Montana Mountain Snowpack Looking Good Entering Runoff Season

Streamflow Forecasts above Average for Spring and Summer

After low flows in some of Montana’s rivers last summer caused issues for irrigators, anglers and recreationists, the spring and summer runoff this year looks to yield above average streamflows, according to snowpack data released by the USDA Natural Resources Conservation Service (NRCS).

Snowpack across the state is above normal for May 1 in all but a few sub-basins. Basins west of the Divide, which typically peak during the month of April, are all above normal with high elevations still gaining as of the end of the month. East of the Divide, where snowpack at higher elevations typically peaks a bit later towards the end of April to mid-May, also saw excellent gains during the month.

“Last month there was some concern over the lack of snowpack in some basins east of the Divide that provide irrigation and municipal drinking water, but April provided relief via abundant mountain snowfall and valley precipitation,” said Lucas Zukiewicz, NRCS water supply specialist for NRCS in Montana. “Two of these basins in southwest Montana, the Ruby River Basin and Hyalite drainages, have snowpack that is now normal for April 1.”

Abundant precipitation throughout this water year in most of Montana and healthy snowpack totals on May 1 have resulted in streamflow forecasts that are above average for most rivers in the state. In addition, the melt at higher elevations has been slightly delayed in some basins this year due to the cool and wet weather experienced during April.

“Delayed onset of snowmelt generally provides more efficient runoff and helps to keep the water in the mountains until it is needed to sustain streamflows later in the summer,” Zukiewicz said. “Over the last three years there has been early runoff of the seasonal snowpack, which has led to below average flows later in the season.” Streamflow forecasts issued by the NRCS are duration forecasts, or the total amount of water that will pass by a streamflow gauge during runoff season and do not forecast timing or magnitude of flows on any given day.

“The words ‘too much snow’ don’t come out of my mouth very often, but with regards to the snowpack in Wyoming basins, which feed the Bighorn River, it’s the case this year,” he said. Snowfall in the Wind River and Shoshone River basins has been record breaking this year, with snowpack totals over 200 percent of normal in some areas on May 1. Federal water managers have been working to make room for the water that will enter the river systems and reservoirs during runoff this year, increasing outflows from reservoirs in Montana and Wyoming. The May 1 – July 31 seasonal volume forecasts for some of the rivers in Wyoming are approaching record levels, with some over 200 percent of average. Zukiewicz said water users should anticipate above average flows for some time on the Bighorn River.

Monthly Water Supply Outlook Reports can be found here after the 5th business day of the month:http://www.nrcs.usda.gov/wps/portal/nrcs/main/mt/snow/waterproducts/basin/

May 1, 2017 Snow Water Equivalent

River Basin Percent of Normal Percent of Last Year
Columbia River Basin 119 163
 – Kootenai in Montana 121 178
 – Flathead in Montana 125 169
 – Upper Clark Fork 109 140
 – Bitterroot 122 174
 – Lower Clark Fork 124 185
Missouri River Basin 108 144
 – Jefferson 113 135
 – Madison 119 149
 – Gallatin 110 124
 – Headwaters Mainstem 90 130
 – Smith-Judith-Musselshell 83 94
 – Sun-Teton-Marias 129 379
 – St. Mary-Milk 124 200
Yellowstone River Basin 157 174
 – Upper Yellowstone 137 180
 – Lower Yellowstone 172 174
West of the Divide 119 163
East of the Divide 133 166
Montana Statewide 118 159

May 1, 2017 Precipitation

River Basin Monthly Percent of Average Water Year Percent of Average Water Year Percent of Last Year
Columbia River Basin 124 130 129
 – Kootenai in Montana 142 141 128
 – Flathead in Montana 146 136 135
 – Upper Clark Fork 105 113 119
 – Bitterroot 98 117 122
 – Lower Clark Fork 123 136 135
Missouri River Basin 126 128 125
 – Jefferson 120 119 119
 – Madison 142 141 147
 – Gallatin 154 132 127
 – Headwaters-Mainstem 97 110 110
 – Smith-Judith-Musselshell 119 110 108
 – Sun-Teton-Marias 95 125 151
 – St. Mary-Milk 105 149 123
Yellowstone River Basin 168 153 150
 – Upper Yellowstone 140 145 154
 – Lower Yellowstone 181 161 152
West of the Divide 124 130 129
East of the Divide 137 137 138
Montana Statewide 130 132 131

