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Turnagain Area Avalanche Advisory
Thursday, March 4th 2010 7:00 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 Thursday March 4th, 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).


WEATHER ROUNDUP
-The winds have backed off at all ridge top weather stations this morning. Average winds speeds are light this morning between 5mph-16mph with strong gusts up to 34mph.
-In the last 24 hours (5am-5am), the snotel sites recorded: 1.2 inches of water at Turnagain Pass with 11 inches of new snow, 1.4 inches of water and 14 inches of new snow at Grandview, and 0.2 inches of water and 6 inches snow at Summit Creek.
-The current radar shows most of the precip over Prince William Sound hitting Cordova, but the Kenai radar shows quite a bit of precip directly over the Kenai Mountains.
-Temps the same at most weather stations compared to yesterday ranging from 32 degrees F at sea-level and 20 degrees F at 3800.


AVALANCHE DISCUSSION
Todays avalanche danger will decrease to CONSIDERABLE due to a less intense weather forecast for the next 24 hours, but dangerous avalanche conditions still exist. Natural avalanches occurred yesterday morning 3/3/2010 and are still possible today, but the more dangerous aspect to todays snowpack will be human triggered avalanches which will be likely on slopes steeper than 35 degrees.

Yesterday, the snowpack was reactive to a variety of triggers. Human and artificially triggered avalanches created medium sized avalanches in the top 1-2 feet of new storm snow. Natural avalanches were observed on Lipps and Pyramid around Turnagain Pass, and several naturals were reported in Girdwood Valley. Most of these avalanches probably happened early yesterday morning 3/3/2010, but the wind covered them up and made them difficult to see from a distance. Odds are,there were more natural avalanches around the area Turnagain Arm area, but we could not see them. Long story short, whenever natural avalanches happen, its wise to give the snowpack at least 24-48 hours to settle down before venturing into aggressive terrain. Remember that 90% of avalanches happen during storms and within 24 hours following a storm. We are still in that window, dont take your chances on steep slopes today.

The structure of the snowpack has been showing signs for the past 2 days that it is too weak on steep slopes for this recent load of snow and wind slabs. Most of the observed or reported avalanches have been small to medium in size, but that is all it takes to bury a skier, snowmachiner, or snowboarder.

Today, the size of avalanches could be bigger because Turnagain Pass received anCNFAIC Staff 1.2 of water and 11 of snow in the last 24 hours. That brings the total to 3.5 inches of water and over 25 inches of new snow at 1800 (more snow at higher elevations) in the past 72 hours. All this new snow is sitting on top of a slippery bed surface. There is over 3 feet of snow on top of that slippery bed surface in places like Tincan; so, that layer is becoming a deep slab problem. We need to give the mountains some time to adjust to this new snowpack.

Traveling on big slopes steeper than 35 degrees will be dangerous today. The type of storm snow that we have is tricky because these are the types of conditions that require precise trigger points where the 2nd, 3rd, or 4th person finds that specific trigger point and creates a deep avalanche that is too difficult to escape. A lot of times these trigger points are on steep rollovers in the middle of a slope where you are too committed to escape the slab. Slabs underneath rock bands are anCNFAIC Staff common trigger point in these types of conditions.


WEATHER FORECAST (National Weather Service)
WESTERN PRINCE WILLIAM SOUND-
INCLUDING...WHITTIER...SEWARD...GIRDWOOD...MOOSE PASS
510 AM AKST THU MAR 4 2010

...HIGH WIND WATCH IN EFFECT FROM FRIDAY MORNING THROUGH FRIDAY
EVENING THROUGH PORTAGE VALLEY AND TURNAGAIN ARM...

.TODAY...SNOW IN THE MORNING...THEN SCATTERED SNOW SHOWERS IN THE
AFTERNOON. SNOW ACCUMULATION UP TO 3 INCHES. HIGHS IN THE MID 20S
TO MID 30S. VARIABLE WIND 10 MPH BECOMING SOUTHEAST 10 TO
20 MPH IN THE AFTERNOON.
.TONIGHT...SCATTERED SNOW SHOWERS IN THE EVENING...THEN SNOW
AFTER MIDNIGHT. AREAS OF BLOWING SNOW WILL REDUCE VISIBILITIES TO
LESS THAN A MILE AT TIMES. SNOW ACCUMULATION 2 TO 5 INCHES. LOWS IN
THE MID 20S TO LOWER 30S. SOUTHEAST WIND 15 TO 30 MPH. THROUGH
PORTAGE VALLEY AND TURNAGAIN ARM...SOUTHEAST WIND 15 TO 25 MPH
INCREASING TO 35 TO 50 MPH AFTER MIDNIGHT.
.FRIDAY...SNOW IN THE MORNING...THEN SNOW AND RAIN IN THE
AFTERNOON. SNOW ACCUMULATION 3 TO 7 INCHES. HIGHS IN THE 30S.
SOUTHEAST WIND 15 TO 30 MPH EXCEPT SOUTHEAST 65 TO POSSIBLY 85 MPH
THROUGH PORTAGE VALLEY AND TURNAGAIN ARM.

Temperature / Precipitation
SEWARD 33 26 37 / 80 80 80
GIRDWOOD 36 27 36 / 100 60 80


Short Term Weather Model Forecasts (NAM, WRF, GFS) for the Kenai Mountains near Turnagain Pass
Sea-level: temps are forecasted between 27-36 and between 0.25 of water forecasted
3000: temps are forecasted in the range of 23-32 degrees F with winds 10 mph
6000: temps are forecasted in the range of 14-23 degrees F with winds 10-30 mph

WEATHER STATION SUMMARY for last 24 hours at TURNAGAIN PASS
3800-Sunburst Wx Station
Current Temp: 20 (same as yesterday)
Winds: In last 24 hours winds have been light to strong averaging 5-32mph with extreme gusts up to 52mph

2600-Seattle Ridge Wx Station
Winds: In last 24 hours winds have been light to moderate averaging 5-25mph with an extreme gust of 41mph

1800-Center Ridge Wx Station
Current Temp: 27 degrees (same as yesterday)
Precip: 1.2 new water, 11 new snow, total snowpack depth of 121

Thanks for checking todays avalanche advisory. The next one will be posted tomorrow Friday March 5, 2010.

 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: 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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