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Warning:
Use care and common sense when applying snow stability information, and consult other sources whenever possible. For example: consult the NWAC weather and avalanche forecasts, as well as ski area or highway department avalanche personnel during the winter or early spring, and talk with Forest Service or Park Service rangers during the later spring and summer. These observations provide an historical framework and general guideline to trends in snow pack stability. You are responsible for using and applying any information. Choice not Chance causes most avalanche accidents. Each report shown is a snapshot of the snowpack structure at a certain time and a certain place. It is a fact that the snow pack is highly variable, very dynamic, and snow structure and related stability can and do change within a few feet and often within a few hours, sometimes dramatically. |
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Snowpack Information Exchange - Search Reports
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NWAC photos
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| Reporter |
Region |
Activity |
Date |
Location |
| Alex Laudon |
South/Central OR |
Skiing |
2010-06-05 |
North Sister, East Face |
| This morning, June 5, I sighted a very large slab avalanche on the east face of North Sister while flying at 39,000ft. The crown was probably about 1000ft below the summit, so likely at about 9,000ft or so. The avalanche propagated across most of the face. Maybe R4D3. Likely wet slab. I took a photo and will post it if the avalanche is visible. Alex |
| Garth Ferber |
Central Cascades WA |
Skiing |
2010-04-09 |
Alpental |
| We got to accompany the patrol into the N b-c just before it was opened. There we triggered a couple small ~10" soft slabs on steep ~40+ deg slopes. Pit on a SE aspect off the top of Chair 2 at 5200' had 37" of generally homogeneous snow increasing from F to 4F to 1F with depth, on a 1/2" crust from early this week(?). A CT12Q2 at about 10" possibly associated with the temporary storm soft slab that we saw. No noticeable wind effects in area but large cornices on Denny-Chair ridge. A large natural had run off Chair Peak. Watch out if significant sun gets on all this new snow! |
| Jerry Casson |
Central Cascades WA |
Skiing |
2010-04-09 |
Stevens Pass: Heather Ridge |
| 18" of storm snow over crust. Skied E slope 30-35 deg at 5000' with no slab release. Snow near crust was moist. Skied N aspect at 5000' 35-38 deg and triggered two small 18" soft slabs, size 1. Snow on N side near crust was dry (poorer bond?). No other signs of instablility noted. Good skiing with little wind effect. |
| Garth Ferber |
Central Cascades WA |
Skiing |
2010-04-05 |
Moonlight Bowl, Skyline Ridge, Stevens Pass |
| A short work tour generally on SE to NE aspects 4-5000'. Mostly sunny through when we left about 2 pm. Sun effects the main concern these aspects and elevations. We saw small but increasing natural loose snow avalanches and some big snowballing on steep (40 deg+) slopes getting sun. Avi danger considerable? Surface snow conditions on sunny slopes not surprisingly becoming mashed potatoes by early afternoon. Upper snow pack in a pit on ENE aspect 5000' was basically damp increasing F snow with depth to late March crust at 32". N slopes likely still holding powder. |
| Jeremy Allyn |
South Cascades WA |
Skiing |
2010-04-04 |
Crystal Backcountry |
| A bit blustery out there today with moderate to strong ridge top winds from the E, SE through mid day, then swinging to more S and SW in our location. Toured through Bullion Basin to Pt 6479 north of Crown Point. West aspects getting loaded at the crest with some cracking and small cornice drops pulling out minor slabs. Much of Union Creek and all of Crown looked wind affected. There was a steady snow plum off Pickhandle all day (meet folks who skied in here who mentioned no signs of instability, as well as in Union Creek) Ski quality was excellent in the more protected NW bowl off 6479 - floaty and deep with ski pen 40-60 cms. No instabilities found on slopes up to 40 deg. Conditions deteriorated through the day with wind slabs stiffening, more cracking, and small pockets pulling out on lee terrain. I ski cut the true north aspect off the top of 6479 triggering a wind slab that propagated pretty far to the east and running almost full path to the basin below. SS/AS/R3/D2, 40-55cm crown. This slope was getting cross-loaded all day and is a frequent runner, so it wasn't too surprising. Descended back to the NW and climbed up East Peak for a final run. On lee loaded terrain snow stability went from good to fair, with pockets of poor by tonight. |
| Jerry Casson |
Central Cascades WA |
Skiing |
2010-04-01 |
Crystal Mountain South Back |
| Hasty pit on West aspect at 5800': 15cm dry f over 25cm 4f windslab on crust. mod-hard hand shear on crust Q2. Good skiing on 35-40 deg slopes NW-NE aspects with no signs of instability. Also, cut small cornice on north aspect with no slab release. Calm winds during the day and extensive 5mm surface hoar observed even on ridges and exposed slopes. Some sluffing and pinwheels on solar aspects later in the day. Overall, stability appeared moderate on most slopes. |
| Jeff Ward |
North Cascades WA |
Skiing |
2010-03-22 |
WA Pass, Silverstar, Hairpin and Tower |
