This is an archived advisory related to an avalanche fatality March 6. There was no advisory in effect on Mar 6, this was the most recent one. A general statement was issued covering a wider area for Mar 6 and that follows. The problem layer in the avalanche was listed as forming around Feb 1 but there is no mention of that below. Both the expired advisory and the later general statement were prepared by Nick Burks, who died in the Mar 6 avalanche. Wallowa Avalanche Center (NE Oregon) Backcountry Avalanche Forecast Elkhorns Issued: Sunday, March 3, 2024 - 7:00AM Expires: Monday, March 4, 2024 - 7:00AM Author: Nick Burks THE BOTTOM LINE Significant accumulations of new snow accompanied by winds from the south have built wind slabs on NW-E facing slopes near and above the treeline. Heavy snowfall has created sensitive storm slabs near the treeline. You will likely trigger one of these avalanches if you venture onto terrain steeper than 30 degrees. Avoiding avalanche terrain is recommended. Avalanche Forecast Avalanche Danger for Sunday, March 3, 2024 All elevations - Considerable Avalanche Problems (2) Problem #1: Wind Slab Aspect/Elevation: NW through E near and above treeline Likelihood: Very Likely Size: Small (D1) to Large (D2) Southerly winds have built wind slabs near and below ridgelines. Wind slabs, 2-3' thick, are likely to be found on slopes facing NW-N-E. The effects of recent wind-loading may present as smooth hard pillows lurking below ridgelines or sub-ridges mid-slope, as cornices hanging imposingly over steep slopes, or as stiff punchy windboard. Look for and avoid steep slopes (>30 degrees) with large overhanging cornices, smooth textured wind pillows, and/or deposition zones with convex rollovers. You may find reactive wind slabs at lower elevations. Be cautious around leeward terrain features mid-slope like sub-ridges and gullies. Problem #2: Storm Slab Aspect/Elevation: All aspects near and above treeline Likelihood: Possible Size: Small (D1) to Large (D2) The Elkhorn Mountains have received 2+' of new snow since Monday. This significant load puts a lot of stress on the snowpack, which, in turn, creates a potential unstable storm slab problem. Near treeline and above human-triggered avalanches are likely. Avoid potential trigger points like convex rollovers, rocky areas or cliffbands, and steep areas beneath cornices. On Thursday, forecaster Micheal Hatch found an upside down snowpack on the west shoulder of Gunsight Mountain. The top 8" was denser than the 10" below. This inverted snowpack was likely formed by the strong winds and the warmer temperatures overnight. That top 8" was very touchy and reactive in snowpack tests. On a north aspect at 7800', he did find a layer of buried surface hoar down about 2 feet. Slopes that may harbor buried surface hoar are W-N-E aspects near treeline and above. Surface hoar usually forms on slopes more protected from the wind and free of dense trees. We have at least one report of a recent human-triggered avalanche off of Poster Ridge in the backcountry south of Anthony Lakes ski area. Forecast Discussion The storm that began Monday 2/26 has deposited 1-3' of new snow across our forecast zones. This storm has been marked by strong winds out of the SE, S, and SW. These winds have moved a lot of snow and built wind slabs on NW through E-facing slopes. Many of these slabs formed on top of a melt-freeze crust. This crust would be an excellent sliding surface for the heavy slab that sits on top of it, all it needs is a trigger. That trigger could be you or the additional weight of the new snow. Avoid traveling on or below wind-loaded slopes. On slopes not affected by the wind- storm slabs and dry loose avalanches lurk. Reports (3/1) from sledders in the Southern Wallowas indicate heavy sluffing on N-E facing steep slopes. In the Northern Wallowas, ski guides report (3/1) lots of snow moving below the treeline, with storm slabs and dry loose avalanches running on steep unsupported slopes. These observations illuminate a Red Flag, recent avalanches, and tell us we should avoid avalanche terrain until the snow has had time to settle. In the Northern Wallowas, there are reports of collapsing and recent avalanches. One avalanche reported by a long-time backcountry skier had a crown that wrapped onto Phat Ridge in the Wing Ridge area. Phat Ridge is a common up track. In the Western Wallowas (part of the Southern Wallowas forecast zone) ski guides intentionally triggered two small avalanches yesterday (3/2). Both avalanches were on north-facing slopes between 7300 and 7600 (near treeline). Surface Hoar- When this storm began there was well-developed surface hoar everywhere. This 2/26 layer of surface hoar has been found in the Elkhorns and in the Southern Wallowas. Propagating results were observed in Extended Column Tests on this layer yesterday 50cm down. The Valentine's Day surface hoar was also found yesterday in the Southern Wallowas. While the distribution of these layers is patchy, it does exist and is reactive. This creates uncertainty, you should dig down to look for these layers of surface hoar. If you don't have those snowpack