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Turnagain Area Avalanche Advisory
Tuesday, February 2nd 2010 6:35 am by CNFAIC Staff
ARCHIVED ADVISORY - All advisories expire after 24 hours from the posting date/time.
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BROUGHT TO YOU BY
The Bottom Line
Good morning backcountry travelers this is Matt Murphy with the Chugach National Forest Avalanche Information Center on Tuesday February 2 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).


WEATHER ROUNDUP
The radars are clear. There are no major storms near the Gulf of Alaska. Ridgetop winds have been calm to light at all wx stations in the past 24 hours and are currently calm to light. Temps have dropped at all wx stations this morning by 2-4 degrees F compared to yesterday. Temps are mild ranging from 29 degrees F at sea-level and 25 degrees at 3800. The weather forecasts listed below do not indicate anything significant that will effect the snowpack today.


AVALANCHE DISCUSSION
Todays avalanche danger for the Turnagain Pass area will remain at LOW.

However, there are some serious concerns with the future our snowpack. The rain crust that formed on Jan 7 is still showing signs of instability in many of our pits. The stability test scores have become variable in different locations, but we still are finding some alarmingly clean shears
-look on the forecasters video button on the top left of this screen or click on http://www.youtube.com/user/ChugachAvalanche#p/a/u/0/5awB3GZSWwU

Until recently, we have been finding very consistent failures slightly above that crust. Now we are finding a wider range of stability test results from moderate failures to no failures.

We are having a hard time finding a pattern with recent stability tests, CNFAIC Staff than we are getting variable results. Maybe this variability indicates that we are moving away from a widespread future avalanche concern to more of an isolated pocket avalanche concern. We dont know where all of those isolated pockets will be; but, based on the results that you can see in the video, Id guess that the steep rolls below 2000 on the west face of Eddies could be one of those landmines.

Below 2000
There are a lot of different layers of crusts, buried surface hoar, and junky facets underneath some of those crusts at lower elevations. Keep in mind that places like Placer Valley, Kern Creek, Peterson Creek, and Girdwood Valley all have terrain that is steep with big consequences at these lower elevations. Part of the reason why our recent results on Eddies were so noteworthy is because there was a layer of surface hoar on top of the rain crust. We have not seen surface hoar on top of that crust in any of our CNFAIC Staff pits. Around Turnagain Pass, we know that the biggest surface hoar crystals this year have formed at elevations less than 2000. We need more information about this dangerous combination, but I dont like it.

Above 2000
We have a persistent weak layer of light density snow between the rain crust and the softer snow on the surface. For the most part, this weak layer has not been reactive to human triggers since Jan 17, but it shows up in most of our test pits. One theory is that it does not have enough of a slab or load on top of it yet. For the most part, the actual rain crust goes up to about 3000, but we have been finding a smooth bed surface up to ridgetops near 4000 that formed during the same storm on Jan 7. This bed surface has been showing similar results as the rain crust.

Part of the reason we keep dwelling on this problem is because the snow above the rain crust has a poor structure with all 3 of the main ingredients for avalanches: a bed surface (slippery rain crust), a weak layer (lighter density snow sitting on top of rain crust), and a slab of denser snow on top that weaker snow.

We will most likely not see any major problems till we get a RAPID change of snow, wind, or temperature.

Always remember that safe backcountry travel requires training and experience. You control your own risk by choosing where, when, and how you travel.

Thanks for checking todays avalanche advisory. The next one will be posted tomorrow Wednesday February 3.

WEATHER FORECAST (National Weather Service)

WESTERN PRINCE WILLIAM SOUND-
INCLUDING...WHITTIER...SEWARD...GIRDWOOD...MOOSE PASS
500 AM AKST TUE FEB 2 2010
.TODAY...SKIES BECOMING PARTLY CLOUDY BY AFTERNOON. AREAS OF FOG IN
THE MORNING. HIGHS IN THE UPPER 20S TO MID 30S. LIGHT WINDS EXCEPT
NORTH 15 MPH NEAR SEWARD.
.TONIGHT...PARTLY CLOUDY IN THE EVENING...THEN MOSTLY CLOUDY WITH
ISOLATED SNOW SHOWERS AFTER MIDNIGHT. PATCHY FOG AFTER MIDNIGHT.
LOWS 10 TO 25 ABOVE. LIGHT WINDS EXCEPT NORTH 15 MPH NEAR SEWARD AND
WEST 15 MPH NEAR WHITTIER

Temperature / Precipitation
SEWARD 34 22 24 / 0 20 20
GIRDWOOD 32 21 21 / 0 20 0


Short Term Weather Model Forecasts (NAM, WRF, GFS) for the Kenai Mountains near Turnagain Pass
Sea-level: GFS shows .05 inches of water forecasted today
3000: temps are forecasted between 23-32 degrees F with winds 5 mph
6000: temps forecasted between 14-23 degrees F with winds 5 mph

 Show the Complete North American Avalanche Danger Scale
1 Low Alpine / Above 2,500' Travel Advice: Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.
1 Low Treeline / 1,000'-2,500' Travel Advice: Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.
1 Low Below Treeline / Below 1,000' Travel Advice: Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.

This is 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).

Winter snowmachine use open/closed status and riding conditions updates

Riding status is not associated with avalanche danger. An area will be open to motorized use in accordance to the Forest Management Plan when snow coverage is adequate to protect underlying vegetation. Backcountry hazards including avalanche hazard are always present regardless of the open status of motorized use areas.

(Updated: Jan 13, 2019 )

AREA STATUS WEATHER AND RIDING CONDITIONS
Glacier District
Johnson Pass: Open
Placer River: Open
Skookum Drainage: Open
Turnagain Pass: Open
Twentymile: ClosedClosed. Forest Service is monitoring conditions.
Seward District
Carter Lake: Open
Lost Lake Trail: OpenPlease stay on trail to avoid resource damage through forested areas.
Primrose Trail: OpenPlease stay on trail to avoid resource damage through forested areas.
Resurrection Pass Trail: ClosedClosed for the 2018/19 season. Next season will be open to motorized use.
Snug Harbor: Open
South Fork Snow River Corridor: Open
Summit Lake: Open

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The information in this advisory is from the U.S. Forest Service, which is solely responsible for its content. This advisory describes general avalanche conditions and local variations always occur. This advisory provided by the Chugach National Forest, in partnership with Friends of the Chugach National Forest Avalanche Information Center.


USFS SNOW AND AVALANCHE HOTLINE (907) 754-2369
If you have comments or questions regarding CNFAIC operations or winter recreation management, please email staff@chugachavalanche.org
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