CNFAIC LogoCNFAIC Logo
Turnagain Area Avalanche Advisory
Tuesday, December 22nd 2009 6:54 am by CNFAIC Staff
ARCHIVED ADVISORY - All advisories expire after 24 hours from the posting date/time.
Previous ForecastNext Forecast
BROUGHT TO YOU BY
The Bottom Line
Good morning backcountry travelers this is Lisa Portune with the Chugach National Forest Avalanche Information Center on Tuesday, December 22 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
Placer River Drainage is open to snowmachining. Twentymile remains closed.

WEATHER ROUNDUP
In the last 24 hours, 5 inches of new snow fell in Turnagain Pass and 3 inches fell in Summit Lake with possibly up to 10 inches at the higher elevations. The winds were nuking yesterday from sea level to the ridgetops, and it proceeded to rain down low on the first day of winter. Turnagain Pass saw gale to storm-force east winds yesterday averaging 35-45mph with gusts in the 60s and 70s. The winds at Summit Lake averaged 25-40mph with gusts in the 50s and 60s. Mountain temperatures ranged from the mid 20s to low 30s while the rain/snow line in Turnagain Pass hovered around 600-700 feet.
As of 4 am this morning, ridgetop winds are currently averaging 20-40mph out of the east to southeast with gusts in the 40s and 50s in Turnagain Pass and Summit Lake. It is lightly raining in Girdwood right now with temperatures ranging from 38F at sea level to 22F at 3800 feet. The storm force front over the western gulf will gradually weaken today with the rain and snow tapering off by this evening. Hot on its tail, however, is anCNFAIC Staff strong low, so get ready for round two tomorrow. Expect east winds decreasing to 15-30mph today along with a couple more inches of snow at the higher elevations. Mountain temperatures will remain on the warm side, ranging from the low 20s to low 30s.

-The Center Ridge Wx Station at 1800 feet/Turnagain Pass-
recorded 5 inches of new snow and 0.4 inches of water in the last 24 hours. The current temp is 30F (2 degrees colder than yesterday) with a total snowpack depth of 58 inches.

-The Sunburst Wx Station at 3800 feet/Turnagain Pass-
recorded gale to storm-force east winds the last 24 hours averaging 35-45mph with gusts in the 60s and 70s. The current temp is 22F (same as yesterday) with winds averaging 40 mph out of the east.

-The Summit Lake Wx Station at 1200 feet-
recorded 3 inches of new snow and 0.1 inches of water in the last 24 hours. The current temp is 30F (1 degree colder than yesterday) with a total snowpack depth of 32 inches.

-The Fresno Ridge Wx Station at 3400 feet/Summit Lake-
recorded strong to gale-force southeasterly winds the last 24 hours averaging 25-40mph with gusts in the 50s and 60s. The current temp is 23F (2 degrees colder than yesterday) with winds averaging 30mph out of the southeast.

The weather forecast for:
WESTERN PRINCE WILLIAM SOUND-
INCLUDING...WHITTIER...SEWARD...GIRDWOOD...MOOSE PASS

500 AM AKST TUE DEC 22 2009

...STRONG WIND TODAY THROUGH PORTAGE VALLEY AND TURNAGAIN ARM...
...STRONG WIND WEDNESDAY MORNING THROUGH WEDNESDAY NIGHT...

