Turnagain Pass

Good morning backcountry travelers. This is Jon Gellings with the Chugach National Forest Avalanche Information Center on Tuesday, April 12th 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 today is LOW with pockets of MODERATE. Many avalanche prone slopes in our core advisory area of Turnagain Pass are unlikely to avalanche today, but certain places contain a higher possibility of triggering a slab avalanche. These pockets of MODERATE include steep North facing slopes at upper elevations that are showing reactive buried layers of surface hoar, as well as on steep, sun-affected slopes during the afternoon.

AVALANCHE DISCUSSION

We are not at a full-on LOW danger rating, so steeper slopes over 35 degrees should be approached with caution if you are uncertain of their stability. Many people have been out over the past few days skiing and riding steep North facing slopes and couloirs, with no incidents or reported avalanches since last Friday. However, with a few buried layers of surface hoar recently showing clean and fast shears (Q1), prudent personal decision making is necessary to abate this hazard.

Our main concern is still for persistent slab avalanches. While they are becoming less likely, as Wendy stated yesterday, they are still possible and could end up biting you if unaware of their presence and current reactivity. Here is a video from yesterday, showing exciting compression test results, even though several people had previously skied this slope and similar ones throughout Turnagain Pass without triggering anything.

A pit profile for this location is available here.

Outlying areas outside of Turnagain Pass containing deeper recent snowfalls and/or higher elevations likely still show signs of an increased hazard, and should be travelled through accordingly.

The secondary concern for today is for wet snow avalanches on steep slopes directly facing the sun during the warmest part of the day (1:00pm-6:00pm). Lower elevation slopes facing this direction are likely to become saturated up to several feet deep, but are unlikely to avalanche unless they are on steep, unsupported slopes. Sinking into snow beyond your ankles should clue you into this increasing instability.

Encyclopedia of avalanche terms.

WEATHER ROUNDUP

Winds are not likely to increase significantly, therefore will not affect the snowpack adversely. Temperatures should be reaching into the upper 30’s, potentially affecting the stability on lower elevation slopes, as well as on Southerly aspects during the afternoon. There is a bit of precipitation moving around in Prince William Sound, but radar, satellite, forecasts, and models all point to no significant impact in Turnagain Pass.

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 TUE APR 12 2011

.TODAY…MOSTLY CLOUDY WITH SCATTERED SNOW SHOWERS IN THE MORNING…

BECOMING PARTLY CLOUDY IN THE AFTERNOON. HIGHS IN THE 40S. LIGHT

WINDS EXCEPT NORTH 10 TO 15 MPH NEAR SEWARD.

.TONIGHT…PARTLY CLOUDY. ISOLATED RAIN AND SNOW SHOWERS IN THE

EVENING. LOWS IN THE LOWER 20S TO LOWER 30S. VARIABLE WIND TO 10 MPH.

NEAR WHITTIER…WEST WIND 15 TO 30 MPH.

.WEDNESDAY…PARTLY CLOUDY. ISOLATED RAIN AND SNOW SHOWERS IN THE

AFTERNOON. HIGHS IN THE 40S. VARIABLE WIND 10 MPH INLAND. NEAR SEWARD

AND WHITTIER…NORTH TO WEST WIND 15 TO 30 MPH.

TEMPERATURE / PRECIPITATION

SEWARD 45 27 45 / 30 20 20

GIRDWOOD 43 22 43 / 0 20 0

WEATHER STATION SUMMARY for Turnagain Pass:

-3800′ Sunburst Wx Station-

20 degrees. ENE wind 9mph gusting to 15mph.

-2600′ Seattle Ridge Wx Station-

24 degrees. SE wind 11mph gusting to 15mph.

-1800′ Center Ridge Wx Station-

26 degrees. No new snow.