May-July 50% Exceedance Forecasts

River Basin Highest Point Forecast* Lowest Point Forecast** Basin Avg Forecast***
Columbia 152% 102% 126%
Kootenai, Montana 145% 124% 131%
Flathead, Montana 152% 117% 135%
Upper Clark Fork 136% 102% 125%
Bitterroot 117% 108% 112%
Lower Clark Fork 130% 119% 125%
Missouri 125% 78% 109%
Jefferson 125% 92% 109%
Madison 116% 111% 114%
Gallatin 108% 101% 105%
Headwaters Mainstem 113% 108% 111%
Smith-Judith-Musselshell 94% 78% 86%
Sun-Teton-Marias 119% 93% 112%
St. Mary 125% 124% 124%
Yellowstone River Basin 244% 94% 153%
Upper Yellowstone 167% 94% 134%
Lower Yellowstone 244% 125% 172%

Note: Streamflow forecasts are issued for multiple points on rivers and streams within a major river basin and are given as a range of exceedance probabilities. Consult the individual river basin of interest to see the range of values for streams of interest.

*Highest point forecast is the highest 50% forecast of all forecast points within the basin.

**Lowest point forecast is the lowest 50% forecast of all forecast points within the basin.

***Basin average forecast is an average of all 50% forecasts within the basin.

From: Natural Resources Conservation Service

Snowy February Improves Snowpack in Montana and Streamflow Prospects for Spring

 BOZEMAN, Mont., March 7, 2017 – February brought a notable change to the weather patterns that were experienced during the month of January, according to snowpack data collected by the USDA Natural Resources Conservation Service, Montana.

 

Record breaking snowfall for the month of February was experienced in northern and southern river basins of the state during the first two weeks of the month. Snow blanketed the Rocky Mountain Front at the beginning of the month, with low elevations and valleys receiving more than 3 feet of snow. Flattop Mountain SNOTEL (snow telemetry) site in Glacier National Park set a new record for February snowfall and received 12.5 inches of snow water during the month, well above the 30 year normal of 5.3 inches for February. Further south, Cooke City received copious amounts of snow, prompting the first ever “Extreme” avalanche warning for the area when Fisher Creek SNOTEL received 10.9 inches of snow water between Jan. 31 and Feb. 11. Statewide, 12 SNOTEL sites set new records for February totals, and six sites were second highest.

 

Lucas Zukiewicz, NRCS water supply specialist for Montana, said all basins experienced substantial improvements over the month with many now at near to above normal for March 1, and most basins are also near to above last year at this time. “There are some sub-basins that remain below normal for this date due to the late onset of snowpack this year and sub-par November and January snowfall,” Zukiewicz said. “One major basin is still recovering from near record low early season snow; the Smith-Judith-Musselshell will be reliant on spring precipitation to make up ground before spring and summer runoff.”

 

February typically isn’t one of the “big” snow months for Montana, he said, but this year proved otherwise. As we make the transition into spring, precipitation is favored along and east of the Continental Divide.

 

“Near normal conditions on this date is great news, but there is still a month to a month and a half before snowpack generally peaks in the mountains of Montana,” Zukiewicz said. “The coming months and their weather patterns will play a critical role in the timing and magnitudes of water in the rivers this coming spring and summer.”

 

Streamflow forecasts across the state reflect the near to above normal snowpack in many basins, and above average water year-to-date (Since Oct 1, 2016) precipitation. Many forecast points are near to above average for many rivers and streams for the April – July time period, but some remain below average due to lack of seasonal snowpack in some central Montana basins. Detailed forecasts for 98 streams in Montana can be found in the March 1st, 2017 Water Supply Outlook Report.

 

Monthly Water Supply Outlook Reports can be found here after the 5th business day of the month:http://www.nrcs.usda.gov/wps/portal/nrcs/main/mt/snow/waterproducts/basin/

 

March 1, 2017, Snow Water Equivalent
River Basin % of Normal % Last Year
Columbia 96 107
Kootenai, Montana 97 113
Flathead, Montana 97 109
Upper Clark Fork 95 101
Bitterroot 99 105
Lower Clark Fork 98 117
Missouri 100 109
Jefferson 103 97
Madison 113 126
Gallatin 98 108
Headwaters Mainstem 100 97
Smith-Judith-Musselshell 77 73
Sun-Teton-Marias 115 185
St. Mary-Milk 98 151
Yellowstone River Basin 140 173
Upper Yellowstone 128 147
Lower Yellowstone 152 197
West of the Divide 96 107
East of the Divide 120 138
Montana State-Wide 102 113
March 1, 2017, Precipitation
River Basin Monthly % of Average Water Year % of Average Water Year % of Last Year
Columbia 190 120 118
Kootenai, Montana 215 130 114
Flathead, Montana 193 125 124
Upper Clark Fork 161 108 113
Bitterroot 166 106 108
Lower Clark Fork 209 124 123
Missouri 186 131 132
Jefferson 183 122 122
Madison 201 140 151
Gallatin 164 129 126
Headwaters Mainstem 173 117 119
Smith-Judith-Musselshell 158 114 108
Sun-Teton-Marias 220 123 154
St. Mary-Milk 222 159 145
Yellowstone River Basin 198 146 166
Upper Yellowstone 207 145 153
Lower Yellowstone 196 149 182
West of the Divide 190 120 118
East of the Divide 194 136 146
Montana State-Wide 189 128 128
April-July 50% Exceedance Forecasts
River Basin Highest Point Forecast* Lowest Point Forecast** Basin Avg Forecast***
Columbia 143% 93% 104%
Kootenai, Montana 107% 100% 105%
Flathead, Montana 143% 93% 110%
Upper Clark Fork 115% 100% 105%
Bitterroot 102% 94% 99%
Lower Clark Fork 108% 98% 103%
Missouri 129% 58% 102%
Jefferson 129% 82% 106%
Madison 122% 108% 115%
Gallatin 101% 91% 96%
Headwaters Mainstem 106% 100% 104%
Smith-Judith-Musselshell 89% 58% 74%
Sun-Teton-Marias 119% 85% 106%
St. Mary 113% 110% 111%
Yellowstone River Basin 199% 83% 118%
Upper Yellowstone 148% 83% 119%
Lower Yellowstone 199% 90% 118%

