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HYDROLOGIC OUTLOOK March 10, 2011

Posted by mikeheard in Uncategorized.
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GUS75 KTFX 102231
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WATER SUPPLY OUTLOOK
NATIONAL WEATHER SERVICE GREAT FALLS MT
331 PM MST THU MAR 10 2011

…MONTANA WATER SUPPLY OUTLOOK AS OF MARCH 2011…

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 2011 SUMMER SEASON PROJECTS WATER SUPPLIES EAST AND WEST OF THE CONTINENTAL DIVIDE TO BE ABOVE AVERAGE. THESE FORECASTS ASSUME NEAR NORMAL MOISTURE AND RUNOFF  CONDITIONS FOR MARCH THROUGH JULY AND DO NOT ACCOUNT FOR MUCH BELOW AVERAGE…70 PERCENT OR LESS…OR ABOVE AVERAGE…110 PERCENT OR MORE…SNOWMELT OR SPRING RAINS.

FEBRUARY WAS ANOTHER MONTH OF WINTER WEATHER FOR MONTANA.
TEMPERATURES ACROSS THE STATE AVERAGED OVER 8 DEGREES BELOW
AVERAGE…MAKING FEBRUARY 2011 THE COOLEST SINCE 2001 AND THE 24TH COOLEST ON RECORD FOR THE STATE. PRECIPITATION AND SNOWFALL CAME IN ABOVE AVERAGE…IT WAS THE 13TH WETTEST OF RECORD AND THE THIRD CONSECUTIVE MONTH OF ABOVE NORMAL PRECIPITATION. HEAVIEST AMOUNTS FELL WEST OF THE DIVIDE AND OVER PORTIONS OF CENTRAL MONTANA.
BILLINGS…GLASGOW…GREAT FALLS…HELENA…LIVINGSTON AND MISSOULA ALL SET ONE OR MORE DAILY RECORDS FOR TOTAL PRECIPITATION AND/OR TOTAL SNOWFALL. GREAT FALLS ALSO SET A RECORD FOR THEIR SNOWIEST FEBRUARY. THE HIGHEST AMOUNTS OF PRECIPITATION WERE 7.91 INCHES AT
MULLAN PASSAND 10.1 INCHES AT STAHL PEAK SNOTEL NEAR LINCOLN.

SNOWPACK…
MARCH 1 MOUNTAIN SNOWPACK CONTINUES THE TREND OF THE PREVIOUS THREE MONTHS COMING IN ABOVE AVERAGE AND WELL ABOVE LAST YEAR AT THIS TIME. THE SNOW WATER CONTENT ON MARCH 1 REPRESENTS ABOUT 82 PERCENT OF THE SEASONAL SNOWFALL WEST OF THE DIVIDE AND 75 PERCENT OF THE SEASONAL SNOWFALL EAST OF THE DIVIDE.

MOUNTAIN SNOWPACK AS OF MARCH 1…
PERCENT OF    PERCENT OF
AVERAGE      LAST YEAR
STATEWIDE                            113           165
WEST OF THE CONTINENTAL DIVIDE       115           178
EAST OF THE CONTINENTAL DIVIDE       110           153

PERCENT OF    PERCENT OF     JANUARY
AVERAGE      LAST YEAR   PERCENT CHANGE
COLUMBIA BASIN            115           178           +2
MISSOURI BASIN            111           148           -2
YELLOWSTONE BASIN         108           158           +3
ST. MARY BASIN            111           158           +3
ST. MARY/MILK BASIN       144           154          -11

PRECIPITATION…

MOUNTAIN PRECIPITATION AVERAGES FOR FEBRUARY BY BASIN…

WEST OF THE CONTINENTAL DIVIDE       106
EAST OF THE CONTINENTAL DIVIDE       105

MOUNTAIN AND VALLEY PRECIPITATION AVERAGES FOR FEBRUARY…
PERCENT OF    PERCENT OF
AVERAGE      LAST YEAR
STATEWIDE                            110           229
WEST OF THE CONTINENTAL DIVIDE       110           283
EAST OF THE CONTINENTAL DIVIDE       110           193

MOUNTAIN AND VALLEY PRECIPITATION AVERAGES FOR THE WATER YEAR…
PERCENT OF    PERCENT OF
AVERAGE      LAST YEAR
STATEWIDE                            113           145
WEST OF THE CONTINENTAL DIVIDE       114           162
EAST OF THE CONTINENTAL DIVIDE       112           131

