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Avalanche Advisory

Turnagain Area Avalanche Advisory
Friday, March 22nd 2019 7:00 am by Heather Thamm
ARCHIVED ADVISORY - All advisories expire after 24 hours from the posting date/time.
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The Bottom Line

The avalanche danger will remain HIGH today due to heavy rain, above freezing temperatures and strong wind in Turnagain Pass, Girdwood, and Portage. Natural wet slab avalanches are likely below 3000'. In the alpine natural storm slabs 2-3+ feet deep are also likely today and have the potential to step down into a very deep and dangerous avalanche. Travel in avalanche terrain is not recommended.


PORTAGE VALLEY: Very large avalanches have been observed in Portage over the week and are expected to continue today. Travel in avalanche terrain including runout zones, like Byron Glacier Trail is not recommended.

SUMMIT LAKE (& INTERIOR EASTERN KENAI MTS): Large avalanches have the potential to release in old buried weak layers. Natural and human triggered avalanches remain likely with the added stress of rain, new snow and wind loading today. Avoiding avalanche terrain - slopes steeper than 30 degrees and all runout zones is recommended.

SEWARD/LOST LAKE: Similar to Turnagain - warm temperatures, rain and strong winds will impact this zone today. Wet slab avalanches are likely in the mid and lower elevations and storm slabs likely in the alpine. Travel in avalanche terrain is not recommended.


 Show the Complete North American Avalanche Danger Scale
4 High Alpine / Above 2,500' Travel Advice: Very dangerous avalanche conditions. Travel in avalanche terrain not recommended.
4 High Treeline / 1,000'-2,500' Travel Advice: Very dangerous avalanche conditions. Travel in avalanche terrain not recommended.
4 High Below Treeline / Below 1,000' Travel Advice: Very dangerous avalanche conditions. Travel in avalanche terrain not recommended.
Special Announcement

There will be intermittent traffic delays Friday, March 22, 2019 on the Seward Highway and Portage Glacier Highway for Avalanche Hazard Reduction work. This includes mileposts 88 to 85 on the Seward Highway, South of Girdwood and milepost 5 and Bear Valley on the Portage Glacier Highway. Motorists should expect delays of up to 45 minutes between 10:00 AM and 3:00 PM today.

Yesterday, on March 21, 1999 a massive avalanche took the lives of 6 snowmachiners on Seattle Ridge. Our deepest condolences are with the family and friends of those lost that day. In commemoration, CNFAIC forecasters and Friends of CNFAIC, will be at the Turnagain Pass motorized lot on Saturday, March 23rd, from 12pm - 2pm. We welcome any and all to stop by for a hot dog, say hi, chat about the current avalanche conditions, and test your avalanche rescue gear. We'll have a few beacons buried so you can practice your skills. 

Feeling sporty? Want to support avalanche education in Alaska? Head to the Alaska Avalanche School Ski-Mo (uphill/downhill) fundraiser race at Arctic Valley on Sunday, March 24th at 1pm. For more information click HERE. Great fun! Great cause! 


Avalanche Problem 1

Wet Slab

Almost Certain
Very Likely
Likely
Possible
Unlikely

Chance

Historic
Very Large
Large
Small

Size

Heavy rain and strong winds will remain the primary weather factors initiating a wet avalanche cycle below 2500’ today. Numerous large and very large wet slab avalanches have been releasing over the last two days and will continue through today. In some areas wet slab avalanches are taking the entire winter snowpack and leaving behind impressive piles of dirty debris. In other places, drier avalanches are releasing in the alpine and taking out the entire avalanche path - like Lipps West face seen yesterday. Many popular slopes are still intact, hanging in balance and may avalanche at any time. Today’s message is simple - stay well away from any avalanche terrain including runout zones! Wet slab avalanches are unpredictable and unsurvivable if someone was to get caught. 

Storm Slabs:
Today expect rain/snow line to fluctuate between 2000’ and 2500’. In the alpine, above 2500’ where 2-3+ feet of new snow has fallen over the last few day storm slabs are expected to be unstable. Strong Easterly winds 30-40mph and up to another 1-2’ of snow will be adding stress to the upper elevation snow pack. Natural storms slabs are likely where the snow is dry and could initiate very large avalanche in an older deeper layer of the snowpack.

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. Warm temps and rain have saturated the snowpack below 2000’ and numerous large wet slab and dry slab avalanches have released. Today up to .5” of rain is forecasted below 2500’ in the interior areas of the Kenai and with it more natural avalanche activity.

Natural avalanche on Lipps seen yesterday morning 3/21/19  

 

Many wet slab avalanches have been releasing on Seattle Ridge (SE aspect) over the last few days, but many slopes still remain intact and could release at any time. 

