Despite the initial warmth experienced earlier this winter, Montana is now grappling with a prolonged period of sub-zero temperatures and arctic cold fronts. This abrupt shift serves as a timely reminder that weather patterns can change unexpectedly, necessitating vigilance and awareness of potential ice jam flooding.
Ice jam flooding, a phenomenon prevalent along Montana’s rivers and streams, occurs when sub-zero temperatures precede sudden warm-ups, typically from now until March. Additionally, spring breakup can trigger ice jams as temperatures rise.
Traci Sears, the Montana National Flood Insurance Program Coordinator at the Department of Natural Resources and Conservation, emphasizes the importance of remaining observant to rapidly changing conditions throughout the winter season. “We urge residents to always be prepared for the possibility of flooding,” says Sears.
A sequence of sub-zero temperatures followed by a rapid warm-up can lead to the formation of ice jams, also known as ice dams — clusters of ice obstructing river or stream flow. As melting ice starts to move, it can become lodged at bridges, bends, or narrower reaches, sometimes causing flash floods during sudden breakups downstream.
“The result can cause dangerous conditions for those living adjacent to ice jams when the water has nowhere to go causing rapid flooding with little or no warning,” said Sears.
In addition to threatening homes and private property, rising waters can impact fishing access sites, roads, and hiking trails, prompting closures. Sears advises residents living near rivers or streams to develop a flood evacuation plan and consider the following precautions:
• Purchase flood insurance, as it typically needs to be acquired 30 days before a flood event.
• Ensure an adequate supply of drinking water, as flooding may compromise local water systems.
• Clear snow from homes and structures to prevent potential issues.
• Be prepared to transport or elevate valuables where practical.
• Never venture onto a frozen river or ice jam, as thermal currents in rivers are unpredictable and ice stability can change rapidly, leading to injury or drowning.
• Keep a vigilant eye on children and pets when near rivers and streams during winter recreation.
To learn more about the National Flood Insurance Program, visit https://www.floodsmart.gov/.
For up-to-date information on stream flows and potential flood conditions, visit the Montana All-Hazards Weather Monitor website at https://www.weather.gov/byz/