CALENDAR YEAR 2011 AND WATER YEAR 2011 PERCENT OF NORMAL
PRECIPITATION FOR SELECTED CITIES ARE SHOWN BELOW…

PERCENT OF NORMAL      PERCENT OF NORMAL
CALENDAR YEAR 2011      WATER YEAR 2011
CITY              JAN 1 TO FEB 28        OCT 1 TO FEB 28

BILLINGS                 69                    109
BOZEMAN                  37                     85
BUTTE                    70                     86
CUT BANK                  M                      M
DILLON                   13                    114
GLASGOW                 400                    221
GREAT FALLS             187                    177
HAVRE                   176                    161
HELENA                  127                    148
KALISPELL               135                    132
LEWISTOWN                73                    106
MILES CITY               69                     54
MISSOULA                198                    157

RESERVOIRS…

MAJOR RESERVOIR STORAGE AS OF MARCH 1
PERCENT OF    PERCENT OF
AVERAGE      LAST YEAR
STATEWIDE                            111           109
WEST OF THE CONTINENTAL DIVIDE       133            93
EAST OF THE CONTINENTAL DIVIDE       105           115

PERCENT OF NORMAL RESERVOIR STORAGE AS OF MARCH 1 FOR SELECTED
RESERVOIRS…

RESERVOIR                            PERCENT OF NORMAL
MAR 1         MAR 1
2011          2010

BIGHORN RESERVOIR                     103           112
CANYON FERRY RESERVOIR                 94           105
CLARK CANYON RESERVOIR                113           114
FLATHEAD LAKE                         105            98
FORT PECK LAKE                        115            85
FRESNO RESERVOIR                      192            99
MARCH 9…164 PERCENT
GIBSON RESERVOIR                       36            52
HEBGEN RESERVOIR                      106           108
HUNGRY HORSE RESERVOIR                115           127
LAKE ELWELL / TIBER RESERVOIR         115           109
LAKE KOOCANUSA                        124           178
LAKE SHERBURNE                        237           133
LIMA RESERVOIR                        133           114
NELSON RESERVOIR                      124           114
PISHKIN RESERVOIR                     109           108
SWIFT RESERVOIR                        79           105
WILLOW CREEK RESERVOIR                126           125

STREAMFLOW…

STREAMFLOW FORECAST FOR THE PERIOD APRIL 1 THROUGH JULY 31…ASSUMING
NORMAL PRECIPITATION

STATEWIDE                          110
WEST OF THE CONTINENTAL DIVIDE     115
EAST OF THE CONTINENTAL DIVIDE     106

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.

MOST
PROBABLE REASONABLE REASONABLE
FORECAST   MAXIMUM    MINIMUM
PERIOD  /PCT AVG/ /PCT AVG/  /PCT AVG/
COLUMBIA RIVER BASIN

KOOTENAI RIVER
LIBBY RESVR INFLOW      APR-SEP    105       126        84
CLARK FORK
ABOVE BLACKFOOT RIVER   APR-SEP    111       165        57
ABOVE MISSOULA          APR-SEP    113       146        80
BELOW MISSOULA          APR-SEP    110       137        84
ST. REGIS               APR-SEP    112       147        76
NEAR PLAINS             APR-SEP    114       139        89
BLACKFOOT RIVER
NEAR BONNER             APR-SEP    122       158        85
BITTERROOT RIVER
AT MOUTH                APR-SEP    106       128        84
NORTH FORK FLATHEAD RIVER
NEAR COLUMBIA FALLS     APR-SEP    113       132        94
MIDDLE FORK FLATHEAD RIVER
NEAR WEST GLACIER NR    APR-SEP    116       134        98
SOUTH FORK FLATHEAD RIVER
HUNGRY HORSE RES INFLOW APR-SEP    121       146        97
FLATHEAD RIVER
COLUMBIA FALLS          APR-SEP    117       139        95
FLATHEAD LAKE INFLOW    APR-SEP    117       140        93

