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NRCS Says Snowpack Still On The Rise

Posted at 1:59 PM, Apr 05, 2018
and last updated 2018-04-05 15:59:45-04

BOZEMAN, Mont., April 5, 2018 – Unlike February, snowfall wasn’t record-breaking in Montana during March, but it was sufficient to keep the snowpack near to well above normal on April 1, according to snow survey data collected by the USDA Natural Resources Conservation Service (NRCS). “One thing is for sure; it’s been a snowy winter across the state of Montana,” said Lucas Zukiewicz, NRCS water supply specialist for Montana, “and there’s still more to come.”

Last month, records were set for both monthly totals for February snowfall, and for total snowpack accumulation on March 1. Many snowpack measuring locations that feed Montana’s rivers and streams remain record high for April 1. Ten SNOwpack TELemetry (SNOTEL) and snowcourse locations remain the highest on record for this date, and 12 measurement locations are the second highest on record. These sites can be found in the mountains that feed the Upper Yellowstone River, Upper Clark Fork and Missouri Mainstem River basins, where snowfall has been abundant throughout the winter months. “Although not record-setting like these regions, the snowpack in other river basins across the state is well above normal for this time of year,” Zukiewicz said.

2018 is looking to go down as one of the biggest snow years on record for some parts of the state, prompting questions on how it compares to other memorable snowpack years. “1972, 1997, 2011 and 2014 were all big winters across the state, and many are wondering how this year compares,” Zukiewicz said. “So far, the only snowpack that has topped all other water years for peak snow water contained in the snowpack is the area near Cooke City which feeds the Clark’s Fork River of the Yellowstone River.”

For the most part, the snowpack in the rest of the state hasn’t reached the levels of 1997, 2011 and 2014. “During those years, snowpack peaked at the beginning of May to early June. For now, it looks like there is still a lot of winter left to come and this year could break more records if it keeps going.” Zukiewicz said.

Long-range predictions by the National Weather Service’s Climate Prediction Center continue to forecast above average precipitation and below average temperatures through the end of April.

Due to the abundant snowfall, many measurement locations have already reached, or exceeded, the normal amount of snow water that is typically contained in the snowpack before runoff occurs, all but assuring at least normal surface water supply this spring and summer, Zukiewicz said. Long-duration volumetric streamflow forecasts issued for the April 1 – July 31 period are well above average for most stream gages in the state, and could approach record levels this spring and summer at the stream gage at Belfry, Mont., located along Clark’s Fork of the Yellowstone.

“Having a big snowpack is a double-edged sword,” Zukiewicz said. “You know there will be plenty of snowpack to feed the rivers, which is typically great news, but the uncertainty of how and when it will come out can keep you up at night.”

The coming month will be critical in determining how much water is available in the snowpack for runoff this spring, and the day-to-day and week-by-week weather patterns during May and June will determine the timing and volumes of water in Montana. Water users are encouraged to read the May 1, 2018, NRCS Water Supply Outlook Report, which will summarize the conditions that occurred over the month of April, and help water users prepare for runoff this spring and summer.

Individual point forecasts for streams and rivers can be found in the monthly NRCS Water Supply Outlook Report and should be consulted as conditions vary from basin to basin, and even within the basins themselves.

Monthly Water Supply Outlook Reports can be found at the website below after the 5th business day of the month:

https://www.nrcs.usda.gov/wps/portal/nrcs/mt/snow/waterproducts/basin/

April 1, 2018, Snow Water Equivalent

River Basin

% of Normal

% Last Year

Columbia

137

134

Kootenai, Montana

128

122

Flathead, Montana

136

130

Upper Clark Fork

156

170

Bitterroot

134

128

Lower Clark Fork

124

117

Missouri

133

145

Jefferson

135

134

Madison

124

118

Gallatin

130

148

Headwaters Mainstem

169

190

Smith-Judith-Musselshell

130

186

Sun-Teton-Marias

142

122

St. Mary-Milk

140

149

Yellowstone River Basin

135

102

Upper Yellowstone

152

128

Lower Yellowstone

121

85

West of the Divide

137

134

East of the Divide

133

119

Montana State-Wide

137

137

April 1, 2018, Precipitation

River Basin

Monthly % of Average

Water Year % of Average

Water Year % of Last Year

Columbia

93

123

95

Kootenai, Montana

93

113

81

Flathead, Montana

101

129

96

Upper Clark Fork

103

130

114

Bitterroot

99

119

100

Lower Clark Fork

69

115

85

Missouri

111

119

95

Jefferson

117

111

93

Madison

121

113

82

Gallatin

113

124

98

Headwaters Mainstem

111

137

120

Smith-Judith-Musselshell

90

117

111

Sun-Teton-Marias

90

136

104

St. Mary-Milk

107

130

88

Yellowstone River Basin

98

122

83

Upper Yellowstone

99

138

95

Lower Yellowstone

98

108

72

West of the Divide

93

123

95

East of the Divide

103

121

89

Montana State-Wide

102

124

95

April-July 50% Exceedance Forecasts

River Basin

Highest Point Forecast*

Lowest Point Forecast**

Basin Average Forecast***

Columbia

231%

107%

134%

Kootenai, Montana

124%

110%

118%

Flathead, Montana

158%

112%

131%

Upper Clark Fork

231%

148%

170%

Bitterroot

128%

113%

121%

Lower Clark Fork

144%

107%

130%

Missouri

174%

95%

125%

Jefferson

161%

95%

126%

Madison

114%

111%

113%

Gallatin

123%

115%

120%

Headwaters Mainstem

135%

128%

132%

Smith-Judith-Musselshell

174%

117%

141%

Sun-Teton-Marias

141%

99%

123%

St. Mary

123%

119%

121%

Yellowstone River Basin

194%

83%

133%

Upper Yellowstone

194%

97%

147%

Lower Yellowstone

159%

83%

119%

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.