Good morning backcountry travelers this is Kevin Wright with the Chugach National Forest Avalanche Information Center on Saturday, January 22nd 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 seem to be stuck in the MODERATE hazard range. Natural avalanches are unlikely (we have had at least one report of a natural in the last few days) and human triggered avalanches are possible in specific areas. Recent small wind slabs have proven to be sensitive to human (and dog) triggers.
We have two specific concerns right now: the old snow and the new snow. The old snow continues to be suspect, but the recent evidence is mostly circumstantial. In column tests we find hard failures on buried surface hoar, and facets above and below the Thanksgiving rain crust. The most recent confirmed avalanche on these old layers was almost 2 weeks ago. As the most recent storm fades from memory the reactivity of those layers also becomes less likely, but not impossible. I’m not ready to start trusting those layers in consequential terrain yet. For me to be satisfied it’s going to take a big storm and a significant avalanche cycle followed by demonstrable stability.
We’re starting to focus on the effects of our new snow from the last few days, but the total amount is still almost insignificant. We’ve had one report of highly reactive small wind slabs in Winner creek. The slabs were 1 foot deep or less but had wide propagation. It didn’t sound like dangerous conditions because the slabs were small and manageable. As soon as we get enough snow to increase the size of those slabs the danger rating will increase.
We’ve had up to 5 inches of snow the last few days. In some areas that light snow is being blown into drifts up to 1 foot deep. The Weather Service continues to forecast small amounts of snow for our region but the total so far has been on the low end of their estimates. Today anCNFAIC Staff 0-5 inches is predicted for Eastern Turnagain Arm.
Avalanche forecasters in the region continue to be on heightened alert as we wait for new snow. The recent cold and clear weather has built numerous weak layers that will be unable to support a large amount of new snow. The recent surface hoar formation (see photo) is likely to be a very poor bonding surface and weak layer when it gets a slab on top of it. I suspect that deeper weak layers will play a role in the next avalanche cycle as well.
IF we get significant snow this weekend the hazard will correspondingly INCREASE.
Encyclopedia of avalanche terms.
AnCNFAIC Staff small amount of snow fell last night. The total snowfall in the last few days is 2-5 inches. Temperatures have moderated into the mid to high 20s. Wind has been gusting into the 20s from variable directions. Snow showers are forecasted but it doesn’t look like significant amounts will accumulate today.
Lisa 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 SAT JAN 22 2011
…STRONG WIND SUNDAY AND SUNDAY NIGHT THROUGH PORTAGE VALLEY AND
ALONG TURNAGAIN ARM…
.TODAY…SNOW IN THE MORNING…THEN PARTLY CLOUDY WITH A CHANCE
OF SNOW SHOWERS IN THE AFTERNOON. SNOW ACCUMULATION UP TO 1 INCH.
HIGHS IN THE MID 20S TO LOWER 30S. NORTHWEST WIND 10 TO 15 MPH
EXCEPT WEST 15 TO 25 MPH NEAR WHITTIER. NEAR SEWARD…NORTH WINDS 15
TO 25 MPH.
.TONIGHT…PARTLY CLOUDY WITH A SLIGHT CHANCE OF SNOW SHOWERS IN THE
EVENING…THEN MOSTLY CLOUDY WITH A CHANCE OF SNOW AFTER MIDNIGHT.
LOWS IN THE LOWER TO MID 20S. VARIABLE WIND 10 MPH EXCEPT NORTH 15
MPH NEAR SEWARD.
.SUNDAY…A CHANCE OF SNOW IN THE MORNING…THEN SNOW AND RAIN LIKELY
IN THE AFTERNOON. SNOW ACCUMULATION UP TO 4 INCHES. AREAS OF BLOWING
SNOW WITH VISIBILITIES REDUCED TO ONE HALF MILE AT TIMES…MAINLY
PORTAGE VALLEY TO ALONG EASTERN TURNAGAIN ARM. HIGHS IN THE 30S.
NORTH TO EAST WINDS 15 TO 30 MPH. THROUGH PORTAGE VALLEY AND
TURNAGAIN ARM…EAST WIND 30 TO 45 MPH.
.SUNDAY NIGHT…SNOW AND RAIN LIKELY. AREAS OF BLOWING SNOW. LOWS IN
THE UPPER 20S TO MID 30S. SOUTHEAST WIND 30 TO 45 MPH DECREASING TO
15 TO 30 MPH AFTER MIDNIGHT. THROUGH PORTAGE VALLEY AND TURNAGAIN
ARM…EAST WIND 35 TO 45 MPH.
.MONDAY…RAIN AND SNOW LIKELY IN THE MORNING…THEN A CHANCE OF RAIN
AND SNOW IN THE AFTERNOON. HIGHS IN THE LOWER TO MID 30S. SOUTHEAST
WIND 10 TO 25 MPH. THROUGH PORTAGE VALLEY AND TURNAGAIN ARM…EAST
WIND 25 TO 40 MPH DECREASING TO 15 TO 25 MPH IN THE AFTERNOON.
.MONDAY NIGHT…CLOUDY WITH A CHANCE OF RAIN AND SNOW. LOWS IN THE
.TUESDAY THROUGH WEDNESDAY…SNOW LIKELY. HIGHS 25 TO 35. LOWS IN THE
.WEDNESDAY NIGHT THROUGH FRIDAY…MOSTLY CLOUDY WITH A CHANCE OF
SNOW. LOWS 15 TO 25. HIGHS IN THE 20S.
TEMPERATURE / PRECIPITATION
SEWARD 29 21 37 / 80 40 90
GIRDWOOD 26 18 33 / 80 40 60
WEATHER STATION SUMMARY for Turnagain Pass:
-3800′ Sunburst Wx Station-
Temperature 21 degrees. Light wind trending from the east.
-2600′ Seattle Ridge Wx Station-
Current temperature 25. Light to moderate wind from the SE.
-1800′ Center Ridge Wx Station-
Temperature 27 degrees. One inch new snow recorded.