Warm temperatures and Low pressure in the Gulf of Alaska will bring rain to ~2000’ today and snow showers above. In the alpine Easterly winds 20-35mph will form isolated wind slabs on leeward terrain features. The size of these wind slabs will depend on how much snow falls. Areas closer to the coast (Portage, Girdwood and North end of Turnagain Pass) could see 4-6” of snow by early evening. Interior areas will see less precipitation. New snow will be falling on a variety of slick surfaces and bonding may be poor. Surfaces include firm crusts on W-S-E facing aspects in the alpine and surface hoar and near surface facets on shaded Northern aspects. Look for blowing snow, shooting cracking – steep leeward terrain features will be the most suspect for triggering a wind slab. Keep in mind its spring-time and be ready for wet loose activity on solar aspects if the sun comes out.
WET LOOSE: In the lower elevations below 2000’ where a stout crust has formed rain will start to soften this surface crust. If this crust starts to deteriorate and become wet and unsupportable, triggering a wet loose avalanche in steeper terrain will be possible.
CORNICES: Cornices remain very large along some ridgelines in the alpine. Give them a wide berth and avoid travel directly below them.
South of Turnagain in Summit Lake and areas in the interior Kenai Peninsula have a variety of old weak layers within the snowpack. The last observed slab avalanche was 10 days ago on the West face of Butch. A stout crust has formed on all elevations below 3000’ and on solar aspects in the alpine. Triggering a persistent slab 2-3’ deep is becoming an outlier at this time, but worth noting if headed to Summit Lake. Be aware of a variety of avalanche conditions ranging from small isolated wind slabs to wet loose. This area is more likely to see sun in the afternoon. Otherwise conditions are very similar to Turnagain.
Wind slabs will be forming on a variety of surfaces. Surface hoar has been seen on North aspect (top photo) and stout crusts (bottom photo) on all aspects below 3000′ and W-S-E aspects in the alpine.
Glide cracks have been opening and releasing across our region over the last two weeks. This is the entire snowpack gliding downhill and spontaneously releasing. So far all of this activity has occurred on East, South, and West facing slopes below 3000’. This week Turnagain Pass has been the most active. Glide avalanches are not associated with a human trigger and release without warning. These avalanches, even small ones, are extremely destructive. The best way to manage this problem is avoidance. Identify existing cracks and plan your route to avoid being under a glide. Many cracks are opening in popular terrain and may require an unusual route to avoid their runout. This is a case of ‘don’t be caught in the wrong place at the wrong time’.
Recent glide avalanches and lots of glide cracks on popular terrain in Turnagain. From left to right – Magnum, Corn Biscuit, and Lipps – SW aspects
Yesterday: Skies were sunny to partly cloudy. Temperatures reached the mid 40Fs to low 50Fs at sea level. Ridgetop temps were in the upper 20Fs during the day and dropped to the low-20Fs overnight. Ridgtop winds were light from the Northeast increasing into the 20s mph overnight. Light rain starting falling this morning with 0.1″ recorded at Turnagain Pass. Rainline is estimated around 1800′.
Today: Snow showers are expected above 2000′ 4-6″ of snow possible. Rain is expected in the lower elevations with up to 0.5″ of rain. Areas further from the coast will see less precip today and a chance for broken skies in the afternoon. Easterly ridge top winds are expected to be 20-35mph. Temperatures at sea level will be in the mid-40Fs and temps along ridgetops may reach the low-30Fs.
Tomorrow: Scattered snow and rain showers are expected on Sunday. Easterly Ridgetop winds will decrease to 5-15mph. Light precipitation is expected with rain below 2500′ and a few inches of snow possible in the upper elevations. Temperatures at sea level will be in the 40Fs to low 50Fs. Ridge top temps are expected to range from mid-20s to low-30Fs.
**SNOTEL data for Center Ridge and Summit was unavailable after 5am (reads 4am due to daylight savings.) 24-hour precip for Turnagain was recorded on the Turnagain DOT RWIS weather station.
|Temp Avg (F)||Snow (in)||Water (in)||Snow Depth (in)|
|Center Ridge (1880′)||35||0||**0.1||65|
|Summit Lake (1400′)||35||0||0||20|
|Alyeska Mid (1700′)||36||0||.01||57|
|Temp Avg (F)||Wind Dir||Wind Avg (mph)||Wind Gust (mph)|
|Seattle Ridge (2400′)||31||ESE||3||11|