An early morning snow shower is expected to be followed by freezing rain in the Treasure Valley, according to a winter weather advisory issued Tuesday afternoon by the National Weather Service.
"The morning commute could be quite hazardous," said Steve Parker, a weather service meteorologist at the Boise Airport.
As much as a tenth of an inch of freezing rain could fall before temperatures increase and rain without the icy component comes down, Parker said.
The Ada County Highway District plans to apply liquid de-icer to major roads beginning at 2 a.m. Wednesday. The magnesium chloride the agency uses helps prevent ice from forming on roadways.
Crews will continue covering roads until the storm ends. The weather service predicts the ice storm could last from 5 a.m. to noon. The highway department uses a priority system when responding to winter storms. Major intersections, bridges, schools and hills are among the top priorities.
The Ada County Highway Department maintains more than 2,200 miles of roads. State highways, including Eagle Road, Chinden Boulevard, as well as Interstate 84 and the Boise Connector, are managed by the Idaho Transportation Department.
If the freezing rain is heavy enough, it could cause some power lines to break. People should be cautious and assume that any fallen lines are energized, said Stephanie McCurdy, a spokeswoman for Idaho Power.
"If you encounter a downed line, stay away," she said.
There is a 30 percent chance of freezing rain again Wednesday night, with a chance of rain and snow throughout the rest of the week, according to the weather service.