Good morning backcountry travelers this is Kevin Wright with the Chugach National Forest Avalanche Information Center on Thursday, March 10th 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).
Today’s avalanche danger rating is Low with pockets of MODERATE. The primary concern is shifting over to sunny South face exposures. Afternoon high temperatures are causing some concern as the direct sun melts the surface snow. The old concern of deeper instability is not completely gone, but is diminishing over time.
Warmer daytime temperatures and intense sun is starting to change our concern as we enter Spring. Winter’s not over yet, but it’s important to realize that the South faces are being affected in the late afternoon. This temperature graph from Granite creek in Turnagain Pass illustrates the wild temperature shifts that direct sun exposure is causing.
This issue is confined to late afternoon and Southern aspects only. The most common type of instability that people see is sun induced point releases or slow moving skier triggered sluffs. It’s good to keep in mind that these smaller events can be the catalyst for more serious slab releases, especially when we have major weaknesses everywhere in the backcountry. There have been a couple of heat induced slab releases in the Girdwood valley over the last few days.
For full disclosure, we still need to mention the deeper weaknesses. Very few people have been out in the steeper mountains over the last 2 weeks because of poor snow conditions. Just because nobody has found those weaknesses doesn’t mean they went away. The ongoing problems related to thin snowcover and facets above and below the Thanksgiving rain crust are still present.
The strong temperature swing throughout the day should continue today. Lows at night are reaching near zero in some areas. Highs in the day can reach to the 30s in sheltered sunny areas. High pressure continues with sunny skies and light wind. No precip is shown in the forecast.
I 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:
WESTERN PRINCE WILLIAM SOUND-
620 AM AKST THU MAR 10 2011
.TODAY…SUNNY. HIGHS IN THE MID 20S TO LOWER 30S. LIGHT WINDS
EXCEPT NORTH 20 MPH NEAR SEWARD. NEAR WHITTIER…SOUTHWEST WIND 15
TO 25 MPH.
.TONIGHT…CLEAR. LOWS 5 BELOW TO 15 ABOVE EXCEPT IN THE LOWER
20S NEAR SEWARD AND WHITTIER. LIGHT WINDS EXCEPT NORTH 15 MPH NEAR
SEWARD. NEAR WHITTIER…SOUTHWEST WIND 15 TO 25 MPH DURING THE
.FRIDAY…SUNNY. HIGHS IN THE MID 20S TO LOWER 30S. LIGHT WINDS.
.FRIDAY NIGHT…CLEAR. LOWS ZERO TO 20 ABOVE…COOLEST INLAND.
TEMPERATURE / PRECIPITATION
SEWARD 30 20 29 / 0 0 0
GIRDWOOD 29 13 27 / 0 0 0
WEATHER STATION SUMMARY for Turnagain Pass:
-3800′ Sunburst Wx Station-
Temperature 13 at 0600. Light wind from the NE.
-2600′ Seattle Ridge Wx Station-
Temperature 13 at 0600. Light and variable wind.
-1800′ Center Ridge Wx Station-
Temperature 12 degrees at 0600. No new snow.