Good morning. This is Wendy Wagner with the Chugach National Forest Avalanche Information Center on Friday, April 13th 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.
Mark your calendars and join us for the first annual “Corn Harvest” event: April 22nd from 4-7pm at motorized lot in Turnagain. Free food, beacon park, etc., all provided by the Friends of the CNFAIC as an Avalanche Center Awareness day – see you there!! (Remember, it’s not too late to become a Friends member and/or donate to help support the avalanche center operations).
The danger will rise to CONSIDERABLE today for wet avalanches and glide avalanches as we enter our third day of very warm, around-the-clock, temperatures. Natural avalanches are possible on all steep slopes, these could be large and run far into valley bottoms. There is also a MODERATE danger for a person to trigger a slab avalanche on northerly slopes above 2500ft, failing on buried surface hoar 10-20″ deep. A lot of avalanche potential exists out there right now and thoughtful, conservative travel in the backcountry is required to stay safe.
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. Yesterday, several glide avalanches released, three of which were on the sunny east side of Seattle Ridge. Several wet loose avalanches released as well, both human triggered and naturally. Some of these loose snow slides pulled out small slabs, a sign the pack is warm all the way through.
Primary Concern – Wet Avalanches and Glide Avalanches
With continued round-the-clock above freezing temperatures at the mid and upper elevations the snow is quickly saturating and becoming rotten and isCNFAIC Staffmal. Refreezes have been shallow and not strengthening the pack overnight. Today is the third day with these warm conditions and the old-timer rule of thumb says: “this is when things really start to fall apart”. The naturally occurring wet loose slides we have been seeing have not gouged very deep or triggered larger slabs – yet – but that could all change today and through the next week or more with larger avalanches possible. Staying out from under any steep slope or gully and avoiding tight drainages that form a ‘gauntlet’ with slide potential from both sides will be prudent – not only during the afternoon but during the earlier part of the day as well.
For anyone traveling out of the gauntlet of drainages and sticking to the ridgelines, cornices should be avoided. They are reaching the tipping point of failure with the above freezing temperatures – not to mention the risk of falling into a ‘cornice crevasse’ (where they are pulling away from the ground).
Secondary Concern – Persistent Slab
More and more upper elevation northerly slopes are losing their dry snow and becoming damp and crusty, however, the buried surface hoar remains. We continue to find this layer 10-20″ deep. These types of slabs are becoming harder to trigger but increase creep in the slab above, due to the warm temperatures, can help reactivate the layer.
It was anCNFAIC Staff gorgeous day in the backcounty yesterday – goggle tans are growing. Temperatures climbed further once again to near 40F on the ridgetops and the upper 40’s at sea level. Winds were light and variable.
Today, anCNFAIC Staff HOT day is on tap with temperatures reaching 50F below treeline and the mid 40’s above. Overnight, a bit of cloud cover has held in some heat and temperatures this morning are about 2-5F warmer than yesterday morning, mid 30’s around 1500ft and low 30’s on the ridges. Check out the graph below for Sunburst’s past week of steadily climbing temperatures. Winds are expected to remain calm to light, blowing ~5mph from the southeast. A change in weather is headed our way Saturday night as a warm system with rain to ~1500-2000ft moves in from the Gulf.
Sunburst weather station at 3800ft on Turnagain Pass:
CNFAIC Weather Page and the NWS forecast
Chris 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.