Good morning backcountry travelers this is Jon Gellings with the Chugach National Forest Avalanche Information Center on Thursday, December 23rd 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).
Placer River and the Skookum Drainage are opened to motorized use today on 12/23. Adequate snow is present to prevent resource damage. These areas consist of the lands south of Portage Valley, and west to the ridgeline above the Placer valley. Twentymile motorized corridor is still closed to motorized use until adequate snow falls to prevent resource damage.
Today the avalanche hazard is LOW, with pockets of MODERATE. Natural avalanches and human triggered avalanches are unlikely for the most part, while small human triggered avalanches are still possible in steep upper elevation windloaded terrain. Be on the lookout for pockets of sensitive wind slab in isolated areas at upper elevations.
Nothing is changing rapidly in our snowpack in Turnagain Pass. December 3rd was our last big snow day, which gave us 10″ of new snow at Center Ridge. Since then, not much has been happening besides weakening of the surface snow and the snow grains around the Thanksgiving Rain Crust. Even though we are not currently seeing much in the way of new avalanche activity, our present surface snow will likely be very conducive to avalanches whenever we get anCNFAIC Staff large precipitation or wind storm. The Thanksgiving Rain Crust has been observed anywhere from 4″ down, to well over 4ft down. Faceting processes are not presenting themselves in the deeply buried areas, but sluffing of the top several inches of low density snow was presenting itself.
We have also been seeing a few buried layers of surface hoar in areas, and some have been in all areas. Most have been constructed during inversions since the first week of December, and are usually easily located at middle elevations. It has proven tricky to find these layers without a question in many areas, but the most reactive layer has been spotted repeatedly about 4-6″ above the Thanksgiving Rain Crust. Luckily it has very little energy, and would not likely propagate a fracture. Be alert when travelling through areas where surface hoar tends to be preserved, such as wind-protected areas near trees and large rocks, as well as gullies and chutes where winds are unable to blow the surface hoar grains over.
For those of you who plan on going to recreate in the Placer and Skookum areas, be mindful that the track is currently not placed, and that there may be many hidden hazards on your way to your destination. Always ride with a friend, and have communication devices in case a stranding occurs due to equipment malfunctions. Cell phones have limited reception in areas of these drainages, so bring a backup communication device in case the cell phone can not get a good tower.
Check out an encyclopedia of terms here: www.fsavalanche.org/Encyclopedia.aspx
We no longer have an inversion, with temperatures being colder as you gain elevation. Winds have been very consistent over the past 24 hours, as evidenced by the wind roses on the weather page. A Strong Wind Warning is issued by the NWS for the Whittier area, so be careful if recreating there today. This weather event is due to a large pressure gradient between the 1042mb High pressure giving us clear weather, and the 977mb Low pressure out near SE Alaska. The radar is currently clear again today, so expect sunny skies again today. Satellite images also suggest that our area will be clear of thick clouds. The National Weather Service is predicting that the next time we see falling snow will be on Christmas.
Kevin 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-
INCLUDING THE CITIES OF…WHITTIER…SEWARD…GIRDWOOD…
512 AM AKST THU DEC 23 2010
…HIGH WIND WARNING REMAINS IN EFFECT UNTIL NOON AKST TODAY NEAR
A HIGH WIND WARNING REMAINS IN EFFECT UNTIL NOON AKST TODAY.
SOUTHWEST WINDS 25 TO 40 MPH WITH GUSTS 55 TO 75 MPH WILL PERSIST
NEAR WHITTIER THROUGH LATE THIS MORNING AND THEN BEGIN TO SLOWLY
DIMINISH THIS AFTERNOON.
A HIGH WIND WARNING MEANS A HAZARDOUS HIGH WIND EVENT IS EXPECTED
OR OCCURRING. PEOPLE ARE URGED TO SECURE LOOSE OBJECTS THAT COULD
BE BLOWN AROUND OR DAMAGED BY THE WIND.
500 AM AKST THU DEC 23 2010
…HIGH WIND WARNING REMAINS IN EFFECT UNTIL NOON AKST
TODAY NEAR WHITTIER…
…STRONG WIND THROUGH LATE THIS AFTERNOON NEAR SEWARD…
.TODAY…SUNNY. HIGHS ZERO TO 15 ABOVE INLAND AND IN THE LOWER 20S
ALONG THE COAST. NEAR SEWARD…NORTH WIND 15 TO 30 MPH WITH GUSTS
TO 45 MPH. NEAR WHITTIER…SOUTHWEST WIND 25 TO 40 MPH WITH GUSTS
55 TO 75 MPH. ELSEWHERE…NORTH TO WEST WIND TO 15 MPH.
.TONIGHT…CLEAR. LOWS 5 BELOW TO 20 BELOW INLAND AND IN THE
TEENS ALONG THE COAST. NEAR SEWARD…NORTH WIND 10 TO 25 MPH
WITH GUSTS TO 35 MPH. NEAR WHITTIER…SOUTHWEST WIND 15 TO 30 MPH
WITH GUSTS TO 50 MPH. ELSEWHERE…LIGHT WINDS.
.FRIDAY…SUNNY. HIGHS 10 BELOW TO 5 ABOVE INLAND AND 15 TO 20
ABOVE ALONG THE COAST. NEAR SEWARD…NORTH WIND 10 TO 25 MPH.
NEAR WHITTIER…SOUTHWEST WIND 15 TO 25 MPH WITH GUSTS TO 40 MPH.
TEMPERATURE / PRECIPITATION
SEWARD 22 11 18 / 0 0 0
GIRDWOOD 6 -5 6 / 0 0 0
WEATHER STATION SUMMARY for Turnagain Pass:
-3800′ Sunburst Wx Station-
recorded light west winds yesterday averaging 6-10mph and temps dropping from 14F to 5F. The current temp is 6F with 8mph winds out of the west.
-2600′ Seattle Ridge Wx Station-
recorded mostly light north winds yesterday averaging 4-10mph. Temps increased from 4F to 8F during the day. The current temp is 10F with light 4mph winds out of the north.
-1800′ Center Ridge Wx Station-
recorded no new snow since Monday’s 1″. Temps yesterday warmed up from 2F to 10F. The current temp is 11F with a sensed total snowpack depth of 53 inches.