Early-winter snowfall built a good foundation of snow around the Wood River Valley, but as the season passes its midpoint, snowpack is falling below normal.
Snowpack in the Big Wood River basin is now at 79 percent of normal. Little Wood snowpack is 70 percent of normal, according to the Natural Resources Conservation Service. Snowpack Big Lost River basin snowpack is at 70 percent and the Salmon River basin is at 100 percent.
Snowpack levels are higher in the far northern and far southern parts of the state, with 115 percent in the northern panhandle and 131 percent in the Owyhee drainage of southwestern Idaho.
However, Travis Wyatt, a meteorologist with the Pocatello office of the National Weather Service, said that despite the lower-than-normal local snowpack, conditions remain good for irrigation season. Wyatt said ground saturation from heavy rains in September is keeping streamflows unusually high, filling local reservoirs. According to data collected by the U.S. Geological Survey, the current 172 cubic-feet-per-second flow in the Big Wood River at Hailey is about 115 percent of normal.
Little snow is in the forecast for the Wood River Valley for the next two weeks; “snow showers” are forecast for two days—this Saturday and next Saturday.
Meanwhile, eastern Idaho and western Wyoming are getting “hammered” with snow, Wyatt said.
He said that’s a typical scenario, due to a high-pressure air mass off the Pacific coast keeping easterly-moving air to the north, rotating in a clockwise direction. It flows southeast across Washington and southwestern Montana into eastern Idaho, leaving the rest of southern Idaho—including Bald Mountain—in a big dry area.
“That’s a very common thing that sets up—this high-pressure air mass off the coast,” he said. “You don’t do well in those conditions. You need a south wind.”
That occurs when there’s a low-pressure air mass off the coast—then the moving air rotates counter-clockwise, bringing storms up to central Idaho from the southwest.
“You normally get some low-pressure upper-air lows, but you’ve not gotten any this year,” Wyatt said.
Current U.S. Weather Service forecast is for the high-pressure system to remain in place for at least the next month. Wyatt said that could get broken down periodically, but dry weather is likely to prevail for the rest of the winter.