January 1, 2021 Spring and Summer Streamflow Forecasts
Upper Missouri Basin
The high elevation snow pack in the Upper Missouri Basin as of January 1
was near to above average. The snow pack in the St. Mary Basin was 110 percent, and the
Milk River Basin was 145 percent.
December precipitation across the Upper Missouri Basin was below average.
Basin precipitation summaries for the Missouri Basin include: Milk St. Mary,
77 percent; Milk Canada, 46 percent; Lower Milk, 13 percent; above Toston,
57 percent; Toston to Ft. Peck, 44 percent.
December 2020 Upper Missouri Mean Precip Oct-Dec WY2021 Upper Missouri Mean Precip
Stream flow in the Upper Missouri Basin is forecast to be
below average during the upcoming Spring and Summer.
The St. Mary River is forecast to have 65 percent of average
April-September flows. Runoff is expected to range around
85 percent of average for the Missouri Basin above Fort Peck,
Montana.
Upper Missouri January 1, 2021 Spring and Summer Streamflow Forecasts
Of the four major irrigation reservoirs in Montana; Lima
Reservoir had 138 percent average storage, Clark Canyon was
holding 108 percent of average water, Gibson Reservoir had 84
percent of average stored water, and Fresno Reservoir had
67 percent of average stored water.
Yellowstone Basin
The high elevation snow pack in the Yellowstone Basin was above average
on January 1. The snow pack in the Upper Yellowstone Basin was 96 percent
of average. The snow packs in the Wind, Bighorn, and Shoshone Basins were 82,
83, and 99 percent of average, respectively. The snow packs in the Tongue
and Powder basins were 86 and 75 percent of average, respectively.
Precipitation during December was below average. The upper Yellowstone
River Basin received 50 percent of average precipitation while the
Lower Yellowstone River Basin reported 39 percent of average. The
Bighorn Basin received 55 percent of average precipitation while the
Wind River Basin received 87 percent of average. The Little Bighorn -
Upper Tongue Basin received 75 percent of average and the Powder River
had 61 percent of average precipitation.
December 2020 Yellowstone Mean Precip Oct-Dec WY2021 Yellowstone Mean Precip
Forecast stream flow in the Yellowstone Basin is below average
for the upcoming Spring and Summer. Stream flow for the
Yellowstone River above Sidney, Montana is forecast to be about
80 percent of average. Flow in the Tongue Basin is expected to be
69 percent of average. Flows in the Powder River are expected
to be about 52 percent of average.
Monthend storage at Boysen Reservoir was 100 percent of average.
Stored water in Buffalo Bill Reservoir was 126 percent of average.
Monthend storage was 101 percent of average at Bighorn Reservoir.
Yellowstone January 1, 2021 Spring and Summer Streamflow Forecasts
Platte Basin
The high elevation snow pack in the Upper North Platte Basin was
112 percent of average on January 1. The snow pack in the North Platte
Basin below Seminoe Reservoir was 109 percent of average. The snow
pack in the South Platte Basin was 108 percent of average.
Precipitation during December in the Upper North Platte Basin was 74
percent of average. In the Lower North Platte Basin, precipitation
was 94 percent of average. The North Platte Plains below Guernsy
Reservoir had 70 percent. The South Platte Mountains had 92
percent whereas the Plains had 105 percent of average December
precipitation.
December 2020 Platte Mean Precip Oct-Dec WY2021 Platte Mean Precip
Stream flow in the Platte Basin is forecast to be below
average during the upcoming Spring and Summer. Runoff
for streams above Seminoe Reservoir are expected to be
about 59 percent of average. Streams in the South Platte
Basin above South Platte, Colorado can expect 73 percent
of average flow. For the remainder of the South Platte
basin, flows are expected near 68 percent.
Stored water in the South Platte Basin was 87 percent of average
on January 1.
