Another Atmospheric River moved into the region Monday with strong winds and heavy snow above ~7000’. The storm began Sunday night when temperatures were colder allowing for some lighter winter snow to fall. By Monday, however, the sub-tropical nature of the system brought warm temperatures and heavy dense snow. Remember that stronger, more resistant snow over a weaker layer is the recipe for slab avalanches. Mammoth Mountain Ski Patrol reported many results from control work on Monday with the same paths sliding multiple times throughout the storm.
Storm Totals as of 5 AM today:
Virginia Lakes: 16”
Tioga Pass: 21"
Gem Pass: --
Agnew Pass: --
June Mtn. Weather Plot: 22”
Mammoth Pass: --
Sesame Snow Study Plot: 22”
Rock Creek: 9”
South Lake: --
Sawmill: 10”
The strong Southwesterly flow aloft associated with this system formed Wind Slabs throughout the region through Tuesday. June Mountain Ski Patrol reported large and extremely sensitive wind slabs in the J7 area during Tuesday’s control work. One skier who ventured beyond the Mammoth Mountain Ski Area boundary triggered an avalanche large enough to bury or kill a person. Luckily he suffered only minor injuries. Due to the strong winds and local channeling, wind slabs may be encountered in unusual locations today and in normally sheltered areas, possibly lower in elevation than usual.
Last night the area received another 2 to 6 inches of snow. This will keep small storm slabs a problem for today. Temperatures will dip much colder across the region today and tonight and snow is forecast to taper off before this evening. Winds, however, will remain in the 15-35 mph range with ridge top gusts in the 60s. New snow and continuous winds will keep sensitive wind slabs forming throughout the forecast period. So while sunnier skies and new snow may make backcountry travel very tempting, we will still be stuck with elevated avalanche danger. Remember, the first sunny day after a storm is often when people get caught in slides. Stay alert!
