Good morning backcountry travelers. This is Wendy Wagner with the Chugach National Forest Avalanche Information Center on Monday, March 28th 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).
The avalanche danger is LOW with pockets of MODERATE for soft slab avalanches in the old storm snow. These pockets are scattered in the mid to high elevations where the new snow has not bonded to the old snow surface. Later this afternoon, watch for any fresh wind slabs as the winds will pick up with a slight chance for an inch or two of snow.
Soft slab avalanches remain the primary concern. Though much of the new snow from Thursday and Friday last week has now settled out and is sticking to the slopes, this is not the case everywhere. There remain scattered locations where the new snow is sitting on a thin weak layer which is tricky to identify. These soft slabs may propagate wider than expected. Most prone, and dangerous, are areas with over a foot of new snow. Watch for any shooting cracks or whoomphing, especially on ridgelines, rollovers or under cliffs. However, these “obvious clues” may be diminishing with time but the weakness may still exist so a heads up is warranted.
Folks getting out this afternoon or evening will want to watch for an increase in the winds and potentially an inch or two of new snow. If the winds do begin to transport snow, new or old, be wary of any fresh wind drifts or slabs in leeward terrain, these will likely be sensitive.
Many southerly aspects sport a stiff sun crust and with some cloud cover and winds softening should be minimal. Any possible human initiated wet loose sluffing will be confined to lower elevations with warm temperatures.
Keep in mind, in areas with a thin snow cover and added new snow there is a chance to trigger an avalanche that breaks into the weak layers near the ground. This can be tested, to certain degree, by probing into the snowpack with a probe or a pole to feel for loose weak snow under a stiff slab. Trigger spots for this problem are isolated but could be hanging the balance.
Encyclopedia of avalanche terms.
After a warm day yesterday, skies have been mostly clear overnight with temperatures dipping into the high-teens with light east winds. Today it looks like partly cloudy skies in the morning with temperatures rising into the 30’s. This afternoon the low pressure system in Gulf will begin to head out way increasing east winds nearing 20mph this evening. Clouds should build in during the afternoon with what looks like anCNFAIC Staff shot for a few more inches of snow Monday night.
Jon 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 MON MAR 28 2011
.TODAY…SNOW AND RAIN LIKELY. SNOW ACCUMULATION UP TO 2 INCHES.
HIGHS IN THE MID 30S TO LOWER 40S. LIGHT WINDS EXCEPT NORTH 10 MPH
.TONIGHT…SNOW AND RAIN. SNOW ACCUMULATION 1 TO 4 INCHES…HIGHEST
INLAND AND HIGHER ELEVATIONS. LOWS IN THE UPPER 20S TO MID 30S.
VARIABLE WIND 10 MPH EXCEPT EAST 10 TO 25 MPH THROUGH PORTAGE VALLEY
AND TURNAGAIN ARM.
.TUESDAY…RAIN AND SNOW. PATCHY FOG. NO SNOW ACCUMULATION. HIGHS
IN THE MID 30S TO LOWER 40S. EAST WIND 10 TO 15 MPH EXCEPT EAST 20
TO 35 MPH THROUGH PORTAGE VALLEY AND TURNAGAIN ARM.
.TUESDAY NIGHT…RAIN AND SNOW LIKELY. LOWS AROUND 30. VARIABLE
WIND 10 MPH EXCEPT EAST 15 TO 25 MPH THROUGH PORTAGE VALLEY AND
.WEDNESDAY…SNOW AND RAIN LIKELY. HIGHS AROUND 40. VARIABLE WIND
10 MPH EXCEPT EAST 10 TO 25 MPH THROUGH PORTAGE VALLEY AND
.WEDNESDAY NIGHT…RAIN AND SNOW LIKELY. LOWS 25 TO 35.
.THURSDAY…RAIN AND SNOW LIKELY. HIGHS 35 TO 45.
TEMPERATURE / PRECIPITATION
SEWARD 40 32 40 / 60 100 80
GIRDWOOD 37 28 38 / 60 90 60
WEATHER STATION SUMMARY for Turnagain Pass:
-3800′ Sunburst Wx Station-
19 degrees. NE winds light.
-2600′ Seattle Ridge Wx Station-
22 degrees. SE winds light.
-1800′ Center Ridge Wx Station-
21 degrees. No new snow.