Turnagain Pass

Good morning backcountry travelers. This is Wendy Wagner with the Chugach National Forest Avalanche Information Center on Sunday, February 13th 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).

BOTTOM LINE

The avalanche danger is MODERATE in thin snowpack areas for deep slab avalanches. Triggering an avalanche that breaks into the deeper buried weak layers, from either an area with a shallow overall snow cover or a thin spot in rocky terrain is possible. Also, there are pockets of MODERATE on leeward slopes for wind slabs that have formed within the recent new snow.

AVALANCHE DISCUSSION

Today’s primary concern remains for deep slab avalanches. It has been 6 days since we have had any reports of avalanche activity breaking into the older weak layers formed during the December dry spell (the last being the slide on Magnum in the Turnagain Pass area). With only 4-8 inches of new snow this week, not much has occurred to change our current deep slab problem. Areas likely to be trigger spots continue to be the shallower snowpack regions and steep rocky terrain. As people begin to push onto the more radical, extreme slopes, they are more likely to find one of these ‘sweet’ spots where they could trigger a deeper slide. The consequences are high for an avalanche that steps down into these deeper buried weak layers.

Several folks were getting out and about yesterday with a few venturing into slightly steeper terrain. There was widespread loose snow sluffing in the new low density ‘cold smoke’ powder that fell on Thursday and Friday. Considering the modest amount of new snow, these loose sluffs were minor avalanche concerns. In addition, a few smaller wind slabs were triggered in the Turnagain Pass area. These were soft and not packing too much of a punch, yet some did run fairly far (see photo gallery). All activity was confined to the new snow and was relatively shallow, in the 4-12 inch range.

Today’s secondary concern is for wind slabs. Even though the winds have been light, the recent new snow is also light, making it easy for the wind to transport and deposit snow onto leeward slopes. Due to the cold temperatures, low density snow and potentially increasing winds, I am expecting shallow wind slabs and loose snow sluffing to be fairly easy to initiate again today. These could run faster and further than expected on steeper slopes that have a wind or rain curst underneath.

Below is a photo of a soft slab avalanche triggered by a ski cut on the west face of Lipps yesterday. Check out the photo gallery for details and CNFAIC Staff photos from yesterday.

Encyclopedia of avalanche terms.

WEATHER ROUNDUP

Sunny skies, single digit temperatures and mostly light winds prevailed yesterday. Overnight, temperatures remained in the minus single digits while the winds blew mainly out of the north and west around 5mph and gusting into the mid teens. Today temperatures will remain in the single digits and winds are forecast to pick up slightly from the north, gusting into the 20’s on the ridglines. Skies will likely be partly cloudy and there is a chance for a skiff of snow. As it looks from the radar, the snow showers near Whittier are trying to spill over into our neck of the woods.

ANNOUNCEMENTS

The Friends of the CNFAIC (FCNFAIC) needs your thoughts! With a new staff of forecasters and a list of previously completed goals, the program is growing and potentially heading in new directions. The FCNFAIC wants to know what you have to say about YOUR avalanche center, so please complete the following anonymous survey by February 20th. Thank you in advance for taking it!

Click here to take survey

or cut and paste the address directly:

https://www.surveymonkey.com/s/THWXVCD

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-

INCLUDING…WHITTIER…SEWARD…GIRDWOOD…MOOSE PASS

500 AM AKST SUN FEB 13 2011

…STRONG WIND THROUGH MONDAY EVENING FOR SEWARD AND WHITTIER…

.TODAY…SNOW CHANGING TO SCATTERED SNOW SHOWERS THIS AFTERNOON.

AREAS OF BLOWING SNOW…VISIBILITIES NEAR ONE HALF MILE NEAR

WHITTIER. SNOW ACCUMULATION AROUND 1 INCH. HIGHS ZERO TO 15

ABOVE…COOLEST INLAND. NORTH TO WEST WINDS 15 TO 30 MPH. NORTH

WINDS 30 TO 50 MPH NEAR SEWARD. SOUTHWEST WINDS 40 TO 60 MPH NEAR

WHITTIER.

.TONIGHT…DECREASING CLOUDS. ISOLATED SNOW SHOWERS IN THE EVENING.

LOWS 10 BELOW TO 10 ABOVE…COOLEST INLAND. NORTH TO WEST WINDS 15 TO

30 MPH. NORTH WINDS 30 TO 55 MPH NEAR SEWARD. SOUTHWEST WINDS 45 TO

65 MPH NEAR WHITTIER.

.MONDAY…SUNNY. HIGHS 5 BELOW TO 15 ABOVE…COOLEST INLAND. NORTH

TO WEST WINDS 15 TO 30 MPH. NEAR SEWARD…NORTH WINDS 15 TO 30 MPH.

GUSTS TO 55 MPH IN THE MORNING. NEAR WHITTIER…SOUTHWEST WINDS 45

MPH WITH GUSTS TO 65 MPH IN THE MORNING. .

.MONDAY NIGHT…CLEAR. LOWS 10 BELOW TO 5 ABOVE…COOLEST INLAND.

NORTHWEST WIND 10 TO 25 MPH. NEAR WHITTIER…WEST WIND 40 TO 55 MPH

DECREASING TO 15 TO 30 MPH AFTER MIDNIGHT.

.TUESDAY…MOSTLY SUNNY. HIGHS 15 TO 25. NORTHWEST WIND 10 TO

20 MPH EXCEPT NORTH 10 TO 25 MPH NEAR SEWARD.

TEMPERATURE / PRECIPITATION

SEWARD 8 1 12 / 40 20 0

GIRDWOOD 9 -9 10 / 50 20 0

WEATHER STATION SUMMARY for Turnagain Pass:

-3800′ Sunburst Wx Station-

Temperature -3 degree. Light wind gusting to 12 from the west.

-2600′ Seattle Ridge Wx Station-

Temperature -1 degrees. Wind gauge iced over.

-1800′ Center Ridge Wx Station-

Temperature 4 degrees. 5-8 inches of 8-10% snow fell Friday.