.TODAY...RAIN AND SNOW TAPERING OFF TO SHOWERS THIS AFTERNOON. SNOW
ACCUMULATIONS SNOW SHOWERS AND RAIN. SNOW ACCUMULATION 1 TO 4 INCHES.
HIGHS IN THE MID 30S TO LOWER 40S. NORTH TO EAST WINDS 15 TO 30 MPH
DECREASING TO 10 TO 20 MPH IN THE AFTERNOON. THROUGH PORTAGE
VALLEY AND TURNAGAIN ARM...EAST WIND 35 TO 50 MPH DECREASING TO
TO 30 MPH IN THE AFTERNOON.
.TONIGHT...RAIN AND SNOW LIKELY. SNOW ACCUMULATION 1 TO 4 INCHES.
LOWS IN THE UPPER 20S TO MID 30S. NORTH TO EAST WINDS 15 TO 25 MPH
WITH GUSTS TO 40 MPH.
.WEDNESDAY...SNOW AND RAIN. SNOW ACCUMULATION 1 TO 4 INCHES.
HIGHS IN THE MID 30S TO LOWER 40S. NORTH TO EAST WINDS 15 TO 30 MPH
WITH GUSTS TO 50 MPH. HIGHER GUSTS TO 65 MPH THROUGH PORTAGE VALLEY
AND ALONG TURNAGAIN ARM.

TEMPERATURE / PRECIPITATION

SEWARD 38 31 39 / 100 80 80
GIRDWOOD 36 29 37 / 100 50 60


AVALANCHE DISCUSSION
Gale to storm-force winds plus 5-10 inches of new snow in the last 24 hours means that human-triggered avalanches are likely on steep windloaded slopes. Although the snow and wind will taper off today, the snowpack is still adjusting to this heavy load from new and windblown snow. For today, the avalanche danger is rated CONSIDERABLE on all wind-loaded slopes steeper than 35 degrees. All CNFAIC Staff slopes have a MODERATE danger. Careful snowpack evaluation, cautious routefinding, and conservative decision-making are essential today.

Yesterday and last nights wind and new snow added considerable energy to the snowpack and increased the avalanche hazard. The good news is the warm temperatures are pasting together these new windslabs. Keep in mind, however, these warm dense slabs are sitting on weak faceted snow that formed the second week of December during the inversion, most notably at the low to mid elevations up to 2500 feet.

Jon and I toured up to the top of the alders on Sunburst yesterday looking to see how the buried surface hoar was reacting to the extra load from windblown snow. We stayed off the upper slopes because a) we couldnt see anything above treeline and b) the wind was blowing so hard it sounded like freight trains roaring down the mountainside. The biggest, most well-preserved surface hoar is below 2000 feet on protected slopes below treeline. From 1000 to 2000 feet elevation, the surface hoar was buried under 6 inches of warm slabby snow and was not reactive on any of our tests slopes. This is still not enough of a load to cause problems on this layer. Newly-formed surface windslab, about 1-4 inches thick at these lower elevations, easily cracked around our splitboards as we skinned up. This was just a small scale version of what was going on up higher.

Carl 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

 Show the Complete North American Avalanche Danger Scale
3 Considerable Alpine / Above 2,500' Travel Advice: Dangerous avalanche conditions. Careful snowpack evaluation, cautious routefinding and conservative decision-making essential.
3 Considerable Treeline / 1,000'-2,500' Travel Advice: Dangerous avalanche conditions. Careful snowpack evaluation, cautious routefinding and conservative decision-making essential.
3 Considerable Below Treeline / Below 1,000' Travel Advice: Dangerous avalanche conditions. Careful snowpack evaluation, cautious routefinding and conservative decision-making essential.

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: Mar 22, 2019 )

AREA STATUS WEATHER AND RIDING CONDITIONS
Glacier District
Johnson Pass: Open
Placer River: ClosedClosed as of 3.20.19 due to lack of snow.
Skookum Drainage: ClosedPlacer access closed as of 3.20.19 due to lack of snow.
Turnagain Pass: Open
Twentymile: ClosedClosed as of 3.20.19 due to lack of snow.
Seward District
Carter Lake: Open
Lost Lake Trail: ClosedClosed as of 3/22. Unfortunately HEAVY rain over the past week has washed much of the snow off the lower stretches of this trail.
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: ClosedClosed as of 3.20.19 due to lack of snow.
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
© 2019 Chugach National Forest Avalanche Information Center. All rights reserved.
FCNFAIC