Good morning backcountry travelers this is Kevin Wright with the Chugach National Forest Avalanche Information Center on Friday, January 21st 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).
These little shots of snow are teasing us, not really creating a big jump in the hazard, however the new snow does give us the last key ingredient for avalanches. I think the danger rating still fits into the MODERATE range, meaning that natural avalanches are unlikely and human triggered avalanches possible. Be aware that it’s on an increasing trend and it is directly tied to the amount of new snow we get. 2-6 inches of snow is forecasted today, which could be enough to make natural avalanches possible on isolated terrain features.
We got a couple of good public observations yesterday that confirmed the changing trend of the backcountry hazard. The Winner creek region got a little more snow than Turnagain pass, which caused highly reactive small wind slabs. It was described as manageable ski cutting the slabs because they were only 1 foot deep or less, light density, and the terrain was low consequence. The nature of the slabs (touchy, and up to 130 feet wide) should catch our attention.
AnCNFAIC Staff observation was near Kenai lake where a natural avalanche was observed falling toward the lake during the beginning of this storm.
The nature of these small storms over the top of old junky snow makes it difficult to talk in general terms about the backcountry. At some point we will reach a critical mass where the new snow is heavy enough and consistent enough that widespread avalanching will be a major concern. Right now I think we’re dealing with a manageable hazard but the backcountry traveler needs to be hyper-aware of what is going on. The depth of this new snow should be obvious with quick hand pits and should be monitored continuously as you travel in the backcountry. The wind distribution of this new snow is also important and should be obvious right now if you are paying attention.
To recap our old snow history: 6 weeks of clear and cold weather since early December has built a weak foundation and a poor bonding surface to accommodate our current storm snow. Facets around the Thanksgiving rain crust and buried surface hoar are the primary concerns. Exposed rain crust on scoured areas is also suspect and won’t easily hold new snow.
IF the Weather Service forecast is wrong and we get significant snow this weekend the hazard will correspondingly INCREASE.
Encyclopedia of avalanche terms.
The weather radar is showing significant snowfall over the Kenai and Turnagain arm this morning. The direction it’s coming from (Southwest) makes me believe our precip today will be on the low end of the forecasted range in Turnagain Pass. Yesterday there was 2-4 inches of new snow, and anCNFAIC Staff inch fell overnight. Temperatures have risen again since yesterday and are now in the high 20s. Predictions are calling for above freezing temperatures at sea level today and rain in some areas. Wind is expected to be light through the region.
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 AKST FRI JAN 21 2011
.TODAY…SNOW…MIXED AT TIMES WITH RAIN. ISOLATED POCKETS OF
FREEZING RAIN INLAND. PATCHY FOG. SNOW ACCUMULATION 1 TO 4 INCHES…
HIGHEST NORTH OF SEWARD. HIGHS IN THE MID 20S TO MID 30S…COOLEST
INLAND. VARIABLE WIND TO 15 MPH. NEAR SEWARD…NORTH WIND 10 MPH
SHIFTING TO THE SOUTHEAST IN THE AFTERNOON.
.TONIGHT…PATCHY FOG IN THE EVENING. SNOW LIKELY. SNOW ACCUMULATION
UP TO 3 INCHES. LOWS 15 TO 25. VARIABLE WIND 10 MPH.
.SATURDAY…RAIN AND SNOW LIKELY. SNOW ACCUMULATION UP TO 1 INCH.
HIGHS IN THE UPPER 20S TO MID 30S. LIGHT WINDS EXCEPT WEST 10 TO 15
MPH NEAR WHITTIER.
.SATURDAY NIGHT…A SLIGHT CHANCE OF SNOW SHOWERS IN THE EVENING…
THEN SNOW LIKELY AFTER MIDNIGHT. LOWS IN THE 20S. VARIABLE WIND TO 10
MPH. NEAR SEWARD…LIGHT WINDS BECOMING NORTH 10 TO 20 MPH AFTER
.SUNDAY…SNOW AND RAIN LIKELY. HIGHS IN THE UPPER 20S TO MID 30S.
EAST WIND 10 TO 20 MPH INCREASING TO 15 TO 30 MPH IN THE AFTERNOON.
NEAR SEWARD…NORTH WIND 10 TO 25 MPH.
.SUNDAY NIGHT…CLOUDY WITH A CHANCE OF RAIN AND SNOW. LOWS IN THE
.MONDAY…RAIN AND SNOW. HIGHS IN THE 30S.
.MONDAY NIGHT…SNOW LIKELY. LOWS 25 TO 35.
.TUESDAY…SNOW AND RAIN LIKELY. HIGHS 25 TO 35.
.TUESDAY NIGHT AND WEDNESDAY…SNOW LIKELY. LOWS IN THE 20S. HIGHS 25
.WEDNESDAY NIGHT AND THURSDAY…MOSTLY CLOUDY WITH A CHANCE OF SNOW.
LOWS 15 TO 25. HIGHS 25 TO 35.
TEMPERATURE / PRECIPITATION
SEWARD 36 21 34 / 100 60 60
GIRDWOOD 26 20 31 / 100 60 60
WEATHER STATION SUMMARY for Turnagain Pass:
-3800′ Sunburst Wx Station-
Temperature 22 degrees. Wind in the teens gusting to the 20s from the ENE
-2600′ Seattle Ridge Wx Station-
Current temperature 25. Light to moderate wind from the SE.
-1800′ Center Ridge Wx Station-
Temperature in the high 20s. No new snow recorded since yesterday.