Landowners along the banks of the Rogue River are being warned of possible lowland flooding this weekend if storms now moving through Southern Oregon live up to their billing.

Landowners along the banks of the Rogue River are being warned of possible lowland flooding this weekend if storms now moving through Southern Oregon live up to their billing.

The National Weather Service has issued a flood watch for the Rogue River at Eagle Point, below the former Gold Ray Dam site and in the Grants Pass area through Sunday as a mix of rain and snowmelt is expected to swell the Rogue and many of its tributaries.

Only up to an inch of rain is expected to fall in Medford, but the snow level will jump above 7,000 feet today, triggering forecasts of the highest inflows of the season into Lost Creek Lake.

The U.S. Army Corps of Engineers expects the lake to rise 10 feet in three days before settling out at full pool Sunday.

"It's a pretty dramatic system," said meteorologist Marc Spilde at the Weather Service's Medford office. "It's a long, potent plain of moisture that's stretched across the Pacific Ocean to Asia.

"We call them atmospheric rivers," he said.

The Rogue was expected to crest near but below flood stage near Eagle Point and Grants Pass around midday Saturday, according to the Natural Resource Conservation Service.

Snow levels are forecast to plunge to mountain pass levels Saturday evening and hover below 2,000 feet by Sunday, when a few inches of snow will dust local mountains, Spilde said.

"It's only going to be here 24 to 36 hours, so it's not an extended one," Spilde said. "That might help."

The Corps of Engineers saw the storm coming and prepped for it Thursday by increasing Lost Creek Lake releases to 4,500 cubic feet per second into the upper Rogue River. That will make more room for capturing inflows today and Saturday, said Jim Buck, the Corps' Rogue Basin operations manager.

Flows into the reservoir were forecast to peak Saturday just shy of 11,000 cfs, almost double the highest this season, Buck says.

Corps hydrologists will keep a close eye on flows at Dodge Bridge, where Highway 234 crosses the Rogue, and at Grants Pass. They will adjust outflows if necessary, Buck said.

Flows were forecast to peak at about 17,000 cfs Saturday at Dodge Bridge, where Buck said the goal is to keep flows from eclipsing the flood stage of 20,000 cfs. Flows Saturday were forecast to peak at 44,000 cfs at Grants Pass, just under the goal of 45,000 cfs, Buck said.

Capturing enough inflow to keep Rogue flows below those target levels at Dodge Bridge and Grants Pass means Lost Creek Lake is forecast to fill by mid-day Sunday, Buck said. The lake was 10 feet shy of full Thursday.

The flood watch declaration means flooding is possible but not imminent in the watch areas.

Flood watches also have been declared for most of Northern California as well as the Southern Oregon coast, where rainfall hit rates of up to an inch per hour Thursday, according to the weather service.

Rain and snowmelt were far less severe in the Applegate River Basin, but outflows from Applegate Lake were increased to 750 cfs to prep for the storm.

Reach reporter Mark Freeman at 541-776-4470, or email at mfreeman@mailtribune.com.