| Overall the stability in this area has been improving over the last week. The main concern has, and continues to be, the bond of the "new" snow that fell on Thursday March 11th. This bond is much better on shaded slopes producing hard, sudden planar results on compression test. On solar aspects, which now seems to be anything other than due north, this snow sits on top of a sun crust and seems to be a little slower to bond. Test on these colder slopes are producing moderate, sudden planar results. We did have one skier triggered avalanche on a steep SE aspect at approximately 7,500' on this interface (size 2 running approximately 500 vertical feet with a crown depth of 30 cms). This avalanche ran through a shaded colder aspect and pulled out a slab of the same depth. Ski quality has been good on wind protected north aspects above 6,000'. We were also finding some good corn skiing on South and West aspects. |
| Jeff Ward |
North Cascades WA |
Skiing |
2010-03-22 |
Correction |
| Correction to post below. We are finding moderate compression results on solar aspects and hard results on north aspects. |
| Jeremy Allyn |
North Cascades WA |
Skiing |
2010-03-19 |
Boston Basin |
| Toured into Boston Basin and skied the Quien Sabe Glacier on Sahale today. No snow at the BB trailhead (3200ft). Took the Midas Creek approach which is getting boney at the bottom - ski or boot crampons are advised until treeline. Less new snow in the alpine than expected, with ski pen 0-20cms. Lots of wind post recent storm has created variable surfaces and everything is sitting on a hard supportable crust that is icy when it is exposed. The NW Face of Sahale had a recent wind slab pull out mid slope (D2+), 35-40deg, 1-2 ft crown. Across the basin a large climax avalanche had run on rocky unsupported terrain climbers right of the approach to Forbidden's east ridge - D3, SW asp, glide cracks above. Similar slopes threaten one of the approaches to Sharkfin Col. Limiting exposure to overhead hazard, especially unsupported steep slops receiving sun, seems warranted. Ski quality on the upper glacier was good, below was fair to poor. HS and overall snow structure in the alpine still seems like winter. Mid to low elevations it seems like June in this area. I chose to do a long descending traverse to Cascade Pass. Most west asp paths off Sahale Arm had run earlier in the day - all loose, D1-2 with a few entraining enough snow to destroy a car, the snow had clearing become wet but was refreezing fast. Skiing from Cascade Pass to the summer parking lot was smooth, supportable, and very icy in spots. No major avy activity in this area except for one climax in cliffy terrain low down on a west asp. The Cascade River Rd is in fantastic shape with parking at mile 21! |
| Garth Ferber |
Central Cascades WA |
Skiing |
2010-03-15 |
Vicinity of Crystal Lakes near Crystal Ski Area |
| A variety of aspects sampled on a ski tour. Quick pit obs generally for 6200-6400' elev range. A NE slope had 20" recent 4F snow over a crust, CT25 Q2 at 20" not remarkable. A NW slope had 27" recent 4F snow over thin crust over 1/2" of previous hoar frost now rounds, CT28 Q1.5 in the previous hoar so that layer no longer reactive this pit. A SSE slope had 20" of 4F M/W snow on a crust with ~1/4" of liquid water collecting on the crust. Snow conditions generally still decent good powder NW-NE slopes. Steep sun exposed slopes had plenty of good sized natural pinwheels to look out for but not quite to point of loose snow avalanches. Our party concluded avi danger mod-consid mainly steep slopes facing sun. Snow generally more consolidated and lower danger lower elevations. |
| Jeremy Allyn |
Central Cascades WA |
Skiing |
2010-03-14 |
Crystal Mtn and Snoqualmie Pass |
| Skied the north slope descent off Chair Peak today down to Snow Lake. Strong east wind was blowing any snow available for transport and maintaining/building thin surface slabs on the lee of most alpine features up high. We approached the NE Buttress of Chair via the upper notch - major heat was hitting that steep slope and the lack of a good up route made this ascent feel very spicy. Once off the ridge, ski quality on this north aspect stayed excellent and we had limited cracking, no skier triggers, and very little sluffing. Later we skied a few laps on occasionally very steep terrain off the NW asp above Snow Lake and had no movement in the snowpack - well settled, dry (almost bordering on moist) snow at this elevation (4-5K). Fewer avalanche observations than expected - a few 20cm slabs on steep, northerly aspects in unsupported terrain in the alpine, and an older deeper release off the high traverse below Chair's North Face. Minor snowballing on solar aspects with no loose slides observed.
I spent Saturday morning at Crystal Ski area and then went to the terrain between Hen Skin Lake and Bear Gap (5400-5900 north aspects). Ski pole pen in this zone was to the armpit. Boot pen was to the crotch. Probing felt a minor crust at 70cm and then nothing until 2 meters. Very deep with minimal layering. We had a moderately large whumpf on a 20deg slope above the lake. Skiing in small but steep features was great. I'd give any bigger north aspect features a wide berth here despite the warming and settlement. |
| Jeff Ward |
North Cascades WA |
Skiing |
2010-03-14 |
Baron Yurt, Near Harts Pass |
| We observed a widespread natural cycle on Thursday 3/11. These avalanches were on a variety of aspects but none of the avalanches stepped down to the deeper SH instabilities. We were still finding reactive SH layers down 30, 50 and 65 cms on shaded terrrain. Test results showed moderate, sudden planar and sudden collapse results on the cold aspects and resistant planar results on the storm snow new snow interface on solar aspects.
