Saturday, February 19th 2011 6:58 am by Kevin Wright
ARCHIVED ADVISORY - All advisories expire after 24 hours from the posting date/time.
The avalanche hazard rating is MODERATE with a complex set of specific concerns. Weather today could dramatically change the avalanche conditions in the new storm snow depending on what happens. Pockets of CONSIDERABLE danger are possible in specific areas that got more snow and more wind. Human triggered sluffs (point releases) are certain today and isolated pockets of soft windslab are likely. If any areas get significant wind the resulting slabs could be easily triggered and dangerous.
Yesterdays snowfall was light and dry, measuring 8 inches through the Turnagain Pass region. A couple more inches fell overnight. Human triggered sluffs were easily triggered off the steeper slopes and they fell long distances. The sluffing that we witnessed was confined to the upper inches of the new storm snow. The new snow was quite loose, but specific areas had just the smallest bit of cohesiveness, which made slabbing possible in isolated areas. The light density will make it easily affected by changing weather conditions including wind and heat from the sun, which could make wider slabbing a fast change this afternoon.
Summit lake had the largest regional snowfall that we know of and combined with the weakest old layers this could be a dangerous combination today. CNFAIC Staff areas that got more snow or more wind could be dangerous as well. Its important for the individual to assess the changes as they happen this afternoon. This light, dry snow will be prone to rapid change to more dangerous avalanche conditions if subjected to the right circumstances. Wind transport could move a lot of snow quickly and form triggerable slabs. Were getting to the warmer side of winter when the sun has heat to it. South facing slopes could catch enough sun today to cause natural sluffing or natural slab release in the new storm snow.
We cant forget about the old deep slab concerns quite yet. New snow and stress will make it more likely to trigger these deeper slabs, especially in the shallow zones around Summit lake and the Interior Kenai. The worst case scenario today would be triggering a soft slab in the new storm snow that stepped down into the older persistent weak layers and started a larger avalanche. This will be less likely but difficult to predict and much more dangerous than the new storm snow. Check out an example of a recent avalanche that happened this way: See photo and analysis here.
(OUTSIDE FORECAST AREA)
The Hatcher Pass road was closed last night due to avalanche concerns. A reported avalanche put debris across the road 1 mile above Archangel road. Officials will be assessing the hazard this morning to possibly reopen the road today.
Encyclopedia of avalanche terms.
Yesterdays storm was widespread from Anchorage to Portage and put more snow in less likely areas. Summit lake got 12 inches, Turnagain Pass 8 10 inches, and Girdwood 10 inches. Temperatures remained cold to sea level and wind was mostly confined to Turnagain Arm. Clear skies are expected today with wind near Whittier and Seward. Currently wind at the ridgetops is light to moderate, with a chance to increase through the day. Temperatures should remain in the teens and 20s this afternoon.
The Forest Service is installing winter use bridges across Granite creek in Turnagain Pass. Be aware of an ice road from the Lyon creek bridge south towards Johnson Pass on the West side of the highway. Heavy equipment will also be used in the area.
The Friends of the CNFAIC (FCNFAIC) needs your thoughts! With a new staff of forecasters and a list of previously completed goals, the program is growing and potentially heading in new directions. The FCNFAIC wants to know what you have to say about YOUR avalanche center, so please complete the following anonymous survey by February 20th. Thank you in advance for taking it!
Click here to take survey
or cut and paste the address directly:
Wendy 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-
500 AM AKST SAT FEB 19 2011
...STRONG WIND THIS MORNING THROUGH LATE TONIGHT NEAR WHITTIER...
.TODAY...DECREASING CLOUDS IN THE MORNING...BECOMING MOSTLY SUNNY IN
THE AFTERNOON. BLOWING SNOW NEAR WHITTIER. HIGHS IN THE 20S...COOLEST
INLAND. NORTHWEST WIND 10 TO 20 MPH EXCEPT WEST 30 TO 50 MPH NEAR
WHITTIER AND NORTH 15 TO 30 MPH NEAR SEWARD.
.TONIGHT...MOSTLY CLEAR. BLOWING SNOW NEAR WHITTIER. LOWS ZERO TO 15
ABOVE...COOLEST INLAND. NORTHWEST WIND 10 TO 20 MPH EXCEPT WEST 30 TO
50 MPH NEAR WHITTIER AND NORTH 15 TO 30 MPH NEAR SEWARD.
.SUNDAY...PARTLY CLOUDY IN THE MORNING THEN BECOMING MOSTLY
CLOUDY WITH ISOLATED SNOW SHOWERS. HIGHS IN THE LOWER TO MID 20S.
NORTH AND WEST WIND 10 TO 15 MPH EXCEPT WEST 20 TO 35 MPH NEAR
.SUNDAY NIGHT...MOSTLY CLOUDY IN THE EVENING THEN BECOMING PARTLY
CLOUDY. LOWS 10 TO 20 ABOVE...COOLEST INLAND. WEST WIND 10 TO 25 MPH
EXCEPT WEST 30 TO 45 MPH NEAR WHITTIER.
.WASHINGTONS BIRTHDAY...PARTLY CLOUDY. HIGHS IN THE 20S. NORTHWEST
WIND 15 TO 30 MPH EXCEPT WEST 30 TO 45 MPH NEAR WHITTIER.
.MONDAY NIGHT...MOSTLY CLEAR. LOWS 5 TO 15.
TEMPERATURE / PRECIPITATION
SEWARD 29 13 27 / 0 0 20
GIRDWOOD 22 12 21 / 0 0 20
WEATHER STATION SUMMARY for Turnagain Pass:
-3800 Sunburst Wx Station-
Temperature 7 degrees and falling. Recent max gust to 15 from the WNW.
-2600 Seattle Ridge Wx Station-
Temperature 10 on a decreasing trend. Max gust in the last hour of 23 from the NW.
-1800 Center Ridge Wx Station-
Temperature 14 degrees and decreasing. 8 inches new snow yesterday, anCNFAIC Staff 2 last night with some settlement. Density estimated at 8%.
|Show the Complete North American Avalanche Danger Scale|
|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).
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: Feb 15, 2018 )
|AREA||STATUS||WEATHER AND RIDING CONDITIONS|
|Johnson Pass:||Open||Please access trail thru open gate and park trucks/ trailers along the road toward the trailhead. Please keep the turnaround (near large signboard) clear for vehicles to TURN AROUND!|
|Turnagain Pass:||Open||Please avoid riding on “Rookie Hill“ and other areas with exposed vegetation. Thank you!|
|Carter Lake:||Open||Open 2/16.|
|Lost Lake Trail:||Closed|
|Resurrection Pass Trail:||Open||Resurrection Pass trail is open to snowmachine use during the 2017/18 winter season.|
|South Fork Snow River Corridor:||Closed|
SNOW AND AVALANCHE HOTLINE (907) 754-2369
If you have comments or questions regarding CNFAIC operations or winter recreation management, please email email@example.com
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