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Avalanche Advisory

Turnagain Area Avalanche Advisory
Forecaster:   Graham Predeger  
Thursday, January 8th 2015
Created: Jan 8th 6:41 am
2 Moderate Alpine / Above 2,500' Travel Advice: Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.
2 Moderate Treeline / 1,000'-2,500' Travel Advice: Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.
0 NO RATING Below Treeline / Below 1,000'
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The John Byrne Family
Special Announcement

Join us for our final Fireside Chat this Thursday, January 8th, in Anchorage! Topic: Mountain Weather and Snowpack.  CNFAIC forecaster and resident meteorologist Wendy Wagner will be taking a close look at the current state of the snowpack at Turnagain Pass along with a look into "when is it going to snow?".  You won’t want to miss this, and the best part is that it’s FREE!!!

Do you ski or snowmachine in Hatcher Pass?  The Hatcher Pass Avalanche Center (HPAC) and the Alaska Avalanche School (AAS) are leading an Observer’s Workshop for backcountry enthusiasts who are interested in submitting snow and avalanche observations to the HPAC.  More info can be found by clicking here. 


The Bottom Line

The avalanche danger is MODERATE today at all elevations above 1,000.  With rapidly warming temperatures overnight and in-coming moisture, the trend will be for increasing danger throughout the day.  If we see an inch or more of rain and ridgetop temperatures continuing to climb north of the mid-30’s, the danger may rise to CONSIDERABLE by late in the day.  Wet slabs and wind slabs up to 2 feet deep will be possible for a skier to trigger above 2,500’, particularly later in the day as the storm ramps up.  Large avalanches in isolated areas could be possible in these upper elevations as a wet slab could step down into a buried weak layer.  The rain/ snow line is expected to be somewhere in the 2,500 – 3,000’ band today.

Below 2,500’ small, wet-loose snow avalanches will be possible to initiate in steep terrain, (>35 degrees) particularly later in the day on your egress back to the parking lot. 

Make no mistake before driving to the trailhead; today appears to be a warm, wet and windy storm day, making for less than pleasant conditions in the backcountry.


Primary Concern

Today marks a significant pattern change in our weather from the cold, dry high pressure of the last several days to another warm, moist air mass spilling into south-central Alaska. The two factors effecting stability the most today will be rapidly rising temperatures and rain; potentially up to 3,000’.

Wet slab avalanches will be possible to trigger as yesterday’s dry surface becomes saturated at elevations below the rain/ snow line.  These may be up to 2’ deep and conceivably could step down into buried weak layers that we know exist throughout the Turnagain and Girdwood Valley zones.  Below 2,500’ our snowpack is strong and lacks energy.  That being said, the surface has already seen rapid warming at this elevation band and as it becomes saturated with rain later in the day, skiers will be able to initiate wet loose ‘push-alanches’ and point releases in steep terrain, though a cohesive slab will be unlikely at this lower elevation band. 

Perhaps more concerning for today; temperatures began their climb across the forecast area yesterday with some dramatic upticks in the mercury this morning (9 deg F in 12 hrs @ Center ridge, 18 deg F in 12 hrs @ Grandview and 28 deg F in 12 hrs at Granite!).  This is a big red flag as rapid warming such as this leads to a loss of strength within the snowpack. Though not as dramatic yet (7am) at ridgetop locations, if temps continue to increase throughout the day, particularly in the upper elevations, expect avalanche danger to follow suite with wet slabs becoming more likely.

Temperatures, winds and RH are all on the rise today throughout the forecast area.


Secondary Concern

Today’s new load is unlikely to be enough to tip the balance and initiate a persistent slab.  However, the warming trend over the past 24hrs is acting to decrease the strength of buried weak layers.  Rapid warming combined with the potential for a skier-triggered wet slab to step down into buried weak layers has us continuing to keep an eye on this avalanche problem.  


Additional Concern

With very little snow available for transport, wind slabs today will be relegated to the upper elevations and comprised of new snow.  These will grow throughout the day above the rain/ snow line and expect them to become increasingly sensitive to human triggers as the storm progresses. As of 6am this morning ridgetop winds are gusting to 60mph in advance of precipitation.


Mountain Weather

Yesterday was the end of a period of high pressure and temperature inversions.  Clear skies, light winds, and temps in the low teens at 1,000’ (mid- 20’s at ridge tops) have dominated the region for several days now.  Make way for our latest warm-up….

Today we can expect warm, wet and windy conditions in the eastern Turnagain arm area.  As of 6am this morning the temperature at Turnagain pass is 41 degrees with rain just beginning to show up on the radar.  At ridgetop locations, temperatures are in the low-30’s now and will likely see mid-30’s by late in the day.  Ridgetop winds will be from the east in the 30-60mph range.  The rain/ snow line will be hovering around 3,000’ with .6 – 1” of water forecasted by late tonight. 

Unfortunately more warm, unsettled air is on tap for south central Alaska this weekend and into the latter half of next week.  Now may be a good time to book that last minute trip to Hawaii or Jackson Hole, depending on what you’re in need of more!

 

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

  Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880') 33   0 32 
Summit Lake (1400')  24  1  .2
Alyeska Mid (1700') 30   .5 .06  25.5 

 

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

  Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812') 31   E  16  65
Seattle Ridge(2400')  31  E  17  49

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: Mar 15, 2017 )

AREA STATUS WEATHER AND RIDING CONDITIONS
Glacier District
Johnson Pass: OpenPlease park on road in and leave the turnaround (near outhouse) open for trailers to turn around.
Placer River: Open
Skookum Drainage: OpenSkookum drainage closes to motorized use on April 1 annually as per the Chugach National Forest Plan document.
Turnagain Pass: Open
Twentymile: Open
Seward District
Carter Lake: Open
Lost Lake Trail: OpenPlease STAY ON existing and hardened trail surface through the lower sections of this route.
Primrose Trail: OpenPlease STAY ON existing and hardened trail surface through the lower sections of this route.
Resurrection Pass Trail: ClosedClosed for 2016/17 winter season. This is a non-motorized season. This alternates every other year and will open again during the 2017/18 winter.
Snug Harbor: Open
South Fork Snow River Corridor: Open
Summit Lake: Open

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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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