Turnagain Pass

Good morning backcountry travelers this is Matt Murphy with the Chugach National Forest Avalanche Information Center on Thursday March 11th, 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).

WEATHER ROUNDUP

-The winds are currently calm to light at all ridge top weather stations averaging 0-7mph with light max gust up to 16mph.

-In the last 24 hours (5am-5am), the snotel sites recorded: 0.1 inch of water and 4 inches of snow settlement at Grandview, and 0.0 inches of water and 2 inches snow settlement at Summit Creek.

-The current radars are mostly clear.

-Temps have cooled off at all weather stations by 2-3 degrees since yesterday morning except for Summit Creek which increased by 10 degrees. Current temps are 6 degrees F at sea-level and negative 6 degrees F at 3800′.

AVALANCHE DISCUSSION

Today’s danger level will decrease to MODERATE due to lack of significant weather in the past 24-48 hours, time since the last major storm, and a weak weather forecast for today.

Snowfall totals from Monday’s storm at the highway elevation snow stakes at Turnagain Pass were 31 inches at Eddies, 31 inches at the Motorized lot, 22 inches at Sunburst, and 19 inches at Johnson Pass. Yesterday’s tour up Tincan found variable depths due to wind so it’s hard to say exactly how much snow fell at higher elevations. We did not see, feel, hear, or observe any obvious signs of instability on Tincan Common or in the trees yesterday. We got no results from stomping on test slopes or ski cuts. From this tour on this moderate terrain, everything hinted towards LOW danger, but the snowpack is still moving and adjusting from that last load.

The snotel sites are still showing 9-11 inches of settlement in the last 48 hours; so, the snowpack is still actively moving. Yesterday was our first day of getting baseline observations; so, we really don’t have a full picture of stability at Turnagain Pass yet. The uncertainty level is still a little fuzzy. Even though almost everything is hinting toward LOW danger, there have still been some unusual surprises in recent avalanche reduction work.

Anytime there is anything unusual in the snowpack you should be cautious, and there have been some unusual avalanches since Tuesday. Keep your terrain moderate today and save the big lines for anCNFAIC Staff day. There are still some land mines out there, especially on big steep terrain.

Glide cracks are secondary concern today since this new load of snow is still actively settling and moving. A full depth release avalanched a couple days before Monday’s storm in Girdwood Valley (see photo gallery). Glide cracks are like cornices in that they are wild cards that are very difficult to predict.

WEATHER FORECAST (National Weather Service)

WESTERN PRINCE WILLIAM SOUND-

INCLUDING…WHITTIER…SEWARD…GIRDWOOD…MOOSE PASS

500 AM AKST THU MAR 11 2010

…STRONG WIND THROUGH THIS AFTERNOON NEAR WHITTIER…

.TODAY…PARTLY CLOUDY. HIGHS IN THE LOWER TO MID 20S. WEST WIND 30

TO 45 MPH NEAR WHITTIER. NORTH WIND 25 TO 35 MPH NEAR SEWARD.

NORTHWEST WIND 10 TO 15 MPH ELSEWHERE.

.TONIGHT…MOSTLY CLOUDY WITH SCATTERED SNOW SHOWERS. LOWS ZERO

TO 15 ABOVE. WEST WIND 15 TO 30 MPH NEAR WHITTIER. NORTH WIND 15 TO

25 NEAR SEWARD. NORTHWEST WIND TO 10 MPH ELSEWHERE.

.FRIDAY…MOSTLY CLOUDY WITH SCATTERED SNOW SHOWERS. HIGHS IN THE

LOWER 20S TO LOWER 30S. VARIABLE WIND TO 10 MPH. NEAR SEWARD…NORTH

WIND 10 MPH.

Temperature / Precipitation

SEWARD 26 7 29 / 0 30 30

GIRDWOOD 21 13 30 / 0 30 30

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

Sea-level: temps are forecasted between 13-21 and between 0.0-0.1” of water forecasted

3000′: temps are forecasted in the range of (negative 4) to 5 degrees F with winds 10-15 mph

6000′: temps are forecasted in the range of (negative 4) to 5 degrees F with winds 15-20 mph

WEATHER STATION SUMMARY for last 24 hours at TURNAGAIN PASS

3800′-Sunburst Wx Station

Current Temp: -6 (2 degrees colder than yesterday)

Winds: In last 24 hours winds have been calm to light averaging 0-10mph with moderate max gust of 17mph

2600′-Seattle Ridge Wx Station

Winds: In last 24 hours winds have been calm to light averaging 0-6mph with an light max gust of 12mph

1800′-Center Ridge Wx Station

Current Temp: not working

Precip: not working

Thanks for checking today’s avalanche advisory. The next one will be posted tomorrow Friday March 12, 2010.