April 1, 2021 Spring and Summer Streamflow Forecasts
Upper Missouri Basin
The high elevation snow pack in the Upper Missouri Basin as of April 1
was near to below average. The snow pack in the St. Mary Basin was 92 percent, and the
Milk River Basin was 76 percent.
March precipitation across the Upper Missouri Basin was below average.
Basin precipitation summaries for the Missouri Basin include: Milk St. Mary,
42 percent; Milk Canada, 17 percent; Lower Milk, 28 percent; above Toston,
56 percent; Toston to Ft. Peck, 32 percent.
March 2021 Upper Missouri Mean Precip Oct-Mar 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
82 percent of average for the Missouri Basin above Fort Peck,
Montana.
Upper Missouri April 1, 2021 Spring and Summer Streamflow Forecasts
Of the four major irrigation reservoirs in Montana; Lima
Reservoir had 127 percent average storage, Clark Canyon was
holding 105 percent of average water, Gibson Reservoir had 68
percent of average stored water, and Fresno Reservoir had
64 percent of average stored water.
Yellowstone Basin
The high elevation snow pack in the Yellowstone Basin was near average
on April 1. The snow pack in the Upper Yellowstone Basin was 101 percent
of average. The snow packs in the Wind, Bighorn, and Shoshone Basins were 96,
98, and 97 percent of average, respectively. The snow packs in the Tongue
and Powder basins were 103 and 119 percent of average, respectively.
Precipitation during March was below average. The upper Yellowstone
River Basin received 55 percent of average precipitation while the
Lower Yellowstone River Basin reported 49 percent of average. The
Bighorn Basin received 64 percent of average precipitation while the
Wind River Basin received 159 percent of average. The Little Bighorn -
Upper Tongue Basin received 89 percent of average and the Powder River
had 96 percent of average precipitation.
March 2021 Yellowstone Mean Precip Oct-Mar 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
75 percent of average. Flow in the Tongue Basin is expected to be
68 percent of average. Flows in the Powder River are expected
to be about 63 percent of average.
Monthend storage at Boysen Reservoir was 107 percent of average.
Stored water in Buffalo Bill Reservoir was 131 percent of average.
Monthend storage was 102 percent of average at Bighorn Reservoir.
Yellowstone April 1, 2021 Spring and Summer Streamflow Forecasts
Platte Basin
The high elevation snow pack in the Upper North Platte Basin was
97 percent of average on April 1. The snow pack in the North Platte
Basin below Seminoe Reservoir was 119 percent of average. The snow
pack in the South Platte Basin was 101 percent of average.
Precipitation during March in the Upper North Platte Basin was 101
percent of average. In the Lower North Platte Basin, precipitation
was 175 percent of average. The North Platte Plains below Guernsy
Reservoir had 263 percent. The South Platte Mountains had 168
percent whereas the Plains had 234 percent of average December
precipitation.
DecemberFebruary 2021 Platte Mean Precip Oct-Mar 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 73 percent of average. Streams in the South Platte
Basin above South Platte, Colorado can expect 68 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 99 percent of average
on April 1.
North Platte Streamflow Fcst South Platte Streamflow Fcst
FGUS63 KKRF 021240
ESPKRF
WATER SUPPLY FORECAST
NWS MISSOURI BASIN RIVER FORECAST CENTER
PLEASANT HILL MISSOURI
0736 AM CDT FRIDAY APRIL 02, 2021
DATA CURRENT AS OF: APRIL 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 593 52 1071 367 1140
SBDW4N
Bighorn R at Kane Apr-Sep 1072 63 1710 689 1690
LVEW4N
Greybull R at Meeteetse Apr-Sep 103 58 172 52 177
MEEW4N
Buffalo Bill Resvr Inflow Apr-Sep 460 60 619 340 765
CDYW4N
St. Mary R nr Babb Apr-Sep 393 74 462 332 535
SMYM8N
St. Mary R at Intl Boundary Apr-Sep 458 69 554 387 660
SMBM8N
