Weather will play the decisive role in how or if conditions worsen in Lincoln County this week.

The National Weather Service issued a flash flood watch through Wednesday afternoon related to the potential failure of the Lower Flower Creek Diversion structure, which could result in flooding of certain areas in Libby. 

For Libby’s old water supply reservoir, referred to as the Lower Flower Creek Diversion Structure, engineers decided the safest course of action is a controlled release of water to reduce pressure on the structure, particularly with additional rain forecasted. They described the action as a “risk mitigation operation, not an emergency response.”

Last week’s heavy rain caused damage to the structure. Forecast rainfall has the potential to cause additional damage to the structure, bringing the risk for uncontrolled water released into the town of Libby.  The main Flower Creek Dam is stable and functioning as designed.

A high wind advisory is in effect for the Kootenai/Cabinet region until 3 a.m. Tuesday and a high wind watch is in effect through Wednesday afternoon.

National Weather Service forecasters say winds could range from 20 to 40 miles per hour with gusts ranging from 40 to 60 miles per hour.

Officials said damaging winds could blow down trees and power lines with widespread power outages possible. Travel could be difficult, especially for high profile vehicles. Gusty winds will blow around unsecured objects. Tree limbs could be blown down and a few power outages may result.

For the high wind watch, bursts of heavy snow and winter driving conditions are possible in higher valleys, over mountain passes and along the Divide.

In the NWS’s hydrologic outlook, heavy rain or snow could increase the risk for rock and landslides as well as rising creeks and rivers.

The prolonged atmospheric river is expected to impact Western Montana and Northcentral Idaho through Wednesday, bringing moderate to heavy precipitation. Snow levels are anticipated to start around 7,000 feet on Monday before falling to valley floors behind a cold front early Wednesday. 

The most likely rainfall scenario forecasts .75 to 1.25 inches for the valleys of Lincoln, Mineral, Sanders and Flathead counties in northwest Montana. One-and-one-half to three inches are expected in the mountains. A high-end scenario could bring a total of four inches to the Cabinet and Purcell mountains.

For Thursday and Friday, a mixture of rain and snow is forecast while the weekend could be snowy.