The storm snow is sitting on SH on some shaded and wind protected slopes, but on solar aspects it is sitting on a sun crust. We experience widespread whomphing, most pronounced on higher, wind exposed terrain.
The natural cycle ran on both sun crusts and NSF's, with the largest avalanches observed on wind loaded east aspects, up to size 2.5. Most of the avalanches that ran on the sun crusts did not propagate far and were limited to size 1.
Ski quality is good to excellent on most aspects with a little bit of wind effect on some slopes and minor sun effect on SW and W aspects below 6,500'.
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| Chris Cass |
South Cascades WA |
Skiing |
2010-03-13 |
Tatoosh Range |
| Observed abundant crowns (estimated average height of about 2 feet+) from recent natural slides mostly on NW through NE aspects along convex rolls above about 5,000-ft.
Fresh snowfall from late yesterday and overnight noted coating slide debris.
Small shooting cracks (about 6-8" deep, propagating about 6-to-12") noted in newest snowfall when stepping on a small test roll.
Dug pit on a wind-loaded NE aspect near 5,800-ft. About 3 feet of recent storm snow/wind-transported snow overlying a thin crust. Shovel compression test results: easy failure on newest snowfall (CT 8 at about 15 cm deep). Deeper relatively easy failure at 90 cm (CT 11), seemingly on a slightly faceted thin crust (also noted a clean 'popping' break on this layer).
Spooky snowpack as expected. Skied 2 good powder runs all on low angle terrain. |
| Josh |
North Cascades WA |
Skiing |
2010-03-12 |
Highway 20 corridor |
| Skied between 6500 and 4000' on southeast and east aspects. We encountered highly variable new snow depths in trees. Open areas received 21" or more near deposition zones. Above treeline, we observed significant 'whumping', cracking and were able to ski-cut several small soft slabs. We observed a natural avalnche (size 1.5) in lower-angled terrain that released mid-track in an opening within otherwise timbered slopes. Pits -- CT18Q2 running 2-3 cm above the old-new snow interface; the sliding surface is a pervasive ice crust at ~20" depth on more southern aspects, whereas more easterly aspects had a less well-developed ice layer, but more pockets of buried surface hoar along the new-old contact. Warming temps throughout the day helped the snow below ~5800 feet stabilize, whereas the alpine remained colder and more sensitive. By late afternoon, ridgetop winds were moderate and were moving a significant amount of snow from the NW. |
| Jeff Ward |
Central Cascades WA |
Skiing |
2010-03-09 |
Sherpa Glacier, Mt. Stuart |
| Ski quality is still good above 4,500' on shaded terrain. Sun exposed terrain has a very solid crust that did not soften on Tuesday (3/9). Above 7,000' there has been enough wind to make the skiing variable but generally good. We found some small pockets of wind slab but no other signs of current instability. There was evidence of a very large size 3.5 avalanche that came down the glacier, but with very little snow during the past few weeks it was hard to tell how old it was. The crown was at approximately 7,500' on steep NE facing terrain and ran to 5,500', cleaning out all of the west side of the glacier down to rock and water ice on the steepest breakover. |
| Jeremy Allyn |
North Cascades WA |
Skiing |
2010-03-07 |
Baker ski area to Mt Baker |
| A great day out on a traverse from Baker ski area to Coleman Pinnacle, then down and up the Rainbow Glacier and up the majority of the Park Glacier on Mt Baker. Light to moderate winds from the south and cool temps kept the snow quality good at/above 6K - especially on glaciated terrain. Below that, anything feeling the sun became moist by mid day and then locked up tight by day's end. Solar, temperature, and wind affected slopes had a variety of surfaces, much of which were skiable and supportable, but potentially hazardous in a fall. Steep west aspects had deeper foot and ski penetrations as one would expect this time of year. True north aspects held very good quality skiing with ski pen between 15-20cms. Very little recent/old avalanche observations observed with the exception of - south aspects of Table Mtn had the usual loose slides with every path producing to size D2-2.5 (why do people continue to traverse high across this slope?). We saw two thicker windslabs (D2 to 45-50cms) that looked recent - one cornice induced off a steep NE asp at 5500ft on Ptarmigan with lots of propagation, and one on the Rainbow Gl, 6K, NE asp, on a steep convexity. Bed surfaces are a pencil hard crust. Above this, little to no activity. Other observations - surface hoar growth minimal to non-existent, cornices are huge, sagging, and starting to fall - with this season's low snowpack, alpine features are much less filled in, more convoluted, and travel on glaciers demands the use of a rope earlier than normal - with the return of winter this next week, there will be lots of crusts and loose faceted snow for storm cycle slabs to run on. The amount of wind during these next snowfalls will be super key in my decision making. Have fun out there!
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