Billings, MT -

Forecasters say Montana's bitterly cold winter could mean an active ice jam season as warm weather begins loosening up large blocks of river ice next month.

Tom Frieders, warning coordinator for the National Weather Service in Billings, says forecasters will monitor the situation by calling people who live along rivers and by watching stream gauges for indications of blocked flows or ice dam breakage.

The Billings Gazette reports the state's longest rivers record the most ice jams, simply because there are more miles of water to jam up. Since records have been kept in 1893, the Missouri River tops the list at almost 170 jams, followed by the Yellowstone with 120.

West of the Continental Divide, the Clark Fork River leads with almost 40 ice jams.