The Powder River in eastern Montana happens to be the first dealing with flooding issues. Specifically, and ice jam seven miles south of Broadus is their culprit and causing concern.
The gorgeous stretch of the Bitterroot River, south of Missoula is experiencing minor flooding now and is under a Flood Advisory until Tuesday evening.
There is an ice jam on the Gallatin River already causing flooding south of Gallatin Gateway. Flood Warning is in effect until 6pm Sunday night. Details here: