Aspen ===== Current Keywords: CONSIDERABLE, crown, human triggered, low pressure, natural, naturals, paths, precipitation , slab, slabs, start zones, stresse, weak layer, weak layers, wind slabs, Mountain Weather and Avalanche Forecast for the Aspen Zone Forecast Issued on 2/11/2008 6:24:53 AM Forecaster: John Snook Weather Synopsis Persistent northwest flow will keep periods of light snow going through tonight into Tuesday for the northern and central mountains. Favored northwest aspects will do best with several inches of snow by Tuesday afternoon. Gusty, but not extreme, winds are likely over and east of the Continental Divide. Precipitation diminishes Tuesday night. The next low pressure system is expected to drop into the Great Basin on Wednesday. Colder air and snow drops in from the north starting Wednesday afternoon. The models at this time are inconsistent with the movement of this storm, but unsettled weather is likely for most of the state on Thursday. Weather Monday Night Tuesday Tuesday Night Temperature(°F) 15-20 3-8 15-20 Wind Speed(mph) 15-25 G40 15-25 G35 15-25 Wind Direction WNW NNW NW Sky Cover Overcast Overcast Mostly Cloudy Snow(in) 2-4 0-2 0-1 Snowpack Discussion There was a natural cycle in the Aspen zone on Saturday, likely due to quickly warming temperatures. We don't have a great deal of detail, but 3 large slabs in the Willow Creek Drainage, near Snowmass, SE aspects, between 11,500 and 11,800 feet. One crown was estimated at around 9 feet deep. Another large slab was skier triggered a little further down drainage and ran about 2,000 vertical, crown about 4 feet deep. A natural was reported on Hunter Peak, E to SE aspect around 12,500 feet. A second hand report of some slides on the west aspect of Highlands Ridge. No details on those. Over near Marble, Elk Mtn north of town, several large naturals were reported. These were on SE aspects and started near the ridgeline, though some did fail further down slope. They propagated quite wide, hinting at some stored energy. Crowns were around 3 feet deep. Many naturals, some to the ground, were observed in Express Creek between Ashcroft and Taylor Pass. Most running on either Friday or Saturday on W to SW aspects near or below treeline. Another observer on Sunday reported no recent slide activity while touring above Ashcroft. The snowpack on slopes facing North through East through South, near and above treeline, has become a complicated mess of slabs from recent wind events. Plenty of strong over weak layering exists in the upper snowpack on these aspects as a result. This strong wind has loaded paths with slabs well below their normal start zones and you can expect to find slabs in unusual places. Avalanches have the potential to step down through these multiple layers and become large and destructive. The stiff nature of the wind slabs means that they have to potential to propagate over long distances as well. Below treeline areas have a tricky and highly variable snowpack as well. The presence of some large and destructive avalanches below treeline during the last week inspires little confidence for slopes much steeper than 30 degrees at this time. Slopes facing SW-S-SE have been producing the largest avalanches recently and they should be approached with lots of respect. A long period of colder weather with little sunshine means that some of the older weak layers buried in our snowpack have remained a persistent problem. Every day we have been discussing the complexity of the snowpack and the potential for deep slab instability. The combination of new snow and high winds has stressed this complex snowpack. Avalanche Danger Avalanche danger for the Aspen Zone is rated an overall CONSIDERABLE today. Natural avalanches are possible and human triggered ones probable on all slopes at this time. If triggered, these avalanches have the potential to be large and very destructive. Now is not the time to tackle steeper terrain or big lines. Save those for a day with better stability. Since nearly every aspect and elevations zone has its own set of slab and weak layer problems, choosing safe terrain will be the only way to avoid an avalanche incident at this time. The CAIC Aspen office needs your avalanche, snowpack, or weather observations. Drop us and e-mail at [57]caic@qwest.net with any observations you have from today. Front Range =========== Current Keywords: CONSIDERABLE, MODERATE, avalanche danger, human triggered, low pressure, natural, naturals, precipitation , settle, shears, slab, slabs, start zones, wind slabs, Mountain Weather and Avalanche Forecast