HYDROLOGIC OUTLOOK
NATIONAL WEATHER SERVICE GREAT FALLS MT
1215 PM MST THU JANUARY 13 2005
...MONTANA WATER SUPPLY OUTLOOK AS OF JANUARY 2005...
MONTANA WATER SUPPLY FORECAST ISSUED BY THE NATIONAL WEATHER
SERVICE OFFICE IN GREAT FALLS IN COOPERATION AND
COORDINATION WITH THE NATIONAL WEATHER SERVICE OFFICE IN
MISSOULA AND THE NATURAL RESOURCES CONSERVATION SERVICE... USDA.
THE WATER SUPPLY OUTLOOK FOR THE 2005 SUMMER SEASON PROJECTS
WATER SUPPLIES WEST OF THE CONTINENTAL DIVIDE TO BE BELOW AVERAGE.
EAST OF THE CONTINENTAL DIVIDE... WATER SUPPLIES ARE FORECAST TO BE
BELOW TO WELL BELOW AVERAGE. THESE FORECASTS ASSUME NEAR NORMAL
MOISTURE AND RUNOFF CONDITIONS FOR JANUARY THROUGH JULY AND DO NOT
ACCOUNT FOR MUCH BELOW AVERAGE... 70 OR LESS... OR ABOVE AVERAGE...
110 OR MORE... SNOWMELT OR SPRING RAINS.
SNOWPACK...
THE SNOWFALL SEASON IS OFF TO A MUCH WORSE START THAN LAST YEAR AT
THIS TIME. STATEWIDE... THE SNOWPACK IS 31 PERCENT BELOW LAST YEAR.
ON JANUARY 1... THE SNOW WATER CONTENT SHOULD BE ABOUT 45 PERCENT OF
THE AVERAGE SNOWPACK PEAK... WHICH OCCURS DURING APRIL. THIS YEAR...
THE SNOW WATER CONTENT IS ABOUT 32 PERCENT OF THE PEAK OR 13 PERCENT
BELOW AVERAGE. RAINFALL IN SEPTEMBER AND OCTOBER WAS ABOVE AVERAGE
TO WELL ABOVE AVERAGE IN MOST AREAS IMPROVING SOIL MOISTURE
CONDITIONS. NOVEMBER AND DECEMBER MOISTURE WAS BELOW AVERAGE OVERALL.
THE SUN-TETON-MARIAS BASINS RANK SECOND LOWEST IN 45 YEARS... FIRST
LOWEST WAS 2003. THE BEARS PAW MOUNTAINS RANK THIRD LOWEST IN 33
YEARS BEHIND 2003 AND 2002.
MOUNTAIN SNOW WATER CONTENT
PERCENT OF PERCENT OF
AVERAGE LAST YEAR
STATEWIDE 71 69
WEST OF THE CONTINENTAL DIVIDE 66 65
EAST OF THE CONTINENTAL DIVIDE 77 76
PRECIPITATION...
MOUNTAIN AND VALLEY PRECIPITATION AVERAGES FOR DECEMBER
PERCENT OF PERCENT OF
AVERAGE LAST YEAR
STATEWIDE 75 76
WEST OF THE CONTINENTAL DIVIDE 72 96
EAST OF THE CONTINENTAL DIVIDE 78 63
MOUNTAIN AND VALLEY PRECIPITATION AVERAGES FOR THE WATER YEAR
PERCENT OF PERCENT OF
AVERAGE LAST YEAR
STATEWIDE 79 79
WEST OF THE CONTINENTAL DIVIDE 77 79
EAST OF THE CONTINENTAL DIVIDE 81 79
CALENDAR YEAR 2004 AND WATER YEAR 2005 PERCENT OF NORMAL
PRECIPITATION FOR SELECTED CITIES ARE SHOWN BELOW.
PERCENT OF NORMAL PERCENT OF NORMAL
CALENDAR YEAR 2004 WATER YEAR 2005
CITY JAN 1 TO DEC 31 OCT 1 TO DEC 31
BILLINGS 74 75
BOZEMAN 67 97
BUTTE 40 86
CUT BANK 78 61
DILLON 75 93
GLASGOW 93 111
GREAT FALLS 75 94
HAVRE 59 101
HELENA 36 106
KALISPELL 68 68
LEWISTOWN 82 95
MILES CITY 94 69
MISSOULA 44 110
DECEMBER AND WATER YEAR PRECIPITATION AVERAGES FOR 2005 AND
2004 BY CLIMATE DIVISIONS ARE SHOWN BELOW.
CLIMATE MONTH OF WATER YEAR
DIVISION DECEMBER OCT 1 TO DEC 31
2005 2004 2005 2004
WESTERN 49 84 48 68
SOUTHWEST 68 213 66 78
NORTH CENTRAL 88 123 83 95
CENTRAL 56 183 57 106
SOUTH CENTRAL 33 116 76 82
NORTHEAST 106 193 75 102
SOUTHEAST 41 151 78 79
RESERVOIRS...
