Good morning backcountry travelers this is Lisa Portune with the Chugach National Forest Avalanche Information Center on Wednesday, January 19th 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).
We are starting an incentive program to encourage everyone to submit snow and avalanche observations. Each quality observation will earn you one chance to win a monthly $100 gift certificate. At the end of this season all the submissions will go into a drawing for an avalanche beacon of your choice. Thanks for all the great work, and keep sending in those observations!
The avalanche danger rating remains at MODERATE this morning with areas of CONSIDERABLE hazard developing later today as 4-8 inches of new snow accumulates and the winds get stronger. This new snow will fall on a variety of weak layers that formed during our cold dry spell the last two weeks…including surface hoar, wind crusts, hard windslab, and sugary faceted snow. Wind drifted snow more than 6 inches thick will be sensitive to human triggers. An outside chance also remains of triggering a deeper slab avalanche in thin, rocky starting zones at the higher elevations.
The last 2 weeks of cold clear weather did a number on the snow surface. There’s all sorts of ugliness out there. Giant to micro-sized surface hoar, wind crusts, hard windslab, exposed ice crusts, and sugary faceted snow will all be buried by the new snow today. This new snow will not bond very well to the old snow surface, so expect some reactive softslabs up to a foot deep on windloaded slopes later today.
Our deeper slab instabilities consist of numerous layers of buried surface hoar that formed in December and facets above and below the Thanksgiving Rain Crust. During the past few weeks we also had some hard windslab form over weak faceted snow near ridgetops and in crossloaded terrain. While the likelihood of triggering an avalanche on one of these layers is minimal today, the poor structure of the snowpack demands caution.
Persistent weak layers and hard windslab are difficult-to-manage hazards. Slope cuts are generally not effective with these types of instabilities because they tend to break above and around you. Plus you have to find just the right spot to trigger the whole thing…usually a hard-to-recognize shallow area in the snowpack. Storm snow and softslab instabilities, on the CNFAIC Staff hand, tend to break right under your sled, board, or skis and are more of a manageable hazard.
Encyclopedia of terms: www.fsavalanche.org/Encyclopedia.aspx
It has been 14 days since our last snowfall. That should finally change today with 4-8 inches forecasted above 1000 feet. Yesterday ridgetop winds were light while mountain temps ranged from the single digits to mid teens. Winds picked up last night and are now averaging 15-25mph out of the east. Temps have warmed up this morning to the mid teens at the higher elevations, while sea level temps remain in the single digits. Skies are currently cloudy. The NWS has issued a Blizzard Warning for Portage Valley and Turnagain Arm today. Ridgetop winds are forecasted to average 25-30mph out of the east with gusts in the 40’s. Look for sea level temps to warm up today while alpine temps will remain in the teens. We’ll see a break in between systems tonight and tomorrow with much warmer temps by the end of the week.
Kevin 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 AKST WED JAN 19 2011
…BLIZZARD WARNING IN EFFECT FROM 10 AM THIS MORNING TO 4 PM
AKST THIS AFTERNOON THROUGH PORTAGE VALLEY AND EASTERN TURNAGAIN
.TODAY…SNOW DEVELOPING THIS MORNING. AREAS OF BLOWING SNOW.
VISIBILITIES REDUCED TO ONE QUARTER MILE OR LESS AT TIMES THROUGH
PORTAGE VALLEY AND ALONG TURNAGAIN ARM LATE THIS MORNING THROUGH
AFTERNOON. SNOW ACCUMULATION 2 TO 6 INCHES. HIGHS IN THE MID TEENS TO
LOWER 30S…COOLEST INLAND. NORTH TO EAST WINDS 15 TO 30 MPH.
PORTAGE VALLEY AND TURNAGAIN ARM…EAST WINDS 10 TO 25 MPH INCREASING
30 TO 45 MPH LATE THIS MORNING.
.TONIGHT…MOSTLY CLOUDY WITH A CHANCE OF SNOW. LOWS 15 TO 25…
COOLEST INLAND. NORTHEAST WIND 10 TO 20 MPH IN THE EVENING
BECOMING LIGHT. NEAR SEWARD…NORTH WIND 15 TO 25 MPH.
.THURSDAY…MOSTLY CLOUDY IN THE MORNING THEN BECOMING PARTLY
CLOUDY. HIGHS IN THE LOWER 20S TO LOWER 30S…COOLEST INLAND.
LIGHT WINDS EXCEPT NORTH 20 MPH NEAR SEWARD.
TEMPERATURE / PRECIPITATION
SEWARD 26 23 30 / 100 100 0
GIRDWOOD 18 17 19 / 70 70 0
WEATHER STATION SUMMARY for Turnagain Pass:
-3800′ Sunburst Wx Station-
recorded light westerly winds yesterday with temps ranging from 9F to 11F. The winds picked up last night and are now averaging 15-20mph out of the NE. Temp is currently 10F.
-2600′ Seattle Ridge Wx Station-
recorded light and variable winds yesterday with temps ranging from 8F to 16F. The winds picked up last night and are now averaging 25-30mph out of the SE. Temp is currently 14F.
-1800′ Center Ridge Wx Station-
recorded no new snow the last 14 days. Temps yesterday ranged from 4F to 9F. The current temp is 17F.