Milk R nr Western Crossing Apr-Sep 20 49 51 10 41
PDBM8N
Milk R nr Eastern Crossing Apr-Sep 41 51 134 20 81
ERNM8N
North Platte R nr Northgate Apr-Sep 154 51 279 104 300
NGTC2
Encampment R nr Encampment Apr-Sep 88 59 125 64 150
ECRW4
Encampment R nr Encampment Apr-Sep 98 61 135 74 160
ECRW4N
Rock Cr nr Arlington Apr-Sep 49 95 59 39 52
KCRW4
Rock Cr nr Arlington Apr-Sep 50 94 59 39 53
KCRW4N
Seminoe Resvr Inflow Apr-Sep 453 56 696 311 805
SETW4
Seminoe Resvr Inflow Apr-Sep 611 64 852 463 955
SETW4N
Laramie R nr Woods Landing Apr-Sep 33 31 73 21 108
WODW4
Laramie R nr Woods Landing Apr-Sep 68 48 108 48 142
WODW4N
Little Laramie R nr Filmore Apr-Sep 58 105 74 46 55
SMTW4
Little Laramie R nr Filmore Apr-Sep 60 105 76 48 57
SMTW4N
Antero Resvr Inflow Apr-Sep 17 98 23 12 17
ANRC2N
Spinney Mountain Resvr Inflow Apr-Sep 38 67 49 27 56
SPYC2N
Elevenmile Canyon Resvr Inflow Apr-Sep 43 71 56 30 60
EVNC2N
Cheesman Lk Inflow Apr-Sep 74 65 117 52 114
CHEC2N
S Platte R at S Platte Apr-Sep 146 71 226 110 205
SPTC2N
Bear Cr at Morrison Apr-Sep 14 67 32 7 21
MRRC2N
Clear Cr at Golden Apr-Sep 63 54 96 45 117
GLDC2N
St. Vrain Cr at Lyons Apr-Sep 70 63 121 59 111
LNSC2N
Boulder Cr nr Orodell Apr-Sep 36 69 53 28 52
OROC2N
S Boulder Cr nr Eldorado Sprgs Apr-Sep 23 56 38 15 40
BELC2N
Cache La Poudre at Canyon Mouth Apr-Sep 153 73 238 105 210
FTDC2N
Lima Resvr Inflow Apr-Sep 24 30 47 17 78
LRRM8N
Clark Canyon Resvr Inflow Apr-Sep 59 37 99 41 159
CLKM8N
Beaverhead R at Barretts Apr-Sep 85 44 129 65 194
BARM8N
Ruby R Resvr Inflow Apr-Sep 59 60 74 46 97
ALRM8N
Big Hole R nr Melrose Apr-Sep 450 80 673 352 560
MLRM8
Big Hole R nr Melrose Apr-Sep 515 90 738 418 570
MLRM8N
Hebgen Resvr Inflow Apr-Sep 389 90 441 328 430
HBDM8N
Ennis Resvr Inflow Apr-Sep 676 91 794 579 745
ELMM8N
Gallatin R nr Gateway Apr-Sep 262 58 356 210 455
GLGM8
Gallatin R nr Gateway Apr-Sep 262 58 356 210 455
GLGM8N
Gallatin R at Logan Apr-Sep 224 44 376 170 505
LOGM8
Gallatin R at Logan Apr-Sep 363 61 499 294 595
LOGM8N
Missouri R at Toston Apr-Sep 1954 78 2632 1660 2510
TOSM8N
Missouri R at Fort Benton Apr-Sep 2972 81 4071 2636 3690
FBNM8N
Missouri R nr Virgelle Apr-Sep 3411 80 4703 2982 4280
VRGM8N
Missouri R nr Landusky Apr-Sep 3677 82 5003 3208 4490
LDKM8N
Missouri R below Fort Peck Dam Apr-Sep 3798 80 5185 3299 4730
FPKM8N
Gibson Resvr Inflow Apr-Sep 456 114 647 396 400
AGSM8N
Marias R nr Shelby Apr-Sep 363 81 527 285 450
SHLM8N
Musselshell R at Harlowton Apr-Sep 54 52 102 37 104
HLWM8N
Yellowstone R at Yellowstone Lk Apr-Sep 471 59 574 378 795
YLOW4
Yellowstone R at Yellowstone Lk Apr-Sep 652 78 777 527 840
YLOW4N
Yellowstone R at Corwin Sprgs Apr-Sep 1305 69 1627 1102 1880
CORM8
Yellowstone R at Corwin Sprgs Apr-Sep 1562 79 1918 1330 1980
CORM8N
Yellowstone R at Livingston Apr-Sep 1602 75 2005 1362 2130
LIVM8
Yellowstone R at Livingston Apr-Sep 1921 83 2361 1643 2310
LIVM8N
Yellowstone R at Billings Apr-Sep 2435 65 3353 1984 3730
BILM8
Yellowstone R at Billings Apr-Sep 3394 80 4309 2886 4260
BILM8N
Yellowstone R at Miles City Apr-Sep 5157 71 6773 4172 7250
MILM8N
Yellowstone R at Sidney Apr-Sep 5314 70 7041 4295 7540
SIDM8N
Boulder R at Big Timber Apr-Sep 178 59 248 149 300
BTMM8
Boulder R at Big Timber Apr-Sep 218 67 288 190 325
BTMM8N
Stillwater R nr Absarokee Apr-Sep 301 60 404 240 505
SRAM8
Stillwater R nr Absarokee Apr-Sep 355 65 458 297 550
SRAM8N
Clks Fk Yellowstone R nr Belfry Apr-Sep 403 73 536 319 550
BFYM8
Clks Fk Yellowstone R nr Belfry Apr-Sep 475 79 609 392 600
BFYM8N
Bighorn R nr St. Xavier Apr-Sep 1565 61 2432 1090 2550
STXM8N
Little Bighorn R nr Hardin Apr-Sep 52 51 82 37 103
HRDM8N
Tongue R nr Dayton Apr-Sep 63 75 80 46 83
DAYW4N
Tongue R nr Decker Apr-Sep 141 65 214 101 215
DSLM8N
Tongue R Resvr Inflow Apr-Sep 141 66 216 101 215
DKRM8N
Powder R at Moorhead Apr-Sep 142 65 284 93 220
MHDM8N
Powder R nr Locate Apr-Sep 152 62 318 99 245
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
