Good morning backcountry travelers this is Jon Gellings with the Chugach National Forest Avalanche Information Center on Monday, December 27th 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).
Today the avalanche hazard is LOW, with pockets of MODERATE. Natural avalanches and human triggered avalanches are unlikely throughout our general advisory area, while small human triggered avalanches are possible in steep upper elevation windloaded terrain. Be on the lookout for pockets of sensitive wind slab in isolated areas at upper elevations.
We still have a cold snowpack, even though temperatures yesterday were fairly warm compared to what we have been seeing recently. We still have layers of facets and surface hoar which are buried in the snowpack, and they do not look like they are leaving anytime soon.
The most unstable layer recently has been the layer of facets growing underneath the Thanksgiving Rain Crust (TRC). Tests yesterday on Tincan and Eddies revealed that this layer is exhibiting signs of moderate to high strength, with fairly low energy and non-planar breaks. Once we get a large stress load on this snow, which could happen in a few days, expect failures within this layer throughout our advisory area.
In steeper, more exposed slopes at higher elevations, the TRC has been observed much closer to the surface than in most CNFAIC Staff areas. This is due to variability of winds throughout the alpine terrain, which can leave a large wind pillow of 3 ft new snow in one spot, while there is 3 inches of new snow 5 ft away. Recent human triggered avalanche activity points out that these areas have been showing increased activity over CNFAIC Staff areas. The soft snow on top of the TRC was noticed to sluff off easily when stressed in high-angle terrain.
The most significant recent avalanche report was in Goat Couloir up Crow Creek Rd. A backcountry skier was caught briefly before he/she was able to regain control and ski to the flank to wait while the avalanche debris cascaded the rest of the way down the slope. This area encompasses terrain in excess of 50 degrees steep at an elevation of around 6000 ft a.s.l. Utilize safe travel procedures whenever you are out in the backcountry, but more cautious and conservative decision making in committing terrain is essential. After all, being able to tell stories of your enjoyable day to your friends is much more delightful than getting visited while in the hospital or worse.
Check out an encyclopedia of terms here: www.fsavalanche.org/Encyclopedia.aspx
There is an inversion going on currently in the Girdwood area, with a less-defined one going on in Turnagain Pass. Temps at sea level are in the lower teens, while ridgetops are in the low to mid 20s. Models show a bit of a cool down happening this evening, but should not be a large difference from todays temps. Wind gusts have been moderate to strong, while sustained winds have been fairly light. There are a few blobs of precipitation out in Prince William Sound heading our way, but the smaller previous waves never made it beyond the glaciers on the west side of the waterway. Satellite images are showing that it will be hit or miss as to whether or not our skies will be cloudy or clear for the majority of today. Snow is making it into our forecasts more often recently, which seems to be happening due to a northward shift in the jet stream. It looks like we may take a direct hit by the jet stream winds and storms on Wednesday. We will soon see if this weather event actually comes to fruition.
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 MON DEC 27 2010
.TODAY…MOSTLY CLOUDY WITH SCATTERED SNOW SHOWERS. HIGHS 10 TO 20
ABOVE EXCEPT IN THE MID TO UPPER 20S ALONG THE COAST. NEAR
SEWARD…NORTH WIND 20 TO 35 MPH DECREASING TO 15 MPH IN THE
AFTERNOON. ELSEWHERE…VARIABLE WIND 10 MPH.
.TONIGHT…MOSTLY CLOUDY. A SLIGHT CHANCE OF SNOW SHOWERS ALONG
THE COAST. LOWS 5 BELOW TO 10 ABOVE EXCEPT IN THE LOWER TO MID 20S
ALONG THE COAST. LIGHT WINDS EXCEPT NORTH WIND TO 15 MPH NEAR SEWARD.
.TUESDAY…MOSTLY CLOUDY. A SLIGHT CHANCE OF SNOW SHOWERS ALONG
THE COAST. HIGHS IN THE TEENS INLAND AND MID TO UPPER 20S ALONG
THE COAST. LIGHT WINDS.
TEMPERATURE / PRECIPITATION
SEWARD 25 21 25 / 40 20 20
GIRDWOOD 18 11 16 / 30 0 0
WEATHER STATION SUMMARY for Turnagain Pass:
-3800′ Sunburst Wx Station-
recorded single-digit light northeast winds yesterday, with a 5 hour period of gusts over 20mph, up to 37mph, and temps from 18F to 20F. The current temp is 20F with 9mph winds out of the northeast.
-2600′ Seattle Ridge Wx Station-
recorded mostly light southeast winds yesterday averaging 1-7mph, while temps ranged from 20F to 24F during the day. The current temp is 19F with light 5mph winds out of the southeast.
-1800′ Center Ridge Wx Station-
recorded 1″ new snow in the past 24hrs. Temps yesterday ranged from 17F to 26F. The current temp is 22F with a total snowpack depth of 53 inches.