Winter weather advisories cover I-80, I-70 and the Bighorns with up to 15 inches of snow

Winter weather advisories took effect across three states on Monday, November 2, with forecast snow topping out at 15 inches on Cloud Peak in Wyoming’s Bighorn Mountains. Gusts of up to 55 mph were also in the forecast for the Interstate 80 summit between Cheyenne and Laramie. Four National Weather Service offices, in Cheyenne, Denver, Billings and Riverton, issued the products that cover those corridors.

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The 15-inch number is the advisory-wide maximum, and it applies only to the highest terrain. Roads see far less: 2 to 4 inches near Interstate 80, 3 to 7 inches around the Eisenhower Tunnel on Interstate 70, and up to 10 inches on Highway 14 through the northern Bighorns. For drivers the larger hazards are wind, wet snow on bridges and visibility that can fall below a quarter mile.

A Winter Weather Advisory is the lower of the National Weather Service’s two winter tiers. It signals snow, ice or wind that will make travel hard but that careful driving can usually manage, while a warning is reserved for conditions that threaten life and property. The Eastern times in the Autoblog summary convert to Mountain time by subtracting two hours, so the Laramie Range advisory began at 8 a.m. local time and the Riverton product at 1 a.m.

Interstate 80 from Cheyenne to Laramie: two rounds of snow and 55 mph gusts

According to Autoblog’s rundown of the advisories, the South Laramie Range product, which includes the Interstate 80 summit, ran from 10 a.m. Eastern Monday to 1 a.m. Tuesday. Forecasters expected 2 to 4 inches in two rounds, one Monday morning and a second Monday evening after a lull, with gusts reaching 55 mph and poor visibility during the evening commute. A separate advisory for the North Snowy Range Foothills, which takes in Arlington and Elk Mountain along the same interstate, ran from 7 a.m. to 7 p.m. Eastern with 2 to 4 inches of wet snow, gusts to 40 mph and slick bridges and overpasses.

The National Weather Service office in Cheyenne listed a Winter Weather Advisory and a Wind Advisory among its active alerts, and said in its Monday update that a Pacific storm system would exit that night, leaving cold temperatures and lingering rain and snow through sunrise Tuesday. The office added that the rest of the week should be seasonably cool and mostly dry, which keeps the worst of the travel window to about a day.

Interstate 70 at the Eisenhower Tunnel and Colorado’s traction law

The Denver and Boulder forecast office covers elevations above 9,000 feet in Summit County, the Mosquito Range and the Indian Peaks, a footprint that takes in the Eisenhower Tunnel, Berthoud Pass, Winter Park and Breckenridge. The forecast was 3 to 7 inches of snow from 7 a.m. Eastern Monday until 2 a.m. Tuesday, with slippery roads during both commutes.

Colorado’s traction law applies on Interstate 70 between Dotsero and Morrison from September 1 through May 31. Drivers need tires with at least 3/16 inch of tread plus four-wheel or all-wheel drive, M+S-marked tires, mountain-and-snowflake winter tires or tires the manufacturer rates as all-weather; otherwise chains or an approved traction device are required. A standard citation costs $100 plus a surcharge, rising to $500 plus a surcharge if the vehicle blocks one or more lanes. Live road conditions are posted on COtrip, the state’s traveler information service.

Highway 14 and Cloud Peak in the Bighorns

NWS Billings put the northern Bighorn Mountains, in Montana and Wyoming, under an advisory until 10 p.m. Eastern Monday. The forecast called for up to 10 inches of snow, gusts to 45 mph and the heaviest snow Monday morning, with visibility possibly dropping below a quarter mile. Highway 14 through the range was the road flagged, with travel expected to be very difficult.

NWS Riverton handled the southeastern Bighorns above 9,000 feet, where the advisory ran from 3 a.m. to 7 p.m. Eastern Monday. Snow there was forecast at 6 to 10 inches, with 10 to 15 inches at Cloud Peak’s highest elevations and gusts up to 55 mph. Granite Pass was set for 5 to 8 inches and Powder River Pass for up to 2, a spread that shows how sharply totals change with elevation across a single range.

WYDOT blow-over restrictions on Interstate 80

Gusts of 55 mph can topple high-profile vehicles, and the Wyoming Department of Transportation has closed Interstate 80 to light, high-profile vehicles during wind events since 2011. In 2023 it began listing specific weights on part of the corridor so trailer and commercial drivers can check whether a load is at risk; where those signs are not available, the warning reads “Extreme Blow Over Risk.” Restrictions appear on overhead signs and on the state’s 511 tools. Blow-over crashes peak in winter, most often in February and December.

The Wyoming 511 site links to conditions by route, closures, chain-law notices and the Wyoming Travel Authorization Program, which lets drivers use sections of a closed road when authorities judge it safe. The 511 phone line is 1-888-996-7623.

This article was produced with the assistance of AI and reviewed by Morning Overview editors prior to publication.

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