Good Morning backcountry travelers, this is Matt Murphy with the Chugach National Forest Avalanche Information Center on Wednesday, January 21, 2009 at 7am. This will serve as a general backcountry avalanche advisory issued 5 days a week Wednesday-Sunday for the Turnagain Arm area (Turnagain Pass is the core advisory area). Local variations always occur.
Huge THANKS to the USDA Natural Resources Conservation Service for fixing the Center Ridge weather station. Its great to have the station working again.
I would also like to apologize to DOT for parking in a bad spot along the highway yesterday. You guys are the reason why we have Turnagain Pass; so, I should not have parked in the way of where you need to get work done. I will stick to the main parking areas from now on.
MOUNTAIN WEATHER ROUND UP
In the last 24 hours…
–The DOT weather station near the crest the highway at Turnagain Pass at 1000 feet–
Is recording a temp of 24 degrees (8 degrees colder than yesterday), calm winds, high RH 94%, and a total snowpack depth of 41 inches.
–The Center Ridge weather station at 1800 feet in Turnagain Pass–
Has recorded zero new snow or water and is reporting a temp of 18 degrees (8 degrees colder than yesterday). Total snow depth is 65 inches
–Sunburst weather station along the ridge at 3800 feet in Turnagain Pass–
Recorded calm winds averaging 0-6 mph from the W with gusts to 10 mph. Current temperature is 27 degrees F (3 degrees warmer then yesterday)
-Surface Analysis Maps-
From 3 am Tuesday to 9pm last night…
High pressure moving up from the south right toward us followed by a bunch of weak storms over the Aluetians
The analysis from 9pm last night showed the main flow moving south to north just to our west heading toward the Aluetians. It is forecasted to shift to a west to east flow in the next 2 days or so.
Shows that we are on the fringe of a wall of clouds that is moving southeast to northeast to our west
-General Weather Observations-
All weather station except Sunburst are colder today than yesterday by 3-8 degrees. Sunburst is 3 degrees warmer. Winds have been very calm and relative humidity is high.
Primary avalanche concerns
-Deep slabs 2-6 feet thick on top of Januray Facets
Secondary avalanche concerns
-Glide Cracks (see photos)
WATCH OUT SITUATIONS
-Higher elevations above 4,000 feet
-Runs that do not have a clean run out
AVALANCHE AND SNOWPACK DISCUSSION
This past storm left behind deep slabs about 2-6 feet deep on top of a weak layer of facets that formed in early January. Rain and wet snow saturated the top 1-2 feet of the snowpack up to elevations of about 2800 feet. The wind really hammered the elevations above 2800 feet up to the ridges. Deep slab instability is our biggest concern.
I agree with the concensus from the people I trust the most in the mountains. It seems unlikely that you will trigger this deep slab, but it will be a huge avalanche if you do. We are still in the process of gathering information about our new snowpack; so, the level of uncertainty remains high.
There are plenty of places to stay safe in the backcountry today, but we all need to work hard at keeping our human factors in check.
We went up Seattle Ridge yesterday to dig some pits in Main Bowl and Repeat Offender (see pits in photo gallery). We found a couple inches of soft powder on top of a fairly supportable and sometimes breakable rain crust. Plus, we found thost January facets about 3-4 feet deep. They were still dry, showing signs of rounding out, and did not react to the normal range of compression stability tests; however, we did not trust the snow enough to ski the cooler line back down to the bench at the snowmachine up-track. It was difficult, but we skied a mellower line. I need more info before I completely trust this snowpack.
WESTERN PRINCE WILLIAM SOUND-
500 AM AKST WED JAN 21 2009
.TODAY…PARTLY CLOUDY. HIGHS IN THE MID 20S TO MID 30S…COLDEST
INLAND. NEAR SEWARD AND WHITTIER…NORTH TO WEST WIND 25 TO 40 MPH
DECREASING TO 15 TO 25 MPH BY AFTERNOON. ELSEWHERE…LIGHT WINDS.
.TONIGHT…MOSTLY CLOUDY. LOWS 5 TO 15 ABOVE INLAND AND 15 TO 25
ALONG THE COAST. LIGHT WINDS EXCEPT NORTH TO WEST WINDS 10 TO 20 MPH
NEAR SEWARD AND WHITTIER.
.THURSDAY…MOSTLY CLOUDY. A CHANCE OF SNOW SHOWERS IN THE AFTERNOON.
HIGHS IN THE LOWER 20S TO LOWER 30S. NORTH TO EAST WIND 5 TO 15 MPH.
TEMPERATURE / PRECIPITATION
SEWARD 32 24 30 / 0 0 40
GIRDWOOD 30 12 25 / 0 0 20
Thanks for checking the CNFAIC avalanche advisory. Have a great day.