for the Front Range Zone Forecast Issued on 2/11/2008 6:24:18 AM Forecaster: John Snook Weather Synopsis Persistent northwest flow will keep periods of light snow going through tonight into Tuesday for the northern and central mountains. Favored northwest aspects will do best with several inches of snow by Tuesday afternoon. Gusty, but not extreme, winds are likely over and east of the Continental Divide. Precipitation diminishes Tuesday night. The next low pressure system is expected to drop into the Great Basin on Wednesday. Colder air and snow drops in from the north starting Wednesday afternoon. The models at this time are inconsistent with the movement of this storm, but unsettled weather is likely for most of the state on Thursday. Weather Monday Night Tuesday Tuesday Night Temperature(°F) 18-23 5-10 18-23 Wind Speed(mph) 20-30 G50 20-30 G40 15-25 G35 Wind Direction WNW WNW WNW Sky Cover Overcast Overcast Mostly Cloudy Snow(in) 2-4 1-3 0-1 Snowpack Discussion Three additional slides were reported from the Berthoud Pass area, all naturals, ENE to SSE aspects above treeline. Instability tests showed some lower numbers, without clean shears, and from about a foot to 4 feet deep. CDOT had some good results off the 7 Sisters Saturday morning, also a slide that may have run Friday with a shoot, but could not be seen, was reported on the west side of Loveland Pass on an ESE aspect above treeline. A large natural popped out of the Number 3 Sister Friday night, it left debris 8-10 feet deep on Loveland Pass. An observer around the Bear Lake area of Rocky Mountain National Park noted strong winds but little snow left in fetch zones to move. Snow depth averaged 60" and there were few signs of instability despite the continued existence of a weak basal layer. CDOT got a good sized avalanche to run in the SE facing Stanley Path near Berthoud Pass on Friday. Parts of the slide ran to the ground. Of note is that the slide started near treeline and nothing ran from the higher start zones. The strong winds have likely stripped snow from above treeline elevations and it is now loaded as large wind pillows closer to treeline. Lee aspects (N-E-S) close to treeline are likely to have the greatest avalanche danger at this time. New snow in the forecast will fall primarily west of and over the Continental Divide. Our concern shifts to human triggered slides. It will be easy to push into bigger terrain as visibility improves and temperatures warm. It has been cold, and the snowpack will want to settle and gain strength, but it can have trouble doing that slowly if people are out pounding on the fresh and still tender slabs A lot of hard slab has developed over the last few days, these are insidious beasts, beautiful to watch from a distance, but really sucks to be in one. The largest concerns are on N-E-S aspects near and above treeline where hard wind slabs have developed. Avalanche Danger The avalanche danger for the Front Range zone is currently CONSIDERABLE on NW-NE-SE-S aspects all elevations, and it is MODERATE elsewhere. Grand Mesa ========== Current Keywords: LOW, avalanche danger, low pressure, precipitation , whumpfing, wind slab, Mountain Weather and Avalanche Forecast for the Grand Mesa Zone Forecast Issued on 2/11/2008 6:25:23 AM Forecaster: John Snook Weather Synopsis Persistent northwest flow will keep periods of light snow going through tonight into Tuesday for the northern and central mountains. Favored northwest aspects will do best with several inches of snow by Tuesday afternoon. Gusty, but not extreme, winds are likely over and east of the Continental Divide. Precipitation diminishes Tuesday night. The next low pressure system is expected to drop into the Great Basin on Wednesday. Colder air and snow drops in from the north starting Wednesday afternoon. The models at this time are inconsistent with the movement of this storm, but unsettled weather is likely for most of the state on Thursday. Weather Monday Night Tuesday Tuesday Night Temperature(°F) 27-32 10-15 27-32 Wind Speed(mph) 5-15 5-15 0-10 Wind Direction NW N N Sky Cover Mostly Cloudy Mostly Cloudy Mostly Cloudy Snow(in) 0-1 0 0 Snowpack Discussion It has been more than a week since we have heard about any slide activity on the Grand Mesa. Steep slopes near treeline that have built up several layers of wind slab are the areas of greatest concern. You will find these areas on exposed north-east-south aspects. It As always, you need to watch for signs of instability such as whumpfing noises, propagating cracks, or recent slide activity. If you observe these signs, then