February 1, 2021 Spring and Summer Streamflow Forecasts
Upper Missouri Basin
The high elevation snow pack in the Upper Missouri Basin as of February 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.
January precipitation across the Upper Missouri Basin was below average.
Basin precipitation summaries for the Missouri Basin include: Milk St. Mary,
36 percent; Milk Canada, 13 percent; Lower Milk, 21 percent; above Toston,
71 percent; Toston to Ft. Peck, 49 percent.
January 2021 Upper Missouri Mean Precip Oct-Jan 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 72 percent of average
April-September flows. Runoff is expected to range around
87 percent of average for the Missouri Basin above Fort Peck,
Montana.
Upper Missouri February 1, 2021 Spring and Summer Streamflow Forecasts
Of the four major irrigation reservoirs in Montana; Lima
Reservoir had 136 percent average storage, Clark Canyon was
holding 105 percent of average water, Gibson Reservoir had 74
percent of average stored water, and Fresno Reservoir had
71 percent of average stored water.
Yellowstone Basin
The high elevation snow pack in the Yellowstone Basin was below average
on February 1. The snow pack in the Upper Yellowstone Basin was 89 percent
of average. The snow packs in the Wind, Bighorn, and Shoshone Basins were 67,
76, and 87 percent of average, respectively. The snow packs in the Tongue
and Powder basins were 88 and 74 percent of average, respectively.
Precipitation during January was below average. The upper Yellowstone
River Basin received 67 percent of average precipitation while the
Lower Yellowstone River Basin reported 67 percent of average. The
Bighorn Basin received 37 percent of average precipitation while the
Wind River Basin received 54 percent of average. The Little Bighorn -
Upper Tongue Basin received 92 percent of average and the Powder River
had 66 percent of average precipitation.
January 2021 Yellowstone Mean Precip Oct-Jan 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
89 percent of average. Flow in the Tongue Basin is expected to be
75 percent of average. Flows in the Powder River are expected
to be about 53 percent of average.
Monthend storage at Boysen Reservoir was 102 percent of average.
Stored water in Buffalo Bill Reservoir was 127 percent of average.
Monthend storage was 103 percent of average at Bighorn Reservoir.
Yellowstone February 1, 2021 Spring and Summer Streamflow Forecasts
Platte Basin
The high elevation snow pack in the Upper North Platte Basin was
77 percent of average on February 1. The snow pack in the North Platte
Basin below Seminoe Reservoir was 71 percent of average. The snow
pack in the South Platte Basin was 75 percent of average.
Precipitation during January in the Upper North Platte Basin was 91
percent of average. In the Lower North Platte Basin, precipitation
was 103 percent of average. The North Platte Plains below Guernsy
Reservoir had 98 percent. The South Platte Mountains had 62
percent whereas the Plains had 72 percent of average December
precipitation.
DecemberJanuary 2021 Platte Mean Precip Oct-Jan 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 65 percent of average. Streams in the South Platte
Basin above South Platte, Colorado can expect 65 percent
of average flow. For the remainder of the South Platte
basin, flows are expected near 67 percent.
Stored water in the South Platte Basin was 90 percent of average
on February 1.
North Platte Streamflow Fcst South Platte Streamflow Fcst
FGUS63 KKRF 021553
ESPKRF
WATER SUPPLY FORECAST
NWS MISSOURI BASIN RIVER FORECAST CENTER
PLEASANT HILL MISSOURI
0931 AM CST TUESDAY FEBRUARY 02, 2021
DATA CURRENT AS OF: FEBRUARY 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 661 58 1233 409 1140
SBDW4N
Bighorn R at Kane Apr-Sep 1054 62 1762 715 1690
LVEW4N
Greybull R at Meeteetse Apr-Sep 111 62 217 54 177
MEEW4N
Buffalo Bill Resvr Inflow Apr-Sep 548 72 756 424 765
CDYW4N
St. Mary R nr Babb Apr-Sep 392 73 481 340 535
SMYM8N
St. Mary R at Intl Boundary Apr-Sep 457 69 578 393 660
