Utah Avalanche Center
New member
March 18, 2007 - 6:48 am
AVALANCHE WARNING!!! >>>
A SPECIAL AVALANCHE ADVISORY REMAINS IN EFFECT FOR THE MOUNTAINS OF NORTHERN UTAH. RECORD BREAKING WARM TEMPERATURES HAS CREATED A CONSIDERABLE TO HIGH AVALANCHE DANGER. LARGE AND DANGEROUS NATURAL AVALANCHES ARE PROBABLE ON STEEP MOUNTAINS SLOPES. PEOPLE WITHOUT EXCELLENT AVALANCHE AND ROUTE FINDING SKILLS SHOULD STAY OUT OF THE BACK COUNTRY THIS WEEKEND. SUMMARY >>> Danger by
ASPECT & ELEVATION
BOTTOM LINE
on slopes over 35 degrees
The avalanche danger is CONSIDERABLE today on and below slopes of about 35 degrees and steeper, and may rise to HIGH this afternoon as the day heats up. Slides can be triggered on steep slopes of all aspects and elevations, and both human triggered and natural avalanches are possible. A few of these slides have the potential to be very large, dangerous, and long running.
Forecaster: Drew Hardesty LINKS: -Danger scale- -Encyclopedia- -Text only- CURRENT CONDITIONS >>> LINKS TO MORE INFO: NWS SNOW PAGESNOTEL MAP
Skies are clear with light westerly winds along the ridgetops with a few stations recording gusts into the low 20s every now and then. More importantly, overnight lows dipped just to the upper 30s and 40s, with cooler air filtering down to the lower elevations. Any refreeze will be shallow and superficial in nature. Decent corn conditions exist on steep sunny aspects, but you may be too late if you havent left by now. High north still holds a few decent patches of soft settled powder.
RECENT AVALANCHES AND SNOWPACK INFO >>> LINKS TO MORE INFO
AVALANCHE LISTPHOTOSACCIDENTSSNOW PROFILES Explosive testing continues to produce impressive, yet spotty results. One 10 lb airblast on a steep upper elevation east-northeast aspect at one of the Park City resorts pulled out a wet slab 3 deep and 100 wide, ultimately stepping to the ground 6 deep and 200 wide. Other ski areas and the DOT crow-barred out a few wet slabs in the upper elevations but we didnt hear about much in the backcountry. AVALANCHE CONCERNS >>> WHERE PROBABILITY SIZE TREND Likely
Unlikely Large
Small Increasing
Danger Same Decreasing
Danger over the next 8 hrs In my experience, wet slab avalanches can be the most difficult to forecast. Its usually more about decreased strength of the snowpack, rather than increased stress through rapid loading as we all know and love for cold snow avalanches. Supportable corn slab avalanches, particularly with remnant faceted grains, may be the most devious of all. Theyll support you like a hard slab until you collapse the crust, with it pulling out above or adjacent to you, digging in to the wet grains what, 8-20 beneath you. This weeks accident above Silver Lake in Big Cottonwood Canyon and the two remotely triggered wet slabs (photos) best illustrate the point. Cornices will continue to be sensitive and glide avalanches in Stairs, Broads Fork and Mill B South are likely over the next couple of days as well.
WHERE PROBABILITY SIZE TREND Likely
Unlikely Large
Small Increasing
Danger Same Decreasing
Danger over the next 24 hrs Thinner rocky areas may still be trigger points for mostly dry slab avalanches in the upper elevation northwest through northeast facing slopes with our poor snowpack structure. Remotely triggered slides are still possible.
Well, what to do? First, avoid descents on the steep sun-exposed slopes during and just after the heat of the day. If you can get some snow moving with turns and youre riding in the snow rather than on top of it, move to a more westerly aspect or around to the north. Plunge a ski or probe pole to see the depth of refreeze and depth altogether. Give more caution to those slopes with a thinner isothermal snowpack with a thinner refreeze. Recognize that cold snow avalanches with buried persistent weak layers can be a bit more sensitive. Regardless, it almost always comes down to timing and terrain. When thing start to fall apart, hug the ridges and sub-ridges, and avoid being above or in steep-walled terrain traps like these (525k for higher resolution).
