Professional Observation

Observation Details

Signs of Unstable Snow

Snow Stability

Key Points

From Friday April 8th to Sunday April 10th, toured in the upper McGee Canyon drainage. Despite very warm temps, good snow was found and conditions for access were reasonable given the rapidly changing snow line and depth. On our way in, we walked 2.6 miles to the creek crossing which is currently well-bridged, and another .75 miles to the next log bridge before putting skis on. On the way back most of this had melted and we walked about 3.75 miles in shoes. Views into Convict look roughly the same, probably have to walk to Mildred Lake before skiing.

Coverage is thin but adequate for travel in the lower elevations, the greatest hazards being traveling in the drainage where high flow is causing lots of open water. HS at Big McGee Lake (10500′) was 75cm. Lake edges are melting out, and surfaces are down to ice with water pooling during the day. For those traversing Rock Creek to Mammoth, the descent down Halfmoon Pass is dry, Hopkins pass is without a cornice and is easily passable, and the climbs up Pretty Pass and Pika Pass both look to be mostly dry.

Natural activity:  2 recent Sz. 1.5 glide avalanches that ran on smooth rock slabs on south aspects at ~11,500′, and several Sz. 1-2 loose wet avalanches that ran on E and S aspects at 12,000′.
Skier triggered activity: 1 Sz. 1 skier intentional loose wet on 38deg. slope, 13,000′, SE asp. and 1 Sz. 1.5 skier accidental loose wet (down 35-40cm) on steep unsupported slope, 10,700′, E asp.

With the poor to non-existent overnight recovery, timing was critical, and we found that even with moderate to strong winds cooling the surface, the strong solar radiation made descending early mandatory. Even at 13,000′ steep slopes on due south aspects were ready by 11am (though lower angles came in later) and were out of condition by 12:30.