SASKATCHEWAN RIVER BASIN

ST. MARY RIVER
BABB NR                 APR-SEP    110       126        94

MISSOURI RIVER BASIN

RED ROCK RIVER
LIMA RES INFLOW         APR-SEP     93       133        54
BEAVERHEAD RIVER
CLARK CANYON INFLOW     APR-SEP     85       144        34
BARRETTS                APR-SEP     71       133        29
RUBY RIVER
RUBY RESERVOIR INFLOW   APR-SEP    102       135        69
BIG HOLE RIVER
NEAR MELROSE            APR-SEP    108       142        74
MADISON RIVER
HEBGEN RES INFLOW       APR-SEP     98       114        82
ENNIS RESERVOIR INFLOW  APR-SEP     93       112        74
GALLATIN RIVER
NEAR GALLATIN GATEWAY   APR-SEP    103       125        81
LOGAN                   APR-SEP    106       140        72
MISSOURI RIVER
TOSTON                  APR-SEP     99       132        67
FORT BENTON             APR-SEP    101       134        68
VIRGELLE                APR-SEP    100       134        67
NEAR LANDUSKY           APR-SEP    100       134        67
BELOW FORT PECK DAM     APR-SEP     89       117        61
SHEEP CREEK
WHITE SULPHUR SPRINGS   APR-SEP    125       160        92
SUN RIVER
GIBSON RES INFLOW       APR-SEP    110       132        88
MARIAS RIVER
NEAR SHELBY             APR-SEP    106       149        63
MUSSELSHELL RIVER
HARLOWTON               APR-SEP    120       196        43
MILK RIVER
WESTERN CROSSING        APR-SEP    130       179        81
EASTERN CROSSING        APR-SEP    161       233        89
YELLOWSTONE RIVER
YELLOWSTN LK OUTLT…WY APR-SEP    105       124        86
CORWIN SPRINGS          APR-SEP    112       130        93
NEAR LIVINGSTON         APR-SEP    110       130        90
BILLINGS                APR-SEP    107       133        80
MILES CITY              APR-SEP    103       129        76
NEAR SIDNEY             APR-SEP    103       130        77
BOULDER RIVER
BIG TIMBER              APR-SEP    106       130        83
STILLWATER RIVER
NEAR ABSAROKEE          APR-SEP     91       113        70
CLARKS FORK YELLOWSTONE RIVER
NEAR BELFRY             APR-SEP    105       124        87
LITTLE BIGHORN RIVER
NEAR HARDIN             APR-SEP     97       133        60
TONGUE RIVER
TONGUE RIVER RES INFLOW APR-SEP     88       134        42
POWDER RIVER
MOORHEAD                APR-SEP     98       150        47
LOCATE                  APR-SEP     98       154        42

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.

SURFACE WATER SUPPLY INDEX…

THE SURFACE WATER SUPPLY INDEX…SWSI…IS A MEASURE OF AVAILABLE SURFACE WATER AVAILABILITY FOR THE SPRING AND SUMMER MONTHS. WATER USERS WHO RELY ON MOUNTAIN PRECIPITATION CAN USE THE INDEX TO EVALUATE SEASONAL SURFACE WATER SUPPLIES. THE SWSI ACCOUNTS FOR MOUNTAIN SNOWPACK…MOUNTAIN PRECIPITATION…
STREAMFLOW…RESERVOIR STORAGE AND SOIL MOISTURE. SWSI VALUES ARE CALCULATED FOR 54 BASINS IN MONTANA. SWSI VALUES ARE PROVIDED BY THE NATURAL RESOURCES CONSERVATION SERVICE…USDA.

NUMBER OF BASINS
SWSI RATING         SURFACE WATER CONDITION      2011    2010
-3.0 TO -4.0            EXTREMELY DRY              0      14
-2.0 TO -2.9            MODERATELY DRY             0      13
-1.0 TO -1.9            SLIGHTLY DRY               0      13
-0.9 TO +0.9            NEAR AVERAGE              11       7
+1.0 TO +1.9            SLIGHTLY WET              22       1
+2.0 TO +2.9            MODERATELY WET            14       0
+3.0 TO +4.0            EXTREMELY WET              4       1
NOT AVAILABLE              1       3

