Turnagain Pass

Good morning backcountry travelers. This is Jon Gellings with the Chugach National Forest Avalanche Information Center on Tuesday, March 1st 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 is MODERATE for triggering a wind slab at ridgeline elevations. These avalanches are the most possible in steep rocky terrain and cross loaded gullies. Any new avalanche also has the possibility of breaking into old weak layers, creating a larger avalanche.

AVALANCHE DISCUSSION

Wind slabs are still our primary concern today. These features could allow a backcountry traveler to get out onto a steep slope before fracturing above them. Now that these slabs have been sitting in place for a few days, they are likely to be more resistant to initial failure, but if it happens, there could be wider propagation. Many areas have been wind scoured down to crusts, old tracks, and facets, making for poor riding conditions. Searching for softer surface conditions could lead you right into wind loaded terrain. These wind slabs could possibly be triggered in steep rocky terrain, as well as on slopes and in gullies which have been cross loaded.

Our secondary concern is of avalanches breaking into old weak faceted snow, which could produce a much larger avalanche. We can not forget about this instability, even if it is several days or weeks until a new avalanche breaks down to these layers. Areas with an average snow cover of less than 5-6 feet deep are more prone to this type of instability, especially if the slope in question is steep and has been recently wind loaded. These unmanageable hard slabs are likely difficult to trigger, but can break if the right spot is found.

WEATHER ROUNDUP

Winds are unlikely to be strong enough to transport any more snow today, although some areas near Turnagain Arm may see a few snow plumes near ridges. Temperatures look like they will be similar to yesterday, and there is no new precipitation forecasted for today.

ANNOUNCEMENTS

An APU student is conducting a survey on backcountry skiing group dynamics. Click on the link to participate in research on avalanche safety. Click here to take survey

The Forest Service is installing winter use bridges across Granite creek in Turnagain Pass. Be aware of an ice road from the Lyon creek bridge south towards Johnson Pass on the West side of the highway. Heavy equipment will also be used in the area.

I will issue the next advisory tomorrow morning at 7am. If you get out in the backcountry give us a call at 754-2369 or send us your observations using the button at the top of this page. Thanks and have a great day.

The NWS weather forecast for:

WESTERN PRINCE WILLIAM SOUND-

INCLUDING…WHITTIER…SEWARD…GIRDWOOD…MOOSE PASS

500 AM AKST TUE MAR 1 2011

.TODAY…SUNNY. HIGHS IN THE LOWER 20S TO LOWER 30S. VARIABLE

WIND TO 10 MPH. NEAR SEWARD AND WHITTIER…NORTH AND WEST WIND

15 TO 25 MPH WITH GUSTS TO 35 MPH DECREASING TO 10 TO 20 MPH

IN THE AFTERNOON.

.TONIGHT…CLEAR. LOWS 10 BELOW TO 5 ABOVE EXCEPT IN THE TEENS

ALONG THE COAST. LIGHT WINDS. NEAR SEWARD…NORTH WIND 10 TO 20 MPH.

NEAR WHITTIER…WEST WIND TO 15 MPH WITH GUSTS TO 30 MPH.

.WEDNESDAY…SUNNY. HIGHS IN THE LOWER 20S TO LOWER 30S.

VARIABLE WIND TO 10 MPH. NEAR SEWARD…NORTH WIND 10 TO 20 MPH.

NEAR WHITTIER…WEST WIND 15 TO 25 MPH WITH GUSTS TO 35 MPH.

TEMPERATURE / PRECIPITATION

SEWARD 28 17 27 / 0 0 0

GIRDWOOD 20 5 20 / 0 0 0

WEATHER STATION SUMMARY for Turnagain Pass:

-3800′ Sunburst Wx Station-

(@ 4am) Temperature 12 degrees. NW winds 5-10mph, gusting to 20.

-2600′ Seattle Ridge Wx Station-

Temperature 15 degrees. Calm NW winds gusting to 10.

-1800′ Center Ridge Wx Station-

Temperature 11 degrees. No new snow.