North Platte Streamflow Fcst South Platte Streamflow Fcst
FGUS63 KKRF 041753
ESPKRF
WATER SUPPLY FORECAST
NWS MISSOURI BASIN RIVER FORECAST CENTER
PLEASANT HILL MISSOURI
0903 AM CST MONDAY JANUARY 04, 2021
DATA CURRENT AS OF: JANUARY 01, 2021
MISSOURI/YELLOWSTONE/PLATTE RIVER BASIN FORECASTS
50% % 10% 90% AVG
FORECAST POINT PERIOD (KAF) AVG (KAF) (KAF) (KAF)
--------------------------------------------------------------------
Boysen Resvr Inflow Apr-Sep 696 61 1198 419 1140
SBDW4N
Bighorn R at Kane Apr-Sep 996 59 1796 673 1690
LVEW4N
Greybull R at Meeteetse Apr-Sep 121 69 201 55 177
MEEW4N
Buffalo Bill Resvr Inflow Apr-Sep 578 76 770 402 765
CDYW4N
St. Mary R nr Babb Apr-Sep 366 68 485 313 535
SMYM8N
St. Mary R at Intl Boundary Apr-Sep 423 64 574 362 660
SMBM8N
Milk R nr Western Crossing Apr-Sep 32 78 70 16 41
PDBM8N
Milk R nr Eastern Crossing Apr-Sep 52 64 115 25 81
ERNM8N
North Platte R nr Northgate Apr-Sep 156 52 300 57 300
NGTC2
Encampment R nr Encampment Apr-Sep 89 59 139 40 150
ECRW4
Encampment R nr Encampment Apr-Sep 98 61 148 49 160
ECRW4N
Rock Cr nr Arlington Apr-Sep 39 75 55 26 52
KCRW4
Rock Cr nr Arlington Apr-Sep 39 74 56 26 53
KCRW4N
Seminoe Resvr Inflow Apr-Sep 426 53 764 161 805
SETW4
Seminoe Resvr Inflow Apr-Sep 569 60 916 272 955
SETW4N
Laramie R nr Woods Landing Apr-Sep 42 39 92 15 108
WODW4
Laramie R nr Woods Landing Apr-Sep 77 54 127 39 142
WODW4N
Little Laramie R nr Filmore Apr-Sep 42 77 72 29 55
SMTW4
Little Laramie R nr Filmore Apr-Sep 45 78 74 31 57
SMTW4N
Antero Resvr Inflow Apr-Sep 17 100 25 11 17
ANRC2N
Spinney Mountain Resvr Inflow Apr-Sep 40 72 65 25 56
SPYC2N
Elevenmile Canyon Resvr Inflow Apr-Sep 44 74 72 26 60
EVNC2N
Cheesman Lk Inflow Apr-Sep 76 67 148 49 114
CHEC2N
S Platte R at S Platte Apr-Sep 145 71 259 92 205
SPTC2N
Bear Cr at Morrison Apr-Sep 12 58 25 6 21
MRRC2N
Clear Cr at Golden Apr-Sep 73 62 124 42 117
GLDC2N
St. Vrain Cr at Lyons Apr-Sep 73 66 113 46 111
LNSC2N
Boulder Cr nr Orodell Apr-Sep 36 70 57 26 52
OROC2N
S Boulder Cr nr Eldorado Sprgs Apr-Sep 23 57 41 11 40
BELC2N
Cache La Poudre at Canyon Mouth Apr-Sep 148 70 257 71 210
FTDC2N
Lima Resvr Inflow Apr-Sep 36 47 66 21 78
LRRM8N
Clark Canyon Resvr Inflow Apr-Sep 79 50 120 44 159
CLKM8N
Beaverhead R at Barretts Apr-Sep 106 54 148 68 194
BARM8N
Ruby R Resvr Inflow Apr-Sep 77 80 95 56 97
ALRM8N
Big Hole R nr Melrose Apr-Sep 423 76 588 257 560
MLRM8
Big Hole R nr Melrose Apr-Sep 481 84 644 315 570
MLRM8N
Hebgen Resvr Inflow Apr-Sep 398 93 510 289 430
HBDM8N
Ennis Resvr Inflow Apr-Sep 690 93 821 498 745
ELMM8N
Gallatin R nr Gateway Apr-Sep 229 50 308 153 455
GLGM8
Gallatin R nr Gateway Apr-Sep 229 50 308 153 455
