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ROUNDUP, Mont. (AP) — Ice jams and melting snow prompted flood warnings and advisories Sunday for parts of southern and eastern Montana.

Musselshell County authorities warned residents to watch for flooding caused by ice jams in the Musselshell River. Ice jams have been reported near Roundup, Dean Creek and Goulding Creek, leading to a flood warning to initially be issued by the National Weather Service on Saturday.

Musselshell County emergency officials said Sunday that one major ice jam had broken up, creating some more room for the rest of the ice floating down the river. However, flooding from ice jams had closed at least one road and other low-lying areas.

Jams form when ice becomes lodged in a river, backing up the water behind it and causing the river to spill over its banks. They can be unpredictable, moving at unexpected times and slowing or refreezing during the night.

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The weather service’s warning advised people to move equipment and livestock from lowland areas.

Residents near the Musselshell River downstream in Petroleum and Garfield counties were under a flood watch, while residents upstream in Golden Valley County were under an advisory for possible flooding.

Flood advisories due to snowmelt have been issued for Broadwater, Jefferson and parts of Gallatin counties.

Increasing rain and snow showers are expected to add to the threat of flooding in those areas, officials said.