Over the last two weeks we’ve seen some big storms and some impressive avalanche activity. Yesterday was similar, except it arrived with very warm temperatures and heavy rain to ridgetops. In Turnagain Pass .9” of rain was recorded and in Girdwood (Alyeska midway) 2.74” of rain was recorded. This is a lot of water in short period of time, especially in Girdwood and the Northern side of Turnagain Pass. We estimate rain/snow line fluctuated between ~3000’and ~2500’. Ridge top winds were in the 40-60’s mph with a gust to 101mph on Sunburst. Numerous natural wet slabs were observed on Seattle Ridge by the afternoon and Portage Valley reached 50F. Temperatures have remained above freezing overnight at Seattle Ridge weather station (2400’) and overcast skies are keeping the snowpack insulated. This means the snow is still wet and saturated in the mid and lower elevations. Wet slab avalanches are not something to mess with. These are unpredictable and unsurvivable if someone was to get caught. Until temperatures drop below freezing and the snowpack has a chance to drain, we recommend avoiding avalanche terrain. To compound this situation another storm is expected to arrive late afternoon with another round of heavy rain and strong winds overnight.
In the alpine, where 1-3’ of snow fell yesterday, storm slabs are expected to be unstable. Strong Easterly winds 25-40mph will continue throughout the day and will be adding stress to the upper elevation snow pack. Natural and human triggered storms slabs 2-3′ are likely where the snow is dry.
South of Turnagain in the Summit Lake and areas in the interior Kenai Peninsula have a very poor snow structure with variety of old weak layers (facets and buried surface hoar) in the mid and base of the snowpack. Not as much precipitation fell overnight, but temperatures remain very warm. Winds and warm temperatures will be adding stress to the snowpack today and triggering a dangerous slab avalanche 1-3’ thick remains likely in the alpine. Triggering a wet avalanche is likely below treeline.
Natural wet slab avalanches on Seattle Ridge near the motorized lot yesterday afternoon.
Natural wet slab avalanche entraining snow to the ground on Seattle Ridge, SE aspect, near Bertha Creek.
Several glide cracks have released in the last few days including one on Seattle Ridge yesterday. In Girdwood two were observed yesterday on Raggedtop and Penguin Ridge. Similar to wet slab avalanches these are very unpredictable and impossible to manage.
Glide avalanche on Seattle Ridge released yesterday, just North of the uptrack.
Yesterday: Temperatures increased into the 40Fs at sea level and mid 30Fs at ridgetops. Portage Valley hit 50F yesterday morning. Heavy rain fell below 3000′ most of the day. Turnagain pass recorded .9 € of rain. Alyeska midway recorded 2.76 € or rain and Bear Valley in Portage recorded 2.02 € of rain. Ridgetop winds were Easterly, 40-60 mph with gusts in the 70-80s. Overnight temperatures remained above freezing at 2400′ at Seattle Ridge weather Station with obscured skies.
Today: Rain will continue throughout the day and become heavy rain by this evening as another storm tracks through our region. Today 0.3 € rain is expected with 1 € of rain overnight. Temperature will remain in the 40Fs at sea level, mid 30Fs in the mid elevations. Rain/snow may drop a little by this evening to ~2000′. Strong Easterly ridgetop winds 30-40mph will continue today bumping into the 50-60’s by this evening.
Tomorrow: Skies will remain obscured, and rain is expected to continue through the day. Above freezing temperatures will continue in the lower and mid elevations. Strong winds will start to diminish by Saturday morning.
*Seattle Ridge weather station anemometer has been experiencing some issues and may be under reporting wind data.
|Temp Avg (F)||Snow (in)||Water (in)||Snow Depth (in)|
|Center Ridge (1880′)||39||rain||0.9||78|
|Summit Lake (1400′)||41||rain||0.4||28|
|Alyeska Mid (1700′)||37||rain||2.74||73|
|Temp Avg (F)||Wind Dir||Wind Avg (mph)||Wind Gust (mph)|
|Seattle Ridge (2400′)||35||*SE||*20||*50|