avoid steep terrain in these areas. Avalanche Danger The avalanche danger for the Grand Mesa zone is LOW overall. Please send observations from this or any other zone to [57]caic@qwest.net San Juan North ============== Current Keywords: CONSIDERABLE, MODERATE, avalanche danger, bed surfaces, crown, crowns, explosive, front, low pressure, natural, naturals, paths, precipitation , settle, slab, slabs, windslabs, Mountain Weather and Avalanche Forecast for the Northern San Juan Mountain Zone Forecast Issued on 2/11/2008 6:33:35 AM Forecaster: Mark Rikkers Weather Synopsis Persistent northwest flow will keep periods of light snow going through tonight into Tuesday for the northern and central mountains. Favored northwest aspects will do best with several inches of snow by Tuesday afternoon. Gusty, but not extreme, winds are likely over and east of the Continental Divide. Precipitation diminishes Tuesday night. The next low pressure system is expected to drop into the Great Basin on Wednesday. Colder air and snow drops in from the north starting Wednesday afternoon. The models at this time are inconsistent with the movement of this storm, but unsettled weather is likely for most of the state on Thursday. Weather Monday Night Tuesday Tuesday Night Temperature(°F) 23-28 3-8 22-27 Wind Speed(mph) 10-20 10-20 15-25 Wind Direction NW NNW NNW Sky Cover Mostly Cloudy Mostly Cloudy Partly Cloudy Snow(in) 0 0 0 Snowpack Discussion The past few days of warm, sunny weather with moderate winds have allowed the snowpack to settle down a bit. With the nice weather and great visibility, backcountry observers are getting further out in the field. While reports confirm that natural avalanche activity has decreased significantly since the spate of large, direct-action avalanches that occurred during our recent storm cycle, observations of recent natural and triggered avalanches continue to come in. A skier triggered a slide near Telluride on Revelation, going into Bear Creek, on Friday or Saturday. The slide started at treeline on a SSE aspect - it ran about 2,000 vertical feet and over some big cliffs. Highway forecasters in Silverton got some large avalanches to release with helicopter mitigation efforts on Saturday, with most results coming out of sunny aspects. An important note here is that several of these avalanches came out of paths that have run more than once already this season and are now repeating their performances on the same bed surfaces. Also near Silverton, one recent natural was reported in Minnehaha Basin on a SSW aspect that ran for 2,500 vertical feet. On Sunday, Telluride HeliTrax got two large avalanches to run with their mitigation efforts. One hard slab with a crown up to 8 feet deep pulled out of a generally east-facing roll above treeline. This terrain feature had all the ingredients for an avalanche recipe: a steep, wind-affected, convex roll with exposed rocky outcroppings and thin weak zones just to the side of areas with a much deeper snowpack. This is a perfect example of a place to avoid while traveling in the backcountry! Further east, near Lake City, a couple recent naturals were observed. They started above treeline on north to east aspects. The crowns were estimated at 3-6 feet deep and the slides ran 1500 to 2500 vertical. Recent winds stiffened the upper snowpack, particularly in the alpine but also in exposed areas below treeline. These windslabs, however thin or thick, can be reactive, particularly on steep convex rolls. Remember that hard, cohesive slabs have the potential to propagate over long distances. The upper snowpack continues to be the area of primary concern and sunny aspects continue to be the most reactive. Our snowpack has persistent weaknesses in it that are likely to linger - remember that explosive-triggered deep slab fractures have been reported as recently as Sunday. Avalanche activity in the past few weeks has been reported from virtually all aspects and elevations. However, the trend has been that south and southeast slopes are the most reactive - consider that fact for your ascents, not just your descents. If you head out in the backcountry today, keep the recent avalanche trends in the forefront of your mind and remember to use strict backcountry protocol at all times. Avalanche Danger The avalanche danger is CONSIDERABLE on southeast and south aspects at all elevations; the danger is MODERATE on other aspects and elevations. Human-triggered avalanches remain possible to probable on slopes 35 degrees and steeper - be wise out there! [57]Please let us know if you see any avalanche activity