In partnership with: Utah Division of State Parks and Recreation, The Friends of the Utah Avalanche Center, Utah Department of Emergency Services and Homeland Security and
keeping you on top
December 30, 2006 7:30 am
Good morning, this is Evelyn Lees with the
Up in the mountains, skies are mostly clear this morning, and temperatures have warmed overnight into the low to mid twenties at many locations. The winds have shifted to a more northerly direction and decreased to less than 15 mph, except for pesky speeds of up to 20 mph, with gusts to 30 across the highest terrain. Snow surface conditions include variable wind sculpted, wind drifted, wind blasted, and breakable crusts in open bowls and along the ridgelines. But the good news is that quality turns do exist in shallow powder on your favorite wind sheltered, mid elevation, shady slope.
Snowpack and Avalanche Conditions:
Yesterday, people had varying experiences with the widespread, poorly bonded wind drifts (slabs) - some were stubborn or just plain non reactive, while others cracked out up to a couple meters wide. But even those that cracked were very shallow generally less than 6 deep. There was also evidence of a small natural cycle of these wind slabs from sometime Thursday. Today, continue to avoid steep, wind drifted slopes as it may still be possible to trigger one of these hard wind drifts. Watch for drifts at both mid elevation breakovers as well as along the ridgelines. Though they are generally very shallow, triggering one of these hard drifts could knock you off your feet and send you for a ride over a cliff or into trees on steep slopes.
Also keep in mind that on most aspects there are several buried layers of weak facets. Yesterday, one Ogden area resort had an explosive triggered slide in a tight, east facing chute that was 3' deep x 100' wide, stepping down to the ground on facets. Also half a dozen slides have been triggered in the backcountry on the uppermost facet layer over the past 10 days (click for avalanche list). To trigger one of these faceted layers (Click for a snowpit from the 29th), youd need the infrequent combination of wind loading adding significant weight and a denser, stiff slab to a slope where the faceted weak layer exists.
Bottom Line for the
The avalanche danger is MODERATE on any slope steeper than about 35 degrees with recent deposits of wind drifted snow. Be especially cautious on slopes facing west through north through east, where slides could break deeper on a faceted weak layer. However, these areas are isolated, and most backcountry terrain has a LOW danger.
A high pressure ridge building
in across the
Yesterday, Wasatch Powderbird Guides flew in Cardiff and American Fork,
and today will fly in Silver, Days, Cardiff, Mineral, Grizzly, White Pine,
American Fork, Cascade and the Sessions.
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(For early morning detailed avalanche activity report hit option 8)
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We appreciate any snowpack and avalanche observations you have, so please leave us a message at (801) 524-5304 or 1-800-662-4140, or email us at [email protected]. (Fax 801-524-6301)
The information in this advisory is from the U.S. Forest Service, which is solely responsible for its content. This advisory describes general avalanche conditions and local variations always occur.
Drew Hardesty will update this advisory by 7:30 on Sunday morning, and thanks for calling.