Turnagain Pass

Good morning backcountry travelers this is Lisa Portune with the Chugach National Forest Avalanche Information Center on Monday, December 6th 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).

WEATHER ROUNDUP

Sunny skies, light winds, and temps in the 20’s made for anCNFAIC Staff beautiful day in the mountains yesterday…as long as you were above the fog. Our last snowfall was Friday when 8-14 inches fell in Turnagain Pass accompanied by gale force easterly winds. It is snowing lightly this morning with mountain temps in the 20’s and light ridgetop winds. Today temperatures will remain in the 20’s while winds should stay on the light side as well. We may get an inch or two of snow this morning out of a front moving west from the gulf, but nothing substantial.

AVALANCHE DISCUSSION

Today the avalanche hazard has decreased to MODERATE overall. Small to medium sized human-triggered avalanches

1-2 feet deep are still possible on steep windloaded slopes. Natural avalanches are unlikely. Use caution on steep unsupported convex terrain near ridgetops and in crossloaded gullies.

Numerous small human triggered avalanches were reported Saturday but nothing yesterday, while most of our natural avalanches happened late Friday at the tail end of the storm. The culprit is a layer of surface hoar that formed last week during the cold clear weather. Underneath the surface hoar is 6 inches of low density faceted snow, which in turn is sitting on the dreaded Thanksgiving Rain Crust. The new snow in non wind-affected terrain is not slabby enough yet to propagate a fracture, so our primary concern today is mainly on any windloaded slopes up high where the surface hoar and rain crust are buried under a dense slab of snow. Jon and I got loud whumphing and 25-30ft. long shooting cracks on a windloaded slope above treeline two days ago…obvious signs of an unstable snowpack. One of our observers, however, reported no signs of instability yesterday while snowmachining in Main Bowl on the backside of Seattle Ridge. He also watched a skier on Widowmaker Peak where the new snow only sluffed on the layer of surface hoar.

For the first time in 4 weeks, no new glide avalanches were observed this past weekend. The new snow is covering up many of the existing cracks that have not yet avalanched, so be extra cautious on your descent.

Jon 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:

INCLUDING…WHITTIER…SEWARD…GIRDWOOD…MOOSE PASS

500 AM AKST MON DEC 6 2010

.TODAY…SNOW. SNOW ACCUMULATION 2 TO 4 INCHES. HIGHS IN THE LOWER

20S TO MID 30S…COOLEST INLAND. VARIABLE WIND TO 10 MPH. NEAR

SEWARD…NORTH WIND 15 TO 30 MPH. NEAR WHITTIER…WEST WIND 10 MPH

INCREASING TO 20 MPH GUSTING TO 30 MPH BY LATE MORNING.

.TONIGHT…MOSTLY CLOUDY WITH SCATTERED SNOW SHOWERS. LOWS IN THE MID

TEENS TO MID 20S…COOLEST INLAND. LIGHT WINDS. NEAR SEWARD… NORTH

WIND 15 TO 25 MPH. NEAR WHITTIER…WEST WIND TO 20 MPH GUSTING TO 30

MPH.

.TUESDAY…CLOUDY WITH A CHANCE OF SNOW. HIGHS IN THE 20S TO MID

30S…COOLEST INLAND. LIGHT WINDS. NEAR SEWARD… NORTH WIND 15 TO

25 MPH. NEAR WHITTIER…WEST WIND TO 20 MPH GUSTING TO 30 MPH.

TEMPERATURE / PRECIPITATION

SEWARD 34 27 36 / 40 30 50

GIRDWOOD 24 20 23 / 40 30 30

WEATHER STATION SUMMARY for Turnagain Pass:

-3800′ Sunburst Wx Station-

recorded light northeast winds yesterday averaging 5-10mph and temps ranging from 20F to 23F. The current temp is 23F with light winds out of the northeast.

-2600′ Seattle Ridge Wx Station-

stopped working but recorded temps ranging from 21F to 25F yesterday. The current temp is 21F.

-1800′ Center Ridge Wx Station-

recorded no new snow in the last 24 hours. Temps yesterday ranged from 20F to 26F. The current temp is 23F.