Dangerous avalanche conditions exist. The National Weather Service has issued a Winter Storm Warning through 5:00 PM tonight. Small to large wind slabs are very likely to be triggered today, and natural activity is likely. Close to three inches of snow water equivalent has been added to the snowpack since Wednesday. This load may be sufficient to see avalanche activity failing on buried layers of surface hoar and near surface facets that formed in January, which could increase slab depths by a foot or more. Deep hard slabs are also a concern on high, north facing terrain. TRAVEL IN AVALANCHE TERRAIN IS NOT RECOMMENDED.
Six to eight inches of new snow has fallen in the past 24 hours. Strong westerly ridgetop winds at 15 to 25 miles per hour with gusts to 53 have formed wind slabs at all elevations. These slabs, which could reach depths of two feet, have formed on graupel and dense snow. Skiers and riders daring to enter avalanche terrain are very likely to trigger these slides. Natural activity is likely.
The chance continues for backcountry travelers, especially those on snow machines, to trigger very large deep slab avalanches on northerly aspects above an elevation of 9,000 feet. If triggered, these dangerous hard slabs could involve the full depth of the snowpack.
( Discussion is generated from the previous day's afternoon forecast. )The National Weather Service has extended their Winter Storm Warning through 5 PM on Tuesday. Another Pacific trough will move into the region overnight bringing another round of moderate to heavy snowfall before decreasing in intensity on Tuesday. Overnight lows in the mountains will be in the low teens before rising to near 20 during the day. Very strong southwesterly ridgetop winds at 30 to 40 miles per hour will continue before decreasing to 15 to 25 in the morning.On Tuesday, the general avalanche hazard is expected to be High in the Tetons. Both human triggered and natural slab avalanches involving the recent snowfall will be likely. These slides will range in depth from one to three feet. Snow water equivalents since Wednesday could reach five inches by tomorrow. This load might be sufficient to see avalanche activity failing on the faceted snow from January. TRAVEL IN AVALANCHE TERRAIN IS NOT RECOMMENDED DURING PERIODS OF HIGH AVALANCHE DANGER.Less snow has fallen in the Togwotee Pass and Greys River forecast areas, and the general avalanche hazard is expected to be Considerable. There, skiers and riders are likely to trigger recently developed wind slabs, which could range in depth from one to two feet. Natural avalanche activity will also be possible. Similar weak layers of facet snow from January exist in these areas, but with snow water equivalents in the range of two to three inches since Wednesday, they are less likely to fail. The chance of triggering full depth avalanches lingers on northerly aspects above 9,000 feet. Cautious route finding and careful snowpack evaluation will be essential for safe travel.