GLGM8N
Gallatin R at Logan Apr-Sep 222 44 354 132 505
LOGM8
Gallatin R at Logan Apr-Sep 350 59 475 241 595
LOGM8N
Missouri R at Toston Apr-Sep 2007 80 2604 1378 2510
TOSM8N
Missouri R at Fort Benton Apr-Sep 3110 84 4010 2277 3690
FBNM8N
Missouri R nr Virgelle Apr-Sep 3603 84 4798 2742 4280
VRGM8N
Missouri R nr Landusky Apr-Sep 3912 87 5142 2915 4490
LDKM8N
Missouri R below Fort Peck Dam Apr-Sep 4082 86 5347 3015 4730
FPKM8N
Gibson Resvr Inflow Apr-Sep 398 100 625 309 400
AGSM8N
Marias R nr Shelby Apr-Sep 387 86 693 285 450
SHLM8N
Musselshell R at Harlowton Apr-Sep 60 57 102 33 104
HLWM8N
Yellowstone R at Yellowstone Lk Apr-Sep 584 73 715 395 795
YLOW4
Yellowstone R at Yellowstone Lk Apr-Sep 793 94 989 557 840
YLOW4N
Yellowstone R at Corwin Sprgs Apr-Sep 1500 80 1827 1072 1880
CORM8
Yellowstone R at Corwin Sprgs Apr-Sep 1795 91 2204 1310 1980
CORM8N
Yellowstone R at Livingston Apr-Sep 1775 83 2145 1309 2130
LIVM8
Yellowstone R at Livingston Apr-Sep 2140 93 2581 1588 2310
LIVM8N
Yellowstone R at Billings Apr-Sep 2689 72 3302 1914 3730
BILM8
Yellowstone R at Billings Apr-Sep 3706 87 4364 2801 4260
BILM8N
Yellowstone R at Miles City Apr-Sep 5626 78 7042 4169 7250
MILM8N
Yellowstone R at Sidney Apr-Sep 5806 77 7288 4295 7540
SIDM8N
Boulder R at Big Timber Apr-Sep 200 67 253 144 300
BTMM8
Boulder R at Big Timber Apr-Sep 241 74 295 184 325
BTMM8N
Stillwater R nr Absarokee Apr-Sep 345 68 429 255 505
SRAM8
Stillwater R nr Absarokee Apr-Sep 402 73 486 311 550
SRAM8N
Clks Fk Yellowstone R nr Belfry Apr-Sep 409 74 535 288 550
BFYM8
Clks Fk Yellowstone R nr Belfry Apr-Sep 481 80 606 360 600
BFYM8N
Bighorn R nr St. Xavier Apr-Sep 1705 67 2539 1066 2550
STXM8N
Little Bighorn R nr Hardin Apr-Sep 69 67 101 42 103
HRDM8N
Tongue R nr Dayton Apr-Sep 62 75 78 45 83
DAYW4N
Tongue R nr Decker Apr-Sep 139 65 201 92 215
DSLM8N
Tongue R Resvr Inflow Apr-Sep 141 66 208 92 215
DKRM8N
Powder R at Moorhead Apr-Sep 116 53 236 57 220
MHDM8N
Powder R nr Locate Apr-Sep 124 50 299 65 245
LOCM8N
Locations with an `N` suffix indicate natural flows excluding
stream augmentations.
KAF: Thousands of Acre-feet
%AVG: Current 50%/AVG
AVG: Average(50%) seasonal runoff voulme as simulated by the river
forecast model considering acontinuous simulation of the basin
response to historic climate data (observed precipitation and
temperatures) over the period of 1981-2010.
The 50%, 10% and 90% columns indicate the probability that the
actual volume will exceed the forecast for the valid time perion
for more information, please visit: www.weather.gov/mbrfc/water
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