MOUNTAIN WEATHER >>> LINKS TO MORE INFO
UAC COMPILATION
NWS ZONAL FORECAST
SEASONAL Wx CHARTS A weak, dry cold front may keep temps from fully spiraling out of control today, though well still see mountain temps in the 40s at 10,000 and 50s at 8000. Winds will be light and westerly. Tomorrow the winds will shift to the southwest ahead of a splitting system on tap for Tuesday night. It should be enough to put 4-8 in the mountains as temps fall back to the upper teens.
GENERAL ANNOUNCEMENTS >>> The Wasatch Powderbird Guides flew avalanche control missions for Little Cottonwood DOT yesterday, and are unlikely to get out today. For more info, call 742-2800.
The UAC and ACE are offering a day long Womens Avalanche Awareness class at Alta on March 22nd covering beacon use and basic safe travel, terrain and snowpack information, for $30. For more details go to: www.altaarts.org.
Listen to the advisory. Try our new streaming audio or podcastsUDOT highway avalanche control work info can be found HERE or by calling (801) 975-4838. Our statewide tollfree line is 1-888-999-4019 (early morning, option 8).For a list of avalanche classes, click HEREFor our classic text advisory click HERE.To sign up for automated e-mails of our graphical advisory click HEREWe appreciate all the great snowpack and avalanche observations weve been getting, so keep leaving us messages at (801) 524-5304 or 1-800-662-4140, or email us at uac@avalanche.org. (Fax 801-524-6301)I will update this advisory by 7:30 on Monday morning, and thanks for calling.
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.
This advisory provided by the Wasatch Cache National Forest, 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 Salt Lake County
The post was created using an automated process maintained by First Tracks! Online.
AVALANCHE WARNING!!! >>>
A SPECIAL AVALANCHE ADVISORY REMAINS IN EFFECT FOR THE MOUNTAINS OF NORTHERN UTAH. RECORD BREAKING WARM TEMPERATURES HAS CREATED A CONSIDERABLE TO HIGH AVALANCHE DANGER. LARGE AND DANGEROUS NATURAL AVALANCHES ARE PROBABLE ON STEEP MOUNTAINS SLOPES. PEOPLE WITHOUT EXCELLENT AVALANCHE AND ROUTE FINDING SKILLS SHOULD STAY OUT OF THE BACK COUNTRY THIS WEEKEND. SUMMARY >>> Danger by
ASPECT & ELEVATION
BOTTOM LINE
on slopes over 35 degrees
The avalanche danger is CONSIDERABLE today on and below slopes of about 35 degrees and steeper, and may rise to HIGH this afternoon as the day heats up. Slides can be triggered on steep slopes of all aspects and elevations, and both human triggered and natural avalanches are possible. A few of these slides have the potential to be very large, dangerous, and long running.
Forecaster: Drew Hardesty LINKS: -Danger scale- -Encyclopedia- -Text only- CURRENT CONDITIONS >>> LINKS TO MORE INFO: NWS SNOW PAGESNOTEL MAP
Skies are clear with light westerly winds along the ridgetops with a few stations recording gusts into the low 20s every now and then. More importantly, overnight lows dipped just to the upper 30s and 40s, with cooler air filtering down to the lower elevations. Any refreeze will be shallow and superficial in nature. Decent corn conditions exist on steep sunny aspects, but you may be too late if you havent left by now. High north still holds a few decent patches of soft settled powder.
