Abundant moisture spilled into the Treasure State from the Pacific during January, boosting snowpack in all river basins to near or above normal for February 1. In some locations, the amount of water added to the snowpack was record setting. Between December 30 and February 1, SNOTEL (SNOwpack TELemetry) sites west of the Continental Divide received up to 18 inches of snow water equivalent, roughly proportionate to 100 to 150+ inches of snowfall. Five SNOTEL sites would go on to set new records for monthly totals, and four SNOTEL sites reported their second highest on record.

In the Columbia River basin, the Lower Clark Fork area is 119% of last year’s snow water equivalent, while the Kootenai is 138% and the Flathead is 133%. The Upper Clark Fork snowpack is at 102% of 2019.

“November and December were particularly dry, resulting in snowpack totals on January 1st that were well below normal in the river basins west of the Divide. The near continuous snowfall and moisture during January was extraordinary, and it helped the river basins to bounce back to near or above normal for snowpack on February 1st. It was quite the month,” said Lucas Zukiewicz, USDA Natural Resources Conservation Service water supply specialist for Montana.

“Although snowfall wasn’t record-setting in river basins east of the Divide, it was near to above normal for the month, helping the snowpack to improve in most areas,” said Zukiewicz. Southwest Montana experienced some of the most dramatic increases with the Jefferson and Madison River basins improving from below normal to near normal for snowpack on February 1. The West Yellowstone area, where mountain snowpack feeds the reservoirs supplying water to the Madison River, was well below normal on Janaury 1. “The mountains above Hebgen Lake received significant snowfall this month, helping to not only improve conditions for winter recreation, but water supply prospects this spring and summer,” said Zukiewicz.

South-central mountain ranges experienced slight increases in snowpack percentages during the month, while north central mountain ranges had a slight decrease from well above normal. “This region had been benefitting from early October snowpack which remained on the ground, keeping snowpack totals near to slightly above normal on January 1st, and it remains there at this time,” according to Zukiewicz.

At this point in the winter, around 60% to 70% of the seasonal peak snowpack has typically accumulated in river basins west of the Divide, while 55% to 65% of the seasonal peak snowpack has accumulated east of the Divide.

Monthly Water Supply Outlook Reports can be found at http://www.nrcs.usda.gov/wps/portal/nrcs/mt/snow/.