|FRIDAY||SATURDAY||SUNDAY & MONDAY|
- Upper Elevations: MODERATE danger due to fresh windslab.
- Mid Elevations: LOW danger.
- Below treeline: LOW danger.
DANGER TREND: Steady as old slabs bond, yet new weakly connected slabs form.
AVALANCHE FORECASTER CONFIDENCE: Good
Wind Slab Avalanches - While the large amount of snow from the February 21-24 storm has been able to setup well, consistently moderate winds have been flagging the higher peaks and drifting snow into new slabs that are not bonded as well. These slabs are found near exposed ridgetops and faces that have been affected by the Northeast wind.
List of Avalanche Problems <here>
TRAVEL ADVISORY: Critical macro and micro-terrain selection will allow you to hunt down preserved snow or subjugate yourself to dangerous, breakable windslab that tries to eat your skis and throw you off balance. These slabs are and will continue to form on western slopes lee to the prominent northeast wind. Evaluate the firmness of these slabs, what lies beneath and their ability to support propagation. Human triggered wind slab avalanches are possible and unpredictable.
Lower down, exposed, wind scoured rain crust makes for constantly changing conditions.
Get down in the snow and evaluate the conditions, expose as few people as possible and have a backup plan. This also pertains to spreading out and giving other parties space. This is a large range with endless options, yet some groups have been seen cutting a slope that others are already on. Please mind the avalanche dangers this entails and give space considering the possibility that the slope could slide and catch many people.
Tuesday-Thursday: When skies cleared, widespread storm related loose avalanches were seen. Mostly on slopes steeper than 40 degrees. A few dry snow avalanches made the transition into the moist snow at lower elevations and ran down into alder. Several storm slab avalanches to size D2.5 were reported from the upper elevations (many steep northern aspect faces such as Catcher’s Mitt and Saphire) – that went during the storm.
Steep pockets of fresh windslab have been reported popping off near ridgelines where the north wind was moving storm snow. On Thursday, surface slabs were not bonding well, yet propagation was not supported. This could quickly change as the slabs get thicker and more rigid.
Avalanche sizing using the destructive scale <here>
Avalanche size estimation aid <here>.
SNOWPACK DISCUSSION: Many people were out slope testing the last few days with sunny skies. Moderate northeast winds quickly took the storm snow and loaded breakable wind slabs on top from Wednesday to Thursday. There are probably some preserved areas out there, but knowing terrain’s exposure to the wind is key to find them.
Thursday, upper elevation snow in Dimond’s Gunbarrels found newly formed wind slabs were not bonding well to underlying layers, but would break locally and not propagate. Deeper down, storm slab layers were evaluated and despite some weak interfaces at density breaks, they were bonding decently with hard ECTN test results on almost planar surfaces with slight steps.
The February 21-24 storm helped remove weak layering in our mid elevations and overall, sped up strengthening of our unseasonally shallow snowpack. In the upper elevations snowpack depth will now be on par with previous years, expect ~6 feet on the ground above 4000′.
Monitor the Feb.21-24 storm snow interface, any residual facets from early February, and any deeper crust/facet combos that may still be present.
Interior of MP 37 and further toward the Tonsina Glacier, the snowpack is known to be generally shallower and colder. Any reports from those areas are appreciated.
Check out the detailed observations <here>.
WEATHER: Expect clouds to move in Friday night with dusting of new snow Saturday, then clear again Sunday. Clouds will build again Monday for more precipitation to arrive Tuesday. 30 mph winds will shift and back down this afternoon and Saturday as weather moves in, then bump back up Sunday from the northeast. Highs will top freezing again in Valdez while in the 20’s near Thompson Pass.
Use links below to follow the up and coming weather.
Valdez – 2/27 AM
Thompson Pass – 2/26 AM
|Current Snow Depth||18″||43″|
|24 Hour Snow / Water Equiv.||0″ / 0″||
0″ / 0″
|Storm Snow / Water: 2/21-24||0″ / 0″||12″ / 3.6″|
|February Snow / Water Equiv.||5.6″ / 4.5″||37″ / 5″|
Total Winter Snowfall / Water Equiv.
|82″ / 15.1″||242″ / 26.3″|
|Snowload in Valdez||20.8 lbs / square foot|
|SNOW DEPTH & WATER SURVEY January 28, 2015||Depth||Snow Water Equivalent|
|Milepost 2.5 Valdez||31″||7.1″|
|Milepost 29 Worthington Flats||54″||11.6″|
|Milepost 37 Tsaina River bridge||40″||5.9″|
- NWS forecast for Northeast Prince William Sound <here>
- NOAA NWS spot forecast for Thompson Pass <here>
- Valdez Glacier UAF weather station at 6600 feet <data here> <map here>.
- Thompson Pass weather <here>.
- Further weather resources <here>
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).
- Upper Elevations: Alpine – Above 2,000 feet
- Mid Elevations: Treeline ~ 2,000 feet
- Lower Elevations: Below treeline – Below 2,000 feet
Run map of some of the forecast area <here> NEWS:
- Develop snow analysis skills at the Avalanche Level 2 March 6-9, 2015.
- Our region is “one of the snowiest places on earth” says the recent weather detective climatologist investigation into the Serendipity / Rendezvous snowfall record set in 1963 <here>.
Free smart phone avalanche forecasts at: http://www.
This forecast expires after 24 hours