MAJOR RESERVOIR STORAGE AS OF JANUARY 1
PERCENT OF PERCENT OF
AVERAGE LAST YEAR
STATEWIDE 68 83
WEST OF THE CONTINENTAL DIVIDE 118 106
EAST OF THE CONTINENTAL DIVIDE 50 69
PERCENT OF NORMAL RESERVOIR STORAGE AS OF JANUARY 1 FOR SELECTED
RESERVOIRS
RESERVOIR PERCENT OF NORMAL
2005 2004
BIGHORN RESERVOIR 77 84
CANYON FERRY RESERVOIR 84 88
CLARK CANYON RESERVOIR 31 26
FLATHEAD LAKE 105 94
FORT PECK LAKE 37 64
FRESNO RESERVOIR 104 56
GIBSON RESERVOIR 85 45
HEBGEN RESERVOIR 101 91
HUNGRY HORSE RESERVOIR 125 110
LAKE ELWELL / TIBER RESERVOIR 99 106
LAKE KOOCANUSA 119 119
LAKE SHERBURNE 185 70
LIMA RESERVOIR 110 18
NELSON RESERVOIR 106 81
PISHKIN RESERVOIR 104 104
WILLOW CREEK RESERVOIR 132 95
STREAMFLOW...
STATEWIDE... STREAMFLOWS ARE FORECAST TO AVERAGE BETWEEN 55 AND
70 PERCENT OF AVERAGE FOR THE PERIOD APRIL 1 THROUGH JULY 31.
WEST OF THE CONTINENTAL DIVIDE... STREAMFLOWS ARE FORECAST TO
AVERAGE BETWEEN 56 AND 70 PERCENT WITH INDIVIDUAL BASINS RANGING
FROM 35 TO 93 PERCENT OF AVERAGE. EAST OF THE CONTINENTAL DIVIDE...
STREAMFLOWS ARE FORECAST TO AVERAGE BETWEEN 53 AND 70 PERCENT WITH
INDIVIDUAL BASINS RANGING FROM 32 TO 96 PERCENT OF AVERAGE.
BELOW ARE AVERAGED RIVER BASIN RUNOFF FORECAST SUMMARIES FOR THE
PERIOD APRIL THROUGH SEPTEMBER. THESE FORECASTS ASSUME NEAR NORMAL
SPRING CONDITIONS AND DO NOT ACCOUNT FOR WELL BELOW AVERAGE... 70 OR
LESS... OR ABOVE AVERAGE... 110 OR MORE... SNOWMELT OR SPRING RAIN.
FORECASTS FOR RIVERS AND SITES WEST OF THE CONTINENTAL DIVIDE ARE
PROVIDED BY THE NORTHWEST RIVER FORECAST CENTER IN PORTLAND...
OREGON. FORECASTS FOR RIVERS AND SITES EAST OF THE CONTINENTAL
DIVIDE ARE FROM THE MISSOURI BASIN RIVER FORECAST CENTER IN PLEASANT
HILL... MISSOURI. ALL FORECASTS ARE IN COOPERATION AND COORDINATION
WITH NATURAL RESOURCES CONSERVATION SERVICE... USDA.
