Good Morning backcountry travelers, this is Carl Skustad with the Chugach National Forest Avalanche Information Center on Friday, January 23, 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.
MOUNTAIN WEATHER ROUND UP
In the last 24 hours…
–The DOT weather station near the crest of the highway at Turnagain Pass at 1000 feet–
Is recording a temp of 29 degrees (5 deg warmer that yesterday), light NE winds and a total snowpack depth of 41 inches.
–The Center Ridge weather station at 1800 feet in Turnagain Pass–
Has a temp of 25 degrees (1 deg colder than yesterday). Total snow depth is 62 inches after 1 inches of settlement from yesterday.
–Sunburst weather station along the ridge at 3800 feet in Turnagain Pass–
Recorded moderate winds averaging 15-20 mph from SE with gusts in the mid 20’s. Current temperature is 18 degrees F (no change from yesterday)
-Surface Analysis Maps-
A 978 mb low is sliding up the Aleutians. It is bringing with it our best chance at precip since last weekend.
Next band of moisture is attached to the low moving up the Aleutians.
Band of precip just south of Chenega in Prince William Sound. This should bring us precipitation this late afternoon.
-General Weather Observations-
SE winds have picked up slightly on all stations but 43 mile. 43 mile weather station is above the RR tracks in Grandview. This station is good at recognizing the changing weather as it is the closest to Prince William Sound. This ridge top station is starting to see winds shifting to the NE. Light precipitation is forecasted this evening.
Primary avalanche concerns
-Deep slabs 2-6 feet thick on top of January facets
Secondary avalanche concerns
-Glide Cracks (now they are bridged over, don’t fall in)
WATCH OUT SITUATIONS
-Higher elevations above 3,000 feet
-Slopes that do not have a clean run out
AVALANCHE AND SNOWPACK DISCUSSION
Our coastal snowpack is drastically different as we climb in elevation. Heavy rains pounded the advisory area 7 days ago from sea level to 2800 ft. Rain runnels and boiler plate surface snow is present. A fresh coat of snow could really help moral at lower elevations. Mid elevations we see softer surface conditions as the rain crust is not as thick. Above 2800 ft the crust is not present as rains did not reach above 2800 ft in most locations.
The avalanche hazard below 2000 is low. Above 2000 feet the chance to trigger an avalanche increases as you get closer to the ridge tops where drier wind driven snow is present. I don’t suspect any natural avalanche activity today, but human triggered avalanches are possible on leeward or cross loaded alpine aspects. These areas could potentially hold large deep wind slabs that if triggered would be very dangerous.
The significant weak layer in our current snowpack is the Dec. facets that were formed during the below zero deg. temps we had over the holidays. This layer of faceted snow is healing below 2800 feet due to the warm wet snow and rain we received. Above 2800 feet these cold facets are still present. In most of our tests this week we are seeing this layer strengthen with moderate Q2,Q3 sheer tests.
Crown profile of natural class 3 avalanche on west face of Magnum, 3000 ft.
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. Deep slab instabilities are bad. You probably will not trigger them, but if you do it will be a huge avalanche. Make sure to check the snowpack you are traveling on or under. Many of you are itching to start checking some projects of the summit list. Take your time with the peaks above 3500 ft. I’ve got the same list and know Goat, Raggedtop, Big League, and Pastoral are all on it. These high snow fields have not been tested since this last storm. Large wind slabs will be present.
500 AM AKST FRI JAN 23 2009
.TODAY…NUMEROUS SNOW SHOWERS IN THE MORNING…THEN SNOW IN THE
AFTERNOON. SNOW ACCUMULATION 1 TO 3 INCHES. HIGHS IN THE UPPER 20S
TO MID 30S. NORTH TO EAST WIND 5 TO 15 MPH EXCEPT EAST 25 TO 40 MPH
THROUGH PORTAGE VALLEY AND TURNAGAIN ARM.
.TONIGHT…SNOW IN THE EVENING…THEN A CHANCE OF SNOW AFTER
MIDNIGHT. SNOW ACCUMULATION UP TO 2 INCHES. LOWS IN THE MID 20S
TO LOWER 30S. NORTH TO EAST WIND TO 15 MPH EXCEPT EAST 15 TO 25 MPH
THROUGH PORTAGE VALLEY AND TURNAGAIN ARM.
.SATURDAY…CLOUDY WITH A CHANCE OF SNOW IN THE MORNING…THEN
SNOW LIKELY IN THE AFTERNOON. SNOW ACCUMULATION UP TO 2 INCHES.
HIGHS 30 TO 35. NORTH TO EAST WIND 10 TO 15 MPH.
.SATURDAY NIGHT…SNOW LIKELY. LOWS IN THE MID 20S TO LOWER 30S.
NORTH TO EAST WIND 10 TO 15 MPH.
.SUNDAY…SNOW LIKELY. HIGHS IN THE UPPER 20S TO MID 30S.
VARIABLE WIND TO 10 MPH.
TEMPERATURE / PRECIPITATION
SEWARD 34 28 32 / 80 80 60
GIRDWOOD 32 28 30 / 80 80 60
Thanks for checking the CNFAIC avalanche advisory. Have a great day.