Dangerous avalanche conditions. Careful snowpack evaluation, cautious routefinding and conservative decision-making essential. Step out slowing to get a feel for how the storm changed the mountain game.
Dr. Cullen is giving a presentation on Backcountry Injuries this afternoon Sunday April 2 at the Fat Mermaid 4-6pm.
Friday April 14: VAC Full Moon FUNraiser with Acoustic Avalanche @ Tsaina Lodge
Above 2,500ft Considerable
1,800 to 2,500ft Moderate
Below 1,800ft Low
Degrees of Avalanche Danger ?
|SUNDAY||MONDAY||TUESDAY & WEDNESDAY|
Likelihood (Human Triggered): Likely
Size: Small – Large
Danger Trend: Decreasing
Forecaster Confidence: Fair
Elevation: Above 2500′
Aspect: more likely on northerly aspects
Terrain: unsupported steep slopes with thin coverage
Distribution: Isolated where windslab exists over facets/depth hoar
Likelihood (Human Triggered): Possible
Size: Small – Large
Danger Trend: Steady
Forecaster Confidence: Poor
AVALANCHE PROBLEM SCALE DESCRIPTORS:
Sensitivity: Non-reactive, Stubborn, Responsive, Touchy
Distribution: Isolated, Specific, Widespread
Likelihood: Unlikely, Possible, Likely, Nearly Certain
Size: Small, Large, Very Large (size scale <here>)
Danger Trend: Increasing, Steady, Decreasing
Forecaster Confidence: Good, Fair, Poor
AVALANCHE PROBLEM TOOLBOX <here>
Continental (Interior) Specific:
Snow up high and rain down low added weight and stress. Human triggered avalanches expected on steep slopes where thin areas serve as trigger points for storm, wind, and persistent problems.
On Thompson Pass (and likely elsewhere), a couple new melt-freeze crusts have formed up to ~2600′. A thinner (1″, 4F) crust near the surface sandwiched several inches of soft snow between a thicker (~3″; 1F+) melt freeze crust almost a foot down. Hand shear testing demonstrated poor crust bonding with very easy results when isolating columns. Propagation was supported at ~2400′ on Thompson Pass on Thursday, when a large collapse occurred of the new storm snow (thick crust and everything above) resting on buried facets below. In areas where the facets did not reside, bonding of new snow was good.
Evaluation of the snowpack down near Cracked Ice Friday showed much better bonding and no propagation. See recent observation.
Higher elevations exposed to wind will likely have fresh wind slab formation that has been bonding well to underlying snow thus far (Q3 w/ steps), unless it is sitting on a persistently weak grain (old facets). A small collapse of newly blown in shallow slab on rocks occurred at ~3000′ on Thompson Pass on a southerly aspect.
The further you get from the pass the new snow levels dramatically decrease. This has been a trend all season, with most of our storms hammering the maritime zone, while leaving the intermountain/continental zones high and dry. Tuesday, heavy snowfall (1”/hour) was falling at 46 Mile slowing decreasing into the interior with only a dusting in Kenny Lake.
Given the poor structure in the interior, you are most likely to trigger a storm slab with a chance of it stepping down to a persistent slab. The interior region, and even some parts of the intermountain region, have a persistent weak layer that has the potential to release the entire season’s snow pack in a very large, catastrophic avalanche. This persistent weak layer is going to be put to the test with the adding up snow load over the next week.
This may be what happened in the large chute on the east face of Mt. Tiekel. It was reported to have avalanched (D2.5) March 28th with in the last 24 hours with dirt in the debris.
Find more photos and observations at the bottom of the page. Sharing your observations creates an informed community.
Recent Avalanche Activity
Continental (Interior) Specific:
Poor visibility have limited observations during the storm. Today’s clearing will allow for a look around. Please share any avalanche activity you see.
- March 31: skier triggered size D2 avalanche at 3500′ North aspect. 40-60cm storm slab failed on buried near surface facets with a old windslab as the bed surface. A possible sympathetic released lower on the same slope, with a crown depth 60-100cm, harder slab.
- March 28: The large chute on the east face of Mt. Tiekel release a D2.5 avalanche which dusted the highway
- March 25: reports of upper elevation (>4500′ elevation) human triggered windslab to size D1.5 to a foot thick releasing off steep slopes, mostly in the Maritime to Intermountain areas
- March 24: significant collapses, as large as whole basins whumphing, in areas on the northerly and easterly outreaches of our Inter-mountain zone, and into the Continental zone.
See Maritime Zone for updated weather.
Additional Info & Media
- Northeast Prince William Sound NWS Weather Forecast
- Middleton Island Radar for Valdez area
- GOES Alaska water vapor satellite loop
- NOAA NWS Recreational spot forecast for Thompson Pass
- Thompson Pass MP 25.7 RWIS weather station 2740′ (Mesowest)
- Valdez Marine Ferry Terminal weather station sea level
- Nicks Happy Valley above MP 30 weather station 4200′ (scroll to Nicks Valley)
- Upper Tsaina River Snotel near MP 32 1750′
- Sugarloaf Snotel 551′
- Above Valdez Glacier Cryosphere program weather station 6600′ <map here>
- Valdez Blueberry Weather Plot observations (scroll to bottom: Valdez City)
- More Mountain Weather resources for Alaska
- GFS 16 Day Model for Valdez
- Model Average Meteogram for Valdez
SNOW CLIMATE ZONES:
- Maritime (Coastal) – from the Port of Valdez to Thompson Pass, all waters flowing into Valdez Arm and everything south of Marshall Pass.
- Inter-mountain (Transitional) – between Thompson Pass and Rendezvous Lodge.
- Continental (Interior) – the dry north side of the Chugach (north of 46 Mile, including the Tonsina River).
Photo of Thompson Pass
Interactive Map of Valdez Forecast Areas w/ Many Resource Layers (Trevor Grams)
NEWS: Our region is “one of the snowiest places on earth” – Serendipity / Rendezvous snowfall record set in 1963 <here>.
Free smart phone avalanche forecasts at: http://www.