BILLINGS, Mont. — The Latest on flooding in western Montana (all times local):

5 p.m.

Officials in western Montana are bracing for flooding that could be the worst in more than 40 years.

Missoula County deputy emergency services coordinator Ken Parks said Sunday that the Clark Fork River by Tuesday could approach major flood stage for the first time since 1975.

Parks says about 40 households in Missoula's Orchard Homes area already have experienced some flooding.

Residents were being notified that they could be asked to evacuate in coming days.

The National Weather Service forecasts that the Clark Fork will crest on Friday. High water also was expected on the Bitterroot, Blackfoot and Clearwater Rivers and around Seeley Lake.

Warm weather has been melting deep mountain snows and swelling rivers and creeks. Thunderstorms in coming days threaten to make matters worse.

Park says no injuries have yet been reported.

3:15 p.m.

Melting snow coupled with heavy rain was forecast to swell rivers and creeks in portions of western Montana over the coming days, with floodwaters that could affect numerous streets and homes in and around Missoula, federal and county officials said Sunday.

The Clark Fork was expected to reach major flood stage before cresting Friday and starting to recede next weekend. The National Weather Service extended a flood warning for the river above Missoula until further notice.

Flooding of streets and homes in the Orchard Homes area of Missoula was expected by Monday night. County officials set up a sandbagging station at the Orchard Homes Country Life Club for residents who want to protect their properties.

Widespread flooding was possible later in the week from East Missoula to the Bitterroot River, including impacts to U.S. Highway 10, forecasters said.

Temperatures expected in the 70s would accelerate the melt of an above-normal mountain snowpack, they said.

Up to three-quarters of an inch of rain could fall in some areas.

Snowmelt at high elevations also was expected to cause minor flooding in the Helena area, south of Wolf Creek, near Augusta and at locations around Lincoln including the Stemple Pass area.

To the north, near Browning and Glacier National Park, Badger Creek below the Four Horns Canal was expected to flood Sunday, although with only minor impacts. A flood advisory for the region was in effect until Monday night.

In eastern Montana, river levels continued to fall after cresting last week. A flood warning was cancelled for the Nashua area but remained in effect for Glasgow until Tuesday morning.

Gov. Steve Bullock on Wednesday declared a statewide flooding emergency. That allows the use of state resources and the Montana National Guard for flood protection.