June 1, 2020 Spring and Summer Streamflow Forecasts
Upper Missouri Basin
The high elevation snow pack in the Upper Missouri Basin as of June 1 was near average. The snow pack above Fort Peck, Montana was 89 percent. The snow pack in the St. Mary Basin was not available, and the Milk River Basin was not available.
May precipitation across the Upper Missouri Basin was near to above average. Basin precipitation summaries for the Missouri Basin include: Milk St. Mary, 82 percent; Milk Canada, 139 percent; Lower Milk, 95 percent; above Toston, 66 percent; Toston to Ft. Peck, 105 percent.
May 2020 Upper Missouri Mean Precip Oct-May WY2020 Upper Missouri Mean Precip
Stream flow in the Upper Missouri Basin is forecast to be above average during the upcoming Spring and Summer. The St. Mary River is forecast to have 128 percent of average June-September flows. Runoff is expected to range around 135 percent of average for the Missouri Basin above Fort Peck, Montana.

Upper Missouri June 1, 2020 Spring and Summer Streamflow Forecasts
Of the four major irrigation reservoirs in Montana; Lima Reservoir had 117 percent average storage, Clark Canyon was holding 109 percent of average water, Gibson Reservoir had 101 percent of average stored water, and Fresno Reservoir had 121 percent of average stored water.
The major hydroelectric reservoirs in Montana (Canyon Ferry and Fort Peck), had monthend storage in the average to above average range; 99 and 119 percent of average water, respectively.
Yellowstone Basin
The high elevation snow pack in the Yellowstone Basin was near to below average on June 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 79, 78, and 88 percent of average, respectively. The snow packs in the Tongue and Powder basins were 80 and 78 percent of average, respectively.
Precipitation during May was below average. The upper Yellowstone River Basin received 88 percent of average precipitation while the Lower Yellowstone River Basin reported 81 percent of average. The Bighorn Basin received 47 percent of average precipitation while the Wind River Basin received 30 percent of average. The Little Bighorn - Upper Tongue Basin received 41 percent of average and the Powder River had 68 percent of average precipitation.
May 2020 Yellowstone Mean Precip Oct-May WY2020 Yellowstone Mean Precip
Forecast stream flow in the Yellowstone Basin is near average for the upcoming Spring and Summer. Stream flow for the Yellowstone River above Sidney, Montana is forecast to be about 120 percent of average. Flow in the Tongue Basin is expected to be 80 percent of average. Flows in the Powder River are expected to be about 72 percent of average.
Monthend storage at Boysen Reservoir was 98 percent of average. Stored water in Buffalo Bill Reservoir was 126 percent of average. Monthend storage was 96 percent of average at Bighorn Reservoir.

Yellowstone June 1, 2020 Spring and Summer Streamflow Forecasts
Platte Basin
The high elevation snow pack in the Upper North Platte Basin was 83 percent of average on June 1. The snow pack in the North Platte Basin below Seminoe Reservoir was 78 percent of average. The snow pack in the South Platte Basin was 60 percent of average.
Precipitation during May in the Upper North Platte Basin was 77 percent of average. In the Lower North Platte Basin, precipitation was 42 percent of average. The North Platte Plains below Guernsy Reservoir had 58 percent. The South Platte Mountains had 63 percent whereas the Plains had 75 percent of average May precipitation.


May 2020 Platte Mean Precip Oct-May WY2020 Platte Mean Precip
Stream flow in the Platte Basin is forecast to be near to below average during the upcoming Spring and Summer. Runoff for streams above Seminoe Reservoir are expected to be about 95 percent of average. Streams in the South Platte Basin above South Platte, Colorado can expect 54 percent of average flow. For the remainder of the South Platte basin, flows are expected near 48 percent.
Stored water in the South Platte Basin was 106 percent of average on June 1.
