Colorado avalanche officials are warning of dangerous conditions that could linger across the mountains.

Following significant snowfall during the holiday, the Colorado Avalanche Information Center (CAIC) reported “considerable” avalanche danger around the state’s northern and central mountains, with a “persistent slab problem” spread across areas popular for Front Ranger skiers and ranges beyond.

On its website, CAIC describes the problem forming when weak layers of snow are buried by additional layers.

“Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky,” the website reads.

CAIC added in its warning at the start of the month: “As we move further from the last storm, avalanches will become harder to trigger — but also harder to predict.”

With more snow and winds, a thicker slab could build over weak layers, creating what’s called a “deep persistent slab.” In a study from 2014, CAIC officials found persistent slab problems account for about 87% of avalanche deaths in Colorado. 

CAIC posts daily forecasts but emphasizes a persistent slab problem “requires a wide safety buffer to handle the uncertainty.” One could benefit from “intimate slope-scale knowledge and tracking of culprit persistent weak layers and avalanche activity over space and time,” CAIC’s website reads.

Officials advise making “conservative decisions” and “avoid traveling below overhead hazards and carefully assess slopes before committing.” Slopes under 30 degrees are safer, CAIC adds, “or southerly slopes without buried crust/facet layers.”