Good Morning backcountry travelers, this is Carl Skustad with the Chugach National Forest Avalanche Information Center on Sunday, March 29, 2009 at 7am. This will serve as a general backcountry avalanche advisory issued 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.
***Join the 2009 6th Annual Jeff Nissman Telemark Festival this weekend at Alyeska Resort. Benifite for the CNF Avalanche Center. WIN HELISKIING TRIP at the beacon park beacon games. check out http://web.mac.com/telepalooza/2009/Poster.html for more details.
*STARTING THE FIRST WEEK OF APRIL, WE WILL ONLY ISSUE ONE ADVISORY PER WEEK ON FRIDAYS, due to staffing and budget limitations. We will update riding conditions (open/closed) and significant avalanche and weather events as needed*
*Last weekend to ride Skookum Valley, Skookum closes to snowmachining on April 1st*
*A large avalanche in Center and Divide Creek (between Johnson and Placer presumable took the life of a snowmachiner yesterday, limited information at this time. Our thoughts and prayers go out to the friends and family. A huge thanks to rescuers that assisted last night.*
MOUNTAIN WEATHER ROUND UP FOR THE LAST 24 HOURS
-General Weather Observations-
Partial clearing yesterday. Ash fall was present over much of the advisory area. Winds are picking up this morning and it looks like we picked up anCNFAIC Staff trace of snow. Alyeska midway is reporting 4-6 inches of new snow. The NWS forecast calls for snow today. 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 22 degrees (2 degrees cooler than yesterday). .2 inches of water but no new snow in the last 24hrs . Total snowpack depth settled anCNFAIC Staff 3 inches yesterday for a total of 99 inches of snow.
–The Sunburst weather station at 3800 feet in Turnagain Pass–
Is recording a temp of 12 degrees (4 deg cooler than yesterday). Winds have been increasing from the east. Average winds are are getting significant averaging in the mid 20’s with gusts to 53.
-Surface Analysis Maps-
A large 967 mb low is just edging into southcentral this morning. Expect high winds on the front and back of this system as contour lines are tight.
As of 5am this morning…. heavy precip over Prince William Sound pushing on shore his morning.
Primary avalanche concerns
-3-6 plus feet of 3 day 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 “January 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 increase today with the storm weather present.
EXTRA CAUTION is advised – todays avalanche hazard is HIGH. Dangerous avalanche conditions. Travel in avalanche terrain is not recommended. Extensive skill, experience, and local knowledge are essential. Natural and human triggered avalanches will be likely on slopes steeper than 30 degrees. Large unstable slabs exist on steep slopes.
The avalanche danger rating is only a starting point. YOU CONTROL YOUR OWN RISK by choosing where, when, and how you travel.
We have reached the the tipping point were the mountains snowpack weight exceeds the strength of the weak layers. Very large avalanches have occurred over the last four 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 preceding a trend of unstable large avalanche events. Very large avalanches were triggered by artillery on the 26th and 27th, 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 investigated the crown face of a large natural avalanche on the 27th to confirm the weak layer responsible for all the recent avalanche activity. We found the large slab of recent snow is resting on the January hurricane rain crust. Faceted on both sides, this is the most significant weak layer we have and is in most cases responsible for our current high avalanche hazard. The slab thickness or snow load on op of this layer varies from 2-10 feet. 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 on the 27th 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! The large avalanche that presumable took a riders life yesterday was triggered from below and propagated very high up the slope. This is yet anCNFAIC Staff example of dangerous heavy slab snow over a weak layer condition we currently have. 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 SUN MAR 29 2009
…BLIZZARD WARNING REMAINS IN EFFECT UNTIL 10 PM AKDT THIS EVENING
THROUGH PORTAGE VALLEY AND TURNAGAIN ARM…
.TODAY…SNOW…POSSIBLY MIXED WITH RAIN IN THE AFTERNOON. SNOW AND
BLOWING SNOW REDUCING VISIBILITY TO ONE QUARTER MILE OR LESS AT TIMES
THROUGH PORTAGE VALLEY AND TURNAGAIN ARM. SNOW ACCUMULATION 2 TO 8
INCHES. HIGHS IN THE 30S. SOUTH TO EAST WIND 25 TO 35 MPH EXCEPT EAST
60 TO 75 MPH THROUGH PORTAGE VALLEY AND TURNAGAIN ARM.
.TONIGHT…SNOW…POSSIBLY MIXED WITH RAIN ALONG THE COAST IN THE
EVENING. SNOW AND BLOWING SNOW REDUCING VISIBILITY TO ONE
QUARTER MILE OR LESS AT TIMES THROUGH PORTAGE VALLEY AND TURNAGAIN
ARM. SNOW ACCUMULATION 2 TO 6 INCHES. LOWS IN THE 20S. SOUTH TO EAST
WIND 15 TO 25 MPH WITH GUSTS TO 50 MPH THROUGH PORTAGE VALLEY AND
TURNAGAIN ARM IN THE EVENING.
.MONDAY…NUMEROUS SNOW SHOWERS IN THE MORNING…THEN ISOLATED
SNOW SHOWERS IN THE AFTERNOON. SNOW ACCUMULATION UP TO 2 INCHES.
HIGHS IN THE UPPER 20S TO MID 30S. SOUTH TO EAST WIND 10 TO 15 MPH.
.MONDAY NIGHT…MOSTLY CLOUDY WITH ISOLATED SNOW SHOWERS. LOWS
10 TO 20 ABOVE. VARIABLE WIND 10 MPH.
.TUESDAY…PARTLY CLOUDY. HIGHS IN THE UPPER 20S TO MID 30S.
LIGHT WINDS. NEAR WHITTIER…WEST WIND 15 TO 25 MPH IN THE
MORNING BECOMING LIGHT.
TEMPERATURE / PRECIPITATION
SEWARD 38 29 35 / 100 80 60
GIRDWOOD 35 26 33 / 100 100 60
This concludes today’s avalanche advisory which will expire in 24 hours. The next advisory will be on Friday, April 3rd. Thanks and have a great day.