Snowpack Still on the Rise, Well Above Average, and Setting Records in Some Parts of Montana
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:
|River Basin||% of Normal||% Last Year|
|Upper Clark Fork||156||170|
|Lower Clark Fork||124||117|
|Yellowstone River Basin||135||102|
|West of the Divide||137||134|
|East of the Divide||133||119|
|River Basin||Monthly % of Average||Water Year % of Average||Water Year % of Last Year|
|Upper Clark Fork||103||130||114|
|Lower Clark Fork||69||115||85|
|Yellowstone River Basin||98||122||83|
|West of the Divide||93||123||95|
|East of the Divide||103||121||89|
|River Basin||Highest Point Forecast*||Lowest Point Forecast**||Basin Average Forecast***|
|Upper Clark Fork||231%||148%||170%|
|Lower Clark Fork||144%||107%||130%|
|Yellowstone River Basin||194%||83%||133%|
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.