Good morning backcountry travelers this is Kevin Wright with the Chugach National Forest Avalanche Information Center on Wednesday, November 17th 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).
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.
We have had no new snow since Friday the 12th. The major changes in last 48 hours are high wind at the ridge tops and a significant swing in temperature. The wind has been transporting snow and contributing to the wind slabs we’ve been seeing since Friday. Temperatures dropped into the low single digits at 3000 ft yesterday but rose again last night. Today we are seeing a temperature inversion in Girdwood and Turnagain pass with lower temperatures in the valleys and higher temperatures at the peaks.
There is a significant high pressure ridge across much of interior Alaska and the Bering Sea competing with a low near Southeast Alaska. This is producing a tight pressure gradient between the two masses and causing the wind between them. The next chance of snow in the forecast is Monday.
The avalanche danger rating will stay at LOW with pockets of MODERATE hazard. The overall feel of the snowpack hasn’t changed much in the last several days. Wind slabs at the ridge tops are an area of concern for backcountry travelers. Skier triggered wind slabs were possible last Saturday and that danger still exists. Yesterday on Lips the wind slabs were prevalent above 2000 feet although they didn’t seem to have much energy in them. Be careful on more committing terrain with bad consequences. These wind slabs are large enough to cause trouble if caught off guard.
We also noticed 3mm surface hoar in the alder zone yesterday on Lips. It quickly disappeared as we climbed into steeper terrain. Take note of this persistent weak layer as you tour and send us your observations if you find any surface hoar at higher elevations. This can be a serious problem when buried by later storms.
The glide cracks and glide avalanches continue to be present, with new ones being observed region-wide on a daily basis. Be aware of your travel routes and try to avoid spending time below the cracks. Research has shown it is nearly impossible to predict when these cracks will release. The only way to reduce your risk from glide avalanches is to avoid traveling below the obvious cracks.
This photo is the South face of Cornbiscuit on 11-16-10. For scale take note that the crack is 4-6 feet deep.
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:
WESTERN PRINCE WILLIAM SOUND-
500 AM AKST WED NOV 17 2010
…STRONG WIND THROUGH THIS MORNING NEAR WHITTIER…
.TODAY…SUNNY. HIGHS IN THE LOWER 20S TO MID 30S…COOLEST
INLAND. NORTHWEST WIND 10 TO 15 MPH. NEAR WHITTIER…WEST WIND 25 TO
35 MPH. GUSTS TO 50 MPH IN THE MORNING. NEAR SEWARD…NORTH WIND 25
TO 35 MPH.
.TONIGHT…MOSTLY CLEAR. LOWS 10 TO 15 ABOVE. NORTH TO WEST WIND
10 TO 20 MPH EXCEPT WEST 20 TO 35 MPH NEAR WHITTIER.
.THURSDAY…MOSTLY SUNNY. HIGHS IN THE UPPER 20S TO UPPER 30S.
NORTH TO WEST WIND 10 TO 20 MPH.
.THURSDAY NIGHT…MOSTLY CLEAR. LOWS IN THE MID TEENS TO LOWER
30S. NORTHWEST WIND 10 TO 15 MPH.
.FRIDAY…SUNNY. HIGHS IN THE UPPER 20S TO MID 30S. NORTH WIND
.FRIDAY NIGHT…MOSTLY CLEAR. LOWS 15 TO 25.
.SATURDAY THROUGH SUNDAY…PARTLY CLOUDY. HIGHS 25 TO 35. LOWS IN
.SUNDAY NIGHT…MOSTLY CLOUDY. LOWS IN THE 20S.
.MONDAY…MOSTLY CLOUDY WITH A CHANCE OF SNOW. HIGHS IN THE 30S.
.MONDAY NIGHT AND TUESDAY…CLOUDY WITH A CHANCE OF SNOW AND
RAIN. LOWS IN THE 20S. HIGHS IN THE 30S.
TEMPERATURE / PRECIPITATION
SEWARD 30 14 35 / 0 0 0
GIRDWOOD 25 12 31 / 0 0 0
WEATHER STATION SUMMARY for Turnagain Pass:
-3800′ Sunburst Wx Station-
Wind has dropped to the single digits. Temperatures jumped significantly from 2 to 16 since yesterday morning.
-2600′ Seattle Ridge Wx Station-
Wind has dropped to single digits. Temperatures rose from 5 to 17 degrees since yesterday.
-1800′ Center Ridge Wx Station-
No new snow recorded since the 12th. Current temperature is 10 degrees. Comparing this to the ridge top weather stations we are seeing an inversion through Turnagain pass. The snow pack is seeing continued settlement with anCNFAIC Staff loss of 1 inch since yesterday.