Turnagain Pass

Good morning backcountry travelers this is Carl Skustad with the Chugach National Forest Avalanche Information Center on Thursday, December 24 at 7 am. This will serve as a general backcountry avalanche advisory issued for Turnagain Arm with Turnagain Pass as the core advisory area (advisory does not apply to highways, railroads, or operating ski areas).

ANNOUNCEMENTS

The beacon park is open at the Alyeska Resort. It’s located opposite the Hotel Alyeska at the tram loop. It’s a great place to practice your beacon rescue skills.

WEATHER ROUNDUP

In the last 24 hours, 6-8 inches of snow fell in Girdwood, 10 inches in Turnagain Pass, and 4 inches in Summit Lake. Approximate 3 day storm totals for Girdwood are 12-15 inches, Turnagain Pass 19 inches, and Summit Lake 9. These amounts are above the snowline. The snowline has fluctuated from sea level to 1200 ft. Almost all precip has been rain from sea level to 800 feet.

-The Center Ridge Wx Station at 1800 feet/Turnagain Pass-

recorded 10 inches of new snow and 1.1 inches of water in the last 24 hours. The current temp is 30.6F (2 degrees warmer than yesterday) with a total snowpack depth of 68 inches. 3 inches of settlement.

-The Sunburst Wx Station at 3800 feet/Turnagain Pass-

is showing 18 mph winds out of the ESE, with gusts of 30 mph. Very high sustained averages and gusts to 74 in the last 24 hours. The current temperature is 24 deg F

-The Summit Lake Wx Station at 1200 feet-

recorded 4inches of new snow and 0.3 inches of water in the last 24 hours. The current temp is 32F ( 3 degrees warmer than yesterday) with a total snowpack depth of 33 inches.

-The Fresno Ridge Wx Station at 3400 feet/Summit Lake-

recorded is showing 22 mph winds with gust of 29 mph out of the SE. Very high averages and gusts to 56 in the last 24

A very strong 962 mb low is located in the gulf spinning shortwave precipitation at us. The jet stream is cruising around the northern hemisphere like a good little jet stream then bam, it hits this low and turns directly north into mainland AK. Heavy cloud cover and mixed precip on the radar and satellite.

The weather forecast for:

INCLUDING…WHITTIER…SEWARD…GIRDWOOD…MOOSE PASS

.500 AM AKST THU DEC 24 2009

.TODAY…RAIN ALONG THE COAST AND RAIN AND SNOW OVER HIGHER

ELEVATIONS. SNOW ACCUMULATIONS UP TO 2 INCHES OVER HIGHER ELEVATIONS.

HIGHS IN THE MID 30S TO LOWER 40S. NORTH TO EAST WIND 10 TO 20 MPH

EXCEPT SOUTHEAST WIND 15 TO 30 THROUGH PORTAGE VALLEY AND TURNAGAIN

ARM.

.TONIGHT…RAIN AND SNOW. SNOW ACCUMULATION 2 TO 4 INCHES OVER HIGHER

ELEVATIONS. LOWS IN THE MID 20S TO UPPER 30S. NORTH TO EAST WIND 10

TO 20 MPH EXCEPT SOUTHEAST WIND 15 TO 30 THROUGH PORTAGE VALLEY AND

TURNAGAIN ARM.

.CHRISTMAS DAY…RAIN AND SNOW LIKELY. SNOW ACCUMULATION UP TO

1 INCH. HIGHS IN THE LOWER 30S TO LOWER 40S. NORTH TO EAST WIND 10 TO

20 MPH EXCEPT SOUTHEAST WIND 15 TO 30 THROUGH PORTAGE VALLEY AND

TURNAGAIN ARM.

.FRIDAY NIGHT…NUMEROUS SNOW SHOWERS. LOWS IN THE LOWER 20S TO

MID 30S. NORTH TO EAST WIND TO 15 MPH.

.SATURDAY…SNOW AND RAIN LIKELY. HIGHS IN THE UPPER 20S TO UPPER

30S. EAST WIND 10 TO 20 MPH.

TEMPERATURE / PRECIPITATION

SEWARD 40 34 38 / 80 80 60

GIRDWOOD 41 37 41 / 80 60 60

AVALANCHE DISCUSSION

It’s hard to say if the current cycle of precip and avalanche activity has peaked yet. I believe it did late yesterday. However, with too much uncertainty the avalanche hazard will elevate one click today. Today’s avalanche hazard is HIGH on steep terrain. Natural avalanches are likely today and human avalanches are very likely on slopes steeper than 35 degrees. All CNFAIC Staff areas have CONSIDERABLE avalanche hazard. Considerable means natural avalanches possible and human triggered avalanches likely.

We actually saw the above-mentioned hazards come to fruition yesterday afternoon. Jon and I climbing out of the rain and into heavy snow and wind on Tincan mountain. Talking with CNFAIC Staff skiers and building observations of our own is the basis for today’s increased hazard. Natural and human triggered avalanches were common on most role overs steeper than 35 degrees. Large spread collapsing was reported. CNFAIC Staff professional reports from the Girdwood Valley indicated similar conditions. The avalanches mentioned failed on the 24 hour old snow interface, 6-8 inches deep, (CTE 4 14cm x2, CTM 14 35cm x2). I’m not convinced that this thinner slab won’t step down to the buried surface hoar in some instances. If this were the case large avalanches would occur. We had limited visibility and could not see upper elevations; however, winds have been ripping and starting zones are loaded.

I will issue the Christmas 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