Turnagain Pass

Good morning backcountry travelers this is Jon Gellings with the Chugach National Forest Avalanche Information Center on Wednesday, January 5th 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 the avalanche hazard is CONSIDERABLE. Natural avalanches are possible, while Human triggered avalanches are likely on steep, unsupported and windloaded terrain in upper elevations. At lower elevations, the stability is showing decreased energy, but is still MODERATE due to active rain and snow on buried layers of surface hoar. There are still dangerous avalanche conditions in many areas, and careful evaluation of the snowpack is essential while travelling around avalanche terrain today.

AVALANCHE DISCUSSION

Our snowpack is still showing signs of increased danger. We were getting small shooting cracks and large whumphs yesterday on Tincan, and were able to see previous avalanches on Eddies, Tincan, Center Ridge, Sunburst, and Magnum. A few small avalanches were observed on a few lower to mid-elevation slopes on Seattle Ridge, but these were fairly confined to crossloaded gullies. I would expect the Seattle Creek side of the Ridge to hold several previous avalanches as well. My primary concern today is of the buried instabilities in and around upper elevation slopes that have been getting stressed and windloaded with dry, transportable snow due to gale force winds.

CNFAIC Staff slopes that were not being windloaded were showing signs of improving stability, but still not great. One of these slopes we found gave us a great opportunity to dig a snowpit, which included several compression tests, as well as an extended column test. You can view a video about it here:

Although the two tests showed a bit of a difference in energy, the important thing to look at is that the compression test failed suddenly and jumped off of the column. A person could definitely trigger something on this layer, which was indicated shortly after the film was created. We were walking around the pit, and a large whumph was heard that broke down at the same layer.

As our cooler weather starts moving in, hopefully it will freeze up and strengthen the warm snowpack at lower elevations. When this happens though, the New Years Crust (NYC) will become a challenging layer to recreate on, which in turn will create a whole new set of hazards to backcountry travellers. Please recreate safely, because getting injured is never fun for anyone involved.

Check out an encyclopedia of terms here: www.fsavalanche.org/Encyclopedia.aspx

WEATHER ROUNDUP

The radar is showing precipitation in Prince William Sound headed our way, but the majority seems to be sticking to the glaciers and to the Sound itself. The cooling trend is on its way once the weakening Low pressure system leaves our area. Satellite images are showing a clearing in the sky headed our way, but might not hold all day due to clouds pushing in and out of our area. Winds should diminish as the weather system heads out too, which could make conditions quite pleasant for a few days if it all comes to fruition.

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

520 AM AKST WED JAN 5 2011

.TODAY…SNOW SHOWERS TAPERING OFF LATE IN THE AFTERNOON. SNOW

ACCUMULATION UP TO 4 INCHES…HIGHEST AMOUNTS INLAND. HIGHS IN THE

30S. VARIABLE WIND TO 10 MPH. THROUGH PORTAGE VALLEY AND

TURNAGAIN ARM…EAST WIND 15 TO 30 MPH WITH GUSTS TO 40 MPH BECOMING

VARIABLE 10 MPH IN THE AFTERNOON.

.TONIGHT…MOSTLY CLOUDY IN THE EVENING THEN BECOMING PARTLY

CLOUDY. LOWS IN THE 20S. LIGHT WINDS EXCEPT NORTH TO WEST WIND 15 TO

30 MPH NEAR SEWARD AND WHITTIER.

.THURSDAY…PARTLY CLOUDY IN THE MORNING THEN BECOMING MOSTLY

SUNNY. HIGHS IN THE LOWER 20S TO MID 30S. LIGHT WINDS EXCEPT

NORTH TO WEST WIND 20 TO 35 MPH NEAR SEWARD AND WHITTIER.

TEMPERATURE / PRECIPITATION

SEWARD 38 27 31 / 100 20 0

GIRDWOOD 36 21 21 / 100 0 0

WEATHER STATION SUMMARY for Turnagain Pass:

-3800′ Sunburst Wx Station-

recorded wind speeds yesterday up to 58mph, and temps cooling from 26F to 23F. The current temp is 23F with 25-40mph winds out of the east-northeast.

-2600′ Seattle Ridge Wx Station-

stopped recording winds on 1/2/11, while temps cooled from 29F to 26F yesterday. The current temp is 26F with 100% relative humidity.

-1800′ Center Ridge Wx Station-

recorded 8-10″ new snow in the past 24hrs, with more currently dropping. During this time, the precipitation added .9″ SWE. Temps yesterday ranged from 30F to 34F. The current temp is 30F with a total snowpack depth of 73 inches.