SMBM8N
Milk R nr Western Crossing Apr-Sep 28 69 57 13 41
PDBM8N
Milk R nr Eastern Crossing Apr-Sep 44 54 107 21 81
ERNM8N
North Platte R nr Northgate Apr-Sep 141 47 280 62 300
NGTC2
Encampment R nr Encampment Apr-Sep 83 56 124 47 150
ECRW4
Encampment R nr Encampment Apr-Sep 92 58 132 57 160
ECRW4N
Rock Cr nr Arlington Apr-Sep 41 79 58 29 52
KCRW4
Rock Cr nr Arlington Apr-Sep 42 78 59 30 53
KCRW4N
Seminoe Resvr Inflow Apr-Sep 433 54 769 187 805
SETW4
Seminoe Resvr Inflow Apr-Sep 576 60 914 305 955
SETW4N
Laramie R nr Woods Landing Apr-Sep 31 29 87 14 108
WODW4
Laramie R nr Woods Landing Apr-Sep 66 46 122 40 142
WODW4N
Little Laramie R nr Filmore Apr-Sep 41 75 71 29 55
SMTW4
Little Laramie R nr Filmore Apr-Sep 43 76 73 31 57
SMTW4N
Antero Resvr Inflow Apr-Sep 16 94 24 11 17
ANRC2N
Spinney Mountain Resvr Inflow Apr-Sep 37 66 65 25 56
SPYC2N
Elevenmile Canyon Resvr Inflow Apr-Sep 40 67 73 27 60
EVNC2N
Cheesman Lk Inflow Apr-Sep 72 63 140 47 114
CHEC2N
S Platte R at S Platte Apr-Sep 136 66 244 87 205
SPTC2N
Bear Cr at Morrison Apr-Sep 12 56 26 6 21
MRRC2N
Clear Cr at Golden Apr-Sep 61 53 106 36 117
GLDC2N
St. Vrain Cr at Lyons Apr-Sep 69 62 106 44 111
LNSC2N
Boulder Cr nr Orodell Apr-Sep 35 66 51 23 52
OROC2N
S Boulder Cr nr Eldorado Sprgs Apr-Sep 21 51 35 10 40
BELC2N
Cache La Poudre at Canyon Mouth Apr-Sep 148 71 264 80 210
FTDC2N
Lima Resvr Inflow Apr-Sep 40 52 70 26 78
LRRM8N
Clark Canyon Resvr Inflow Apr-Sep 79 50 125 52 159
CLKM8N
Beaverhead R at Barretts Apr-Sep 108 56 154 76 194
BARM8N
Ruby R Resvr Inflow Apr-Sep 77 80 97 58 97
ALRM8N
Big Hole R nr Melrose Apr-Sep 390 70 553 258 560
MLRM8
Big Hole R nr Melrose Apr-Sep 448 79 610 315 570
MLRM8N
Hebgen Resvr Inflow Apr-Sep 416 97 529 347 430
HBDM8N
Ennis Resvr Inflow Apr-Sep 744 100 875 612 745
ELMM8N
Gallatin R nr Gateway Apr-Sep 245 54 319 188 455
GLGM8
Gallatin R nr Gateway Apr-Sep 245 54 319 188 455
GLGM8N
Gallatin R at Logan Apr-Sep 247 49 366 157 505
LOGM8
Gallatin R at Logan Apr-Sep 378 63 497 278 595
LOGM8N
Missouri R at Toston Apr-Sep 2034 81 2603 1561 2510
TOSM8N
Missouri R at Fort Benton Apr-Sep 3254 88 4085 2510 3690
FBNM8N
Missouri R nr Virgelle Apr-Sep 3687 86 4738 2906 4280
VRGM8N
Missouri R nr Landusky Apr-Sep 3929 88 5111 3128 4490
LDKM8N
Missouri R below Fort Peck Dam Apr-Sep 4061 86 5343 3211 4730
FPKM8N
Gibson Resvr Inflow Apr-Sep 414 104 607 327 400
AGSM8N
Marias R nr Shelby Apr-Sep 355 79 560 258 450
SHLM8N
Musselshell R at Harlowton Apr-Sep 64 62 109 40 104
HLWM8N
Yellowstone R at Yellowstone Lk Apr-Sep 582 73 722 460 795
YLOW4
Yellowstone R at Yellowstone Lk Apr-Sep 787 94 938 624 840
YLOW4N
Yellowstone R at Corwin Sprgs Apr-Sep 1495 80 1800 1209 1880
CORM8
Yellowstone R at Corwin Sprgs Apr-Sep 1782 90 2119 1408 1980
CORM8N
Yellowstone R at Livingston Apr-Sep 1781 84 2109 1437 2130
LIVM8
Yellowstone R at Livingston Apr-Sep 2144 93 2495 1716 2310
LIVM8N
Yellowstone R at Billings Apr-Sep 2751 74 3246 2084 3730
BILM8
Yellowstone R at Billings Apr-Sep 3771 89 4300 3051 4260
BILM8N
Yellowstone R at Miles City Apr-Sep 5855 81 7125 4533 7250
MILM8N
Yellowstone R at Sidney Apr-Sep 6058 80 7366 4638 7540
SIDM8N
Boulder R at Big Timber Apr-Sep 216 72 256 165 300
BTMM8
Boulder R at Big Timber Apr-Sep 256 79 295 205 325
BTMM8N
Stillwater R nr Absarokee Apr-Sep 345 68 414 279 505
SRAM8
Stillwater R nr Absarokee Apr-Sep 403 73 472 335 550
SRAM8N
Clks Fk Yellowstone R nr Belfry Apr-Sep 416 76 532 325 550
BFYM8
Clks Fk Yellowstone R nr Belfry Apr-Sep 489 82 603 396 600
BFYM8N
Bighorn R nr St. Xavier Apr-Sep 1691 66 2628 1151 2550
STXM8N
Little Bighorn R nr Hardin Apr-Sep 71 69 108 50 103
HRDM8N
Tongue R nr Dayton Apr-Sep 67 80 83 51 83
DAYW4N
Tongue R nr Decker Apr-Sep 151 70 210 102 215
DSLM8N
Tongue R Resvr Inflow Apr-Sep 152 71 217 103 215
DKRM8N
Powder R at Moorhead Apr-Sep 123 56 243 66 220
MHDM8N
Powder R nr Locate Apr-Sep 131 53 306 72 245
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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