Turnagain Pass

Good morning backcountry travelers this is Matt Murphy with the Chugach National Forest Avalanche Information Center on Saturday November 13, 2010 at 7 am. 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).

ANNOUNCEMENTS

All areas designated for snowmachines are still closed. We are measuring the snow in these areas daily, and will open them as soon as there is enough snow to protect the ground and vegetation from being torn up by the tracks of a snowmachine. Thanks for your patience.

WEATHER ROUNDUP

-Not much of a storm forecasted for today

-The radar shows scattered light precip over Prince William Sound

-Winds are generally light to moderate this morning except increasing to strong at Sunburst

-Temps are about the same as yesterday morning. The freeze line made it to about 2000′ yesterday.

AVALANCHE DISCUSSION

Todays avalanche danger is LOW with pockets of MODERATE. The snow that fell 48-72 hours ago came in heavier and with strong winds. There will be some pockets of upside down snow (heavier slab on top of light density snow). These pockets will be largest near ridges, and small human-triggered avalanches will be possible on steep terrain near wind loaded ridges. Medium sized natural avalanches are possible in the form of glide cracks.

Glide Cracks-These features look like crevasses in the snow, similar to crevasses in a glacier. They go all the way down to the ground. When the release, they are slab avalanches and the ground is the weak layer. We have been seeing many of these cracks avalanche recently (within 24 hours), and we should assume that glide crack avalanches are still possible today. Avoid traveling under the path of any of these cracks. See photo gallery for an example of what glide cracks look like. New reports of recent glide crack avalanche activity came in from Main Bowl along Seattle Ridge, and at the southern end of Turnagain Pass.

*Photo shows example of Glide Crack from last year after it avalanched

*Photo shows example of Glide Cracks from last year before avalanching. Don’t travel underneath features that look like these cracks.

We are in an active Glide Crack Avalanche cycle. Avoid traveling underneath these cracks. They avalanche at random times for random reasons.

Secondary areas of concern in the snowpack are crusts and buried surface hoar. Multiple crusts have been observed near Seattle Ridge along the traditional snowmachine up-track (Repeat Offender). These crusts will most likely be the weak layers after the next big storm comes in. The first layer of buried surface hoar was reported in sheltered areas in the tree elevation near Summit Lake. We will keep our eyes on this layer.

WEATHER FORECAST (National Weather Service)

WESTERN PRINCE WILLIAM SOUND-

INCLUDING…WHITTIER…SEWARD…GIRDWOOD…MOOSE PASS

500 AM AKST SAT NOV 13 2010

.TODAY…MOSTLY CLOUDY WITH SCATTERED RAIN AND SNOW SHOWERS. HIGHS IN

THE MID 30S TO LOWER 40S. VARIABLE WIND TO 10 MPH.

.TONIGHT…MOSTLY CLOUDY WITH SCATTERED SNOW SHOWERS. LOWS IN THE

LOWER 20S TO LOWER 30S. LIGHT WINDS.

.SUNDAY…MOSTLY CLOUDY. SCATTERED SNOW AND RAIN SHOWERS IN THE

MORNING. HIGHS IN THE UPPER 20S TO UPPER 30S. VARIABLE WIND TO 10

MPH.

TEMPERATURE / PRECIPITATION

SEWARD 40 29 37 / 40 40 40

GIRDWOOD 37 27 33 / 40 40 40

Today’s Short Term Weather Model Forecasts (NAM, WRF, GFS) for the Kenai Mountains near Turnagain Pass

Sea-level: temps are forecasted between 35-40 and between 0.0-0.1” of water forecasted

3000′: temps are forecasted in the range of 23-32 degrees F with winds 10-20 mph

6000′: temps are forecasted in the range of 14-23 degrees F with winds 20 mph

WEATHER STATION SUMMARY for last 24 hours at TURNAGAIN PASS

3800′-Sunburst Wx Station

Temp (6am): 25 (same yesterday morning)

Winds: In last 24 hours winds have been light-moderate averaging 5-20mph, however, winds have been increasing since 3am averaging moderate to strong 16mph-32mph with an extreme max gust of 44mph. Temps made it as high as 28 degrees at this elevation yesterday.

2400′-Seattle Ridge Wx Station

Temp (6am): 28 (1 degree warmer than yesterday morning)

Winds: In last 24 hours have been light to moderate averaging 7-24 mph with a strong max gust of 31mph. Temps made it as high as 31 degrees at this elevation yesterday.

1800′-Center Ridge Wx Station

Temp (6am): 29 (same yesterday morning)

Precip: 0.2 inches of water, Minus 4 inches of snow due to settlement and warm temps. High temp yesterday was 35 degrees at this elevation.

Thanks for checking today’s avalanche advisory. The next one will be posted tomorrow Sunday November 14, 2010.