Turnagain Pass

Good morning backcountry travelers this is Lisa Portune with the Chugach National Forest Avalanche Information Center on Monday, March 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).

ANNOUNCEMENTS

Telepalooza & Alyeska World Comp March 23-28. Check out details at www.telepalooza.com. The event will have Telemark demos, lessons, races, beacon park games, and a raffle. The raffle has HUGE prizes with all proceeds going to the Friends of the Chugach National Forest Avalanche Center. See you there!

WEATHER ROUNDUP

No new snow fell in the last 24 hours in Turnagain Pass. Our last significant snowfall was four days ago when the pass got 12-18 inches of new snow. Mountain temperatures warmed up to the upper 20’s to mid 30’s yesterday afternoon under high overcast skies while ridgetop winds were light and variable. As of 4am this morning, ridgetop winds are averaging 5-15mph out of the southeast under cloudy skies. Temperatures cooled down at the higher elevations last night and currently range from 18F@3800′ to 24F@1800′ to 31F@sealevel. A weak low in the gulf may produce an inch or two of snow today with light rain at sea level this afternoon. Ridgetop winds should stay on the light side out of the southeast today, averaging 5-15mph, then increase a bit by this evening.

AVALANCHE DISCUSSION

The avalanche danger is rated MODERATE today on all slopes steeper than 35 degrees. This means that natural avalanches are unlikely but human-triggered avalanches are possible on steep slopes. Not much new snow or wind is forecasted for today, so our main concern is older buried weak layers that formed during the last few weeks. These weak layers include slick sun crusts on SE-S-SW aspects, small facets above and below the crusts, and several scattered layers of buried surface hoar on multiple aspects. In CNFAIC Staff words, the spatial variability in our upper snowpack right now is through the roof…pretty commonplace in the springtime. This means that you will have to rely on your own ability to interpret the stability of the snow in front of you.

No new natural or human-triggered avalanches were reported yesterday. High clouds and slightly cooler temperatures kept the wet snow avalanche activity at bay. Three nights of solid below freezing temperatures also helped stabilize our warm snowpack. Matt, Bill, and I toured up Sunburst yesterday and found a 1 inch thick suncrust buried 1.5 feet deep on south and southwest aspects. At 3300 feet on a southwest aspect we found a layer of buried surface hoar directly underneath the suncrust 1.5 feet down. In an Extended Column Test, a fracture on this layer propagated only halfway across the column on the 29th hit, indicating low reactivity. AnCNFAIC Staff group of skiers reported finding a layer of buried surface hoar 2.5 feet down on a north aspect at 3800 feet at the head of Spokane Creek between Lipps and Pete’s North. They got clean easy shears on the 1/4 inch size surface hoar crystals (CTE8,9Q2) and decided to turn around before gaining the ridge. The buried surface hoar was relatively isolated as they did not find any on east and northeast aspects and felt comfortable skiing those slopes. An Alaska Avalanche School class found a mixed bag of conditions on Pete’s North yesterday ranging from easy shears on a buried crust with possible facets to well bonded snow on a northwest aspect. They saw no obvious signs of instability.

When it snows again, our next weak link will be the current snow surface. A 1-3 inch thick melt-freeze crust extends up to 2000 feet elevation on all aspects and makes for some outstanding breakable crust skiing if you’re into that sort of thing. And to further complicate matters, a new batch of surface hoar formed on all aspects up to 3500 feet elevation in addition to anCNFAIC Staff sun crust on southerly slopes during Saturday’s sunny weather.

A glide crack avalanched this past Friday or Saturday on the steep south face of Tincan (see photo below). As always, stay out from underneath those unpredictable gaping cracks because they have their own agenda and can avalanche at any time.

Matt 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:

INCLUDING…WHITTIER…SEWARD…GIRDWOOD…MOOSE PASS

500 AM AKDT MON MAR 22 2010

.TODAY…CLOUDY WITH AREAS OF SNOW…POSSIBLY MIXING WITH RAIN

IN THE AFTERNOON. SNOW ACCUMULATION UP TO 1 INCH. HIGHS IN THE

MID 30S TO LOWER 40S. VARIABLE WIND TO 10 MPH. NEAR SEWARD…NORTH

WIND 10 TO 15 MPH.

.TONIGHT…CLOUDY. SNOW AND RAIN MAINLY ALONG THE COAST…DIMINISHING

AFTER MIDNIGHT. ADDITIONAL SNOW ACCUMULATION UP TO 1 INCH.

LOWS IN THE LOWER 20S TO LOWER 30S…COLDEST INLAND. NORTH TO

EAST WIND TO 15 MPH.

.TUESDAY…CLOUDY. A CHANCE OF RAIN AND SNOW IN THE AFTERNOON.

HIGHS IN THE MID 30S TO LOWER 40S. VARIABLE WIND 10 MPH EXCEPT

NORTH 15 TO 25 MPH NEAR SEWARD.

.TUESDAY NIGHT…SNOW AND RAIN LIKELY. LOWS IN THE UPPER 20S

TO MID 30S. NORTH TO EAST WIND 10 TO 20 MPH.

TEMPERATURE / PRECIPITATION

SEWARD 37 30 38 / 90 60 20

GIRDWOOD 37 27 38 / 70 40 0

WEATHER STATION SUMMARY for Turnagain Pass:

-3800′ Sunburst Wx Station-

recorded light and variable winds yesterday averaging 0-5mph. The current temp is 18F (4 degrees colder than this time yesterday) with winds averaging 5mph out of the southeast.

-2600′ Seattle Ridge Wx Station-

recorded light and variable winds yesterday averaging 0-10mph. The current temp is 21F (2 degrees colder than this time yesterday) with winds averaging 10-15mph out of the southeast.

-1800′ Center Ridge Wx Station-

recorded no new snow in the last 24 hours. The current temp is 24F (1 degree warmer than this time yesterday) with a total snowpack depth of 130 inches (2 inches of settlement in the last 24 hours).