or experienced signs of instability. San Juan South ============== Current Keywords: LOW, MODERATE, avalanche danger, collapse , crown, crust, low pressure, precipitation , settle, Mountain Weather and Avalanche Forecast for the Southern San Juan Mountain Zone Forecast Issued on 2/11/2008 6:25:37 AM Forecaster: John Snook Weather Synopsis Persistent northwest flow will keep periods of light snow going through tonight into Tuesday for the northern and central mountains. Favored northwest aspects will do best with several inches of snow by Tuesday afternoon. Gusty, but not extreme, winds are likely over and east of the Continental Divide. Precipitation diminishes Tuesday night. The next low pressure system is expected to drop into the Great Basin on Wednesday. Colder air and snow drops in from the north starting Wednesday afternoon. The models at this time are inconsistent with the movement of this storm, but unsettled weather is likely for most of the state on Thursday. Weather Monday Night Tuesday Tuesday Night Temperature(°F) 28-33 8-13 27-32 Wind Speed(mph) 10-20 5-15 5-15 Wind Direction WNW NNE N Sky Cover Mostly Cloudy Partly Cloudy Partly Cloudy Snow(in) 0 0 0 Snowpack Discussion One new remote triggered slide was reported from up near Molas Pass. This was on a SE aspect at 11,800 feet, and ran Saturday. The crown was 2-3 feet deep, and it did run in some sparse timber. Another observation from south of Monte Vista told of a firm wind crust but there was a lot of collapse reported in flatter terrain. The snowpack continues to settle and gain strength with the mild weather. It has been behaving much like a maritime snowpack, with most avalanche activity running during, or shortly after a storm cycle. We will start to see slightly cooler temperatures, with a slight increase in winds the next couple of days, but it does not look to change the current danger ratings at all. Avalanche Danger The avalanche danger for the Southern San Juan zone is MODERATE near and above treeline on NW-NE-SE aspects, and LOW elsewhere. [57]Please let us know if you see any avalanche activity or experienced signs of instability. Sangre de Christo ================= Current Keywords: avalanche danger, dense, human triggered, lee , low pressure, precipitation , windslabs, Mountain Weather and Avalanche Forecast for the Sangre De Cristo Zone Forecast Issued on 2/11/2008 6:25:58 AM Forecaster: John Snook Weather Synopsis Persistent northwest flow will keep periods of light snow going through tonight into Tuesday for the northern and central mountains. Favored northwest aspects will do best with several inches of snow by Tuesday afternoon. Gusty, but not extreme, winds are likely over and east of the Continental Divide. Precipitation diminishes Tuesday night. The next low pressure system is expected to drop into the Great Basin on Wednesday. Colder air and snow drops in from the north starting Wednesday afternoon. The models at this time are inconsistent with the movement of this storm, but unsettled weather is likely for most of the state on Thursday. Weather Monday Night Tuesday Tuesday Night Temperature(°F) 28-33 10-15 28-33 Wind Speed(mph) 20-30 5-15 15-25 Wind Direction W WNW NNW Sky Cover Mostly Cloudy Mostly Cloudy Partly Cloudy Snow(in) 0 0 0 Snowpack Discussion We know the winds have been blowing strong from directions ranging from southwest to northwest. Hence, lee aspects ranging from north through east to south are most suspect for human triggered slide activity. The Sangres have a relatively shallow snowpack, capped by a variety of dense windslabs. Given the state of the Sangre De Cristo snowpack, slides that initiate in the upper layers have the potential to break down to the ground. As always, we really like to get observations, even if it is just cloud cover and new snow from the valley floors. Avalanche Danger We have insufficient information to rate the avalanche danger for the Sangre de Cristo zone. Please send observations from this or any other zone to [57]caic@qwest.net Sawatch ======= Current Keywords: CONSIDERABLE, MODERATE, avalanche danger, crown, human triggered, low pressure, natural, natural avalanche, precipitation , slab, slabs, whumpfing, wind slab, wind slabs, Mountain Weather and Avalanche Forecast for the Sawatch Range Zone Forecast Issued on 2/11/2008 6:57:24 AM Forecaster: John Snook Weather Synopsis Persistent northwest flow will keep periods of light snow going through tonight into Tuesday for the northern and central mountains. Favored northwest aspects will do best with several inches of snow by Tuesday