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Turnagain Area Avalanche Advisory
Wednesday, March 24th 2010 6:52 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 Wednesday March 24th, 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
This week is Telepalooza week at Alyeska Resort. There are lots of great events and a fundraiser for the Friends of the Chugach National Forest Avalanche Information Center. Check Alyeska Resort's webpage or www.telepalooza.com for a detailed schedule of events.

WEATHER ROUNDUP
-The winds have backed off and are averaging light to moderate in the 1-25mph range at all ridge top wx stations with strong gusts up to 33mph at Sunburst
-In the last 24 hours (5am-5am), the snotel sites recorded:
0.4 inches of water and 6 inches of new snow at Turnagain Pass
0.6 inches of water and 7 inches of new snow at Grandview
0.0 inches of water and 0 inches of new snow Summit Creek.
-The current radars show scattered moderate precip circulating over Prince William Sound and light precip over the southern Kenai Peninsula
-Temps have increased slightly at all weather stations this morning by 1-3 degrees. Temps at 5am range from 30 degrees F at sea-level and 23 degrees F at 3800.


AVALANCHE DISCUSSION
Todays avalanche danger has increased to MODERATE with pockets of CONSIDERABLE, due to new snow and wind on top fairly poor structured snowpack with buried surface hoar on top of a crust in the top 3 feet.

There is a lot of spatial variability in the snowpack right now including multiple layers of buried surface hoar and buried suncrusts in the top 3 feet of snow. There is a 1 inch thick breakable crust on all aspects up to about 1500-2000. Mid elevations to ridge top elevations generally have multiple buried suncrusts on southern aspects, but these crusts are very aspect dependent and do not wrap around to CNFAIC Staff aspects. Northern aspects at Turnagain Pass are generally thin, cold, and faceted similar to intermountain or continental snowpacks in the lower 48.

There are three main concerns right now:
1. A sun crust with surface hoar on top of this crust is now buried under yesterdays snow. We observed surface hoar on top of this crust in multiple locations. There will likely be some small wind slabs out there today sitting on top of this weak layer on wind loaded slopes.
2. A sun crust that is buried 2-3 feet deep (we have observed surface hoar near this crust) We have been finding moderate to hard failures with smooth shear planes on top and underneath this crust. It might become more reactive with a heavier load on top of it.
3. Multiple layers of buried surface hoar in the top 1-3 feet of snow

Yesterday on a northern Cornbisuit chute, we found a really bad weak layer of facets on top of a block of melt-freeze snow. This adds one more item to our list of spatial variability. Its important to remember that the northern aspects at Turnagain Pass have a completely different snowpack than the southern aspects that most people ski through the season. Its common for people to start exploring these northern aspects this time of year. Its a good idea to approach northern aspects with a different mindset. These aspects are commonly thin and rocky due to predominant winds, and colder due to aspect. It is common to find more facets near these rocky northern aspects.

We know there have been several surface hoar events that have been buried on all aspects over the past couple weeks, but it has been very difficult to find these layers of buried surface hoar in most of our snow stability pits; however, some layers of buried surface hoar have been confirmed in places like: Sunburst, Cornbiscuit, and Spokane Creek.

In our stability tests, its been easy to find moderately clean shears with sparkly snow on top of the shear plane, but we have mostly been find broken stellars on top and underneath these crusts instead of buried surface hoar. Its hard to tell the difference with the naked eye; so, it would be wise to take a closer look with a magnifying glass to confirm if the slope you are about to ski has buried surface hoar on top of any crusts. We know that the surface hoar is buried out there in isolated pockets, but its hard to say exactly where.

There is still not a huge slab on top of these crusts and layers of buried surface hoar in many places, but these types of weak layers have the potential create those surprise avalanches in places like steep rocky terrain or on basketball shaped rollovers on wind loaded slopes.

Glide cracks are secondary concern today. These crevasse like features are those cracks that go all the way to the ground. One of these glide cracks avalanched on Friday or Saturday on the southern aspect of Tincan to the lookers left of Tincan Proper (see photo gallery).


WEATHER FORECAST (National Weather Service)
WESTERN PRINCE WILLIAM SOUND-
INCLUDING...WHITTIER...SEWARD...GIRDWOOD...MOOSE PASS
500 AM AKDT WED MAR 24 2010
.TODAY...NUMEROUS RAIN AND SNOW SHOWERS. UP TO 2 INCHES WET
SNOW ACCUMULATION THROUGH TURNAGAIN PASS. HIGHS 35 TO 40.
NORTH TO EAST WIND 10 TO 25 MPH BECOMING VARIABLE 5 TO 15 MPH
IN THE AFTERNOON.
.TONIGHT...MOSTLY CLOUDY. SCATTERED SNOW AND RAIN SHOWERS
IN THE EVENING...THEN ISOLATED SNOW SHOWERS AFTER MIDNIGHT.
LOWS IN THE LOWER 20S TO LOWER 30S...COLDEST INLAND.
VARIABLE WIND TO 15 MPH.
.THURSDAY...MOSTLY CLOUDY. SCATTERED RAIN AND SNOW SHOWERS
ALONG THE COAST. HIGHS AROUND 40. VARIABLE WIND TO 10 MPH.

TEMPERATURE / PRECIPITATION

SEWARD 38 28 38 / 60 20 30
GIRDWOOD 39 27 40 / 60 30 0


Short Term Weather Model Forecasts (NAM, WRF, GFS) for the Kenai Mountains near Turnagain Pass
Sea-level: temps are forecasted between 27-39 and between 0.0-0.25 of water forecasted
3000: temps are forecasted in the range of 23-32 degrees F with winds 5-10 mph
6000: temps are forecasted in the range of 14-23 degrees F with winds 10-20 mph

WEATHER STATION SUMMARY for last 24 hours at TURNAGAIN PASS
3800-Sunburst Wx Station
Temp (4am): 23 (3 degrees warmer than yesterday morning)
Winds: In last 24 hours winds have been light to moderate averaging 3-23mph with a strong max gust of 33mph

2600-Seattle Ridge Wx Station
Temp (4am): 27 (3 degree warmer than yesterday morning)
Winds: In last 24 hours winds have been light to moderate averaging 1-18mph with a moderate max gust of 32mph

1800-Center Ridge Wx Station
Current Temp: 30 (3 degrees warmer than yesterday morning)
Precip: 0.4 new water 6 new snow


Thanks for checking todays avalanche advisory. The next one will be posted tomorrow Thursday March 25, 2010.

 Show the Complete North American Avalanche Danger Scale
2 Moderate Alpine / Above 2,500' Travel Advice: Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.
2 Moderate Treeline / 1,000'-2,500' Travel Advice: Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.
2 Moderate Below Treeline / Below 1,000' Travel Advice: Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.

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

Subscribe to the Turnagain Area Avalanche Advisory:

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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