An avalanche shut down train traffic along Glacier National Park’s southern boundary from Sunday night until late Monday afternoon, and then another snowslide partially blocked the westbound lane of U.S. 2 near Goat Lick. 

By 5 p.m., plows had cleaned up the highway. 

BNSF Railway spokesman Matt Jones said a maintenance crew discovered the first slide at about 11:30 p.m. Sunday about 10 miles east of Essex.

Both tracks were back in service as of 4 p.m. Monday.

“Initial reports indicated there was about seven feet of debris on the tracks,” Jones said, adding that no trains were struck by the avalanche.

According to The Associated Press, eastbound Amtrak passengers were being bused from Spokane and Whitefish to Shelby while westbound passengers were being bused from Shelby to Whitefish.

Amtrak trains did not arrive as scheduled Sunday night and Monday morning at the Izaak Walton Inn, where about 18 inches of new snow fell Sunday night, said Kelly Fitzgerald, assistant manager at the Essex inn. 

 Montana officials also closed the westbound lanes of Interstate 90 from St. Regis to the Idaho state line Monday because of the threat of an avalanche.

Ed Toavs of the Montana Department of Transportation said six small avalanches covered portions of I-90 on Monday. Crews cleared those slides, but Toavs says there are more cracks in the snow on the mountainsides above the roadway.

Westbound drivers were being diverted at St. Regis. 

The Flathead Avalanche Center issued a special avalanche advisory Monday rating the avalanche danger as “high” on all slopes across Northwest Montana.

Erich Peitzsch, the center’s director, said the avalanche danger was heightened by a rapid warming trend that started Sunday evening. An automated weather site at Pike Creek, located at about 6,000 feet near Marias Pass, measured temperatures at minus 12 degrees Sunday afternoon, but by noon Monday, temperatures had risen to 35 degrees.

Meanwhile, it continued snowing. 

“We basically have heavier snow falling on top of lighter snow,” Peitzsch said. “It’s basically an upside-down snowpack.”

He added that it’s likely there will be natural avalanches across Northwest Montana.

“Very dangerous avalanche conditions exist,” the advisory states. “Travel in avalanche terrain is not recommended and avalanche runout zones should be avoided.”

The avalanche closure on the train tracks Sunday night came just a few hours after U.S. 93 north of Whitefish was reopened following a freight-train derailment on Saturday.

The highway had been closed since 3 p.m. Saturday when 45 empty coal cars derailed just outside Olney. Some of the derailed cars were on a bridge over the highway.

U.S. 93 reopened at 8 p.m. Sunday. During the closure, highway traffic was rerouted on OIney Loop Road.

Meanwhile, a forecast calling for freezing rain and treacherous roads led Missoula County Public Schools to cancel classes again Monday and further postpone high school basketball games that had been called off over the weekend.

That includes basketball games between Flathead and Hellgate. Originally scheduled Thursday, the games were moved to Saturday and then to Monday before the latest postponement.

The University of Montana held classes Monday. The university was closed Friday due to weather.