Timely Snowpack Recovery Improves Spring and Summer Streamflow Forecasts
By Moosetrack Megan

Posted: March 6, 2020

BOZEMAN, Mont., March 5th, 2020 – Following on the heels of January’s abundant snowfall, February also delivered above normal to record-setting snowfall in mountain ranges supplying water to regional rivers and streams. New records were set for February snowfall at seven mountain SNOTEL (SNOwpack TELemetry) sites in southern and central Montana that were favored by the unstable north-northwest flow coming from Canada during the first three weeks of the month.

The recovery in snowpack was well timed. “January and February snowfall took the dismal snowpack totals reported on January 1 along the Montana/Idaho border and improved snowpack to near to above normal on March 1,” said Lucas Zukiewicz, USDA Natural Resources Conservation Service water supply specialist for Montana. “This is great news for water users as we approach spring and summer.” Snowpack totals in all river basins across Montana are now near to above normal for March 1.

At this point in the winter, around 75 to 85 percent of the seasonal peak snowpack has typically accumulated at mountain locations. This data gives forecasters clearer insight into what the snowmelt may yield in seasonal water supply during spring and summer. “Streamflow prospects for spring and summer look to be near to slightly above average at this time due to the healthy snowpack totals we have in the mountains,” Zukiewicz said. However, he warns that “future snowfall, spring precipitation and temperatures during the next three months will play a critical role in both the timing and volumes we experience during runoff this year.”

As the transition into spring continues, weather patterns across Montana will change. Mountains west of the Divide typically experience lower monthly snow totals through spring. However, spring months can be significant to river basins east of the Divide. “Even though spring starts on March 19, there is still typically a lot of winter left to come in the mountains, and the juicy months are on the horizon for some of our east of the Divide river basins. These months can make or break our spring and summer streamflows,” said Zukiewicz.

Long-range forecasts issued by NOAA’s Climate Prediction Center for the next two weeks (March 3-17) indicate better than normal chances of above average temperatures across the state and near to below normal precipitation. “While we’ve got more water than we typically have stored in the snowpack on March 1, I’ve learned from experience it’s never wise to assume we will be in the same shape come May 1,” said Zukiewicz.

Monthly Water Supply Outlook Reports can be found at the website below after the fifth business day of the month: https://www.nrcs.usda.gov/wps/portal/nrcs/mt/snow/

Snow Water Equivalent

3/1/2020

% Normal

% Last Year

Columbia River Basin

112

110

     Kootnenai in Montana

106

116

     Flathead in Montana

112

120

     Upper Clark Fork

112

96

     Bitterroot

116

109

     Lower Clark Fork

107

106

Missouri River Basin

114

96

     Jefferson

113

97

     Madison

99

77

     Gallatin

120

98

     Headwaters Mainstem

120

96

     Smith-Judith-Musselshell

130

106

     Sun-Teton-Marias

115

126

     St. Mary-Milk

130

135

Yellowstone River Basin

116

105

     Upper Yellowstone

115

96

     Bighorn

121

115

     Tongue

119

140

     Powder

132

142

West of Divide

112

110

East of Divide

115

101

Montana State-Wide

113

103

 

Precipitation

3/1/2020

Monthly % Avg

Water Year % Avg

WY % Last Year

Columbia River Basin

121

98

103

     Kootnenai in Montana

104

97

117

     Flathead in Montana

111

102

110

     Upper Clark Fork

131

96

92

     Bitterroot

145

97

93

     Lower Clark Fork

114

94

100

Missouri River Basin

152

101

86

     Jefferson

154

99

87

     Madison

112

89

72

     Gallatin

185

112

86

     Headwaters Mainstem

149

105

85

     Smith-Judith-Musselshell

200

110

94

     Sun-Teton-Marias

120

97

109

     St. Mary-Milk

106

107

114

Yellowstone River Basin

162

104

97

     Upper Yellowstone

153

105

91

     Bighorn

144

108

109

     Tongue

191

109

133

     Powder

167

119

142

West of Divide

121

98

103

East of Divide

148

101

92

Montana State-Wide

137

100

93

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