RECENT AVALANCHES AND SNOWPACK INFO >>> LINKS TO MORE INFO
AVALANCHE LISTPHOTOSACCIDENTSSNOW PROFILES Explosive testing continues to produce impressive, yet spotty results. One 10 lb airblast on a steep upper elevation east-northeast aspect at one of the Park City resorts pulled out a wet slab 3 deep and 100 wide, ultimately stepping to the ground 6 deep and 200 wide. Other ski areas and the DOT crow-barred out a few wet slabs in the upper elevations but we didnt hear about much in the backcountry. AVALANCHE CONCERNS >>> WHERE PROBABILITY SIZE TREND Likely
Unlikely Large
Small Increasing
Danger Same Decreasing
Danger over the next 8 hrs In my experience, wet slab avalanches can be the most difficult to forecast. Its usually more about decreased strength of the snowpack, rather than increased stress through rapid loading as we all know and love for cold snow avalanches. Supportable corn slab avalanches, particularly with remnant faceted grains, may be the most devious of all. Theyll support you like a hard slab until you collapse the crust, with it pulling out above or adjacent to you, digging in to the wet grains what, 8-20 beneath you. This weeks accident above Silver Lake in Big Cottonwood Canyon and the two remotely triggered wet slabs (photos) best illustrate the point. Cornices will continue to be sensitive and glide avalanches in Stairs, Broads Fork and Mill B South are likely over the next couple of days as well.
WHERE PROBABILITY SIZE TREND Likely
Unlikely Large
Small Increasing
Danger Same Decreasing
Danger over the next 24 hrs Thinner rocky areas may still be trigger points for mostly dry slab avalanches in the upper elevation northwest through northeast facing slopes with our poor snowpack structure. Remotely triggered slides are still possible.
Well, what to do? First, avoid descents on the steep sun-exposed slopes during and just after the heat of the day. If you can get some snow moving with turns and youre riding in the snow rather than on top of it, move to a more westerly aspect or around to the north. Plunge a ski or probe pole to see the depth of refreeze and depth altogether. Give more caution to those slopes with a thinner isothermal snowpack with a thinner refreeze. Recognize that cold snow avalanches with buried persistent weak layers can be a bit more sensitive. Regardless, it almost always comes down to timing and terrain. When thing start to fall apart, hug the ridges and sub-ridges, and avoid being above or in steep-walled terrain traps like these (525k for higher resolution).
MOUNTAIN WEATHER >>> LINKS TO MORE INFO
UAC COMPILATION
NWS ZONAL FORECAST
SEASONAL Wx CHARTS A weak, dry cold front may keep temps from fully spiraling out of control today, though well still see mountain temps in the 40s at 10,000 and 50s at 8000. Winds will be light and westerly. Tomorrow the winds will shift to the southwest ahead of a splitting system on tap for Tuesday night. It should be enough to put 4-8 in the mountains as temps fall back to the upper teens.
GENERAL ANNOUNCEMENTS >>> The Wasatch Powderbird Guides flew avalanche control missions for Little Cottonwood DOT yesterday, and are unlikely to get out today. For more info, call 742-2800.
The UAC and ACE are offering a day long Womens Avalanche Awareness class at Alta on March 22nd covering beacon use and basic safe travel, terrain and snowpack information, for $30. For more details go to: www.altaarts.org.
Listen to the advisory. Try our new streaming audio or podcastsUDOT highway avalanche control work info can be found HERE or by calling (801) 975-4838. Our statewide tollfree line is 1-888-999-4019 (early morning, option 8).For a list of avalanche classes, click HEREFor our classic text advisory click HERE.To sign up for automated e-mails of our graphical advisory click HEREWe appreciate all the great snowpack and avalanche observations weve been getting, so keep leaving us messages at (801) 524-5304 or 1-800-662-4140, or email us at uac@avalanche.org. (Fax 801-524-6301)I will update this advisory by 7:30 on Monday morning, and thanks for calling.
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.
This advisory provided by the Wasatch Cache National Forest, 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 Salt Lake County
The post was created using an automated process maintained by First Tracks! Online.