Turnagain Pass

Good morning backcountry travelers this is Kevin Wright with the Chugach National Forest Avalanche Information Center on Thursday, April 7th 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

Today’s avalanche danger rating is rapidly increasing towards HIGH danger. It’s an easy day for decision making. Backcountry travel in the alpine is not recommended.

AVALANCHE DISCUSSION

Yesterday was quite active in the backcountry. You had to be perceptive to notice the clues unless you happened to spring a loaded slope as several people did.

There were several avalanches yesterday including naturals, snowmachine, and skier triggered events. Some of those were remotely triggered including the one below from 400 feet away on Tincan. Collapsing (whoomphing) was evident if you happened to be breaking trail or ventured off an established trail.

The most significant event was a full burial of a ski guide in the Placer/Skookum region. The guide was working on stability assessment when the slope broke. The victim took a 500 foot ride, deployed an airbag, and was still fully buried 4 feet deep. The contributing factors to a successful outcome were fast action by the rescuers, a path clear of rocks, and the victim deliberately holding his backpack strap and jacket collar to facilitate an air pocket. This avalanche happened on a SW aspect at 3500 feet during mid-day yesterday. The suspected weak layer is buried surface hoar from late March.

Based on the distribution of the known avalanches yesterday (Girdwood to Johnson Pass), I think most of our region above tree line will be dangerous over the next few days. The avalanches happened on all aspects having no discrimination between sun and shade.

The snow structure responsible for our current problems is a number of crusts on the sunny aspects with some buried surface hoar mixed in. Shaded North aspects won’t have the sun crusts but the buried surface hoar is larger and weaker. Take a look at this pit from yesterday and CNFAIC Staff recent pits and pictures in the photo gallery.

The “mega storm” coming in today will probably keep most folks out of the backcountry. I am worried about what might happen when this storm breaks. The snowpack will need time to adjust to the new load. Expect touchy conditions for at least 48 hours after the storm ends and possibly longer.

Encyclopedia of avalanche terms.

WEATHER ROUNDUP

Sunny skies broke yesterday with temperatures just warm enough to wet the south faces. Today a large storm is moving through the region. 6-12 inches of snow is expected for Turnagain Pass with SE wind 50-70 mph today. Snow and wind is expected to diminish tonight. The radar is currently showing the image below.

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 AKDT THU APR 7 2011

…STRONG STORM SYSTEM IMPACTING MUCH OF THE STATE TODAY…

A DYNAMIC AND DANGEROUS STORM HAS MOVED INTO THE CENTRAL BERING SEA

WITH A STRONG FRONTAL BOUNDARY APPROACHING THE NORTH GULF COAST.

LIGHT SNOW HAS BEEN FALLING EARLY THIS MORNING ACROSS THE ANCHORAGE

BOWL AS WINDS CONTINUE TO INCREASE ALONG TURNAGAIN ARM AND THE

HILLSIDE. HEAVIER SNOW IS FALLING NEAR GIRDWOOD WHERE APPROXIMATELY 5

INCHES HAS ALREADY BEEN OBSERVED THIS MORNING. THE COMBINATION OF

SNOW AND GUSTY WINDS ALONG TURNAGAIN ARM IS RESULTING IN HAZARDOUS

DRIVING CONDITIONS.

…HIGH WIND WARNING IN EFFECT UNTIL 4 PM AKDT THIS AFTERNOON FOR

PORTAGE VALLEY AND ALONG TURNAGAIN ARM…

.TODAY…SNOW…BECOMING MIXED WITH RAIN AT TIMES AFTER NOON. AREAS

OF BLOWING SNOW. SNOW MAY BE HEAVY AT TIMES IN THE MORNING. SNOW

ACCUMULATION 2 TO 8 INCHES…GREATEST AMOUNTS THROUGH TURNAGAIN PASS.

HIGHS IN THE MID 30S TO LOWER 40S. SOUTHEAST WIND 10 TO 25 MPH WITH

LOCAL GUSTS TO 35 MPH. THROUGH PORTAGE VALLEY AND TURNAGAIN

ARM…EAST WIND 60 TO 75 MPH BECOMING SOUTHEAST AND DECREASING TO 45

TO 60 MPH LATE IN THE AFTERNOON.

.TONIGHT…NUMEROUS RAIN AND SNOW SHOWERS. SNOW ACCUMULATION

UP TO 1 INCH. LOWS IN THE MID 20S TO MID 30S. SOUTH WIND 10 TO

25 MPH EXCEPT SOUTHEAST 30 TO 45 MPH THROUGH PORTAGE VALLEY AND

TURNAGAIN ARM.

.FRIDAY…SNOW AND RAIN SHOWERS. SNOW ACCUMULATION UP TO

3 INCHES. HIGHS IN THE MID 30S TO NEAR 40. SOUTHEAST WIND 10 TO

20 MPH EXCEPT SOUTHEAST 25 TO 40 MPH THROUGH PORTAGE VALLEY AND

TURNAGAIN ARM.

TEMPERATURE / PRECIPITATION

SEWARD 42 35 40 / 100 70 100

GIRDWOOD 39 28 40 / 100 70 80

WEATHER STATION SUMMARY for Turnagain Pass:

-3800′ Sunburst Wx Station-

Currently 17 degree. Wind gusting to 38 from the East.

-2600′ Seattle Ridge Wx Station-

22 degrees at 6am. SE wind to 44mph.

-1800′ Center Ridge Wx Station-

25 degrees at 6am. Snow has started to fall.