Good morning backcountry travelers this is Kevin Wright with the Chugach National Forest Avalanche Information Center on Thursday, March 24th 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).
This morning’s avalanche danger rating is LOW, but pockets of MODERATE may develop if we get the forecasted snow today. Any new snow will have a tough time bonding to the old crusty wind board surface layers.
Our increasing avalanche hazard is going to be related to the amount of snow we get. Last night a couple of inches accumulated in the Portage/Grandview areas but didn’t seem to hit Turnagain Pass and Girdwood.
For today the primary concern is the interface between the new snow and the old snow. After nearly a month without snowfall the surface is a mix of suncrust, wind board, ice crust, and sastrugi. Some sheltered areas also have surface hoar crystals. All of these slippery, low friction surfaces will be a potential sliding surface for the new snow.
The deeper weak layers are less of a concern until we get a larger amount of snow. The poor structure that’s been plaguing us all season is still out there. Check out this pit profile from yesterday. We are finding most areas have a strong upper structure. Shallow zones are harboring weak facets and depth hoar underneath those stronger layers. This is the same recipe that caused the fatal avalanche last weekend at Hatcher Pass. Given enough new snow we will see areas of avalanching within these layers.
Encyclopedia of avalanche terms.
Snow is in the forecast for the next several days. The systems that are producing the weather are somewhat weak and are not expected to produce large amounts of snow. Last night some areas closer to Prince William Sound got 1-2 inches. This trend is expected to continue today with 2-5 inches possible.
Wind is forecasted at 20-30mph from the East. West facing slopes and North and South crossloaded slopes will be the highest concern for new wind slabs.
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-
500 AM AKDT THU MAR 24 2011
.TODAY…NUMEROUS RAIN AND SNOW SHOWERS. SNOW ACCUMULATION UP TO 2
INCHES ABOVE 1000 FT. HIGHS IN THE MID 30S TO LOWER 40S. EAST WIND 10
TO 15 MPH.
.TONIGHT…NUMEROUS SNOW SHOWERS IN THE EVENING…THEN SCATTERED
SNOW SHOWERS AFTER MIDNIGHT. SNOW ACCUMULATION UP TO 1 INCH. LOWS
IN THE MID 20S TO LOWER 30S. VARIABLE WIND TO 10 MPH.
.FRIDAY…MOSTLY CLOUDY. SCATTERED SNOW SHOWERS IN THE MORNING…
THEN SCATTERED SNOW AND RAIN SHOWERS IN THE AFTERNOON. HIGHS IN THE
MID 30S TO LOWER 40S. LIGHT WINDS.
.FRIDAY NIGHT…NUMEROUS SNOW SHOWERS IN THE EVENING…THEN
SCATTERED SNOW SHOWERS AFTER MIDNIGHT. LOWS IN THE LOWER 20S TO
LOWER 30S. LIGHT WINDS EXCEPT NORTH 15 MPH NEAR SEWARD.
.SATURDAY…MOSTLY CLOUDY. SCATTERED SNOW SHOWERS IN THE
MORNING…THEN ISOLATED RAIN AND SNOW SHOWERS IN THE
AFTERNOON. HIGHS IN THE MID 30S TO LOWER 40S. LIGHT WINDS EXCEPT
NORTH 15 MPH NEAR SEWARD.
.SATURDAY NIGHT…MOSTLY CLOUDY WITH SCATTERED SNOW SHOWERS. LOWS
15 TO 25.
.SUNDAY…MOSTLY CLOUDY WITH A CHANCE OF SNOW AND RAIN. HIGHS IN
.SUNDAY NIGHT…MOSTLY CLOUDY WITH A CHANCE OF SNOW. LOWS 15 TO
TEMPERATURE / PRECIPITATION
SEWARD 38 29 40 / 70 60 60
GIRDWOOD 39 28 39 / 60 40 50
WEATHER STATION SUMMARY for Turnagain Pass:
-3800′ Sunburst Wx Station-
Temperature 21. Light to moderate wind from the ENE.
-2600′ Seattle Ridge Wx Station-
24 degrees. Wind at 6-9mph from the SE.
-1800′ Center Ridge Wx Station-
27 degrees. No new snow measured as of 6am.