Good morning backcountry travelers this is Matt Murphy with the Chugach National Forest Avalanche Information Center on Friday November 12, 2010 at 7 am. 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).
All areas designated for snowmachines are still closed. We are measuring the snow in these areas daily, and will open them as soon as there is enough snow to protect the ground and vegetation from being torn up by the tracks of a snowmachine. Thanks for your patience.
-That big storm that was heading our way seems to have fallen apart.
-The radar shows the heaviest precip this morning SE of Cordova, with scattered light precip over Western Prince William Sound
-Winds have backed off since yesterday
-Temps have cooled slightly
Todays avalanche danger is LOW with pockets of MODERATE. Any new snow that fell at the higher elevations yesterday will be heavier than the old snow underneath that new layer. There will be some pockets of upside down snow where it will be possible to trigger small to medium sized human-triggered avalanches especially on wind slabs near ridges. Natural avalanches are possible in the form of glide cracks.
Glide Cracks-These features kind of look like crevasses in the snow that go all the way down to the ground. They can cause slab avalanches where the ground is the weak layer. We have been seeing many of these cracks avalanche recently, and we should assume that glide crack avalanches are still possible today. Avoid traveling under the path of any of these cracks. See photo gallery for an example of what glide cracks look like.
Wind slabs-Yesterday’s strong winds have created numerous wind slabs near ridges. Be cautious on stiff snow or areas that look fat compared to the rest of the slope. This is the first big wind event on what has been light and fluffy snow; so, these wind slabs may be a bit reactive to human triggers.
It’s early season. The snow does strange things in the early season.
Secondary areas of concern in the snowpack are crusts and buried surface hoar. Kevin and Jon found multiple crusts near Seattle Ridge along the traditional snowmachine up-track (Repeat Offender). These crusts will most likely be the weak layers after the next big storm comes in. The first layer of buried surface hoar was reported in sheltered areas in the tree elevation near Summit Lake. We will keep our eyes on this layer.
WEATHER FORECAST (National Weather Service)
WESTERN PRINCE WILLIAM SOUND-
500 AM AKST FRI NOV 12 2010
.TODAY…NUMEROUS RAIN AND SNOW SHOWERS. SNOW ACCUMULATION UP TO 1
INCH OVER THE HIGHER ELEVATIONS. HIGHS IN THE 30S. VARIABLE WIND TO
.TONIGHT…NUMEROUS RAIN AND SNOW SHOWERS. SNOW ACCUMULATION UP TO 2
INCHES. LOWS IN THE LOWER 20S TO MID 30S. LIGHT WINDS BECOMING SOUTH
TO 15 MPH AFTER MIDNIGHT.
.SATURDAY…MOSTLY CLOUDY WITH SCATTERED RAIN AND SNOW SHOWERS. HIGHS
IN THE MID 30S TO LOWER 40S. VARIABLE WIND TO 10 MPH.
TEMPERATURE / PRECIPITATION
SEWARD 39 35 41 / 60 60 40
GIRDWOOD 36 31 37 / 60 60 40
Short Term Weather Model Forecasts (NAM, WRF, GFS) for the Kenai Mountains near Turnagain Pass
Sea-level: temps are forecasted between 31-36 and between 0.25-0.5” of water forecasted
3000′: temps are forecasted in the range of 32-41 degrees F with winds 5-10 mph
6000′: temps are forecasted in the range of 23-32 degrees F with winds 10-15 mph
WEATHER STATION SUMMARY for last 24 hours at TURNAGAIN PASS
3800′-Sunburst Wx Station
Temp (4am): 25 (slightly cooler than yesterday morning)
Winds: In last 24 hours winds have been light-strong averaging 8-36mph with a max gust of 85mph
2600′-Seattle Ridge Wx Station
Temp (4am): 28 (slightly cooler than yesterday morning)
Winds: In last 24 hours have been light to moderate averaging 1-24 mph with a strong max gust of 36mph
1800′-Center Ridge Wx Station
Temp (6am): 29 (slightly cooler than yesterday morning)
Precip: 0.9 inches of water, 4 inches new snow
Thanks for checking today’s avalanche advisory. The next one will be posted tomorrow Saturday November 13, 2010.