Turnagain Pass

Good morning backcountry travelers this is Carl Skustad with the Chugach National Forest Avalanche Information Center on Friday April 2nd, 2010 at 7 am. 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).

ANNOUNCEMENTS

Skookum Valley and Skookum Glacier are closed to motorized vehicles (snowmachines, helicopters, ATVs) except for subsistence uses.. This closure is directed in the current Chugach National Forest Land and Resource Management Plan. Placer River Drainage remains open for motorized use to Spencer Glacier.

WEATHER ROUNDUP

Winds stayed moderate to strong yesterday afternoon before dying off in the late evening. Current winds are light to moderate except for Sunburst ridge were we still see gusts in the teens and 20’s. Snow totals from yesterday morning are: Eddies-13′, Motorized parking lot in Turnagain Pass – 16′, Sunburst – 9′, and Johnson N Trail Head – 4′. This puts our 7 day total snowfall over 30 inches in Turnagain Pass. The radar this morning has precipitation heading east to west onshore near Seward. Not much for the Northern Kenai. Satellite images indicated cloud cover but models show little to no precip accumulation today. Look for the freeze line to go back up to approximately 1400 feet today.

AVALANCHE DISCUSSION

Today’s avalanche danger is MODERATE with pockets of CONSIDERABLE due a complex snowpack consisting of buried weak layers of surface hoar and suncrusts. Newly formed windslabs and buried surface hoar will be the primary avalanche hazards today.

Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully. Natural avalanche unlikely today unless we see the sun or increased wind or precip. Human triggered avalanches possible and likely in pocketed areas. If an avalanche is triggered it could go very large. 3 ft of new snow in the last week on top of buried surface hoar will promote large propagation and dangerous sized avalanches.

Areas where one could likely trigger an avalanche today exist on steep rollovers or hanging snow fields near ridgetops. Wind slabs will be present in the alpine. All aspects have either buried surface hoar (north aspects) or buried sun crusts (south aspects). These weak layers have cross over and duplication on east and west aspects.

We have limited observations from yesterday. If you get out today, routefinding and snow stability evaluation will be key. Take the time to examine the snow in front of you. It will change every few feet. Send us your observations using the submit button on the top of this page.

The sun is a critical “watch out” situation this time of year. Avalanche danger increases quickly during periods of rapid warming temperatures and direct sunlight.

CNFAIC Staff than sunny slopes, the buried surface hoar is a serious concern today. A party reported a large collapse on the ridge near the top of Sunburst 3 days ago. In the past week, there have been several human-triggered avalanches that have occurred on one of the MULTIPLE layers of buried surface hoar that are currently buried 2-4 feet deep in our snowpack.

Terrain management is the key today. Keep your slope angles below 35 degrees. AVOID traveling on any sunny slopes IF the sun comes out and get out of avalanche terrain immediately if it does. Remember that most of the avalanches that failed on the surface hoar have occurred on northern aspects.

Glide cracks are secondary concern today. These crevasse like features are those cracks that go all the way to the ground. Avoid traveling underneath these cracks. A full depth climax avalanche occurred on lower Goat Ridge in Girdwood Valley on 3/30/2010.

WEATHER FORECAST (National Weather Service)

WESTERN PRINCE WILLIAM SOUND-

INCLUDING…WHITTIER…SEWARD…GIRDWOOD…MOOSE PASS

500 AM AKDT FRI APR 2 2010

.TODAY…MOSTLY CLOUDY. NUMEROUS SNOW SHOWERS IN THE MORNING…THEN

SCATTERED RAIN AND SNOW SHOWERS IN THE AFTERNOON. SNOW ACCUMULATION

UP TO 1 INCH. HIGHS IN THE LOWER TO MID 40S. VARIABLE WIND TO 10 MPH.

NEAR SEWARD…NORTH WIND 15 MPH.

.TONIGHT…MOSTLY CLOUDY WITH A CHANCE OF SNOW. LOWS IN THE MID

20S TO LOWER 30S. VARIABLE WIND TO 10 MPH. NEAR SEWARD…NORTH WIND

10 TO 20 MPH.

.SATURDAY…MOSTLY CLOUDY. A CHANCE OF SNOW IN THE MORNING…THEN

SCATTERED SNOW AND RAIN SHOWERS IN THE AFTERNOON. HIGHS

IN THE UPPER 30S TO MID 40S. LIGHT WINDS EXCEPT NORTH 10 MPH NEAR

SEWARD.

.SATURDAY NIGHT…SNOW LIKELY. LOWS IN THE UPPER 20S TO MID 30S.

VARIABLE WIND 10 MPH.

.SUNDAY…SNOW AND RAIN LIKELY. HIGHS AROUND 40. EAST WIND 10 TO 15

MPH.

.SUNDAY NIGHT…MOSTLY CLOUDY WITH SCATTERED SNOW SHOWERS. LOWS

IN THE 20S.

TEMPERATURE / PRECIPITATION

SEWARD 44 29 43 / 60 40 50

GIRDWOOD 45 27 43 / 30 20 30

WEATHER STATION SUMMARY for last 24 hours at TURNAGAIN PASS

3800′-Sunburst Wx Station

Temp (5am): 25 (2 degrees warmer than yesterday morning)

Winds: In last 24 hours winds have been moderate out of the east from 10 mph to the high 30’s.

2600′-Seattle Ridge Wx Station

Temp (5am): 26

Winds: Yesterday saw wind gusts in the 20’s. Currently south winds are light.

1800′-Center Ridge Wx Station

Temp (5am): 26 (1 degrees colder than yesterday morning)

Precip: 0 new snow, total snowpack is 146 after 7 inches of settlement.

Thanks for checking today’s avalanche advisory. I will update this advisory tomorrow Saturday April 3rd, 2010 by 0700.