Good morning backcountry travelers this is Jon Gellings with the Chugach National Forest Avalanche Information Center on Wednesday, January 26th 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).
The avalanche danger rating today is MODERATE. Naturally triggered avalanches are unlikely, but Human triggered avalanches are Possible. DO NOT underestimate this word! Loading processes have currently become lull, but we are well within the amount of time after a storm where the new snow has not quite stabilized yet. If you go onto steep, smooth, leeward, and loaded terrain today, you could potentially activate an avalanche that could break deeper than you expect.
Yesterday we were informed about a full burial that happened on Monday. A snowmachiner triggered and got caught in an avalanche down by Lost Lake, but was dug out expediently by his partner. Limited details about the avalanche include:
-30-40 degrees steep
-2000 ft elevation
-Failed 2-3 feet deep
-Monday, which had a Considerable Danger rating
Thankfully the rider was uninjured, and the riding partner was good at shoveling. Please remember that the majority of fatalities occur on days of Moderate and Considerable Danger. This is because the danger is very apparent during High and Extreme danger periods, while Moderate and Considerable days tend to show less obvious amounts of instability. Please be careful when out recreating, because getting hurt is never fun. A question everybody can ask themselves from this incident is, “Who am I travelling with? Would they be able to dig me out of an avalanche?”
With our storm’s impact being fairly well over, be aware that many slopes may be touchy today. Giving the mountains time to feel comfortable in their new blankets is always a good thing. We are still well within the 24 hr “rule” of post-storm instabilities. Slab avalanches created by the strong winds and several feet of snow could potentially break much deeper than someone may suspect. With poor visibility yesterday, I was only able to see 1 small-to-medium sized natural avalanche on the West face of Magnum. It looked to have broken down to the recently buried layer of surface hoar, but that is a guess at best.If you do see some signs of instability, such as recent avalanches, shooting cracks, or hearing “whoomphing” sounds, please let one of us forecasters know; you may potentially win $100 gift certificate at the end of this month if you submit your observations…
Our week-long storm gave us 24-28 inches of upside-down snow, which has buried numerous types of significant weak layers. Widespread surface hoar that formed January 5-18 is the easiest to find, and will likely be in our snowpits for a long time. The new snow that fell is also sitting on top of CNFAIC Staff variable conditions, including ice crusts, wind crusts, wind slabs, and sugary facets. None of these layers are good to have under a large amount of new snow, because they all tend to bond poorly to new warm snow. The first several inches of cold and light density snow that fell with this storm might preserve the mentioned persistent instabilities for quite some time. Winds up in the start zones have pushed a lot of snow around, so expect possible failures to occur up to several feet deep in upper alpine areas.
Dont forget about our old instabilities either! Persistent weak layers consisting of buried surface hoar from December, as well as facets above and below the Thanksgiving Rain Crust, have been active in the past and could still be re-energized by a large storm. Although it has been over two weeks since the last reported human triggered avalanche on one of these layers, the weight and added energy of our new snowfall has the potential to create new avalanche activity within these layers. Avalanches that are triggered today have the potential to step down to any of these deeper layers, which could create a much deeper and larger avalanche.
Encyclopedia of terms: www.fsavalanche.org/Encyclopedia.aspx
Radar images currently show small amounts of precipitation moving toward our advisory area, while satellite images show clouds in our area, likely for the remainder of the day. Temperatures and winds have decreased since yesterday, which is when the storm’s energy decreased. There is the possibility of more snow today at upper elevations according to NWS, but winds should be light with the passage of this new precipitation. For the near future, there is a strengthening 963mb Low moving into position in the Gulf of AK that, combined with the Jet Stream Forecast, is looking like it will head toward us and be here in a few days.
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 AKST WED JAN 26 2011
.TODAY…SCATTERED RAIN AND SNOW SHOWERS IN THE MORNING…THEN
NUMEROUS RAIN AND SNOW SHOWERS IN THE AFTERNOON. SNOW ACCUMULATION UP
TO 2 INCHES OVER HIGHER ELEVATIONS. HIGHS IN THE UPPER 20S TO UPPER
30S…COOLEST INLAND. LIGHT WINDS.
.TONIGHT…NUMEROUS SNOW SHOWERS. SNOW ACCUMULATION UP TO
2 INCHES. LOWS IN THE LOWER 20S TO LOWER 30S. LIGHT WINDS.
.THURSDAY…PARTLY CLOUDY. HIGHS IN THE UPPER 20S TO MID 30S.
VARIABLE WIND TO 10 MPH. THROUGH PORTAGE VALLEY AND TURNAGAIN
ARM…EAST WIND 10 TO 25 MPH.
TEMPERATURE / PRECIPITATION
SEWARD 38 24 31 / 60 60 0
GIRDWOOD 29 23 33 / 60 60 0
WEATHER STATION SUMMARY for Turnagain Pass:
-3800′ Sunburst Wx Station-
recorded decreasing winds yesterday averaging 15-30mph, with a peak wind of 45 from the NE in the morning. Temperatures were recorded from 23F to 25F during the day. The winds are blowing 9-13mph out of the NE, while the temperature is currently 21F.
-2600′ Seattle Ridge Wx Station-
is currently not recording winds. Temps decreased from 28F to 26F during the day. Temp is currently 25F.
-1800′ Center Ridge Wx Station-
recorded 6 inches of new snow and 0.5 inches of water in the last 24 hours. Then the snowpack started to settle, bringing the total snow depth to 80″. Temps yesterday recorded from 29F to 30F during the day. The current temp is 27F.