Dangerous avalanche conditions exist. A strong winter storm this week deposited nearly three feet of snow and five inches of moisture in the mountains. Strong winds during the snowfall further aided in the development of wind slabs at all elevations. Yesterday these slabs were very sensitive to human triggers and were releasing naturally. No one was injured when one of these natural events hit a truck on the highway near Astoria Hot Springs in the Snake River Canyon. Although not expected to release naturally today, these slabs will continue to be sensitive to backcountry skiers and riders. Conservative decision making is essential.
The chance continues for backcountry travelers to initiate very large and destructive deep slab avalanches that could involve the full depth of the snowpack. The weak snow associated with this problem exists on northwest through northeast aspects above 9000 feet.
Strong southwest to west winds during recent heavy snowfall have formed dense surface slabs on leeward aspects. These slabs lie upon faceted snow formed during last weeks cold period. These slabs will be most sensitive at the higher elevations where slab depths could reach three feet.
( Discussion is generated from the previous day's afternoon forecast. )Snow is to continue overnight with two to four inches of accumulation expected by morning. Little snow is expected during the day as the storm moves to the east and a dry regime takes over for several days. Morning temperatures at higher elevations are to be in the single digits and highs are to be in the teens. Southwest winds are to continue to be on the strong side with twenty to twenty five mile per hour averages. The current avalanche warning for the area is due to expire at 5 am Thursday. The general avalanche hazard will be Considerable in the Teton and Togwotee Pass areas and High in the Southwest Trails/Greys River area. Wind slabs pose at a threat at all elevations and on all aspects. These slabs will be most sensitive at higher elevations where depths could reach four feet in most areas and five feet in the southern portion of the region where more snow has fallen in both this and the most recent storm. These slabs could be easily triggered by backcountry skiers and riders in steep wind loaded areas on Thursday. The possibility also continues to trigger deeper avalanches above 9000 on certain aspects, especially with larger triggers.
