Both directions of Interstate 90 are back open after closing for several hours Friday morning as the travel lanes were under several inches of water.

Westbound lanes between Worthington and Luverne opened by midmorning, and eastbound lanes were back in operation by early afternoon.

The area saw as much as 7 inches of rain, and water from upstream "pooled up" and covered the pavement, said Scott Morgan, a MnDOT assistant maintenance engineer in southwest Minnesota. "We had to wait for the water to recede."

Crews removed debris before opening the road to traffic, but Morgan warned plenty of standing water remained in ditches and medians.

"If you drive off the road, you will be in water," he said.

Video (02:24) A stalled front will ignite more heavy showers and T-storms into Saturday with flooding potential

Other roads in the area, including Hwy. 75 from Luverne to the Iowa border, remained closed Friday afternoon. So did Hwy. 19 from Henderson to Hwy. 169 and Hwy. 59 was open, but lane reductions in place just north of Worthington.

"Heavy rains and flooding have affected many roads in south central and the southwest corner of Minnesota," MnDOT said.

Northfield authorities are cautioning businesses and residents to look out as meteorologists forecast the Cannon River will crest at 901.5 feet this weekend, matching its record 2010 flood levels.

Northfield Police Chief Mark Elliot said the river could wash into some streets but likely wouldn't affect major throughways like Hwy. 3.

"We are taking preventative measures here as are local property owners," Elliot said.

The National Weather Service declared flash-flood warnings for Olmsted, Dodge and Mower County until 5:30 p.m. as sheets of rain moved through the area Friday afternoon. Rice County officials announced several road closures in rural areas Friday afternoon, including near Sakatah and Shields lakes. Parts of southern Minnesota faced more flood warnings Friday night into early Saturday.

In Stillwater, MnDOT workers blocked access to the city's lift bridge over the St. Croix River.

"MnDOT maintenance and bridge crews placed [a] concrete barrier on the non-lift sections of the bridge to act as ballast and raised the lift span approximately 15 feet above the bridge deck," the agency said.

More closures are possible as another round of rain moves in Friday night and Saturday. That prospect has the southern third of Minnesota under a flash-flood watch through Saturday afternoon. The watch does include the Twin Cities metro area, the National Weather Service said.

"Excessive runoff may result in flooding of rivers, creeks, streams, and other low-lying and flood-prone locations," the weather service said.

Floodwaters slowly moving toward the metro have led St. Paul officials to shut down Warner/Shepard Road to vehicles, bicyclists and pedestrians between Hwy. 61 and Eagle Parkway starting at 6 p.m. Sunday. On Friday, Hennepin County officials plan to close County Road 50 between Hwy. 55 in Rockford and County Line Road in Delano. County Road 92 from County Road 6 in Maple Plain and County Road 26 in Minnetrista also will close due to rising water on the Crow River, officials said.

In Windom, heavy rains have caused the Des Moines River and Perkins Creek to overflow, with water rising to knee to waist deep in some residents' backyards, said Paul Johnson, emergency management director for Cottonwood County.

The city at 6 a.m. began offering sandbags at the Windom Arena, and portions of County Roads 13 and 40 have been closed, Johnson said.

Between 2 inches and 5 inches of rain has fallen overnight and an additional 1 to 2 inches of precipitation is possible, the National Weather Service said.

Le Sueur County and the city of Waterville declared a state of disaster Thursday, opening up the eligibility for federal and state relief aid, said the county's emergency management director Tammy Stewig.

"Water's still coming up," Stewig said, adding that some 50 volunteers have arrived to help with sandbags.

Volunteers are also preparing the city of Henderson for this weekend's expected rain.

The city on the Minnesota River has often seen floods, and residents there are hewing to a well-worn script of closing openings in the levee, inspecting pumps and prepping sandbags.

Henderson is preparing patrols to inspect the town's dike as the water rises, Henderson Mayor Keith Swenson said in a phone call Friday.

"Things are getting real," Swenson said. "This is going to be a real flood."