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Avalanche Advisory

Turnagain Area Avalanche Advisory
Saturday, March 16th 2019 7:00 am by Graham Predeger
ARCHIVED ADVISORY - All advisories expire after 24 hours from the posting date/time.
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The Bottom Line

The avalanche danger is HIGH for a fourth consecutive day given the continuation of a series of warm, wet and windy storms depositing heavy snow and rain in rapid succession in the Turnagain Pass area.  Travel in avalanche terrain is not recommended again today.  Avoid slopes 30 degrees or steeper, including runout zones. 

SUMMIT LAKE (& INTERIOR EASTERN KENAI MTS) – Areas around Summit Lake have effectively doubled their seasonal snowpack in the past week and dropped up to a 30” storm slab on a very weak base of facets.  Large to very large human triggered avalanches are very likely again today. Travel in avalanche terrain is NOT recommended in these zones.

SEWARD/LOST LAKE – Coastal areas such as Seward have seen big precip numbers this week, much in the form of rain.  Natural avalanches large enough to bury, injure or kill a person have been observed. Again, 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
  • Please be kind to our DOT plow drivers and give them the space they need to clear the Seward highway corridor.  The more efficient they can be with keeping the highway clear, the quicker they can push back our winter recreation parking areas. 
  • Turnagain Pass 20 years later: On Saturday, March 23rd from 12-2pm swing by the Turnagain Pass moto lot and meet the CNFAIC avalanche forecasters, bring and test your avalanche rescue gear, ask questions and learn about the history of Turnagain Pass and the avalanche center. We’ll even have a few beacons buried so you can test your skills before heading into the hills!
  • Heading to Hatcher Pass? Be sure to check out the Hatcher Pass Avalanche Center Saturday avalanche forecast HERE.

Avalanche Problem 1

Storm Slabs

Almost Certain
Very Likely
Likely
Possible
Unlikely

Chance

Historic
Very Large
Large
Small

Size

Each low-pressure event impacting our area over the past week seems to be bringing slightly warmer temperatures than the last; today will be no exception.  As temperatures increase, the rain/ snow line may reach as high as 2,000’ as this next bout of weather impacts the eastern Kenai Peninsula this weekend.  What does this mean for avalanche activity today?  It means that rain on snow may initiate natural avalanches in the treeline elevations where we’ve seen mostly snow for the past 3+ days.  Any avalanches today will be large and un-survivable as storm slabs alone are 2-3’ deep.  Add winds to that or the potential for an avalanche to step down into weaker layers deeper in the snowpack and we’re flirting with the potential for 5-6’+ deep avalanches.

Though observations and info from the alpine (above) 2,500’ have been minimal since Tuesday, an additional 8-16" of snow forecated and strong easterly winds over known weak layers and crusts create a serious concern for large and destructive avalanches today.  In channeled terrain, debris was running to the valley floor and all the way to sea level in some cases yesterday.  Today the message is simple – Avoid all avalanche terrain, this includes slopes steeper than 30 degrees and all runout zones. 

South of Turnagain Pass: A brief weather window on Thursday allowed observers to view a plethora of natural avalanches that ran mid-storm.  Given a shallower snowpack in these areas, this week’s load is proving generous enough to tip the stress vs. strength balance south of the core Turnagain Pass area.  Suspect areas include Johnson Pass, Lynx Creek and Summit Lake.  

Debris in channelled terrain in the bottom of east facing terrain at the base of Twin Peaks. Just south of Turnagain Pass.  Photo: 3/14.

Storm Totals (Wed 6am - Sat 6am): 

  • Turnagain Pass 1800’:  29” (settled snow) -- 4.3” SWE
  • Girdwood-Alyeska Midway 1700’: ~30” -- 3.14” SWE
  • Summit Lake 1400’: ~19” -- 1.5” SWE
  • Portage Valley 95’: ~5-6 ft snow in upper elevations -- 6.25” rain at reporting station

Mountain Weather

Yesterday: Temperatures in the mid to upper 30’s kept rain the dominant precip type below about ~700’.  Turnagain Pass (1,880’) only saw ~3” of wet, heavy snow (.9” water) as accumulation was barely keeping up with settlement rates.  Ridgetop winds were sustained from the east in the mid 30’s – 40mph with gusts into the low 70’s at Sunburst.

Today: Temperatures continue to climb into the high 30's at 1,000' with the rain/ snow line anticipated to be in the 1,800’ – 2,000’ range.  On average we can expect another ~1” of water though areas such as Portage and Girdwood could see more.  In the alpine this translates to another 8-16” of snow. 

Tomorrow: The active weather pattern continues as yet another surface low moves into southcentral AK.  Expect more rain in the lower elevations, moderate to strong southeasterly winds and ample snow/ whiteout in the alpine.  Rain/ snow line looks to be in the 1,800-2,400' range.

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

  Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880')  32  3  .9 102 
Summit Lake (1400')  35  0 .2  37 
Alyeska Mid (1700') 32  .89  89 

 

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

  Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812')  23  ENE  42 88 
Seattle Ridge(2400')  28 n/a *  n/a*  n/a*

*Seattle Ridge weather station is not reporting reliable wind data at this time.

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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