A storm that moved across the Pacific Northwest is triggering widespread flooding throughout the region, but drier weather for the rest of the week should slow the flow, forecasters said on Monday.
At least an inch of rain fell in the mountains of the Inland Northwest, and was combined with about three inches of snowmelt, said Ron Miller, science officer for the National Weather Service office in Spokane.
The low chance of showers this week – in the 20 percent range – should help ease flooding by later this week, he said.
Most area rivers are expected to crest at or above flood stage through the coming week.
Forecasters said the threat of floods will persist through the next several weeks because of a large remaining snowpack that has just started to melt off.
“We still have a long ways to go to get the snowpack off the mountains,” Miller said.
Spokane saw 0.31 inches of rain on Sunday, and another 0.36 inches of rain through 3 p.m. on Monday. Other locations received up to an inch of rain on Sunday alone.
The rain triggered flooding in the eastern portions of Spokane Valley on Sunday.
An eastbound lane of Interstate 90 had water covering it on temporary construction lanes near Barker Road starting Sunday night. Traffic on Monday was limited to one lane eastbound, which was causing backups, said Al Gilson, Washington State Department of Transportation spokesman in Spokane.
Water was reported over Flora Road on Sunday night.
Rain and warmer temperatures in the mountains over the weekend brought torrents of water down the region’s streams. As much as four inches of water entered streams in northeast Washington and North Idaho.
The Washington State Patrol reported Monday that a section of state Highway 206 to Mount Spokane was threatened by nearby Deadman Creek, which was eroding the embankment along the highway shoulder. Traffic was reduced to one lane with a flagger at the site controlling traffic while workers repaired the shoulder, Gilson said.
In Idaho, the Kootenai County Sheriff’s Department had predicted that the Coeur d’Alene River would crest Monday nearly 1.4 feet above flood stage. However, cooler temperatures Monday afternoon slowed things down, said Maj. Ben Wolfinger.
“I don’t see it rising much more,” Wolfinger said, with the river nearly a foot above flood stage. No homes or businesses are in danger, he said, and all roads are open.
Lake Coeur d’Alene is about 2.4 feet above normal summer level, but 2.6 feet below flood stage. As water flows into the lake, it is expected to crest Thursday or Friday, a few inches below flood stage, Wolfinger said.
That will translate into high flows on the Spokane River later this week, which should remain high for several days as the lake drains.
Hayden Lake is so far draining into an overflow field that was set aside for flooding and allows water to recharge the subsurface aquifer.
The U.S. Army Corps of Engineers sent teams from its Seattle office to help shore up the earthen dam at Hayden Lake and to assist in other areas of North Idaho and Western Montana, said spokeswoman Patricia Graesser. The corps had already sent out about 270,000 sandbags to the region, she said.
The St. Joe River at St. Maries was expected to crest this week at nearly four feet above flood stage. On Sunday, it was 1.2 feet above flood stage. The river was at 35.1 feet at noon Monday, more than two feet above flood stage, and expected to crest above 36 feet. Water was receding on the St. Joe at Calder by Monday afternoon.
Also in Idaho, state Highway 4 between Gem Hill and Frisco roads had water covering it late Sunday.
Chewelah Creek in Chewelah was flooding on Monday, sending water along U.S. Highway 395 near the city park there, Gilson said.
In central Washington, state Highway 410 at Nile Road northwest of Naches was blocked by a mudslide, the state Department of Transportation reported. It is in the same vicinity as a major mudslide that closed a section of the highway in 2009.
Portions of the central and southern Cascades saw 4 to 5 inches of rain over the weekend, in addition to snowmelt.
John Livingston, forecaster for the weather service in Spokane, said last week that flooding problems will persist into June and may affect not only Lake Coeur d’Alene but also Lake Pend Oreille and the Pend Oreille River. This is expected to be the worst year for flooding in the region since 1997, he said.
The Pend Oreille River should crest around 95,000 cubic feet per second at Albeni Falls Dam next week, which could cause some flood problems downstream in Pend Oreille County.
The Kettle River was expected to see moderate flooding.
Other rivers rising to near flood stage are the Moyie, Stehekin, Little Spokane, Snake, Grande Ronde, Kootenai and Okanogan.
Mullan Pass had a record 0.54 inches of rain on Sunday, breaking the previous record of 0.32 inches set in 2009. Record keeping dates to 1938 there.
The National Weather Service had issued a flood warning for small streams of the region due to rain and snowmelt.