afternoon. Gusty, but not extreme, winds are likely over and east of the Continental Divide. Precipitation diminishes Tuesday night. The next low pressure system is expected to drop into the Great Basin on Wednesday. Colder air and snow drops in from the north starting Wednesday afternoon. The models at this time are inconsistent with the movement of this storm, but unsettled weather is likely for most of the state on Thursday. Weather Monday Night Tuesday Tuesday Night Temperature(°F) 18-23 5-10 18-23 Wind Speed(mph) 20-30 G45 15-25 15-25 Wind Direction WNW WNW WNW Sky Cover Mostly Cloudy Mostly Cloudy Mostly Cloudy Snow(in) 0-2 0-2 0 Snowpack Discussion Two natural slides observed on a northeast aspect near Monarch Pass recently. One was a large size 4 soft slab with a 2-6' crown, 700' wide, and 650' vertical. Another large slide was reported from an east aspect above treeline in the Buffalo Peaks area south of Fairplay. There was a natural avalanche reported just on the north side of Hoosier Pass on a southerly aspect above treeline, it was a couple hundred feet wide by a couple hundred vertical. On Sunday there was a report of snowmobiler triggered slide above Upper Hancock Lake near St. Elmo. Two more slides, possibly snowmobile triggered, were noted on the east side of Cottonwood Pass. The larger one had a fracture line of 3-8', about 700' wide, and ran 350' with deposition 15' deep. The next storm system will probably not bring enough snow and wind to greatly change the danger scale, but be sure to check in just in case. We have been discussing the complexity of the snowpack and the potential for deep slab instability for quite some time. Slides can start within the upper snowpack comprised of several layers of wind slabs and recent storm snow. These slides will have the potential to step down into the lower snowpack to create large and dangerous hard slab avalanches. You must constantly watch for signs of instability such as recent slide activity, propagating cracks, and whumpfing noises. These signs tell you to stay away from slopes of greater than 30 degrees. The largest concerns are on N-E-S aspects near and above treeline where hard wind slabs have developed. Do not be fooled onto a steep slope with a supportable wind slab. As you travel downhill, that slab will become weaker. If you break through, you could trigger a large slab avalanche. Human triggered slides are possible to probable on Monday. Avalanche Danger The avalanche danger for the Sawatch zone is CONSIDERABLE on N-E-SW aspects, all elevations. It is MODERATE elsewhere. [57]Please let us know if you see any avalanche activity or experienced signs of instability. Your observations are very important to us! Steamboat ========= Current Keywords: CONSIDERABLE, avalanche danger, cornice, explosives, human triggered, low pressure, precipitation , settle, slab, slabs, stress, Mountain Weather and Avalanche Forecast for the Steamboat and Parks Range Zone Forecast Issued on 2/11/2008 6:24:02 AM Forecaster: John Snook Weather Synopsis Persistent northwest flow will keep periods of light snow going through tonight into Tuesday for the northern and central mountains. Favored northwest aspects will do best with several inches of snow by Tuesday afternoon. Gusty, but not extreme, winds are likely over and east of the Continental Divide. Precipitation diminishes Tuesday night. The next low pressure system is expected to drop into the Great Basin on Wednesday. Colder air and snow drops in from the north starting Wednesday afternoon. The models at this time are inconsistent with the movement of this storm, but unsettled weather is likely for most of the state on Thursday. Weather Monday Monday Night Tuesday Temperature(°F) 20-25 3-8 20-25 Wind Speed(mph) 15-25 G40 15-25 15-25 Wind Direction WNW WNW WNW Sky Cover Overcast Overcast Overcast Snow(in) 3-5 1-3 0-2 Snowpack Discussion We received a second hand report of some slides on the south cornice bowl of Sand Mountain Sunday afternoon, but no other details. The next storm of the winter will arrive Monday morning, and it looks to favor the Steamboat zone. Winds are forecast to strengthen from the west-northwest, but not like they have been. If the forecast verifies there won't be enough snow and wind to cause much change in the danger rating. Our focus shifts to human triggered activity. After a long, cold, snowy and windy storm cycle the snow pack will start to settle and gain strength. It prefers to do this slowly. Any rapid changes to the snowpack can be stressful. Things like explosives, rapid thaws, cornice falls, and