Good morning backcountry travelers this is Carl Skustad with the Chugach National Forest Avalanche Information Center on Saturday, March 6th 2010 at 7 am. This will serve as a general backcountry avalanche advisory issued for Turnagain Arm with Turnagain Pass as the core advisory area (this advisory does not apply to highways, railroads, or operating ski areas).
Wow, that was a good one. A large snow storm moved through the advisory area yesterday depositing lots off snow and very high winds. Snow totals in inches are: Girdwood ~16, Alyeska Mid 16+, Alyeska Top ~24, Turnagain Pass’s Center Ridge 17, and Summit ~6. Areas received from 1.07 to 1.97 inches of water and ridge top winds gust to 93 mph. Most of the storm was over by mid afternoon. Snowpack settlement of 6-8 inches has since occurred.
The current radar shows light scattered snow showers moving over the area today. 1-4 inches of snow is forecasted for today.
Today’s avalanche danger is CONSIDERABLE with pockets of HIGH. Dangerous avalanche conditions. Careful snowpack evaluation, cautious routefinding and conservative decision making will be essential. Natural avalanches possible today and likely in some areas, human triggered avalanches likely and very likely in some areas. Large avalanches are very possible today.
We have limited observations and certainty in the actual stability yesterday’s storm left us. Large amounts of snow, wind, and water weight stressed the snowpack. A natural avalanche cycle of some magnitude certainly happened yesterday. The underlying snowpack and the large amount of settlement that already occurred will help in rebounding our snow stability. However, we are within the 24 hour period following a very large snow event. Human triggered avalanche will happen today. If an avalanche did not already happen naturally, it may be waiting for a trigger, don’t be that trigger. There’s a chance that if you trigger an avalanche today it will be very large and inescapable.
Make conservative choices today as the snowpack adjusts to the new snowload.
Safe backcountry travel requires training and experience. You control your own risk by choosing where, when and how you travel.
WEATHER FORECAST (National Weather Service)
WESTERN PRINCE WILLIAM SOUND-
500 AM AKST SAT MAR 6 2010
.TODAY…SNOW SHOWERS. SNOW ACCUMULATION 1 TO 4 INCHES. HIGHS IN
THE UPPER 20S TO LOWER 30S. SOUTH TO EAST WIND 10 TO 25 MPH BECOMING
VARIABLE 10 MPH IN THE AFTERNOON. THROUGH PORTAGE VALLEY AND
TURNAGAIN ARM…SOUTHEAST WIND 25 TO 40 MPH BECOMING VARIABLE 15 MPH
.TONIGHT…NUMEROUS SNOW SHOWERS NORTH OF MOOSE PASS IN THE
EVENING…THEN MOSTLY CLOUDY WITH SCATTERED SNOW SHOWERS. MOSTLY
CLOUDY ELSEWHERE. SNOW ACCUMULATION UP TO 2 INCHES. LOWS 5 TO 20
ABOVE. LIGHT WINDS EXCEPT WEST WIND 20 TO 35 MPH NEAR WHITTIER AND
NORTH 10 TO 20 MPH NEAR SEWARD.
.SUNDAY…MOSTLY CLOUDY. ISOLATED SNOW SHOWERS IN THE MORNING…
THEN A CHANCE OF SNOW IN THE AFTERNOON. HIGHS IN THE 20S.
VARIABLE WIND 10 MPH. THROUGH PORTAGE VALLEY AND TURNAGAIN ARM…
LIGHT WINDS BECOMING SOUTHEAST 10 TO 20 MPH IN THE AFTERNOON.
.SUNDAY NIGHT…SNOW. AREAS OF BLOWING SNOW. LOWS 15 TO 25. EAST WIND
10 TO 15 MPH. THROUGH PORTAGE VALLEY AND TURNAGAIN ARM…EAST WIND 15
TO 30 MPH INCREASING TO 35 TO 50 MPH AFTER MIDNIGHT.
.MONDAY…SNOW…POSSIBLY MIXED WITH RAIN. AREAS OF BLOWING SNOW.
HIGHS IN THE 30S. EAST WIND 15 TO 30 MPH EXCEPT EAST 40 TO 55 MPH
THROUGH PORTAGE VALLEY AND TURNAGAIN ARM.
TEMPERATURE / PRECIPITATION
SEWARD 32 14 25 / 80 40 50
GIRDWOOD 32 18 23 / 100 60 40
WEATHER STATION SUMMARY for last 24 hours at TURNAGAIN PASS
3800′-Sunburst Wx Station
Current Temp: 14 (1 deg cooler than yesterday)
Winds: have calmed down since yesterday, with averages in the 20’s and gusts in the 40’s out of the east. Yesterday we saw average winds in the 50’s and gusts in the 80’s
2600′-Seattle Ridge Wx Station
Winds: have calmed to high teen averages and gusts in the 20’s out of the SE. Yesterday gusts reached the 60’s.
1800′-Center Ridge Wx Station
Current Temp: 22 degrees (1 degrees cooler than yesterday)
Precip: 17 inches of snow, 1.8 inches of water equivalent, total snowpack depth of 130” after 6 inches of settlement.
Thanks for checking today’s avalanche advisory. The next one will be posted tomorrow Sunday March 7th, 2010.