE.
NOTE...FORECASTS 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
BASIN (50 PERCENT CHANCE OF EXCEEDANCE)
LAKE TAHOE ...................................................... 67
TRUCKEE RIVER ................................................... 71
CARSON RIVER .................................................... 59
WALKER RIVER .................................................... 72
NORTHERN GREAT .................................................. 74
UPPER HUMBOLDT RIVER ............................................ 73
LOWER HUMBOLDT RIVER ............................................ 67
CLOVER VALLEY AND FRANKLIN RIVER ................................ 75
SNAKE RIVER ..................................................... 93
OWYHEE RIVER .................................................... 99
EASTERN NEVADA .................................................. 85
LOWER COLORADO RIVER ............................................ 101
6/ LONG RANGE WEATHER OUTLOOK FOR NEVADA AND THE EASTERN SIERRA...FOR
JANUARY...PRECIPITATION IS EXPECTED TO BE NEAR AVERAGE OVER
THE ENTIRE REGION. TEMPERATURES ARE EXPECTED TO BE SOMEWHAT ABOVE
AVERAGE OVER THE REGION.
THE LONG RANGE OUTLOOK FOR THE MONTHS OF FEBRUARY THROUGH APRIL IS FOR
NEAR NORMAL PRECIPITATION OVER THE ENTIRE REGION. TEMPERATURES ARE
EXPECTED TO BE NEAR NORMAL OVER THE REGION WITH THE EXCEPTION OF EXTREME
SOUTHERN NEVADA WHICH IS EXPECTED TO BE SOMEWHAT WARMER THAN NORMAL.
7/ FOR MORE DETAILED WATER SUPPLY AND STREAMFLOW FORECAST
INFORMATION FOR THE EASTERN SIERRA AND NEVADA...
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/
NATURAL RESOURCES CONSERVATION SERVICE...
HTTP://WWW.NV.NRCS.USDA.GOV/SNOW/INDEX.HTML
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/