Good morning backcountry travelers. This is Jon Gellings with the Chugach National Forest Avalanche Information Center on Tuesday, March 15th 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).
There is a LOW danger today. Common hazards that never go away during the winter, such as cornice breaks or fracturing an old wind slab in steep and rocky terrain, still remain in extreme terrain. Regions with a thin snowpack still have an isolated chance of triggering a deeper avalanche on steep, wind loaded slopes.
Chugach Electric Association, Inc. will be conducting patrol and maintenance of the electrical lines between Summit Lake and Turnagain Pass until April 15th. They will be operating snowmachines near the power lines between Center Ridge and Johnson Pass North T.H. under a special use permit.
We are forecasted to receive precipitation today. The intensity of this event is debatable, but we will let you know how much of what falls where when we know. The million dollar question right now relates to how any new snow will bond to the widespread boilerplate. The first few hours of any storm will be crucial for answering this question.
Today, normal caution is advised. There is still the potential to trigger an avalanche, but it is unlikely and is confined to extreme terrain. Older wind slabs from our previous wind storm could break near steep rocky terrain, as well as in cross loaded gullies with high slope angles. Cornices could also fail due to increased temperatures, so walking along sharp ridgelines could have an increased hazard as well.
Last nights temperatures were elevated from recent night temperatures, indicating that solar affected aspects may not have gone through as deep of an overnight freeze cycle as they recently have been. If the sun has a chance to warm these southerly slopes again today, it has an increased possibility to produce wet snow that can be pushed down a slope.
Yesterday we found that low elevation sheltered areas not previously affected by winds are harboring unburied persistent weak layers, such as surface hoar and near surface facets. Luckily though, most of our starting zones have been wind hammered, so these future weak layers are not as concerning as they could be.
There remains an isolated chance of triggering a larger avalanche into older weak snow in regions with less snow than Turnagain Pass. Places with this concern generally have less than a 5-6 foot deep snowpack.
Encyclopedia of avalanche terms.
Snow is in the forecast, but it is unlikely to be significant enough to increase the avalanche danger today. Models show that Seward is going to receive more precipitation than Turnagain Pass. Winds look to remain pretty minimal today again, so they will probably not be able to move any old snow. Temperatures are currently warmer, but they will likely only be stressing the southern slopes.
I 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 TUE MAR 15 2011
.TODAY…CLOUDY. SNOW DEVELOPING IN THE MORNING. SNOW ACCUMULATION UP
TO 2 INCHES. HIGHS IN THE UPPER 20S TO MID 30S. LIGHT WINDS EXCEPT
NORTH 15 TO 25 MPH NEAR SEWARD.
.TONIGHT…MOSTLY CLOUDY WITH A CHANCE OF SNOW. LOWS IN THE LOWER
TEENS TO LOWER 30S…COOLEST INLAND. LIGHT WINDS EXCEPT WEST
15 MPH NEAR WHITTIER.
.WEDNESDAY…CLOUDY WITH SCATTERED RAIN AND SNOW SHOWERS. HIGHS IN
THE 30S. LIGHT WINDS.
TEMPERATURE / PRECIPITATION
SEWARD 35 28 38 / 80 40 40
GIRDWOOD 28 20 33 / 80 40 40
WEATHER STATION SUMMARY for Turnagain Pass:
-3800′ Sunburst Wx Station-
22 degrees at 5am. Light wind from the NE.
-2600′ Seattle Ridge Wx Station-
24 degrees at 6am. Calm to light wind from the NE.
-1800′ Center Ridge Wx Station-
20 degrees at 5am. No new snow.