Salt River and Wyoming Ranges

The General Avalanche Hazard is MODERATE. Unstable surface and deep slabs exist. These instabilities are assocaited with buried layers of weak faceted snow and are problematic. Surface slabs up to three feet deep were remotely triggered by snowmobilers in the Snake River Range on Monday and Tuesday. Steep unstable slopes have failed after being crossed multiple times. Some steep avalanche prone slopes have been crossed by skiers or snowmobilers without instance while other similar slopes have failed on approach. Dangerous surface slabs and deep slabs to the ground could be trigered by backcountry travelers today on steep snow covered slopes. CAUTION IS ADVISED. The consequences of being caught in one of these slides are severe.

( Discussion is generated from the previous day's afternoon forecast. )An upper level disturbance and colder air aloft will move south down the Continental Divide and across Western Montana. This system will bring a quick shot of new snow to the western mountains tonight. In general 2 to 4 inches of new snow is expected, however convective snow showers may bring up to six inches of new snow to some locations. This snowfall will be accompanied by northwest winds at 10 to 20 miles per hour. A high pressure ridge will quickly build in behind this disturbance. Expect skies to rapidly clear Thursday morning. Early morning temperatures at all elevations are expected to be near minus 10 and to rise to near 10 above during the day. Ridgecrest winds will back to the west and diminish to 10 to 15 miles per hour.The general avalanche hazard is expected to be MODERATE. In the TETON area unstable surface slabs one to three feet in depth persist. These slabs lie upon buried suncrust and surface hoar. These slabs continue to be a hazard to skiers and snowmobliers who venture into steep wind loaded terrain. The new snow and wind overnight is expected to create new isolated pockets of very shallow windslab along the leeward side of the highest ridgelines. These isolated pockets will lie upon excellent sliding surfaces and in very steep cliffy terrain could knock over or sweep skiers who venture onto them over cliffs.In the CONTINENTAL DIVIDE/TOGWOTEE PASS and SOUTHWEST TRAILS/GREYS RIVER areas the surface slab hazards discussed above exist. These areas also have dangerous persistent deep slab instabilities. Weak well developed faceted snow in the base of the snowpack has resulted in numerous human triggered full depth slab avalanches. This weak basal layer lies beneath a supportable upper layer that can provide a false sense of stability. The potential for skiers, snowboarders and snowmobilers to trigger dangerous full depth slab avalanches on steep snow covered slopes persist. These surface and deep slab instabilities have proven to be unpredictable and problematic. During the past several weeks there are numerous instances where a steep slope did not slide when it was first crossed and then later failed after having been crossed multiple times. In addition many steep avalanche prone slopes have been skied or ridden without instance while other similar slopes have failed on approach. CAUTION IS ADVISED.