While Billings and most of Montana’s eastern plains have been buried since December with storm after storm, the state’s mountainous spine has pathetically thin snowpack.
By now, 65 percent of the year’s snowpack should be on the ground, but most of the mountains are woefully behind normal accumulation. Without a break in the winter pattern, water for irrigation and recreation could be scarce in some areas this summer.
The Natural Resources Conservation Service in Bozeman released its February streamflow forecast for Montana on Thursday and it wasn’t good. Assuming normal precipitation through spring, streamflows from April 1 to July 31 will be about 68 percent of average statewide, the forecast said.
The situation is slightly better west of the Divide, where the forecast puts streamflows at 69 percent of normal. East of the Divide, streamflows could be at 67 percent of average. Forecasts statewide are significantly lower than they were at the same time last year.
Current prospects for the Yellowstone River are dismal at 65 percent of average. The upper Yellowstone, the stretch between the river’s source in Yellowstone Park and Custer, has a forecast of 72 percent of normal. But the lower Yellowstone, from Custer to the confluence with the Missouri, is forecast at 53 percent of normal. Much of the lower Yellowstone is fed by snowpack in Wyoming’s mountains, which are also short of snow.
“Spring storms tend to be wetter, and a series of strong storms could change things quickly,” said Roy Kaiser, water supply specialist for NRCS. “But if we have another month like this, we’re looking at something pretty serious to turn this around.”
“We just have to get into a storm pattern,” he said.
January was the third month in a row with below-average snowfall in the mountains, despite a snowy winter everywhere else in Montana.
El Nino can take most of the blame, said Matt Solum, meteorologist at the National Weather Service office in Billings. The El Nino phenomenon, a warming of waters in the Equatorial Pacific that affects climate worldwide, tends to push the jet stream south.
Instead of the normal track that brings big, wet storms originating in the Pacific Northwest barreling toward the mountains, storms this winter are breaking off from big systems to the south and clobbering the plains, he explained. The area around Billings has seemed to be in the middle of those storms.
Statewide, water content in the snowpack is 73 percent of average and 80 percent of last year. East of the Divide it’s 74 percent of average and 78 percent of last year.
For the upper Yellowstone Basin, snowpack was 71 percent of average on Feb. 1, down 6 percent from Jan. 1. The lower Yellowstone was at 67 percent of average, down 9 percent from last month.
Some Eastern Montana basins do have good snowpack, including the Smith-Judith-Musselshell basins at 100 percent of normal and the Milk at 128 percent. But the Missouri Basin has just 80 percent of its normal snowpack.
Mountain precipitation statewide during January was 57 percent of average west of the Divide and 60 percent east of the Divide.
There is more snow in the forecast for the southeastern plains in a storm moving in from the north starting Sunday, Solum said. While it may add another layer to a foundation of snow laid down on the plains in December, the storm is unlikely to provide a needed boost to the mountains.
NRCS issues streamflow forecasts monthly from January to July.