A winter storm could dump up to two feet of snow on Big and Little Cottonwood Canyons by Monday morning, Nov. 2, and trigger traction law restrictions for canyon drivers.

The National Weather Service (NWS) in Salt Lake City issued a Winter Weather Advisory for the Wasatch Mountains south of Interstate 80 and the western Uinta Mountains. The advisory took effect at 9 p.m. MDT Saturday, Oct. 31, and runs through 11 a.m. MST Monday, Nov. 2, according to Country Herald reporting on NewsBreak.

Forecasters expected 8 to 12 inches of snow at higher elevations. Above 10,000 feet in the Little and Big Cottonwood Canyons and the Uinta Mountains, totals of 18 to 24 inches were possible.

ABC4 meteorologist Seth Sanders reported Sunday, Nov. 1, that the moisture came from the remnants of Tropical Storm Vance and would interact with a cold front. Wind gusts of 45 mph were possible, creating hazardous driving conditions. Sanders reported traction laws may be enacted for the Cottonwood Canyons as a result.

What the traction law means for canyon drivers

The Utah Department of Transportation (UDOT) enforces a Class 3 traction designation for Big and Little Cottonwood Canyons, according to UDOT's Cottonwood Canyons page. The rule can take effect up to 24 hours before a storm begins. UDOT had not confirmed activation of the traction law beacons as of the advisory period.

When the beacons outside the canyons are flashing, all vehicles must have at least 5/32-inch tread depth on their tires. The requirements differ by vehicle type:

  • All-wheel or four-wheel drive: M+S or snow tires on all wheels at minimum. Chains, snow socks or three-peak mountain snowflake (3PMSF) tires on all wheels also meet the standard.
  • Two-wheel drive: 3PMSF tires on all wheels at minimum. Chains or snow socks on at least two drive wheels also qualify.

Cottonwood Heights police enforce the traction law at the mouth of Big Cottonwood Canyon. Sandy City police handle the mouth of Little Cottonwood Canyon. The Salt Lake County Sheriff's Office patrols both canyons and the Snowbird Entry 1 merge, according to a Provo.com guide to canyon traction rules. Enforcement focuses on morning uphill and evening downhill traffic. Vehicles that don't comply are turned around at the canyon entrances.

Falling snow levels forecast

Forecasters expected snow levels at about 9,000 feet through much of the storm. By Sunday night, snow could mix with rain as low as 7,000 feet, Sanders reported. By Monday morning, Nov. 2, snow levels were forecast to drop as low as 6,500 feet, reaching mountain valleys and the Wasatch Back.

The bulk of the storm was expected to move out by late Sunday night, with scattered showers lingering through Monday morning and clearing by Monday evening.

UDOT advises canyon travelers to keep fuel, snacks, water and a phone charger in their vehicles. There are no gas stations in either canyon. Current road conditions and traction law status are available at udottraffic.utah.gov and through the @UDOTCottonwoods account on X.