Two Decades of Avalanche Forecasting on the Going-to-the-Sun Road

Every workday, Gabrielle Antonioli wakes up at 3:30 am in her staff quarters in West Glacier. At four in the morning she is at her computer looking at data and models from various weather stations in Glacier National Park.

The National Park Service (NPS) hired Antonioli this year as a seasonal avalanche forecaster, where she works April through June, predicting avalanche conditions for park employees. Your primary mission is to protect the Going-to-the-Sun Road crew as they plow the road that crosses the Continental Divide at Logan Pass.

After writing the forecast, Antonioli goes to the road crew office at 6am to discuss the avalanche conditions with the plow drivers. At 7 a.m., the forecasters drive their government vehicles behind the plow drivers, eventually parting from the trails to park and put their skins on the sky to assess hazards in the field, and act as observers at each avalanche trail for the road crew , while remaining constant radio communication.

“It’s different than other forecasts because you’re making the call for other people, rather than giving them a product so they can make their own decision,” Antonioli said. “Recreational forecasters can choose their own terrain, and we’re entering the terrain that plow drivers are entering. It is often dangerous terrain for skiing. There may not be a plow-sized avalanche that day, but there are definitely man-sized avalanches.”

Park officials launched the avalanche hazard prediction program for snow removal operations on the nearly 50-mile Sun Road 20 years ago to ensure road crew safety. The NPS is working with US Geological Survey (USGS) snow scientists to provide forecasts for equipment operators removing snow from the top 14 miles that is at high risk of avalanches, including multiple destructive avalanche paths.

Plows move under west-facing slide trails including Haystack Creek, Big Bend and Triple Arches and The Garden Wall along the continental divide.

The program was originally started for the safety of park staff, but with Sun Road becoming more frequented by cyclists in the pre-season, the valet has expanded the program to ensure visitor safety and now provides forecasts on the weekends .

In 2019, an avalanche near Triple Arches stranded 13 cyclists on Sun Road on Memorial Day. Another avalanche in 2021 left a group of cyclists trapped between two avalanches near the same slide path.

“This year, for the first time, we officially have a forecaster on duty every weekend,” said Erich Peitzch, a USGS snow scientist who directs the park service’s avalanche program at the Northern Rocky Mountain Science Center. “It came up with the safety department with the park rangers because there have been incidents in recent years where cyclists have been trapped between avalanche debris.”

NPS Avalanche Forecast Gabrielle Antonioli scales a snowfield above the Going-to-the-Sun Road in Glacier National Park. courtesy photo

Anecdotally, Peitzch says e-bikes will allow cyclists to venture farther onto the road and access will be easier.

According to a USGS report released in 2004, there were a few fatal avalanche accidents involving plow drivers in the 1950s and 1960s. In May 1953, a slide caught four park employees, killing two of them clearing snow after a storm, and one employee survived a seven-hour funeral. In 1965, a bulldozer and operator triggered a wet slab, knocking them off the road and injuring the driver. Other incidents resulted in buried machinery and costly damage to infrastructure, including an April 1991 slide that caused $150,000 in damage to the road.

Peitzch recalls a massive avalanche that ran 4,000 feet up the Little Granite Slideway in January 2009, damaging the upper road, destroying much of the forest and hitting the lower road.

“He mowed down a very old forest and made his way all the way into the low angle terrain,” Peitzch said. “We drove in in April and the snow pile was still 20 feet up.”

For Antonioli, she feels fortunate to have a forecasting position where she works with USGS snow scientists to provide a forecast for the NPS. Before being hired, she volunteered for three seasons at Sun Road forecasters while working toward a master’s degree in snow science from Montana State University.

“It’s really fun,” said Antonioli. “It’s a really unique place for forecasting — it’s such a big terrain.”

While Antonioli’s valet position is seasonal, USGS employees work year-round, collecting data and conducting research during the summer months. Last year, Peitzch published a paper detailing how tree-ring data is linked to high-magnitude avalanche events and climate change.

This year, his team is working with Montana State professionals to experiment with remote sensing technology to assess snow surface deformation and its relationship to slide avalanches.

“The whole point of this research is to help improve the program,” Peitzch said.


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