• Ten skiers are missing following an avalanche in the Sierra Nevada mountains.
• Six survivors are stranded, awaiting rescue in increasingly hazardous conditions.
• Rescue efforts include over 46 first responders amidst deteriorating weather.
• A high avalanche danger warning was issued prior to the incident.
• This avalanche could rank among the deadliest in U.S. history if all missing skiers do not survive.

On Tuesday afternoon, rescues were ongoing for a group of backcountry skiers caught in an avalanche near Castle Peak in California's Sierra Nevada mountains. The avalanche occurred around 11:30 a.m., leaving 10 skiers unaccounted for while six other skiers remained stranded at the site, as per the Nevada County Sheriff's Office, which reported the situation around 4:30 p.m. PST. The group was composed of four guides and 12 clients from a ski tour company, according to Los Angeles Times and Reuters.

The rescue efforts have faced significant challenges due to worsening weather conditions, leading to zero visibility and road closures. Authorities expressed concerns about ongoing avalanche risks, leading Captain Russell Greene of the Nevada County Sheriff's Office to state that gaining access to the avalanche site would be "a slow, tedious process." By late afternoon Tuesday, 46 emergency first responders had been deployed, utilizing rescue teams from nearby ski resorts to navigate the situation safely, according to BBC and Los Angeles Times.

As snowfall rates increased to a dangerous 2 to 3 inches per hour on the day of the avalanche and a high danger rating was issued by the Sierra Avalanche Center, the urgency of the rescuers' mission escalated. The center reported that "a widespread natural avalanche cycle is expected" and had warned about the potential for large avalanches earlier that day. Rescue teams were actively trying to reach the stranded survivors, who had taken shelter amidst the harsh conditions, according to Reuters and BBC.

This avalanche incident raises concerns about skier safety in high-risk areas, particularly given the ongoing winter storm and the fact that the areas are not patrolled. Captain Greene reflected on the decision of the tour company to proceed in such unsafe conditions, indicating "I don't think it was a wise choice," highlighting the responsibility tour operators hold regarding client safety. Should all 10 missing skiers fail to be located, it would reflect among the deadliest avalanches recorded in the U.S., as noted by sources including Reuters and BBC.