Turnagain Pass

Good morning backcountry travelers this is Matt Murphy with the Chugach National Forest Avalanche Information Center on Tuesday April 6th, 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).

ANNOUNCEMENTS

Skookum Valley and Skookum Glacier are closed to motorized vehicles (snowmachines, helicopters, ATVs) except for subsistence uses.. This closure is directed in the current Chugach National Forest Land and Resource Management Plan. Placer River Drainage remains open for motorized use to Spencer Glacier.

WEATHER ROUNDUP

-The winds have backed off this morning and are currently light averaging 1-12mph with some strong gusts up to 26mph

-The 24 hour snotel sites are reporting:

-0.7 inches of water (2.2 storm total) and ~7 inches of new snow (26” storm total) at 1800′ at Turnagain Pass

-0.4 inches of water and 8 inches of new snow at 1100′ at Grandview

-0.2 inches of water and 2 inches of new snow at 1400′ at Summit Creek.

-This morning’s (5am) radars show scattered precip over PWS and Kenai Peninsula

-Temps have cooled off at most weather stations by 1-2 degrees compared to yesterday. Above freezing temps made it up to 35 degrees at 1800′ yesterday. This morning’s temperature range is 33 degrees F at sea-level and 20 degrees F at 3800′.

AVALANCHE DISCUSSION

Today’s avalanche danger will remain at CONSIDERABLE, due 2.2 inches of water and over 2 feet of new snow in the past 48 hours. Natural avalanches were observed as recently as 12 noon yesterday. REMEMBER that 90% of avalanches occur during storms and within 24 hours of a storm. We are still in that time frame. Terrain management is key today. Stay away from any big slopes steeper than 35 degrees. This was a big load of snow with wind. The snowpack needs time to adjust. CONSIDERABLE means dangerous avalanche conditions exist.

We have limited observations from yesterday. We went to Tincan but did not make it above 2000′ due to poor visibility, wind, moderate to heavy precip, and deep snow. On this short tour, we did not observe any major obvious signs of instability CNFAIC Staff than some micro collapses under our feet or some small shooting cracks on a steep test slope.

The new snow/old snow interface is the primary concern today. We measured 30 inches of new snow at the Eddies parking lot on the northern end of Turnagain Pass and 12 inches of new snow at Johnson Pass North at the southern end of Turnagain Pass. This new snow is sitting on top of sun crusts on southern aspects.

Two examples of terrain that I would avoid today include (but are not limited to):

-skiing/snowboarding the southern aspect of Sunburst.

-snowmachining on the steep slopes of Repeat Offender above the snowmachine up-track to Seattle Ridge.

Staying alive in avalanche terrain is ALL about timing. We are in a time frame when the odds are stacked up against you. Humans can’t control the snowpack or weather, but we can control our terrain and how we travel on that terrain. Be smart out there and give the mountains the respect that they demand.

The sun is the critical “watch out” situation this time of year. Avalanche danger can increase rapidly to HIGH during periods rapidly warming temps and direct sunlight especially when the sun hits fresh snow like we have right now. AVOID traveling on any sunny slopes IF the sun comes out and get out of avalanche terrain immediately if it does.

Glide cracks are secondary concern today. These crevasse like features are those cracks that go all the way to the ground. Avoid traveling underneath these cracks. Glide cracks and full depth release avalanches have been occurring recently on warm sunny days.

WEATHER FORECAST (National Weather Service)

WESTERN PRINCE WILLIAM SOUND-

INCLUDING…WHITTIER…SEWARD…GIRDWOOD…MOOSE PASS

500 AM AKDT TUE APR 6 2010

.TODAY…SNOW SHOWERS. SNOW ACCUMULATION UP TO 3 INCHES. HIGHS IN THE

MID TO UPPER 30S. VARIABLE WIND 10 MPH.

.TONIGHT…NUMEROUS SNOW SHOWERS. SNOW ACCUMULATION UP TO 1 INCH.

LOWS IN THE LOWER 20S TO LOWER 30S. SOUTHEAST WIND 15 MPH.

.WEDNESDAY…MOSTLY CLOUDY WITH SCATTERED SNOW SHOWERS. HIGHS IN

THE MID 30S TO LOWER 40S. LIGHT WINDS.

.WEDNESDAY NIGHT…PARTLY CLOUDY WITH ISOLATED SNOW SHOWERS. LOWS

IN THE MID TEENS TO LOWER 30S. VARIABLE WIND TO 10 MPH. NEAR

SEWARD…NORTH WIND 10 MPH.

TEMPERATURE / PRECIPITATION

SEWARD 37 26 40 / 80 60 40

GIRDWOOD 39 24 37 / 80 60 40

Short Term Weather Model Forecasts (NAM, WRF, GFS) for the Kenai Mountains near Turnagain Pass

Sea-level: temps are forecasted between 24-39 and between 0.25-0.5” of water forecasted for mid to southern Kenai Peninsula

3000′: temps are forecasted in the range of 23-32 degrees F with winds 10 mph

6000′: temps are forecasted in the range of 14-23 degrees F with winds 10-20 mph

WEATHER STATION SUMMARY for last 24 hours at TURNAGAIN PASS

3800′-Sunburst Wx Station

Temp (5am): 20 (same as yesterday morning)

Winds: In last 24 hours winds have been light to moderate averaging 0-24mph with a strong max gust of 38mph

HIGH TEMP of 21 at 2pm

2600′-Seattle Ridge Wx Station

Temp (5am): 23 (1 degree colder than yesterday morning)

Winds: BROKEN, We will fix ASAP

HIGH TEMP of 28 between 2-5pm

1800′-Center Ridge Wx Station

Temp (5am): 26 (1 degree colder than yesterday morning)

Precip: 0.7 inches of water and probably 7 inches of new snow

HIGH TEMP 35 at 1pm

Thanks for checking today’s avalanche advisory. The next one will be posted tomorrow Wednesday April 7th, 2010.