Good morning backcountry travelers this is Kevin Wright with the Chugach National Forest Avalanche Information Center on Friday, April 8th at 7am. 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).
Today’s avalanche danger rating is CONSIDERABLE for storm snow and wind slab over weak layers of buried surface hoar and sun crusts. The intensity of the storm has diminished but the avalanche hazard will continue to be elevated. Expert avalanche skills are essential for safe travel in the backcountry today.
With the storm peaking yesterday we don’t have a thorough understanding of how our snowpack reacted to the additional load. If the conditions allow it, we will get onto the upper slopes today to do a damage assessment.
A lot of our information yesterday came from remote weather stations. Girdwood received a solid 18-24 inches at higher elevations. Turnagain pass seemed to be well under those amounts, but some areas could be similar. Regardless of exact snowfall numbers, it was a significant shock to an already touchy snowpack. There were undoubtedly natural avalanches happening during the storm. As the storm backs off, the natural activity will die down and our concern shifts to human triggered avalanches.
Wednesday’s skier and snowmachine triggered avalanches (including a full burial) are an indicator that many slopes were ripe to avalanche. After new snow and wind many of the remaining slopes will be either spoiled (avalanched naturally) or close to rotten (ready for the trigger to avalanche). Check the photo gallery for a couple new photos we received yesterday.
There is no doubt in my mind that human triggered avalanches are likely today. Terrain management is key to staying safe. Steeper, higher elevation slopes will be dangerous unless they already slid during the storm.
Encyclopedia of avalanche terms.
The storm peaked yesterday and wind and snowfall both dropped off significantly by 5pm. Highest intensities had snowfall 1-2 inches per hour and wind gusting to near 80mph at the ridge tops. Snow accumulation reached 2 feet in some areas but is very regionally dependent. Today 2-6 inches of snow is predicted with moderate wind from the SE.
Wendy will issue the next advisory tomorrow morning at 7am. If you get out in the backcountry give us a call at 754-2369 or send us your observations using the button at the top of this page. Thanks and have a great day.
The NWS weather forecast for:
WESTERN PRINCE WILLIAM SOUND-
500 AM AKDT FRI APR 8 2011
.TODAY…RAIN AND SNOW SHOWERS. LITTLE OR NO SNOW ACCUMULATION. HIGHS
IN THE MID 30S TO LOWER 40S. SOUTHEAST WIND 10 TO 15 MPH EXCEPT
SOUTHEAST 20 TO 35 MPH THROUGH PORTAGE VALLEY AND TURNAGAIN ARM.
.TONIGHT…SNOW AND RAIN SHOWERS IN THE EVENING…THEN NUMEROUS SNOW
SHOWERS AFTER MIDNIGHT. SNOW ACCUMULATION UP TO 2 INCHES. LOWS IN THE
LOWER 20S TO MID 30S. EAST WIND 10 TO 15 MPH WITH GUSTS TO 25 MPH
ALONG TURNAGAIN ARM AND PORTAGE VALLEY IN THE EVENING.
.SATURDAY…MOSTLY CLOUDY. SCATTERED RAIN AND SNOW SHOWERS. HIGHS IN
THE MID 30S TO LOWER 40S. LIGHT WINDS.
.SATURDAY NIGHT…MOSTLY CLOUDY. SCATTERED SNOW AND RAIN SHOWERS IN
THE EVENING…THEN ISOLATED SNOW SHOWERS AFTER MIDNIGHT. LOWS IN THE
MID 20S TO MID 30S. LIGHT WINDS EXCEPT NORTH 15 TO 20 MPH NEAR
.SUNDAY…MOSTLY CLOUDY. ISOLATED SNOW SHOWERS IN THE MORNING…
THEN ISOLATED SNOW AND RAIN SHOWERS IN THE AFTERNOON. HIGHS IN THE
MID 30S TO LOWER 40S. LIGHT WINDS EXCEPT NORTH 15 MPH NEAR SEWARD.
.SUNDAY NIGHT…CLOUDY WITH ISOLATED SNOW SHOWERS. LOWS IN THE
TEMPERATURE / PRECIPITATION
SEWARD 41 28 43 / 100 70 40
GIRDWOOD 41 22 43 / 100 80 40
WEATHER STATION SUMMARY for Turnagain Pass:
-3800′ Sunburst Wx Station-
Currently 21 degrees. Wind gusting into the 20s from the East.
-2600′ Seattle Ridge Wx Station-
25 degrees at 6am. Wind to the mid teens from the Southeast.
-1800′ Center Ridge Wx Station-
28 degrees at 6am. 4 inches of snow and 0.5 inches of water equivalent measured yesterday.