Gov. Kate Brown and state emergency management officials held a press conference Friday to warn of potential flooding and landslides as snow and ice begins to melt around the state.

Brown, who declared a state of emergency Tuesday due to dangerous winter conditions, said she has "grave concerns" about the weather situation, particularly in eastern Oregon.

Buildings in Bend and Malheur County have collapsed under the weight of ice and emergency supplies are running low. Residents in some rural areas have faced evacuation by snowmobile. A mile-long ice floe on the Snake River is creating serious flood dangers, officials said.

Dangerous weather conditions are expected to remain, even as temperatures rise.

The National Weather Service in Portland issued its preliminary forecast for next week, cautioning that "major flooding" may come as heavy rain is expected next Tuesday and Wednesday. Two to 5 inches of rain are expected throughout the state, meteorologists say.

Brown said "early preparatory efforts" are underway to preempt flood and landslide conditions. State agencies have been working with local authorities and the U.S. Army Corps of Engineers to monitor the situation, she said.

Andrew Phelps, director of the state Office of Emergency Management, said flooding is expected throughout the state -- particularly along the coast and Willamette Valley.

Residents should restock their emergency kits with at least two weeks of supplies, Phelps said, and sign up for emergency notifications with local authorities. Motorists should avoid high water, he said.

Phelps said landslides are "always an issue," and he expects some will occur next week. It's impossible to pin down precisely where and when landslides will strike, he said. State geologists maintain maps of likely landslide areas and officials are coordinating with local authorities to watch for dangerous situations, he said.

All state highways are passable, said Oregon Department of Transportation Director Matt Garrett, but drivers should still exercise "extreme caution."

"We are doing our best given the intensity and duration of this weather event," Garrett said. "Our equipment, our people are out there working."

This season's winter storms have already cost the state transportation agency an extra $3 million, he said.

"That's just the implication on our budget," Garrett said. "There's certainly a cascading effect to the businesses of the state of Oregon as well as our fellow Oregonians."

-- Gordon Friedman

gfriedman@oregonian.com; 503-221-8209