Good morning backcountry travelers this is Lisa Portune with the Chugach National Forest Avalanche Information Center on Sunday, November 14th at 7am. 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).
All areas designated for snowmachines are still closed. We are measuring the snow in these areas daily and will open them as soon as there is enough snow to protect the ground and vegetation from being torn up by the tracks of a snowmachine. Thanks for your patience.
For the first time in 2 weeks, no new snow fell in the last 24 hours in Turnagain Pass. Ridgetop winds were light yesterday, averaging 5-15 mph out of the southeast, while mountain temperatures ranged from the mid 30’s at the middle elevations to the mid 20’s at the upper elevations. Looking out my window at 4am this morning, I see partial clearing through the clouds and a trace of snow on my car. Mountain winds are currently averaging 5-10mph out of the southeast while temperatures this morning range from 22F@3800′ to 27F@1800′ to 31F@sealevel. We may see some scattered snow showers today before a big blocking ridge of high pressure moves over mainland Alaska tomorrow. That means dry, cold, and windy conditions for the next week. Ridgetop winds should be on the light side today, averaging 5-15 mph out of the west, while mountain temperatures will be slightly cooler than yesterday.
Today the avalanche danger remains at LOW overall with areas of MODERATE hazard underneath glide cracks and on steep windloaded terrain near ridgetops. Areas of sensitive windslab still exist at the higher elevations above treeline, so use extra caution before dropping in to steep lines. Yesterday a skier triggered an avalanche on Superbowl Peak on recently formed windslab.
The photo above shows the skier-triggered avalanche from yesterday. The slide ran 800 feet down into the bowl and measured 60-80 feet wide with a crown face of 1.5 to 2 feet deep. The skier most likely triggered it directly underneath his skis judging from the tracks. The cracks propagating off of main crown line indicate a decent amount of stored energy in the slab. Jon and I toured up Tincan yesterday and also found touchy windslab off the southern ridgeline around 3000 feet. 6-12 inch thick windslab fractured easily in my snowpit while CNFAIC Staff skiers reported shooting cracks up higher. These are certainly signs of lingering instability on windloaded slopes, especially at elevations above 3000 feet where colder temperatures keep instabilities around longer. We have yet to find any buried surface hoar in Turnagain Pass, but several folks have found it in the Summit Lake area up to 3200 feet buried 2-3 feet down.
As far as current snow conditions in Turnagain Pass, the surface rain crust disappears around 1500 feet and transitions to powder up to treeline. Above treeline, the snow surface consists of powder, breakable windslab, hard supportable windslab, and sastrugi on the ridgelines.
There are so many glide cracks out there right now I’ve lost count. We are still in an active avalanche cycle with these things, so give them a wide berth. Jon and I saw a few fresh glide avalanches yesterday on our drive up to Turnagain Pass. Lucky for us, we can actually see the hazard and avoid it.
I 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 SUN NOV 14 2010
.TODAY…MOSTLY CLOUDY IN THE MORNING THEN BECOMING PARTLY
CLOUDY. ISOLATED RAIN AND SNOW SHOWERS. HIGHS IN THE 30S.
LIGHT WINDS EXCEPT WEST 10 TO 20 MPH NEAR WHITTIER.
.TONIGHT…PARTLY CLOUDY IN THE EVENING…THEN MOSTLY CLOUDY WITH
ISOLATED SNOW SHOWERS AFTER MIDNIGHT. LOWS IN THE LOWER 20S TO
LOWER 30S. VARIABLE WIND TO 10 MPH. NEAR SEWARD…LIGHT WINDS
BECOMING NORTH 10 TO 20 MPH AFTER MIDNIGHT.
.MONDAY…MOSTLY CLOUDY WITH ISOLATED SNOW SHOWERS IN THE
MORNING…THEN PARTLY CLOUDY IN THE AFTERNOON. HIGHS IN THE LOWER
20S TO LOWER 30S. VARIABLE WIND 10 MPH. NEAR SEWARD…NORTH WIND
INCREASING TO 25 TO 35 MPH IN THE AFTERNOON. NEAR WHITTIER…WEST
WIND INCREASING TO 35 MPH IN THE AFTERNOON.
TEMPERATURE / PRECIPITATION
SEWARD 38 26 28 / 20 0 0
GIRDWOOD 35 23 27 / 30 20 20
WEATHER STATION SUMMARY for Turnagain Pass:
-3800′ Sunburst Wx Station-
recorded light southeasterly winds yesterday averaging 5-10mph. The high temp yesterday was 25F. The current temp is 22F with light and variable and winds.
-2600′ Seattle Ridge Wx Station-
recorded light southeasterly winds yesterday averaging 5-15mph. The high temp yesterday was 29F. The current temp is 24F with winds averaging 10mph out of the southeast.
-1800′ Center Ridge Wx Station-
recorded no new snow in the last 24 hours. The high temp yesterday was 35F at 2pm. The current temp is 27F with a total snowpack depth of 51 inches (minus 2 inches due to settlement in the last 24 hours).