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Avalanche Advisory

Turnagain Area Avalanche Advisory
Forecaster:   John Fitzgerald  
Monday, December 24th 2012
Created: Dec 24th 6:29 am
3 Considerable Alpine / Above 2,500' Travel Advice: Dangerous avalanche conditions. Careful snowpack evaluation, cautious routefinding and conservative decision-making essential.
3 Considerable Treeline / 1,000'-2,500' Travel Advice: Dangerous avalanche conditions. Careful snowpack evaluation, cautious routefinding and conservative decision-making essential.
3 Considerable Below Treeline / Below 1,000' Travel Advice: Dangerous avalanche conditions. Careful snowpack evaluation, cautious routefinding and conservative decision-making essential.
 Show the Complete North American Avalanche Danger Scale
The Bottom Line

The hazard will ratchet up to CONSIDERABLE today above treeline, especially this afternoon.  The hazard below treeline will also rise from MODERATE to CONSIDERABLE later today.  Rapid loading of new windlblown snow alone will make for dangerous avalanche conditions.  Natural avalanches are possible and human triggered avalanches will be likely at all elevations today.  The general trend for the day is an increase in the hazard.


Primary Concern

With the 1-2 combo of new snow and strong winds in the forecast, we have prime conditions for avalanche activity.  It's always good to remember simple rules about snow.  The first one being, 'snow does not like rapid change.'  With these stronger winds, look for loading on slopes to occur lower than normally seen.  Notice that our avalanche problems have changed, literally, overnight.  While wind slabs are the primary problem today, we need to remember what the snow surface looked like before this new loading began.  Above treeline we were seeing a weak snow surface underlain by everything from stiff old windslab to several feet of faceted snow.  This tired old snow we've been looking at is quickly becoming the new weak layer & bed surface.  Wind slabs will be most prominent above treeline.  It will be critical to pay attention to the terrain you are under today and know if you are in a runout zone.  Conservative travel practices will be critical as avalanches starting in the upper elevations have the potential to run into lower elevation runout zones.  Keep in mind that visibility will limit your ability to know where you are in relation to these areas.


Secondary Concern

While it's exciting to finally see the white stuff falling again, it is important to remember what this new snow is falling on; very weak faceted snow.  The second simple rule for snow for today: 'strong snow over weak snow equals a problem.'  The weight of this new load alone should be enough to tip the balance, especially by the afternoon.  By adding in a person or snowmachine to the mix avalanches will be much more likely to occur.  Given what the base of the snowpack looks like, loose and rotten, all areas with new snow should be viewed as guilty until proven innocent.  If you are seeing avalanches, shooting cracks or getting collapsing/whoompfing, it is time to back off of any slopes steep enough to slide.  Expect these signs to become more prevalent throughout the day.


Mountain Weather

The National Weather Service has issued the following statement

...BLIZZARD WARNING REMAINS IN EFFECT FROM 6 AM MONDAY TO 9 AM
AKST TUESDAY FROM TURNAGAIN PASS NORTH...

TIMING...BLIZZARD CONDITIONS WILL BE DEVELOPING MONDAY MORNING AS SNOW INTENSIFIES AND WINDS INCREASE. HEAVY SNOW AND BLOWING SNOW WILL CONTINUE INTO LATE TUESDAY MORNING BEFORE SNOW BEGINS TO DIMINISH IN INTENSITY.

We've seen temps climb since Saturday and snowfall has begun overnight.  4-6 inches of snow has fallen so far in the forecast area.  Temperatures are currently in the low 20's and ridgetop winds are averaging 20 mph out of the East.

Expect snowfall and winds to intensify throughout the day today.  We should expect to see a foot of new snow with ridgetop winds out of the East gusting to 60 mph.  Expect to see snowfall amounts much higher in windloaded starting zones.

The long term outlook calls for more snow and wind to impact our area through the week.  Continue to check the advisory throughout this holiday week as this active weather pattern will contribute to potentially heightened avalanche conditions.

 


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).

Kevin will issue the next advisory Tuesday morning December 25th.

 

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

Subscribe to the Turnagain Area Avalanche Advisory:

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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