people in the wrong spot can still trigger fracture and failure and start slab avalanches. We've been through quite a storm cycle, give the snowpack a chance to gain a little strength before pushing into the big terrain. Recent winds have been strong from the west and northwest. Terrain most suspect would be NE-E-S. Recent patterns from around the state are pointing to weaknesses on these same aspects. Mostly near treeline, as strong winds loaded slabs lower onto slopes. Most fractures are in the 2-5 foot range, and are propagating much wider. There have been a couple close calls in the Gunnison zone recently. All information is pointing to a still tender snowpack that needs a little more time to adjust. Avalanche Danger The avalanche danger for the Steamboat zone is overall CONSIDERABLE. If you have any observations or data to share, please send them to [57]caic@qwest.net. Vail ==== Current Keywords: CONSIDERABLE, MODERATE, avalanche danger, crown, crowns, dens, human triggered, low pressure, natural, naturally, naturals, precipitation , settle, slab, slabs, stresse, Mountain Weather and Avalanche Forecast for the Vail and Summit County Zone Forecast Issued on 2/11/2008 6:24:35 AM Forecaster: John Snook Weather Synopsis Persistent northwest flow will keep periods of light snow going through tonight into Tuesday for the northern and central mountains. Favored northwest aspects will do best with several inches of snow by Tuesday afternoon. Gusty, but not extreme, winds are likely over and east of the Continental Divide. Precipitation diminishes Tuesday night. The next low pressure system is expected to drop into the Great Basin on Wednesday. Colder air and snow drops in from the north starting Wednesday afternoon. The models at this time are inconsistent with the movement of this storm, but unsettled weather is likely for most of the state on Thursday. Weather Monday Night Tuesday Tuesday Night Temperature(°F) 15-20 3-8 15-20 Wind Speed(mph) 20-30 G45 15-25 G35 15-25 Wind Direction WNW WNW WNW Sky Cover Overcast Overcast Mostly Cloudy Snow(in) 2-4 1-3 0-1 Snowpack Discussion A good sized natural was reported off the east ridge of Peak 1 today, and several large slabs were reported fresh Sunday in No Name Gulch north of A-Basin. These were big, and ran on an east aspect. The biggest crowns was estimated at 12 feet deep, and they ran around 10:30. Saddle south of Peak 3 ran naturally as a hard slab recently. Crown estimated at 3-4 feet deep. Peak 10 Ridge NE aspect north of Francies Cabin ran about 2 feet deep, about 60 feet wide, ran into timber. Mt Helen, NE aspect, below treeline, visible from Francies Cabin south deck, 2-3 foot crown, All these reported this afternoon, and probably ran during the storm cycle. Copper ski patrollers reported seeing two naturals that ran in the backcountry on NE aspects near treeline Saturday. These were both fairly deep. A natural slab ran off Red Mtn near Hoosier Pass Saturday starting near 12,500 feet, S to SE aspect. Some large slides were reported on the East side of the Gore, E & NE aspects, running 1000 feet and longer. There were a couple of snowmobiler triggered slides east of Breckenridge (the location details are a bit sketchy) including one that ran to the ground and filled in a bowl about 30' deep. Crown lines were about 6'. Another one had a 15' crown and caught a snowmobiler who was fortunate to ride it out. Another observer noted a natural on a NW aspect of Glacier Mountain, south of Montezuma, with a 3-4' crown that ran to the ground. Pretty active couple of days in this zone. CDOT had good results on the 7 Sisters and Loveland Pass today, some deep, generally E-S aspects near treeline. The threat of natural avalanches has all but ended, but our focus remains on human triggered activity. After a long period of cold, wind, and new snow, the snowpack is stressed. Clear skies and warmer temperatures this weekend has started to settle and strengthen the snowpack. It has a pretty easy time doing that as long as it is not poked and prodded too much. When skies first clear after a long storm cycle, people get keen to wander about and enjoy the blue skies. That is great, just watch those slope angles and continue to think like an avalanche if you are getting into avalanche terrain. If you were a nasty hard slab, where would you want to hang out? Good idea to avoid those dens of ill repute. Avalanche Danger The avalanche danger for the Vail-Summit zone is CONSIDERABLE on NW-NE-SE-S aspects all elevations, and MODERATE elsewhere. Cross loaded terrain facing westerly should be suspect as well.