North Platte Streamflow Fcst South Platte Streamflow Fcst
000
FGUS63 KKRF 041916
ESPKRF
WATER SUPPLY FORECAST
NWS MISSOURI BASIN RIVER FORECAST CENTER
PLEASANT HILL MISSOURI
1402 CDT THURSDAY JUNE 04, 2020
DATA CURRENT AS OF: JUNE 01, 2020
MISSOURI/YELLOWSTONE/PLATTE RIVER BASIN FORECASTS
50% % 10% 90% AVG
FORECAST POINT PERIOD (KAF) AVG (KAF) (KAF) (KAF)
---------------------------------------------------------------------
SBDW4N JUN-SEP 530 73 669 480 722
BOYSEN RESERVOIR INFLOW
LVEW4N JUN-SEP 798 71 978 727 1119
BIGHORN R AT KANE
MEEW4N JUN-SEP 94 50 121 82 190
GREYBULL R NR MEETEETSE
CDYW4N JUN-SEP 426 86 520 379 496
BUFFALO BILL RESERVOIR INFLOW
SMYM8N JUN-SEP 352 128 392 305 274
ST MARY R NR BABB
SMBM8N JUN-SEP 403 129 456 348 313
ST MARY R NR INT BOUNDARY
PDBM8N JUN-SEP 13 68 38 9 19
MILK R NR WESTERN CROSSING
ERNM8N JUN-SEP 28 84 97 21 33
MILK R AT EASTERN CROSSING
NGTC2 JUN-SEP 158 84 184 136 187
NORTH PLATTE R NR NORTHGATE
ECRW4 JUN-SEP 76 81 86 71 93
ENCAMPMENT R NR ENCAMPMENT
ECRW4N JUN-SEP 81 83 92 77 98
ENCAMPMENT R NR ENCAMPMENT
KCRW4 JUN-SEP 38 117 45 37 33
ROCK CR NR ARLINGTON
KCRW4N JUN-SEP 39 118 45 37 33
ROCK CR NR ARLINGTON
SETW4 JUN-SEP 409 88 507 372 463
SEMINOE RESERVOIR INFLOW WY
SETW4N JUN-SEP 530 95 621 493 560
SEMINOE RESERVOIR INFLOW WY
WODW4 JUN-SEP 26 93 40 22 28
LARAMIE R NR WOODS
WODW4N JUN-SEP 50 95 63 46 53
LARAMIE R NR WOODS
SMTW4 JUN-SEP 36 122 46 34 30
LITTLE LARAMIE R NR FILMORE
SMTW4N JUN-SEP 38 121 48 36 32
LITTLE LARAMIE R NR FILMORE
ANRC2N JUN-SEP 6 57 9 5 10
ANTERO RESERVOIR INFLOW
SPYC2N JUN-SEP 18 49 29 14 37
SPINNEY MOUNTAIN RES INFLOW
EVNC2N JUN-SEP 20 49 35 16 41
ELEVENMILE CANYON RES INFLOW
CHEC2N JUN-SEP 37 51 60 30 72
CHEESMAN LAKE INFLOW
SPTC2N JUN-SEP 69 54 103 54 128
SOUTH PLATTE R AT SOUTH PLATTE
MRRC2N JUN-SEP 4 33 5 3 11
BEAR CK AT MORRISON
GLDC2N JUN-SEP 55 63 58 52 87
CLEAR CK AT GOLDEN
LNSC2N JUN-SEP 41 64 48 36 64
ST VRAIN CK AT LYONS
OROC2N JUN-SEP 23 76 27 21 31
BOULDER CK NR ORODELL
BELC2N JUN-SEP 11 49 13 10 22
S BOULDER CK NR ELDORADO SPR
FTDC2N JUN-SEP 118 83 134 106 142
CACHE LA POUDRE AT CANYON MOUTH
LRRM8N JUN-SEP 23 83 30 18 28
LIMA RESERVOIR INFO
CLKM8N JUN-SEP 41 56 54 33 74
CLARK CANYON RESERVOIR INFLOW
BARM8N JUN-SEP 61 66 76 51 93
BEAVERHEAD R AT BARRETTS
ALRM8N JUN-SEP 62 124 73 56 50
RUBY R RESERVOIR INFLOW
MLRM8 JUN-SEP 383 151 471 326 253
BIG HOLE R NR MELROSE
MLRM8N JUN-SEP 425 146 515 369 291
BIG HOLE R NR MELROSE
HBDM8N JUN-SEP 272 125 291 246 218
HEBGEN RESERVOIR INFFLOW