PERIOD MOST REASONABLE REASONABLE
PROBABLE MAXIMUM MINIMUM
FORECAST
( AVG) ( AVG) ( AVG)
COLUMBIA RIVER BASIN
KOOTENAI RIVER
LIBBY RESVR INFLOW APR-SEP 92 126 59
LIBBY APR-SEP 91 121 60
CLARK FORK
ABOVE MISSOULA APR-SEP 69 116 22
BELOW MISSOULA APR-SEP 71 113 28
ST. REGIS APR-SEP 71 123 18
NEAR PLAINS APR-SEP 76 119 32
BLACKFOOT RIVER
NEAR BONNER APR-SEP 70 110 30
BITTERROOT RIVER
AT MOUTH APR-SEP 73 114 32
FLATHEAD RIVER
COLUMBIA FALLS APR-SEP 81 110 52
FLATHEAD LAKE INFLOW APR-SEP 81 121 41
NORTH FORK FLATHEAD RIVER
NEAR COLUMBIA FALLS APR-SEP 86 111 59
MIDDLE FORK FLATHEAD RIVER
NEAR WEST GLACIER NR APR-SEP 80 106 55
SOUTH FORK FLATHEAD RIVER
HUNGRY HORSE RES INFLOW APR-SEP 79 118 40
SASKATCHEWAN RIVER BASIN
ST. MARY RIVER
BABB NR APR-SEP 84 101 68
MISSOURI RIVER BASIN
RED ROCK RIVER
LIMA RES INFLOW APR-SEP 75 134 42
BEAVERHEAD RIVER
CLARK CANYON INFLOW APR-SEP 40 100 16
BARRETTS APR-SEP 50 99 1
RUBY RIVER
RUBY RESERVOIR INFLOW APR-SEP 69 102 37
BIG HOLE RIVER
NEAR MELROSE APR-SEP 54 102 6
MADISON RIVER
HEBGEN RES INFLOW APR-SEP 93 113 73
ENNIS RESERVOIR INFLOW APR-SEP 82 104 61
GALLATIN RIVER
NEAR GALLATIN GATEWAY APR-SEP 83 106 61
LOGAN APR-SEP 78 118 39
MISSOURI RIVER
TOSTON APR-SEP 67 100 34
FORT BENTON APR-SEP 71 103 38
VIRGELLE APR-SEP 73 105 40
NEAR LANDUSKY APR-SEP 69 102 37
BELOW FORT PECK DAM APR-SEP 69 102 36
SHEEP CREEK
WHITE SULPHUR SPRINGS APR-SEP 78 110 47
SUN RIVER
GIBSON RES INFLOW APR-SEP 57 84 31
MARIAS RIVER
NEAR SHELBY APR-SEP 55 115 5
MUSSELSHELL RIVER
HARLOWTON APR-SEP 53 106 6
MILK RIVER
WESTERN CROSSING MAR-SEP 47 84 17
MILK RIVER...AB MAR-SEP 48 81 16
EASTERN CROSSING MAR-SEP 48 83 16
YELLOWSTONE RIVER
YELLOWSTN LK OUTLT...WY APR-SEP 71 94 49
CORWIN SPRINGS APR-SEP 83 105 60
NEAR LIVINGSTON APR-SEP 82 103 62
BILLINGS APR-SEP 80 106 54
MILES CITY APR-SEP 78 104 52
NEAR SIDNEY APR-SEP 77 103 51
BOULDER RIVER
BIG TIMBER APR-SEP 87 116 59
STILLWATER RIVER
NEAR ABSAROKEE APR-SEP 80 102 59
CLARKS FORK YELLOWSTONE RIVER
NEAR BELFRY APR-SEP 69 88 50
LITTLE BIGHORN RIVER
NEAR HARDIN APR-SEP 48 88 45
TONGUE RIVER
TONGUE RIVER RES INFLOW APR-SEP 84 122 45
POWDER RIVER
MOORHEAD APR-SEP 87 133 42
NEAR LOCATE APR-SEP 81 108 55
DEFINITIONS
MOST PROBABLE FORECAST. GIVEN THE CURRENT HYDROMETEOROLOGICAL
CONDITIONS TO DATE...THIS IS THE BEST ESTIMATE OF WHAT THE ACTUAL
RUNOFF VOLUME WILL BE THIS SEASON.
REASONABLE MAXIMUM FORECAST. GIVEN CURRENT HYDROMETEOROLOGICAL
CONDITIONS... THE SEASONAL RUNOFF THAT HAS A TEN (10) PERCENT
CHANCE OF BEING EXCEEDED.
REASONABLE MINIMUM FORECAST. GIVEN CURRENT HYDROMETEOROLOGICAL
CONDITIONS... THE SEASONAL RUNOFF THAT HAS A NINETY (90) PERCENT
CHANCE OF BEING EXCEEDED.
OUTLOOK...
THE CLIMATIC OUTLOOK FOR JANUARY INTO EARLY FEBRUARY INDICATES
THERE ARE BETTER CHANCES TEMPERATURES WILL BE BELOW NORMAL ACROSS
MONTANA. DURING THE SAME PERIOD...THERE ARE BETTER CHANCES
PRECIPITATION WILL BE BELOW NORMAL WEST OF THE CONTINENTAL DIVIDE
WHILE THERE ARE EQUAL CHANCE PRECIPITATION WILL BE ABOVE... BELOW OR
NEAR NORMAL EAST OF THE CONTINENTAL DIVIDE.
THE OUTLOOK FOR THE FEBRUARY THROUGH APRIL PERIOD INDICATES THERE
ARE BETTER CHANCES TEMPERATURES WILL BE ABOVE NORMAL ACROSS MONTANA.
THE OUTLOOK INDICATES THERE ARE EQUAL CHANCES PRECIPITATION WILL BE
ABOVE... BELOW OR NEAR NORMAL FOR ALL EXCEPT EXTREME WESTERN MONTANA
WHERE THERE ARE BETTER CHANCES OF BELOW NORMAL PRECIPITATION.
THE NEXT WATER SUPPLY OUTLOOK FOR 2005 WILL BE ISSUED BY FEBRUARY 15.
LOSS