Good morning backcountry travelers this is Carl Skustad with the Chugach National Forest Avalanche Information Center on Saturday, February 27th 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).
No new snow in the last 24 hours. 48 hour snow accumulation is 5-7″ in the Turnagain Arm Area and slightly more near Anchorage. Yesterday’s winds were light in most locations. Ridgetops saw moderate winds. Light wind transport was present at higher elevations. Ridgetop winds have picked up this morning with gusts in the 20’s. Look for snow showers today with up to 2″ accumulation and an additional 4-8″ tonight. The current radar is clear. The current satellite shows cloud cover present and more moving our way from the southwest. A very large 951 mb low pressure storm is brewing to our southwest. The specifics on this storms destination are not clear but expect it to at least push frontal lows at us starting today.
Today’s avalanche danger will remain MODERATE. Natural avalanches unlikely, human-triggered avalanches possible. Human triggered avalanches should be limited to new snow instabilities. Wind slabs of 6 inches to a foot may be possible in the alpine. Areas to find these wind slabs include: steep rollovers, leeward ridges, and side loaded ribs. The chance of natural avalanche activity will be present if winds continue or increase and transport enough snow onto leeward aspects to trigger small wind slabs.
Yesterday we found 5-6″ of very light density snow over the concrete crust that was formed last week. This amount varied where wind effected it above tree line. We found lots of loose snow sloughs and soft slab snow. Small wind slabs are present in the alpine.
We’ve still found remnants of the old weak layers of concern. Those are the rain crust from January 7th and the buried layer of surface hoar from earlier February. These layers have not been reactive and in many areas got destroyed during last weeks siege. I mention them as a reminder to keep an eye out for them. We would love to hear from you if you see these layers in the snowpack.
Glide cracks and cornices continue to be areas of concern today. Both are total wild cards and are very difficult to predict. We have seen recent failures of both cornices and glide cracks this week. Give them lots of space. Avoid traveling near glide cracks or cornices.
WEATHER FORECAST (National Weather Service)
WESTERN PRINCE WILLIAM SOUND-
500 AM AKST SAT FEB 27 2010
.TODAY…CLOUDY WITH SCATTERED SNOW SHOWERS IN THE MORNING…THEN
SNOW LIKELY IN THE AFTERNOON. SNOW ACCUMULATION UP TO 2 INCHES.
HIGHS IN THE MID 20S TO LOWER 30S. VARIABLE WIND TO 10 MPH
EXCEPT NORTH 10 TO 20 MPH NEAR SEWARD.
.TONIGHT…SNOW. SNOW ACCUMULATION 3 TO 7 INCHES. LOWS IN THE 20S.
NORTH TO EAST WIND 5 TO 20 MPH.
.SUNDAY…RAIN AND SNOW. SNOW ACCUMULATION UP TO 4 INCHES AT
HIGHER ELEVATIONS. HIGHS IN THE 30S. NORTH TO EAST WIND
10 TO 20 MPH EXCEPT EAST 15 TO 30 MPH THROUGH PORTAGE VALLEY
AND TURNAGAIN ARM.
.SUNDAY NIGHT…RAIN AND SNOW. LOWS IN THE UPPER 20S TO MID 30S.
SOUTH TO EAST WIND 10 TO 25 MPH EXCEPT EAST 25 TO 35 MPH THROUGH
PORTAGE VALLEY AND TURNAGAIN ARM.
.MONDAY…RAIN AND SNOW LIKELY. HIGHS IN THE 30S. LIGHT WINDS
EXCEPT EAST 15 TO 30 MPH THROUGH PORTAGE VALLEY AND TURNAGAIN ARM.
TEMPERATURE / PRECIPITATION
SEWARD 30 24 36 / 60 100 90
GIRDWOOD 30 24 36 / 40 100 100
WEATHER STATION SUMMARY for last 24 hours at TURNAGAIN PASS
3800′-Sunburst Wx Station
Current Temp: 11 (1 degrees warmer than yesterday)
Winds: are increasing out of the east averaging 12-18 and gusting into the 20’s.
2600′-Seattle Ridge Wx Station
Winds: are increasing out of the east averaging 12 with gust in the high teens.
1800′-Center Ridge Wx Station
Current Temp: 12 degrees (4 degrees colder than yesterday)
Precip: 0 new water, 0″ new snow, 90″ total snowpack, 2 inches of settlement.
Thanks for checking today’s avalanche advisory. Lisa will post tomorrow Sunday, February 28th.