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Issued
Mon, January 23rd, 2012 - 7:00AM
Expires
Tue, January 24th, 2012 - 7:00AM
Forecaster
Wendy Wagner
Avalanche risk The Bottom Line

Good morning. This is Wendy Wagner with the Chugach National Forest Avalanche Information Center on Monday, January 23rd 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).

BOTTOM LINE

The avalanche danger remains at CONSIDERABLE today for soft slab and wind slab avalanches at all elevations due to continued snowfall over our area again today. Human triggered slab avalanches are likely and can be triggered from below. In the case we receive anCNFAIC Staff intense pulse of moisture, similar to yesterday, the avalanche danger will rise to HIGH. Expert level terrain management skills will be required, such as keeping slope angles low and avoiding runnout zones.

AVALANCHE DISCUSSION

I believe I heard the words “blower pow” about 100 times yesterday – and that is what we got – about 18-22+” of it from the Girdwood Valley to Tunagain Pass. It looks as though Summit Lake was a bit over half that. The light fluffy snow came down at 2-3″ per hour at times and with rising temperatures. The rise in temperature increased the relative density of the snow during the storm which produced an “upside down” structure. Widespread cracking and collapsing was observed with 3-12″ soft slab avalanches easily triggered on steep slopes and rollovers. These were all below treeline where people were finding safe places to ride. Check out yesterday’s obs here.

Cracking above a person on a small shallow slope – possible again today. If the slope was steeper it would likely avalanche.

Below treeline:

Today, soft slab avalanches and sluffs will again be a primary concern on steep slopes and rollovers. Activity similar to yesterday will be likely again today with the addition of new snow and limited time for the storm snow to adjust to the new load. Watch for the red flags of cracking and collapsing. Keeping slope angles low and steering clear of terrain traps is advised.

Above treeline:

If skies clear enough for travel above treeline, very careful and conservative route finding and terrain management is warranted. Winds have effected these areas and wind slab avalanches are likely to be waiting for a trigger. Both wind slab and soft slab avalanches are likely on slopes 35 degrees and steeper and could be anywhere from a foot to 3+ feet deep. Slopes will be possible to be triggered from below today.

Summit Lake: Though less snow has fallen here, the ridgetop winds have increased this morning. Watch for sensitive and fresh wind slab avalanches that have formed in the new snow.

MOUNTAIN WEATHER

Most folks would say it was officially “dumping” yesterday from late morning through the afternoon. Light fluffy snow was falling at rates close to 2-3″ per hour in the Girdwood Valley through Turnagain Pass. Storm totals were between 18-24″ (1-1.5″ of water) in most areas with less seen in the Summit Lake region (10-14″). Temperatures increased from ~5F to 20F during the day. Winds also accompanied the snowfall and were light to moderate below treeline while ridgetop weather stations reported 30-40mph easterly winds gusting 50-60mph.

Overnight light snow showers have added anCNFAIC Staff 10-12″ around Turnagain Pass with only 3-5″ inches both north and south of the Pass. Easterly winds have decreased but are still blowing around 20mph with 40mph gusts (except Fresno ridge, near Summit Lake, where they have been moderate till this morning when they doubled – gusts ~50mph).

Today, expect snow showers to linger and potentially add 4-8″ to our, roughly 2+’, of storm total. Temperatures should remain warm, in the low 20’s below treeline and the mid to upper teens above treeline. Easterly winds are forecast to continue to be around 20mph with gusts near 40mph.

CNFAIC Weather Page and the NWS forecast

Graham will issue the next advisory Tuesday 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.

Mon, January 23rd, 2012
Alpine
Above 2,500'
3 - Considerable
Avalanche risk
Treeline
1,000'-2,500'
3 - Considerable
Avalanche risk
Below Treeline
Below 1,000'
3 - Considerable
Avalanche risk
0 - No Rating
1 - Low
2 - Moderate
3 - Considerable
4 - High
5 - Extreme
Avalanche risk Avalanche risk Avalanche risk Avalanche risk Avalanche risk
Travel Advice Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features. Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern. Dangerous avalanche conditions. Dangerous avalanche conditions. Very dangerous avalanche conditions. Travel in avalanche terrain not recommended. Extraordinarily dangerous avalanche conditions. Avoid all avalanche terrain.
Likelihood of Avalanches Natural and human-triggered avalanches unlikely. Natural avalanches unlikely; human-triggered avalanches possible. Natural avalanches possible; human-triggered avalanches likely. Natural avalanches likely; human-triggered avalanches very likely. Natural and human-triggered avalanches certain.
Avalanche Size and Distribution Small avalanches in isolated areas or extreme terrain. Small avalanches in specific areas; or large avalanches in isolated areas. Small avalanches in many areas; or large avalanches in specific areas; or very large avalanches in isolated areas. Large avalanches in many areas; or very large avalanches in specific areas. Very large avalanches in many areas.
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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.