 

Dirty wet debris seen on the SW facing terrain of Goat Mt shoulder in Girdwood Valley. This avalanche released sometime early Thursday morning (3/21/18). Photo courtesy of G. Creighton.

 


Additional Concern

Glide Avalanches

In addition to wet slab avalanches glide cracks have been releasing over the last few days including one on Seattle Ridge and many in Girdwood Valley. Similar to wet slab avalanches these are very unpredictable and impossible to manage and another reason to avoid avalanche terrain today. 

 

 

                        New glide avalanche on a South aspect of Goat Mt in Girdwood. Photo courtesy D. Nelson


Mountain Weather

Yesterday: Skies were overcast and light to heavy rain was observed throughout our region. Easterly winds were strong (30-40mph) increasing into the 50s mph overnight and several gusts in the 100's at ridgetops. During the day precipitation was heavier near Turnagain Arm, Portage and Girdwood Valley. Overnight intensity increased for a total of 1" of rain in Turnagain and 1.6" of rain at Alyeska Midway station in Girdwood. In Portage 2.27" of rain was recorded near Bear Valley. In the alpine these water totals translate to 1-3' of new snow. Temperatures have remained in the low-40Fs at sea level, mid-30Fs at 1000' and rain/snow line has dropped around ~2000'. 

Today: Rain will be heavy in the morning and early afternoon with another 0.5" - 1.5" or rain is expected today. This is 1-2' of snow in the alpine. Higher precipitation totals will favor Girdwood, Portage and the North side of Turnagain Pass - more coastal areas. Temperatures at sea level will be in the 40Fs and upper 30Fs at 1000'. Rain/snow line will fluctuate between 2000' and 2500' today.  Easterly Ridgetop winds will remain strong 30-40mph with gusts in the 50-60s mph. 

Tomorrow: Rain is expected through the weekend with lighter rain on Saturday. Coastal areas like Portage Valley will see another dose of heavy rain Saturday evening into Sunday. Temperatures will remain in the 40Fs at sea level and mid to upper 30Fs at 1000'. Rain/snow line will be around 2000'. Ridgetop winds from the East will still be elevated, 20-35 mph through Sunday morning. High pressure is in the forecast for Monday and Tuesday, but very warm above freezing temperatures will continue. 

*Seattle Ridge weather station anemometer has been experiencing some issues and may be under reporting wind data.

PRECIPITATION 24-hour data (6am - 6am)

  Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880') 36  rain  1.0  76 
Summit Lake (1400') 38  rain 0.3  27 
Alyeska Mid (1700') 36  rain  1.6  70 

 

RIDGETOP 24-hour data (6am - 6am)

  Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812') 27  ENE  41  103 
Seattle Ridge(2400') 32  *SE  19  75 

This is 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).

Winter snowmachine use open/closed status and riding conditions updates

Riding status is not associated with avalanche danger. An area will be open to motorized use in accordance to the Forest Management Plan when snow coverage is adequate to protect underlying vegetation. Backcountry hazards including avalanche hazard are always present regardless of the open status of motorized use areas.

(Updated: May 06, 2019 )

AREA STATUS WEATHER AND RIDING CONDITIONS
Glacier District
Johnson Pass: ClosedClosed as of 4.3.19
Placer River: ClosedClosed as of 3.20.19 due to lack of snow.
Skookum Drainage: ClosedPlacer access closed as of 3.20.19 due to lack of snow.
Turnagain Pass: ClosedClosed as of 5/6. Thanks for a great season all, see you next winter!
Twentymile: ClosedClosed as of 3.20.19 due to lack of snow.
Seward District
Carter Lake: Closed
Lost Lake Trail: ClosedClosed as of 3.22.19 due to lack of snow
Primrose Trail: ClosedClosed as of 4.3.19 due to lack of snow
Resurrection Pass Trail: ClosedClosed for the 2018/19 season. Next season will be open to motorized use.
Snug Harbor: ClosedClose as of 5.1.2019
South Fork Snow River Corridor: ClosedClosed as of 3.20.19 due to lack of snow.
Summit Lake: Closed

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The information in this advisory is from the U.S. Forest Service, which is solely responsible for its content. This advisory describes general avalanche conditions and local variations always occur. This advisory provided by the Chugach National Forest, in partnership with Friends of the Chugach National Forest Avalanche Information Center.


USFS SNOW AND AVALANCHE HOTLINE (907) 754-2369
If you have comments or questions regarding CNFAIC operations or winter recreation management, please email staff@chugachavalanche.org
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