Note: Streamflow forecasts are issued for multiple points on rivers and streams within a major river basin and are given as a range of exceedance probabilities. Consult the individual river basin of interest to see the range of values for streams of interest.

*Highest point forecast is the highest 50% forecast of all forecast points within the basin.

**Lowest point forecast is the lowest 50% forecast of all forecast points within the basin.

***Basin average forecast is an average of all 50% forecasts within the basin.

 

NRCS: Montana Water Users Prepare For Low Streamflow

After a disappointing winter, Montana water users should prepare for early, below average snowmelt runoff in streams

BOZEMAN, Mont., NRCS— Warm and dry weather patterns persisted through April. Mid and high elevations peaked during the month before transitioning to melt during the last two weeks, according to snowpack data from the USDA Natural Resources Conservation Service (NRCS).

“After high hopes that the weather patterns would turn around month after month, it turned out to be a disappointing year, snowfall-wise, in Montana,” said Lucas Zukiewicz, NRCS water supply specialist for Montana.

Snowpack conditions vary widely across the state, even within river basins. Towards the end of March or early April, low elevation measurement locations melted. Higher elevations retained the early season snow through the winter, experiencing near to slightly below normal snowpacks until the end of April. At 57 percent of normal for May 1, the Missouri River basin currently has the lowest snowpack out of the three major river basins across the state. Substantial declines, due to melt and lack of precipitation, have greatly reduced the snowpack since March 1. Currently, the Yellowstone River basin has the highest percentage of normal snowpack, but it is still only 71 percent of normal for May 1. The Columbia River basin snowpack is currently 61 percent of normal for this date.

may 1 snow water equivalent nrcs

“This year, not only did our snowpacks peak below normal, they also began the runoff season ahead of schedule as well,” Zukiewicz said.  “For water users across the state, this generally means that runoff will occur earlier this year, and when it does, there will be less water.”

Streamflow Forecasts

Aside from the Columbia River basin, where above average precipitation fell in the form of rain this winter, streamflow prospects this spring and summer generally reflect the lack of snowfall. Streamflow forecasts range from near record low (42%) in the Jefferson River basin in southwest Montana to below average (80-87%) on the mainstreams of the Flathead and Kootenai River basins.

This season, river systems that do not contain reservoirs for storage, such as the Gallatin and Upper Yellowstone, will see low streamflows pass through ahead of schedule.   For water users on rivers systems with reservoirs, there is water from last year’s runoff.  Because of last year’s record-breaking snowfall, carryover runoff was stored, leaving most reservoirs near to above average for May 1.

Water year-to-date precipitation (October 1 – May 1) across the state is near to slightly below normal for this time, with the exception of southwest Montana. Precipitation this spring and summer will play a critical role in the volume of runoff experienced this year. East of the Divide, where overall precipitation conditions have been drier this year, May and June are favored for rain and high elevation snow.

“We are coming up on what is typically known as ‘mud season’ in the Montana mountains,” Zukiewicz said.”Usually, people dread this season, but this year I think many will welcome any spring and summer rain, just to have a mud season.”

Conditions vary widely within the river basins this year. For detailed information on individual basin conditions and streamflow forecast points refer to the May 1 Water Supply Outlook Report.

Below are the averaged river basin streamflow forecasts for the period April 1 through July 31. THESE FORECASTS ASSUME NEAR NORMAL MOISTURE AND RUNOFF CONDITIONS MAY THROUGH JULY.

may-june streamflow forecast period

Press Release USDA NRCS. Follow us on Twitter @NRCS_MT.