Turnagain Pass Avalanche Forecast

Good morning backcountry travelers this is Matt Murphy with the Chugach National Forest Avalanche Information Center on Wednesday November 25 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

The Chugach National Forest Glacier Ranger District will open Turnagain Pass to snowmachines today (11/25/09) at 12:00 noon. All CNFAIC Staff areas including Johnson Pass, Placer, Twenty-Mile, and all areas on the Seward Ranger District will remain closed until there is more snow.

ATTENTION SNOWMACHINERS!!!

Avalanche danger may exist at any time in backcountry areas like Turnagain Pass on the Chugach National Forest, whether these areas are open or closed. The US Forest Service does not close areas due to avalanche danger. When areas designated for use by snowmachines on the Chugach National Forest are closed, a primary reason is for the protection of natural resources in accordance with the current Forest Plan. Similarly, on open sign does not mean that it is safe. There are many inherrant dangers associated with traveling in the backcountry including avalanches. Safe backcountry travel requires training and experience. You Control Your Own Risk by choosing where, when and how to travel. The Chugach National Forest Avalanche Information Center provides pertinent information to assist you in making your own decisions for traveling in these backcountry areas.

Opening of these motorized areas in the early season can be subject to immediate closure based on sufficient snow to prevent the tracks of a snowmachine from tearing up vegetation. If the weather changes and the snowpack gets too thin to prevent resource damage, then areas may be closed again. It is your responsibility to check the official open/closed status of these areas with the Chugach National Forest. CNFAIC Staff resources for information regarding these motorized areas can be found through the Glacier Ranger District, and/or the Chugach National Forest Avalanche Information Center.

WEATHER ROUNDUP

Will yesterday’s or today’s weather affect avalanche conditions?

Well, let’s take a closer look at the precip, winds, and temps. There has only been a trace of new precip at the Center Ridge weather station at 1800′ in Turnagain Pass in the past 24 hours. Ridgetop winds at 3800′ on Sunburst and 2600′ on Seattle Ridge were calm to moderate yesterday with strong gusts up to 44mph. Winds are reading calm this morning and are not forecasted by the NWS to pick up till tomorrow. Ridgetop temps are 2-3 degrees warmer this morning averaging 24-26 degrees. Sea level temps are colder than yesterday this morning by about 5 degrees with temps between 30-32 degrees. The NWS is calling for new precip today, but the models only show about ½ inch of water around the Turnagain Pass area. The models are forecasting the temps at the highway elevation to flirt with the freeze line, but show below freezing temps and calm to light winds at 3000′ and 6000′. There is a storm to our south, but the surface maps from yesterday show it getting weaker and also show it moving toward SE Alaska.

AKZ125-260100-

WESTERN PRINCE WILLIAM SOUND-

INCLUDING…WHITTIER…SEWARD…GIRDWOOD…MOOSE PASS

500 AM AKST WED NOV 25 2009

…STRONG WINDS THURSDAY AFTERNOON THROUGH FRIDAY MORNING THROUGH

PORTAGE VALLEY AND ALONG TURNAGAIN ARM…

.TODAY…SNOW AND RAIN. SNOW ACCUMULATION 1 TO 4 INCHES. HIGHS

IN THE 30S. VARIABLE WIND 10 MPH EXCEPT NORTH 10 TO 20 MPH NEAR

SEWARD.

.TONIGHT…SNOW IN THE EVENING…THEN A CHANCE OF SNOW AFTER

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

TO LOWER 30S. LIGHT WINDS EXCEPT WEST 15 MPH NEAR WHITTIER.

.THANKSGIVING DAY…SNOW IN THE MORNING…THEN SNOW AND RAIN IN

THE AFTERNOON. SNOW ACCUMULATION 1 TO 4 INCHES…EXCEPT UP TO 8

INCHES AT HIGHER ELEVATIONS. HIGHS IN THE 30S. THROUGH PORTAGE VALLEY

AND ALONG TURNAGAIN ARM…VARIABLE WIND 10 MPH INCREASING TO EAST 35

TO 45 MPH IN THE AFTERNOON. SOUTH TO EAST WINDS 15 TO 25 MPH

ELSEWHERE.

AVALANCHE DISCUSSION

It does not look like the weather will effect avalanche conditions very much today, but as always be careful it there is ever any rapid change in the weather when traveling in the backcountry.

The current snowpack is showing signs if improved stability since the latest storm on Monday. The avalanche hazard has decreased since yesterday, but there is still a MODERATE avalanche hazard. Small to medium sized human triggered avalanches are still a serious and dangerous concern today. Natural avalanches are unlikely. Moderate avalanche hazard implies elevated caution while traveling in the backcountry. It is not a green light to do what ever you want. Slope angles greater than 35 degrees and rocky complex terrain will be likely areas for human triggered avalanches today.

The early season snowpack in South Central Alaska is always full of surprises 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, snowboarding, or snowmachining yet. The snowpack is still young, give it some time to adjust over the next couple weeks and next couple of storms. I’m still keeping my slope angles less than 35 degrees.