Happy New Year backcountry travelers, this is Matt Murphy with the Chugach National Forest Avalanche Information Center on Thursday, January 1, 2009 at 7am. This will serve as a general backcountry avalanche advisory issued for the Turnagain Arm (Turnagain Pass is the core advisory area). Local variations always occur. Note: We issue advisories 5 days a week Wednesday-Sunday.
MOUNTAIN WEATHER ROUND UP
In the last 24 hours…
-The Center Ridge weather station at 1800 feet in Turnagain Pass-
Still no data. Hopefully it will be back up and running early next week thanks to the Natural Resources Conservation Service. Those guys are awesome. They keep most of the SNOTEL weather stations running around Alaska.
-The Grandview weather station at 1100 feet along the railroad tracks-
Recorded 0 inches of water or new snow. Current temp is -8 degrees F (2 degrees warmer than yesterday)
-Sunburst weather station at 3800 feet in Turnagain Pass-
Recorded consistantly light winds averaging 5-10mph from the WNW with moderate gusts to 17 mph. Current temperature is 2 degrees F (4 degrees colder then yesterday)
-Surface Analysis Maps-
From 3 am Wednesday to 9pm last night…
There is really not much going on above us. The maps show high pressure to our north moving toward us and an old low pressure to our east. These maps also show a big storm out past the tip of the Aluetians that is getting stronger (968-953Mb). Watch out for avalanches if this storm hits us in a couple days.
The analysis from 9pm last night showed the main flow to our south going west-east toward Washington and and British Columbia. There is also a wierd north-south flow just to our west that looks like it would deflect any storm trying to head toward us. The jet stream is forecasted to change in 2 days and move in closer to us.
As of 5:30 am this morning…Shows that big storm just coming into view. CNFAIC Staff than that, there is not much going on over the top of us.
Looks pretty clear
-General Weather Observations-
Compared to yesterday…Temps are about the same at sea-level and on the ridgtops. The winds on Sunburst have been light but steady for the past 24 hours, Brrr.
PRIMARY AVALANCHE CONCERNS
-October Facets on/near the ground
SECONDARY AVALANCHE CONCERNS
-Glide Cracks (see photos)
WATCH OUT SITUATIONS
-Big steep rollovers
-Shallow snow connected to deeper snow (photo gallery)
-If you hear any “whumpfing” or feel any collapsing, then get to safe terrain immediately and call it a day.
AVALANCHE AND SNOWPACK DISCUSSION
Thanks to Sarah for the report from Tincan yesterday. She said she saw surface hoar from the parking lot to the ridgetop, and that it looked like it had grown from what she saw the day before on Sunburst. Sarah’s observations are very important for future avalanche stability. Its really critical that we keep track of where that surface hoar is forming. Please keep the observations coming in. Just click on the link on the right hand side of the screen on the “advisories” page on this website. We can all help keep each CNFAIC Staff safer by sharing information. The cold weather has been forming some really ugly weak layers on and near the current surface that are not a problem today, but will be when the next big storm hits us.
Right now, there are still some small slabs out there that are holding some energy, that could create small human-triggered avalanches on steep isolated terrain features.
Terrain management remains the key to safety with our current snowpack. Thin early season snowpacks (like what we have right now) are not ready for the big lines that Alaska is famous for. There should be plenty of opportunties for that kind of terrain in the spring. Take a look at the weather charts in the photo gallery. You will see that we have less precip and less total snow than we have in the past couple years. We all need to keep our human factors in check and stick to planar slopes with clean runouts, and avoid steep or complex terrain. Use extra caution around rocks, gullies, or steep rollovers.
We have a grab bag of weak layers near the surface that will become a problem when the next big storm comes in….
-The recent clear weather, calm winds and cold temps have created a new batch surface hoar from the highway to the ridgetops in certain areas. Try to take note of where you see these feathery crystals especially on top of those old stiff wind slabs. Let us know where you see this; so, we can pass the word on to everybody else, and have a better idea of where these potentially dangerous areas will be after the next big storm.
-This cold weather has also created a bad temperature gradient in the top 1-2 feet (~40cm) of snow. Snow temperatures taken on Saturday on Sunburst (Thanks Bill) jive with snow temps taken in Main Bowl on Tuesday 12/30/08. Basically, this means that facets are forming in the current surface snow, which can become anCNFAIC Staff bad weak layer in the near future
-There is also a mystery layer of buried surface hoar that formed about 11 days ago that got buried under a couple inches of new snow on 12/23 and 12/25. This layer was most widesread at mid elevations up to 2800 feet, but was also observed on ridgetops up to 3800 feet.
Although the loose sugary facets that formed on the ground in October are showing signs of improved stability, this layer is still a concern for avalanches, especially during and after the next big storm. Every snowpit this season shows that our snowpack consists of a dense slab on top of a weak layer of facets. Most of our stability tests show good stability on that layer of October facets right now; however, snow pits do not tell the whole story, they are only part of the entire avalanche puzzle.
The weak layer of October facets failed during the last big storm (12/8/08) and resulted in large natural avalanches that propogated across very wide areas like Todd’s Run (see photo). This weak layer also failed with human-triggers 5 days after that storm near rocky and complex terrain near steep rollovers. These human-triggered avalanches were small relative to the entire slope and did not propogate very wide. They stayed isolated to specific terrain features, but these were very dangerous for people. I’m not sure, but these facets on the ground might still be an avalanche problem after the next big storm. What do you think?
WESTERN PRINCE WILLIAM SOUND-
500 AM AKST THU JAN 1 2009
.TODAY…PARTLY CLOUDY. HIGHS 5 BELOW TO 15 ABOVE…COOLEST
INLAND. NORTHWEST WIND 10 TO 15 MPH EXCEPT NORTH TO WEST WINDS 25 TO
35 MPH IN SEWARD AND WHITTIER.
.TONIGHT…MOSTLY CLOUDY. LOWS 20 BELOW TO 10 ABOVE…COOLEST
INLAND. NORTHWEST WIND 5 TO 10 MPH EXCEPT NORTH TO WEST WINDS 25 TO
35 MPH IN SEWARD AND WHITTIER. WIND CHILLS 10 BELOW TO
.FRIDAY…MOSTLY CLOUDY WITH ISOLATED SNOW SHOWERS IN THE
MORNING…THEN PARTLY CLOUDY IN THE AFTERNOON. HIGHS 5 TO
15 ABOVE. NORTHWEST WIND 10 TO 20 MPH. WIND CHILLS 10 BELOW TO
25 BELOW IN THE MORNING.
TEMPERATURE / PRECIPITATION
SEWARD 10 1 12 / 0 0 20
GIRDWOOD 3 -6 5 / 0 0 0