
A powerful winter storm is battering four US states today, forcing mountain pass closures and creating life-threatening conditions as authorities urge residents to avoid all non-essential travel.
Idaho, Montana, Washington, and Colorado are experiencing up to 61 centimetres of snow with wind gusts reaching 100 kilometres per hour, making roads impassable across the northern Rockies.
The National Weather Service issued urgent winter storm warnings through Saturday, 6 December, affecting major mountain passes including Lookout Pass, Vail Pass, and Stevens Pass.
Mountain Passes Shut Down Amid Whiteout Conditions
Transportation officials have closed multiple highways as heavy snowfall and fierce winds create near-zero visibility conditions. Tyre chains are now mandatory on several routes, whilst others remain completely impassable.
"Travel could be very difficult to impossible," the National Weather Service warned. "The hazardous conditions could impact morning and evening commutes."
Montana's Little Belt, Big Belt, Bridger, and Gallatin Mountains face warnings through 14:00 MST Saturday. Colorado's Sawatch and Gore mountain ranges are experiencing similar treacherous conditions lasting into early Sunday morning.
Eastern Idaho's Teton Valley has been hit particularly hard, with meteorologists reporting snowfall rates approaching 2.5 centimetres per hour in some locations.
Record Snowfall Totals Across Four States
The Idaho Panhandle Mountains are seeing 15-30 centimetres above 900 metres in elevation. Eastern Idaho and Montana ranges have accumulated 25-46 centimetres, whilst Colorado and Montana high terrain could reach 30-61 centimetres by Sunday morning.
Bear River and Caribou Ranges in Idaho face the heaviest accumulation, with some areas reporting up to 46 centimetres already. Lower elevation valleys have received 2-8 centimetres, though higher amounts persist near mountain passes.
Washington's Western Chelan County, including Stehekin and Stevens Pass, expects 13-25 centimetres with gusts up to 55 kilometres per hour, creating dangerous blowing snow conditions.
Emergency Services on High Alert

Authorities are warning drivers to carry winter survival kits including tyre chains, water, food, and first aid supplies. Backcountry conditions remain extremely dangerous with possible whiteouts and elevated avalanche risk.
Heavy, wet snow combined with strong winds has already caused power disruptions in several mountain communities. Emergency services report multiple vehicles stranded on mountain passes.
The National Weather Service warns that exposed ridges are experiencing wind gusts between 70 and100 kilometres per hour, occasionally reaching higher speeds that could snap tree branches and down power lines.
Storm warnings expire through Saturday afternoon and evening, though winter weather advisories in lower-elevation regions extend into Sunday morning. Residents should monitor local weather reports and delay travel plans until conditions improve significantly.