Turnagain Pass

Good morning backcountry travelers this is Matt Murphy with the Chugach National Forest Avalanche Information Center on Tuesday November 24 at 7 am. This will serve as a general backcountry avalanche advisory issued for Turnagain Arm with Turnagain Pass as the core advisory area(advisory does not apply to highways, railroads, or operating ski areas).

ANNOUNCEMENTS

All areas on the Chugach National Forest designated for snowmachine use are still closed; however, this past storm helped us get closer to opening these areas. We are monitoring this situation closely every day, and will open these areas according to the current Forest Plan as soon as possible. These areas have to remain closed until there is enough snow to prevent resource damage. In CNFAIC Staff words, there has to be enough snow to prevent to tracks of a snowmachine from ripping vegetation.

WEATHER ROUNDUP

The center ridge weather station recorded 29″ of new snow since Sunday night. This jives with my observations from the highway yesterday at 3pm where I found 24 inches of new snow at our snow measuring board at the motorized parking lot. There was less snow further south down the highway with 16″ new snow at Sunburst, and 2-3″ new snow at Johnson Pass Trailhead. Eddies pullout on the northern side of Turnagain Pass had 12″ of wet snow. The rain/snow line was mixed at the highway elevations yesterday. Winds were the strongest between 10am and noon yesterday. Temps have decreased by 1-2 degrees at all weather stations since yesterday morning, and winds have decreased but they are still moderate to strong on ridgetops averaging 19-26mph with gusts to 41 mph this morning. The weather models are forecasting above freezing temps from sea-level to about 1000 feet, and anCNFAIC Staff .5 inches of water in the next 24 hours.

In the past 24 hours…

Sunburst weather station at 3800′ in Turnagain Pass has recorded strong winds averaging 15-46 mph out of the East with gusts as high as 64 mph. Current temp is 22 degrees (1 degrees colder than yesterday).

Seattle Ridge weather station at 2600’in Turnagain Pass has recorded winds averaging 13-32 mph with max gusts of 56mph out of the ESE.

The Center Ridge weather station at 1800′ in Turnagin Pass has recorded 1.2 inches of water with a current temp of 27 degrees (2 degrees colder than yesterday). Total snowpack depth this morning is 42 inches after 4 inches of settlement.

WEATHER FORECAST

AKZ125-250100-

WESTERN PRINCE WILLIAM SOUND-

INCLUDING…WHITTIER…SEWARD…GIRDWOOD…MOOSE PASS

500 AM AKST TUE NOV 24 2009

.TODAY…RAIN AND SNOW SHOWERS. SNOW ACCUMULATION UP TO 3

INCHES…MAINLY AT HIGHER ELEVATIONS. HIGHS IN THE 30S. SOUTH

TO EAST WIND 10 TO 20 MPH BECOMING NORTH TO EAST 5 TO 15 MPH

BY AFTERNOON. THROUGH PORTAGE VALLEY AND TURNAGAIN ARM…SOUTHEAST

WIND 20 TO 35 MPH DECREASING TO 10 TO 20 MPH IN THE AFTERNOON.

.TONIGHT…SNOW SHOWERS LIKELY…ESPECIALLY ALONG THE COAST.

SNOW ACCUMULATION UP TO 2 INCHES. LOWS IN THE MID 20S TO LOWER 30S.

NORTH TO EAST WIND 10 TO 15 MPH. NEAR SEWARD…NORTH WIND 15 MPH

INCREASING TO 20 TO 30 MPH TOWARD MIDNIGHT.

.WEDNESDAY…SNOW LIKELY…POSSIBLY MIXED WITH RAIN ALONG THE

COAST. SNOW ACCUMULATION 2 TO 6 INCHES. HIGHS IN THE LOWER TO

MID 30S. VARIABLE WIND 15 MPH EXCEPT NORTH 10 TO 20 MPH NEAR

SEWARD.

AVALANCHE DISCUSSION

Although the weather has backed off a little bit this morning, there is still a considerable avalanche hazard for skiers and snowboarders today at Turnagain Pass. The hazard has decreased since yesterday, but small to medium sized human triggered avalanches are still a serious and dangerous concern today. Natural avalanches and human-triggered avalanches were reported/observed yesterday from Girdwood Valley to Turnagain Pass. Before this latest storm hit us, the snowpack was about 1 foot deep with sugary facets on the ground. Now that wimpy early season snowpack is buried by a 2-3 feet of new snow that is heavy and wet in places. This is a classic description of a weak snowpack.

The early season snowpack in South Central Alaska is always full of suprises because it needs time to adjust. Every year, people get caught off guard in November and December because they are trying to use Turnagain Pass like they do in the middle of winter. The facts are that the snowpack is not ready for aggressive skiing or snowboarding yet.