Heavy rain to hit Boise area during evening commute, cause some Idaho rivers to flood

Wet weather will hit Southwest Idaho through the middle of the week, coupled with strong winds and some flooding, according to forecasters.

Korri Anderson, a meteorologist with the Boise branch of the National Weather Service, said the Treasure Valley will miss the brunt of the storm, save for some heavy rains and possible thunderstorms on Monday between 4 and 8 p.m.

“It’s not going to really be in Boise, it’s mostly in the mountains,” Anderson said.

Council, Cascade and McCall will each see about 1.8 inches of rain by noon on Tuesday, according to NWS forecasts. Idaho City, Lowman and Stanley will receive between 1 and 1.5 inches, while Caldwell, Nampa, Boise and Meridian will see about half an inch of rain.

The rainfall comes after recent mountain snowstorms — Anderson said some spots got as much as 8 inches of snow on Sunday — creating potential for serious flooding in some places.

According to Anderson, flows on the Boise River will be raised to 1,800 cubic feet per second, which is well below flood stage. But up near Lucky Peak, flows could reach as high as 14,000 cfs. Fortunately, Anderson said, there’s a lot of room in the reservoir to collect all that water.

However, the source of the Weiser River will see quite a bit of rain. The Weiser Basin snowpack is already nearly 50 percent above normal, which means flooding along the river, Anderson said. The Payette River will also reach flood stages.

On Tuesday, the precipitation will turn to snow above 5,000 feet while rain continues to fall in the Valley.

“Bogus should pick up some more snow on Tuesday,” Anderson said.

That same day, winds will start to pick up. The NWS issued a wind advisory for southwest Idaho that begins Tuesday afternoon and lasts until Wednesday night.

Anderson said winds will be between 20 and 35 mph in the Treasure Valley, with some gusts reaching 45 mph.

The storm will continue moving east, where it’s expected to bring blizzard conditions to the Midwest.

“The storm going over us is going to strengthen as it crosses into Colorado and Wyoming,” Anderson said.