Archived Avalanche Information - Not Current This is archived in relation to a fatality on Sunday, Dec 15. The fatal incident occurred slightly south of the official boundary for this advisory. This is a general information statement with no Danger Scale rating. On the 14th there was a more formal bulletin which is posted below. Issued Sunday, December 15, 2024 - 5:00AM Expires Tuesday, December 17, 2024 - 6:00AM Author: Kevin Studley General Avalanche Information PAC Advisory Area THE BOTTOM LINE 1-2 feet of new snow is forecasted in the mountains by Sunday. Breezy south winds and heavy snowfall will create dangerous avalanche conditions. Storm slabs large enough to bury a person will become sensitive to human triggering by Sunday morning. Conditions will be most dangerous above 7000' near and just below ridgelines. Another small storm may bring an additional 3-6" of snowfall Monday into Tuesday. This General Avalanche Information product will be updated on or before Tuesday, December 17th. Forecast Discussion A significant winter storm is bringing 1-2 feet of snow to the mountains this weekend. You can expect to encounter storm slabs across all aspects and all elevations. Slabs will be thickest at upper elevations, especially near wind-affected ridgelines. You can manage your exposure to avalanche danger by dialing back your terrain choices. Pay attention to the terrain you are moving through as the snow piles up. Limiting exposure to slopes steeper than 30 degrees is a good idea as the avalanche danger increases. Look for obvious clues like cracking in the new snow and audible collapses like whumpfing. Between 5000-6500', there is substantially less snow on the ground than elevations above 7000'. Be aware of rocks, logs, and stumps getting buried under new snow. Rain/snow levels are forecasted to rise up to 6000' during the day on Saturday. This will limit snow totals at elevations below 6000'. The past few weeks, people have been getting after some steep, aggressive terrain. A stable and above average snowpack for November and December has permitted good travel and a lot of confidence. It's time to dial back that confidence we've been enjoying the past few weeks. The West Central mountains will be receiving significant snow this weekend with high winds. Our current snowpack will be tested with a heavy loading event. Weak snow formed at (and just below) the surface over a 10 day stretch from late November into early December. That weak snow was buried last weekend under a few inches of new snow. In some areas, there is well preserved surface hoar, other locations may have a solar crust or near-surface facets. Weak layers 3-6" below the surface will likely not hold up under the weight of this new snow. Avalanche danger will rise during the day Saturday and will likely peak between Saturday night and Sunday mid-day. Play it safe this weekend by limiting your time in and around avalanche terrain during peak avalanche danger. That means avoiding slopes steeper than 30 degrees if you are witnessing signs of instability such as cracking, collapsing, or recent avalanche activity. Have a good travel plan with your partners this weekend by discussing where you want to go and what areas you would like to avoid. Consistent communication with your partners is key as conditions change throughout the day. Weather Forecast All Zones Issued Saturday, December 14, 2024 - 7:24AM Author: Kevin Studley A significant storm system moved inland off the Pacific coast Friday night. Southwest flow opened the door bringing warmer air into the region and lots of precipitation. 1-2" of total liquid precipitation is forecasted to impact the West Central mountains, translating to 1-2 feet of snow through Sunday. The bulk of the precipitation is forecasted from Friday night through Sunday morning. With the arrival of the cold front Saturday afternoon/evening, snowfall rates will increase as snow levels drop. Winds are forecasted to decrease slightly and begin shifting out of the NW. Temperatures drop to more seasonal levels Saturday night into Sunday. Mountain locations may experience lingering snow showers during the day on Sunday. Looking ahead, another quick moving and less significant Pacific trough will move inland on Monday and into our region Monday night. Rain/snow levels are forecasted to remain below valley floors, so we should expect all snow with this event. This storm is forecasted to remain colder, but with less moisture. Current forecasts indicate 2-4" in the mountains. This trough moves east on Tuesday and a drying trend looks to take shape over the long range forecast as another upper level ridge builds over the west. This full forecast was issued on the 14th, the day before the incident. Backcountry Avalanche Forecast PAC Advisory Area Issued: Saturday, December 14, 2024 - 6:35AM Expires: Sunday, December 15, 2024 - 6:00AM Author: Kevin Studley THE BOTTOM LINE Over a foot of new snow is forecasted in the mountains by this evening. Breezy south winds and heavy snowfall will create dangerous avalanche conditions by this afternoon. Storm slabs will increase in size and sensitivity throughout the day. Conditions will be most dangerous above 7000' near and just below ridgelines. Avalanche Danger Saturday, December 14, 2024 Above 8,000' - 3 - Considerable 7,000' to 8,000' - 3 - Considerable Below 7,000' - 2 - Moderate Avalanche Problems (1) Problem #1: Storm Slab Likelihood: Likely Size: Small (D1) to Large (D2) A significant winter storm is bringing 1-2 feet of snow to the mountains this weekend. You can expect to encounter storm slabs across all aspects and all elevations today. Sensitivity will increase to reactive today, especially as storm totals increase this afternoon. Slabs will be thickest at upper elevations, especially near wind-affected ridgelines. During the morning hours and/or at elevations below 7000', avalanche size will remain small (D1). During the afternoon and at upper elevations, avalanche size will increase to large (D2). You can manage your exposure to the increasing avalanche danger today by dialing back your terrain choices. Pay attention to the terrain you are moving through as the snow piles up. Limiting exposure to slopes steeper than 30 degrees is a good idea as the avalanche danger increases. Look for obvious clues like cracking in the new snow and audible collapses like whumpfing. Between 5000-6500', there is substantially less snow on the ground than elevations above 7000'. Be aware of rocks, logs, and stumps getting buried under new snow. Rain/snow levels are forecasted to rise up to 6000' during the day on Saturday. This will limit snow totals at elevations below 6000'. Forecast Discussion Today marks a temporary end to an era. The past few weeks, people have been getting after some steep, aggressive terrain. A stable and above average snowpack for November and December has permitted good travel and a lot of confidence. It's time to dial back that confidence we've been enjoying the past few weeks. The West Central mountains will be receiving significant snow this weekend with high winds. Our current snowpack will be tested with a heavy loading event. Weak snow formed at (and just below) the surface over a 10 day stretch from late November into early December. That weak snow was buried last weekend under a few inches of new snow. In some areas, there is well preserved surface hoar, other locations may have a solar crust or near-surface facets. Weak layers 3-6" below the surface will likely not hold up under the weight of this new snow. Avalanche danger will rise during the day Saturday and will likely peak between Saturday night and Sunday mid-day. Play it safe this weekend by limiting your time in and around avalanche terrain during peak avalanche danger. That means avoiding slopes steeper than 30 degrees if you are witnessing signs of instability such as cracking, collapsing, or recent avalanche activity. Have a good travel plan with your partners this weekend by discussing where you want to go and what areas you would like to avoid. Consistent communication with your partners is key as conditions change throughout the day. Weather Forecast All Zones Issued Saturday, December 14, 2024 - 5:06AM Author: Kevin Studley Yesterday, there was a lull between storm systems as a small system moved east. Clouds lingered in the mountains with some areas completely obscured with freezing fog. Winds were increasing out of the south in the afternoon. Temperatures remained cool and relative humidity was high. Last night, a significant storm system began moving inland off the Pacific coast. Southwest flow opened the door bringing warmer air into the region and lots of precipitation. A warm front has been making its way through the area during the overnight hours and should pass through later this morning. Overnight snow totals were less than initially forecasted, as webcams are showing 2-3" around 6000'. However, it appears to be snowing sideways this morning. Winds were gusting into the 20 MPH range this morning out of the south, with temperatures remaining mild (mid to upper 20s) at upper elevation weather stations. Today, expect a short lull in precipitation after the warm front passage and before the upper level low and associated cold front move through Saturday early evening. Temperatures will remain mild ahead of (and along with) the warm front on Saturday. Rain/snow levels may rise up to to 5500-6000' during the day on Saturday before dropping below 4000' Saturday night. The big question is how much it will continue to snow during the day on Saturday. With the arrival of the cold front Saturday afternoon/evening, snowfall rates will increase as snow levels drop. Winds are forecasted to decrease slightly and begin shifting out of the NW. Temperatures drop to more seasonal levels Saturday night into Sunday. 1-2" of total liquid precipitation is forecasted to impact the West Central mountains, translating to 1-2 feet of snow through Sunday. The bulk of the precipitation is forecasted from Friday night through Sunday morning. Mountain locations may experience lingering snow showers during the day on Sunday. Looking ahead, another quick moving and less significant Pacific trough will move inland on Monday and into our region Monday night. Rain/snow levels are forecasted to remain below valley floors, so we should expect all snow with this event. This storm is forecasted to remain colder, but with less moisture. Current forecasts indicate 2-4" in the mountains. This trough moves east on Tuesday and a drying trend looks to take shape over the long range forecast as another upper level ridge builds over the west.