ELMM8N JUN-SEP 508 135 566 452 378
ENNIS RESERVOIR INFLOW
GLGM8 JUN-SEP 285 105 385 234 271
GALLATIN R NR GATEWAY
GLGM8N JUN-SEP 282 104 381 230 271
GALLATIN R NR GATEWAY
LOGM8 JUN-SEP 284 112 425 206 253
GALLATIN R AT LOGAN
LOGM8N JUN-SEP 384 110 504 318 350
GALLATIN R AT LOGAN
TOSM8N JUN-SEP 1650 122 2039 1409 1357
MISSOURI R AT TOSTON
FBNM8N JUN-SEP 2758 137 3247 2467 2017
MISSOURI R AT FORT BENTON
VRGM8N JUN-SEP 3231 138 3733 2866 2337
MISSOURI R NR VIRGELLE
LDKM8N JUN-SEP 3400 138 3910 3025 2469
MISSOURI R NR LANDUSKY
FPKM8N JUN-SEP 3651 138 4194 3268 2650
MISSOURI R BLW FT PECK DAM
AGSM8N JUN-SEP 399 239 456 367 167
GIBSON RESERVOIR INFLOW
SHLM8N JUN-SEP 276 152 363 252 182
MARIAS R NR SHELBY
HLWM8N JUN-SEP 36 67 53 30 53
MUSSELSHELL R AT HARLOWTON
YLOW4 JUN-SEP 837 170 892 803 492
YELLOWSTONE R AT YELLOWSTONE LK
YLOW4N JUN-SEP 531 160 612 482 332
YELLOWSTONE R AT YELLOWSTONE LK
CORM8 JUN-SEP 1498 164 1640 1408 915
YELLOWSTONE R AT CORWIN SPRINGS
CORM8N JUN-SEP 1288 147 1454 1185 878
YELLOWSTONE R AT CORWIN SPRINGS
LIVM8 JUN-SEP 1751 166 1924 1639 1057
YELLOWSTONE R AT LIVINGSTON
LIVM8N JUN-SEP 1605 149 1805 1484 1081
YELLOWSTONE R AT LIVINGSTON
BILM8 JUN-SEP 3414 176 3776 3142 1944
YELLOWSTONE R AT BILLINGS
BILM8N JUN-SEP 3401 138 3782 3138 2461
YELLOWSTONE R AT BILLINGS
MILM8N JUN-SEP 5311 119 5947 4904 4463
YELLOWSTONE R AT MILES CITY
SIDM8N JUN-SEP 5601 120 6287 5195 4666
YELLOWSTONE R AT SIDNEY
BTMM8 JUN-SEP 268 146 305 242 184
BOULDER R AT BIG TIMBER
BTMM8N JUN-SEP 304 137 341 279 222
BOULDER R AT BIG TIMBER
SRAM8 JUN-SEP 519 147 581 460 354
STILLWATER R NR ABSAROKEE
SRAM8N JUN-SEP 521 128 584 464 406
STILLWATER R NR ABSAROKEE
BFYM8 JUN-SEP 409 127 467 369 323
CLARKS FK YELWSTONE R NR BELFRY
BFYM8N JUN-SEP 473 122 530 436 388
CLARKS FK YELWSTONE R NR BELFRY
STXM8N JUN-SEP 1357 80 1612 1235 1707
BIGHORN R NR ST XAVIER
HRDM8N JUN-SEP 44 80 51 40 56
LITTLE BIGHORN R NR HARDIN
DAYW4N JUN-SEP 42 89 48 38 47
TONGUE R NR DAYTON
DSLM8N JUN-SEP 94 80 105 87 117
TONGUE R NR DECKER
DKRM8N JUN-SEP 94 80 106 87 118
TONGUE R RESERVOIR INFLOW
MHDM8N JUN-SEP 55 52 61 50 104
POWDER R NR MOORHEAD
LOCM8N JUN-SEP 64 51 74 59 126
POWDER R NR LOCATE
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 VOLUME AS SIMULATED BY THE RIVER
FORECAST MODEL CONSIDERING A CONTINUOUS 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 PERIOD
FOR MORE INFORMATION, PLEASE VISIT: WWW.WEATHER.GOV/MBRFC/WATER
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