Officials say warmer temperatures and rain could cause flooding, ice jams and heighten the avalanche threat after parts of Montana saw record snow in February.
West Central Montana Avalanche Center director Steve Karkanen says rain expected to arrive in western Montana Tuesday will weaken an already unstable snowpack.
The avalanche danger is high in the Missoula foothills, where a Friday avalanche buried three people. A 68-year-old woman died of her injuries Sunday.
Interstate 90 remained closed Tuesday from St. Regis to the Idaho line because of the avalanche threat.
National Weather Service meteorologist Dave Bernhardt says melting snow could lead to areas of flooding in Helena and west of the Continental Divide.
The weather service says there is the risk of ice jams in southern Montana and northern Wyoming waterways.