analysis skills you should avoid avalanche terrain where it might live (sheltered northerly slopes steeper than 30 degrees). Graupel- This storm has brought a lot of graupel with it. Graupel is small round BB's of snow, it can look like hail. As you can imagine, a layer of BB's isn't very stable. Storm Slabs were reported failing yesterday on a layer of buried graupel 30cm down. These layers of graupel are another source of uncertainty. When our uncertainty increases, our margins of safety should increase too. Make conservative terrain choices and dig down into the snow to look for layers of graupel which could be the weak layer for an avalanche. Weather Forecast Yesterday was partly cloudy with some sun breaks. There were periods of light snow dropping 2-4" throughout the day. While it felt warm when the sun came out and temperatures rose, the snow continued to fall even in the valley bottoms. Winds eased up and were generally light with some moderate gusts out of the SE, S and SW. Today will start partly cloudy. The clouds will increase and snow is forecasted to start midmorning. Light showery snow should deliver 1-3" across the forecast area. Snow levels start near sea level and rise throughout the day to 1000' by this evening. Winds will be light out of the SW and WSW with moderate gusts. General Avalanche Information Issued: Monday, March 4, 2024 - 7:00AM Expires: Thursday, March 7, 2024 - 7:00AM Author: Nick Burks THE BOTTOM LINE 2-3' of new snow has fallen over the last week, much of this snow fell with moderate winds out of the South. Near and above treeline, storm slabs and wind slabs need time to settle and bond. Carefully evaluate any slope over 30 degrees before committing to riding it. Avalanche Forecast Forecast Discussion A storm beginning on Monday (2/26), has brought consistent snowfall to the forecast area. The first 4 days of this storm brought moderate to strong winds out of the SE, S and SW. These winds loaded snow onto E through NW slopes. During this storm cycle, natural and human-triggered avalanches have occurred. The past three days winds have decreased and nice low-density snow has continued to fall. This new snow has obscured some signs of wind loading and wind slabs- we must remember that they are still there. The snowfall is forecasted to continue through Tuesday afternoon. Wednesday looks to be a cool, sunny day with light winds. A prime day to get out into the mountains and perhaps approach some larger objectives. Use caution and carefully evaluate the snowpack, terrain, and consequences of taking a ride before committing to consequential terrain. Besides wind and storm slabs, we have a few layers of unstable snow buried in the snow to be cautious of. When the Storm began well developed surface hoar was everywhere. Slopes facing east, south, and west had a melt-freeze crust on them. During the storm, several layers of graupel were deposited. Please read more about these layers below. Surface Hoar- The layer of surface hoar buried on 2/26 has been found in the Elkhorns, Southern Wallowas and Northern Wallowas. Propagating results were observed in Extended Column Tests on this layer on Saturday (3/2) 50cm down. Sunday (3/3) I found buried surface hoar mixed with graupel sitting on top of the 2/26 crust at 7500' on a NE facing slope in the Northern Wallowas down 80cm. This layer failed in a Compression Test and propagated in an Extended Column Test in extra innings (more than 30 hard whacks from the shoulder). While the distribution of these layers is patchy, it does exist and is reactive. Before riding terrain over 30 degrees with steep convexities it is advised to dig down to look for this layer. A layer of surface hoar buried on Valentine's Day was also found in the Southern Wallowas (3/2). Graupel- This storm has brought a lot of graupel with it. Graupel is small round BB's of snow, it can look like hail. As you can imagine, a layer of BB's isn't very stable. Storm Slabs were reported failing Saturday (3/2) on a layer of buried graupel 30cm down. These layers of graupel are another source of uncertainty. When our uncertainty increases, our margins of safety should increase too. Make conservative terrain choices and dig down into the snow to look for layers of graupel which could be the weak layer for an avalanche. In summary: The riding is really good! A major storm cycle is in the process of ending. The weather is going to clear and call us to step out and step up. New snow avalanche problems are present. There are buried weak layers in the snowpack. Use caution and careful evaluation before getting on steep terrain. Weather Forecast Yesterday the skies were mostly cloudy with occasional light snow showers. Temperatures were in the mid-teens except in the Blues where they reached the mid-twenties. Winds were light to moderate out of the SE, S, and SW. Overnight another round of snow showed up delivering 2-4" of cold snow. Today will be very similar to the past few days. Overcast to mostly cloudy skies. Light snowfall brings 2-4" during the daylight hours. Snow levels stay at 1000'. Winds will be light with moderate gusts switching between W and WSW.