VALUES FOR SPECIFIC BASINS AS OF MAR 1 2011 AND MAR 1 2010 ARE LISTED
BELOW…
SWSI        SWSI
BASIN                                    2011        2010
TOBACCO RIVER                             1.7        -3.2
KOOTENAI FT. STEELE TO LIBBY DAM          1.5        -2.9
KOOTENAI RIVER BELOW LIBBY DAM            2.9        -0.1
FISHER RIVER                              1.5        -2.8
YAAK RIVER                                0.8        -3.4
NORTH FORK FLATHEAD RIVER                 2.3        -3.2
MIDDLE FORK FLATHEAD RIVER                2.1        -3.2
SOUTH FORK FLATHEAD RIVER                 3.7        -0.4
FLATHEAD RIVER AT COLUMBIA FALLS          2.7        -2.4
SWAN RIVER                                3.4        -1.2
FLATHEAD RIVER AT POLSON                  2.4        -2.9
MISSION VALLEY                             NA        -3.5
LITTLE BITTERROOT RIVER                   1.3        -3.6
CLARK FORK RIVER ABOVE MILLTOWN           1.5        -2.2
BLACKFOOT RIVER                           2.4        -2.9
BITTERROOT RIVER                          1.4        -3.4
CLARK FORK RIVER BELOW BITTERROOT RIVER   1.8        -3.0
CLARK FORK RIVER BELOW FLATHEAD RIVER     2.2        -2.9
BEAVERHEAD RIVER                          0.8        -0.8
RUBY RIVER                                1.1        -1.7
BIG HOLE RIVER                            1.2        -1.3
BOULDER RIVER (JEFFERSON)                 0.2        -1.7
JEFFERSON RIVER                           1.8        -0.7
MADISON RIVER                             0.3        -1.8
GALLATIN RIVER                            1.1        -1.4
MISSOURI RIVER ABOVE CANYON FERRY         0.5        -1.6
MISSOURI RIVER BELOW CANYON FERRY         0.1        -1.5
SMITH RIVER                               2.6        -0.2
SUN RIVER                                 1.4        -3.6
TETON RIVER                               1.7        -1.4
BIRCH/DUPUYER CREEKS                      1.3        -2.4
UPPER JUDITH RIVER                        3.5         3.4
MARIAS RIVER ABOVE TIBER                  0.6          NA
MARIAS RIVER BELOW TIBER                  2.7          NA
MUSSELSHELL RIVER                         2.4         1.2
MISSOURI RIVER ABOVE FT. PECK             0.9          NA
MISSOURI RIVER BELOW FT. PECK             1.1        -1.6
ST. MARY RIVER                            2.5        -2.9
MILK RIVER                                3.1        -0.5
DEARBORN RIVER NEAR CRAIG                 2.0        -3.0
YELLOWSTONE RIVER ABOVE LIVINGSTON        1.7        -3.2
SHIELDS RIVER                             2.1        -0.9
BOULDER RIVER (YELLOWSTONE)               2.4        -2.9
STILLWATER RIVER                         -0.1        -3.1
ROCK/RED LODGE CREEKS                    -0.9        -1.0
CLARKS FORK RIVER                         1.5        -3.0
YELLOWSTONE RIVER ABOVE BIGHORN RIVER     1.5        -3.1
BIGHORN RIVER BELOW BIGHORN LAKE          0.4        -1.7
LITTLE BIGHORN RIVER                      1.2        -2.7
YELLOWSTONE RIVER BELOW BIGHORN RIVER     1.0        -2.5
TONGUE RIVER                              1.0        -2.1
POWDER RIVER                              1.1        -1.9

OUTLOOK…

THE OUTLOOK FOR MARCH INDICATES THAT THERE IS A 50 TO 60 PERCENT CHANCE TEMPERATURES WILL BE BELOW AVERAGE WEST OF THE DIVIDE…AND A 40 TO 50 PERCENT CHANCE TEMPERATURES WILL BE BELOW AVERAGE EAST OF THE DIVIDE. THERE IS A 40 TO 50 PERCENT CHANCE PRECIPITATION WILL BE ABOVE AVERAGE OVER WEST…SOUTHWEST AND THE FAR NORTHEAST CORNER OF MONTANA. THERE IS A 33 TO 40 PERCENT CHANCE PRECIPITATION WILL BE ABOVE AVERAGE FROM NORTH CENTRAL TO SOUTHEAST MONTANA.

FOR THE PERIOD APRIL THROUGH JUNE…THERE IS A 40 TO 50 PERCENT
CHANCE TEMPERATURES WILL BE BELOW AVERAGE OVER CENTRAL AND NORTHERN MONTANA. THERE IS A 33 TO 40 PERCENT CHANCE TEMPERATURES WILL BE BELOW AVERAGE ACROSS SOUTHERN MONTANA. FOR PRECIPITATION…FORECAST TOOLS SHOW NO TENDENCIES TOWARD WETTER OR DRIER FOR THIS PERIOD. AS A RESULT…THERE ARE EQUAL CHANCES PRECIPITATION WILL BE ABOVE…BELOW OR NEAR AVERAGE.

THE NEXT WATER SUPPLY OUTLOOK FOR 2011 WILL BE ISSUED BY APRIL 15.

$$

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