Good morning backcountry travelers, this is Carl Skustad with the Chugach National Forest Avalanche Information Center on Saturday, January 3, 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 -13 degrees F (5 deg colder than yesterday)
-Sunburst weather station at 3800 feet in Turnagain Pass-
Recorded moderate NW winds in the mid to upper teens. Current temperature is -16 degrees F (7 degrees colder then yesterday)
-Surface Analysis Maps-
There is a weak low pressure system centered in the gulf (993mb). Strong high pressure remains over south central AK for the weekend. The next low is SE of Kamchatka and will make it’s way to us next week.
-General Weather Observations-
Temperatures dropped again over night. Stations are reporting -9 to -24 F. Winds have picked up slightly, predominately out of the NW, 10 to 20 mph. We did see a few gust reaching 30 mph yesterday and sum snow was noticed being transported on remote ridgetops. We can expect the cold and dry conditions to last into next week.
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
AnCNFAIC Staff day of bitter cold on tap. Summit and Moose Pass are the cold spots, recording -23 deg F. Watch yourself and your partners for signs of frost bite today.
Not much change today or the last few for that matter. If you venture into the cold this weekend you will find mostly clear skies and diamond like snow. Our snow surface is full of surface hoar and near surface facets. This surface condition is very important to remember as it will be our next week layer when buried. You will also find isolated wind slabs in high alpine areas where windy conditions are common. Areas that come to mind include, Upper Winner Creek and Twentymile, Settle Ridge, and Pastoral. Predominant winds have been out of the northwest.
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. Normal travel caution is advise!
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 opportunities 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 widespread 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 propagated 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 propagate 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 SAT JAN 3 2009
.TODAY…MOSTLY SUNNY IN THE MORNING THEN BECOMING PARTLY CLOUDY.
HIGHS 5 BELOW TO 10 BELOW EXCEPT AROUND 10 ABOVE NEAR SEWARD AND
WHITTIER. NORTHWEST WIND 10 TO 25 MPH. GUSTS TO 40 MPH NEAR WHITTIER
DURING THE MORNING. WIND CHILLS 10 BELOW TO 25 BELOW IN THE MORNING.
.TONIGHT…MOSTLY CLEAR. LOWS ZERO TO 15 BELOW. NORTH WIND 10 TO
20 MPH. WIND CHILLS 15 BELOW TO 30 BELOW.
.SUNDAY…MOSTLY SUNNY. HIGHS 10 BELOW TO 10 ABOVE…COOLEST INLAND.
NORTHWEST WIND 10 TO 25 MPH. WIND CHILLS 15 BELOW TO 30 BELOW.
.SUNDAY NIGHT…MOSTLY CLEAR. LOWS ZERO TO 15 BELOW. NORTHWEST
WIND 10 TO 20 MPH WITH GUSTS TO 35 MPH.
.MONDAY…MOSTLY SUNNY. HIGHS 10 BELOW TO 5 ABOVE…COOLEST
INLAND. NORTHWEST WIND 10 TO 20 MPH.
.MONDAY NIGHT…MOSTLY CLEAR. LOWS 5 BELOW TO 15 BELOW.
TEMPERATURE / PRECIPITATION
SEWARD 8 -5 -1 / 0 0 0
GIRDWOOD -5 -14 -1 / 0 0 0