Good Morning backcountry travelers, this is Carl Skustad with the Chugach National Forest Avalanche Information Center on Saturday, March 28, 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. This advisory expires in 24 hours and does not apply to operating ski resorts or highways/railroads.
*STARTING THE FIRST WEEK OF APRIL, WE WILL ONLY ISSUE ONE ADVISORY PER WEEK ON FRIDAYS*
*Last weekend to ride Skookum Valley, Skookum closes to snowmaching on April 1st*
MOUNTAIN WEATHER ROUND UP FOR THE LAST 24 HOURS
-General Weather Observations-
Partial clearing ocured yesterday with snow showers picking up again through the night. A couple inches accumulated in the Girdwood Valley. The NWS forecast calls for snow showers today turning to snow likely tonight. A BLIZZARD WARNING is in effect for this evening.
–The NRCS Center Ridge weather station at 1800 feet in Turnagain Pass–
Has a temp of 24 degrees (2 degrees cooler than yesterday). .2 inches of water and 1 inch of snow was recorded in the past 24 hours . Total snowpack depth settled anCNFAIC Staff 2 inches yesterday for a total of 102 inches of snow.
–The Sunburst weather station at 3800 feet in Turnagain Pass–
Is recording a temp of 16 degrees (4 deg cooler than yesterday). Winds have been increasing from the east. Average winds are in the mid teens with gust in the mid twenties.
-Surface Analysis Maps-
A 1000 mb and a 1001 mb low are over southcentral. A large 980 low is moving up the chain and will be our next weather maker.
As of 5am this morning…. scattered showers over Prince William Sound heading east. The satellite images show partial clearing this morning.
Primary avalanche concerns
-3-6 plus feet of 48 hour old snow on top of multiple weak layers. This is the MOST SIGNIFICANT and MOST DANGEROUS layer of slab snow we have seen all year.
-Below 3000 feet. The “Janurary Hurricane” rain crust buried under 4-6 feet of surface snow. There is a layer of weak sugary faceted snow above and below this hard rain crust.
AVALANCHES AND SNOWPACK
The avalanche hazard will remain the same today.
EXTRA CAUTION is advised – todays avalanche hazard is CONSIDERABLE. Natural avalanches will be possible and human-triggered avalanches will be probable on slopes steeper than 35%. Large unstable slabs exist on steep slopes. Use conservative decision making, careful route finding, and good travel habits. Training and experience are essential!
We have reached the the tipping point were the mountains snowpack weight exceeds the strength of the week layers. Very large avalanches have occurred over the last three days. Long time Avalanche Professionals in the area are calling the recent avalanche activity significant, this means something. What it means is unquantifiable, but when the sage speak I listen. Often times the end of March sees a cycle of large avalanches preceeding a trend of unstable large avalanche events. Very large avalanches have been triggered by artillery in the last couple of days, running 100 % of the possible runout and measuring approx. 6-8 feet deep snapping off trees and anything else in the way!
Matt and I climbed up Sunburst yesterday. At 1000 feet a single jump on Matt’s skies created the largest whooph I have heard in a long time if not ever. It shook the alders! Remember a whooph is a collapsing of a weak layer in the snowpack. This colaps would result in an avalanche if the slope were steep enough. Climbing higher on Sunburst we did a crown profile of a large avalanche on the shoulder about 2500 feet. This class 2 plus avalanche failed on the January rain crust 2-4 feet deep and 200 meeters wide. This avalanche was one of many we saw yesterday. Wide spread natural avalanche activity indicates the balance between strength and stress has been met or exceeded. I believe the steep snowpack that has not avalanched yet could be triggered by a skier or snowmachiner. Likely triggers would include, a skier crashing or jumping off a rock, a snowmachiners track digging deep into the snowpack, a cornice fall, warming sun, or new wind or snow.
A large natural avalanche occurred on the motorized side of the Seward Highway yesterday minutes after the sun came out. This avalanche was north of the Seattle Creek up route and was estimated to be 2-3 feet deep and a mile long. This is a perfect example that areas a still holding unstable snow! AnCNFAIC Staff natural avalanche event of interest occurred on the North Face of Tincan, Todd’s Run. A wall to wall natural ripped out the whole drainage filling the lower bowl with debris! Every mountain out there has a billboard (in the form of recent avalanche activity) hanging on it. Don’t ignore them!
Weather Forecast for
WESTERN PRINCE WILLIAM SOUND-
500 AM AKDT FRI MAR 27 2009
…BLIZZARD WATCH IN EFFECT FROM LATE TONIGHT THROUGH SUNDAY
EVENING THROUGH PORTAGE VALLEY AND TURNAGAIN ARM…
.TODAY…SNOW SHOWERS NORTH OF MOOSE PASS IN THE MORNING…THEN
ISOLATED SNOW SHOWERS IN THE AFTERNOON. SNOW ACCUMULATION 2 TO 4
INCHES. HIGHS IN THE UPPER 20S TO MID 30S. VARIABLE WIND 15 MPH
EXCEPT EAST 15 TO 25 MPH THROUGH PORTAGE VALLEY AND TURNAGAIN
.TONIGHT…SNOW DEVELOPING BY MIDNIGHT. SNOW AND BLOWING SNOW
POSSIBLY REDUCING VISIBILITY TO ONE QUARTER MILE AFTER MIDNIGHT
THROUGH PORTAGE VALLEY AND TURNAGAIN ARM. SNOW ACCUMULATION 3 TO 6
INCHES…GREATEST AMOUNTS NORTH OF MOOSE PASS. LOWS IN THE LOWER 20S
TO LOWER 30S. SOUTHEAST WIND 10 TO 20 MPH EXCEPT EAST 40 TO 55 MPH
WITH POSSIBLE GUSTS TO 70 MPH THROUGH PORTAGE VALLEY AND TURNAGAIN
.SUNDAY…SNOW…MIXING WITH RAIN ALONG THE COAST. SNOW AND BLOWING
SNOW POSSIBLY REDUCING VISIBILITY TO ONE QUARTER MILE THROUGH PORTAGE
VALLEY AND TURNAGAIN ARM. SNOW ACCUMULATION 2 TO 8 INCHES. HIGHS IN
THE 30S. SOUTHEAST WIND 25 TO 35 MPH EXCEPT EAST 50 TO 65 MPH THROUGH
PORTAGE VALLEY AND TURNAGAIN ARM.
.SUNDAY NIGHT…SNOW. SNOW AND BLOWING SNOW POSSIBLY REDUCING
VISIBILITY TO ONE QUARTER MILE IN THE EVENING THROUGH PORTAGE VALLEY
AND TURNAGAIN ARM. LOWS IN THE 20S. SOUTHEAST WIND 15 TO 30 MPH WITH
LOCAL GUSTS TO 50 MPH BECOMING VARIABLE 10 MPH AFTER MIDNIGHT.
.MONDAY…NUMEROUS SNOW SHOWERS. HIGHS IN THE 30S. VARIABLE WIND TO
10 MPH. NEAR SEWARD…SOUTH WIND 10 MPH.
TEMPERATURE / PRECIPITATION
SEWARD 33 29 39 / 20 100 100
GIRDWOOD 31 24 34 / 80 80 80
This concludes today’s avalanche advisory which will expire in 24 hours. The next advisory will be on Sunday, March 29th. Thanks and have a great day.