Good morning. This is Chris Engelhardt with the Chugach National Forest Avalanche Information Center on Saturday, April 14th at 7am. This will serve as a general backcountry avalanche advisory issued for Turnagain Arm with Turnagain Pass as the core advisory area (this advisory does not apply to highways, railroads, or operating ski areas).
This will be our final week of daily avalanche advisories, ending Sunday. We will be issuing one mid-week update on Wednesday and one weekend update on Saturday mornings through April 30th. Checking the photos/observations page regularly will be the best place to find up to date information for the last two weeks of April.
Twentymile drainage is now closed to motorized use due to melt out and break up.
The danger will remain at CONSIDERABLE today for wet avalanches and glide avalanches. Long running natural avalanches have been observed on all aspects receiving lots of solar radiation. Avalanches on steep slopes have been reaching valley bottoms. There also continues to be a MODERATE danger for triggering persistent shallow slab avalanches resting on surface hoar 10-20” deep on northerly slopes above 2500ft.
Although we got some cooler temps last night ~27F on Sunburst with some increasing winds to help refreeze and cool the surface of the snowpack, wet avalanches still remain the biggest concern. Throughout the entire forecast zone this week there has been a large cycle of wet glide releases, wet point releases, small slabs and significant amounts of entrained snow sliding down the mountains. As Wendy stated very well yesterday, “It’s simple: the mountains are heating up and the snowpack is beginning to fall apart – it seems the springtime ‘shed cycle’ is arriving – mid elevations (1500ft – 3000ft) are seeing the greatest effects.” Check out these pictures of all the avalanche activity this week
Primary Concern – Wet Avalanches/Glide Avalanches and Failing Cornices
A lot of the snowpack is becoming or has reached isCNFAIC Staffmal conditions Even with potentially better refreezing during future nights the sunny aspects are losing strength and stability rapidly. Basically, the best thing to do is to severely limit your travel upon or underneath them. The glides seem to be releasing predominantly in the later afternoon between 4pm and 6pm. On Thursday, I observed a buckling glide crack with scalloping snow on Seattle ridge at about 430pm from the motorized lot on Turnagain Pass. When Wendy stopped by around 6pm or so, the glide had released and it nearly hit the snowmachine uptrack. Similar observations have been reported around Girdwood.
Be especially cognizant of steep slopes and tight drainages that form a ‘gauntlet’ with slide potential from both sides
Secondary Concern – Persistent Slab
Every time I dig on a north aspect above 2500ft or so, I still find the buried surface hoar. The layer resides 10-20” deep and is reactive and shears with high quality. It is very tricky, being very reactive to a skier’s weight in some places and totally non-reactive on CNFAIC Staff slopes. It’s safe to say that if you ski a higher north aspect, careful evaluation and forethought is needed before you drop a big line. The surface hoar still lives on after nearly a month of tracking it.
It was the sixth day in a row of bright, sunny, weather yesterday. Temperatures were slightly lower ~40F all around Friday then Thursday’s 50F+ cooker, but still provided for hot and sweaty conditions. Winds continued to remain very calm.
Last night temperatures dropped down to around 27F at 3800Ft on Sunburst and winds started picking up to 20mph early this morning from the east. This was a good change in respect to helping lock up the surface of the snowpack. Temperatures for Monday through Wednesday night were just at or above freezing which greatly sped up the cycle of wet avalanches.
Today, winds and clouds are supposed to increase throughout the day with warm temperatures in the 40’s at 1000ft. Winds will continue to rise and could reach into the 50mph range by this evening accompanied by a 70% chance of precipitation. Snow levels should be above 1100ft and upper elevations are expected to see small accumulations.
This will be my last forecast for the season, thanks to all those that utilize and support the CNFAIC!! Cheers to a great winter and a truly great team!!
CNFAIC Weather Page and the NWS forecast
Wendy will issue the next advisory tomorrow morning. If you get out in the backcountry we want to know what you are seeing. Please send us your observations using the button at the top of this page or give us a call at 754-2369. Thanks and have a great day.