Soft slabs formed yesterday when heavy snowfall was loaded onto to leeward slopes by winds from the southwest to west. These slabs will be sensitive to backcountry travelers at all elevations today in areas where wind loading has occurred. Slabs formed earlier in the week during periods of very strong winds could also be triggered today. Identify features of concern where this loading has occurred and exercise conservative decision making in order to avoid these hazards.
Soft to hard slabs could be triggered on all elevations and aspects today. These slabs lie over surface hoar and faceted snow in most terrain, and in high exposed terrain, lie upon hard snow surfaces. These slabs could have depths to two feet at the higher elevations and to one foot at the lower elevations.
The new snowfall that has already begun is the beginning of a strong upstream disturbance that will deposit significant snowfall through Saturday. The National Weather Service has issued a Winter Storm Warning through 11 pm. Fourteen to twenty inches of snow is expected in the higher country during this period. Winds will veer from the south to the southwest and have averages between thirty and thirty five miles per hour. Mountain temperatures are to rise from the teens in the morning to the mid twenties during the afternoon.The avalanche hazard will be Considerable in the early morning and if forecast snowfall amounts and wind speeds occur, will increase to High during the day. Very sensitive wind slabs lie on a variety of aspects and all elevations. These slabs will increase in both size and sensitivity as the storm continues to load them throughout the day. They are forming on hard snow surfaces in high exposed terrain and faceted snow and surface hoar in all other terrain. Human triggered slides are likely and the possibility of natural avalanche activity will increase throughout the day. In the Togwotee and Southwest trails areas, the chance for deep hard slabs continues on northerly aspects.
