Another wave of snow is expected late Monday and Tuesday morning before the biggest snowstorm of the season leaves Southwest Colorado.

And Tuesday’s commute might be just as dicey as Monday’s, when a semitrailer snarled morning traffic on U.S. Highway 160 between Bayfield and Chimney Rock.

“We’re going to have another round come in (Monday) evening and continue through Tuesday,” said Kris Sanders, meteorologist with the National Weather Service. “Just like the first wave, there will be periods of moderate to heavy snow at times. So, that’s kind of what we’re expecting.”

Also beginning at 6 a.m. Tuesday, the Colorado Department of Transportation will conduct winter maintenance operations on the west side of Wolf Creek Pass.

Motorists will encounter a lengthy delay of up to two hours and are urged to allow for extra travel time Tuesday morning, said CDOT spokeswoman Lisa Schwantes.

Westbound traffic will be stopped at the chain-up station at Treasure Falls, at milepost 157. Eastbound traffic will be stopped at the top of Wolf Creek Pass near the ski area, milepost 167.

Travelers are urged to “know before you go,” she said. Anyone who must be on the road should gather information about weather forecasts and anticipated travel impacts and current road conditions before hitting the road. Information from various CDOT sources is available, including:

Road conditions and travel information: www.COtrip.org.Social media: Twitter @coloradodot and Facebook facebook.com/coloradodot.Sign up for project or travel alerts: bit.ly/COalerts.Scheduled lane closures: codot.gov/travel/scheduled-lane-closures.html.U.S. Highway 160 reopened at 9:50 a.m. Monday.

Details about the crash were sketchy, but Schwantes said she believed the semitrailer was involved in a single-vehicle crash that had blocked both directions of traffic between Bayfield and Chimney Rock.

Calls to the Colorado State Patrol were not returned Monday.

Schwantes said highways across Southwest Colorado will remain snowpacked and drivers should slow down and drive to conditions.

“If you don’t need to travel, stay off the roads. If you must travel, slow down and drive to the conditions,” Schwantes said.

On Monday, CDOT had eight snowplows working in La Plata County, six in Montezuma County, six in Archuleta County and six other snowplows working the passes in Southwest Colorado – Lizard Head, Coal Bank, Molas and Red Mountain.

As of 5 p.m. Monday, chain laws or four-wheel drive or all-wheel drive were required on all Southwest Colorado’s mountain passes.

The snowstorm forced closure of the COVID-19 community testing site at the La Plata County Fairgrounds on Monday. But the site is scheduled to reopen from 10 a.m. to 4 p.m. Tuesday, weather permitting, said Megan Graham, spokeswoman for La Plata County.

Durango-La Plata County Airport Aviation Director Tony Vicari said the snowstorm was a warm one, and crews were able to keep the runway open with only a small, acceptable dusting of snow on the pavement, and normal operations have been maintained.

Vicari said passengers should check with airlines through the storm because flights, especially those going through Denver, might be delayed.

“We’ve been able to keep ahead of it, and we do need the moisture, so that’s good,” Vicari said.

The city of Durango has put its Snow Route rules in effect to allow snowplowing.

The city plows 164 lane miles of road within city limits, and removes snow from 55 blocks in the downtown commercial area.

Snow routes are streets designated important and necessary for safe travel. Motor vehicles may be towed from snow routes if they are not moved when Snow Routes are enacted.

A map of snow routes is available on the city’s website.

In Durango, light traffic on the Monday between Christmas and New Year’s Day, helped keep Southwest Colorado’s workday commute manageable.

Durango Police Department Sgt. Dave Longenette said he had no reports of crashes within city limits as of 8:30 a.m. However, as of 10:45 a.m., DPD issued an accident alert.

Residents involved in nonemergency fender-benders were asked to file reports online by going to the Colorado State Patrol’s website and under the “I Want To” tab clicking on “Crash Information” and then clicking on “File an Online Crash Report.”

A winter storm warning is in effect for the southwestern San Juan Mountains through 5 p.m. Tuesday and snow is expected on and off. Travel is expected to be difficult to impossible during periods of heavy snow. In addition, blowing snow could reduce visibility at times.

An avalanche watch has been issued by the Colorado Avalanche Information Center.

CAIC said new snow will fall on a very weak snowpack, and the avalanche danger will rise Monday afternoon and into Tuesday.

Sanders said Durango might receive up to 6 inches before the storm leaves the region Tuesday late afternoon or evening.

The National Weather Service issued a winter storm warning for the high country of the San Juan Mountains for areas around Silverton, Rico and Hesperus that remains in effect until 5 p.m. Tuesday.

During that time, up to 16 inches could accumulate west of U.S. Highway 550 and up to 18 inches could fall to the east of the highway. Wind gusts could reach as high as 45 mph in areas above 10,000 feet.

“Travel could be very difficult to impossible,” the NWS said. “Patchy blowing snow could significantly reduce visibility.”

According snow totals reported Monday to the Weather Service: As of 10:30 a.m., Coal Bank Pass had 8 inches and Molas and Red Mountain passes each had 6 inches. As of 8 a.m., Vallecito had 5.5 inches. At 7 a.m., Durango had 3 inches. Just west and south of Pagosa Springs, 4.5 inches had fallen as of noon. Silverton had 3.4 inches at 7 a.m.

A smaller storm that is not expected to bring much precipitation might move into Southwest Colorado on Thursday night, Sanders said.

Wolf Creek should get hit the hardest with more than 2 feet of snow expected. Telluride and Silverton are expected to receive up to 18 inches from the multiday storm.

As of 5 a.m. Monday, Purgatory Resort reported 6 inches of snow in the last 24 hours with seven of 11 lifts operating and a base depth of 26 inches. Telluride Ski Resort was reporting 2 inches of snow in the last 24 hours with 16 of 17 lifts open and a base depth of 29 inches. Wolf Creek Ski Area reported 6 inches of snow in the past 24 hours with eight lifts in operation and a midway base depth of 42 inches.

parmijo@durangoherald.com