Aspen ===== Current Keywords: CONSIDERABLE, LOW, MODERATE, avalanche danger, cross loaded, depth hoar, facets, human triggered, natural avalanche, powder , slab, slabs, wind loaded, wind slabs, Mountain Weather and Avalanche Forecast for the Aspen Zone Forecast Issued on 12/13/2007 3:51:09 PM Forecaster: Ann Mellick Weather Synopsis Increasing cloud cover and backing winds indicate the approach of the next weather system. Clouds will continue to build through the remainder of day with light snow beginning late this afternoon in the Northern Mountains, spreading southward overnight. The bulk of the moisture looks to come between midnight tonight through noon on Friday, though showers will linger over the high country through Friday evening. Expect clearing skies and quite cold temperatures by Saturday morning. A few weak ripples roll through on northwesterly flow bringing a slight chance of showers to the Northern Mountains this weekend. Otherwise, look for dry conditions as a ridge builds into the area. Weather Thursday Night Friday Friday Night Temperature(°F) -2 to 3 0-5 0-5 Wind Speed(mph) 10-20 5-15 15-25 Wind Direction SW NW N Sky Cover Overcast Overcast Decreasing Snow(in) 1-4 3-6 0-2 Snowpack Discussion Avalanche activity has slowed down in the Aspen Zone although there have been some recent observations. A large natural avalanche ran near Marble Peak, most likely on the 8th or 9th of this month. This occurred on a NE aspect at about 11,200 ft. This avalanche failed on those weak facets and depth hoar at the base of the snowpack we have written about so much recently. Crown of the avalanche was 3-4 feet deep. The two large snow storms we've had in December have given us a fairly strong middle and upper portion of the snowpack. The real problem layer can be found at the base of the snowpack. On higher elevation slopes facing NW, N, NE, and E, snow from October stuck around through the November dry period and formed that very weak foundation. In many areas of the zone, this layer is now buried at a depth that is ripe for human triggering. We have all the ingredients for some large triggered avalanches--a really weak foundation, a strengthening slab to lure you into a false sense of security, and good powder on the surface. Human triggered slides are still probable on higher elevation shady aspects. Do not let your guard down. Above treeline, winds have been strong enough during the last couple days to transport snow and form new wind slabs at the surface. Winds were out of the South on Tuesday and shifted to the West on Wednesday. Be looking for wind loaded and cross loaded areas on a variety of aspects if you travel at these higher elevations. With more snow in the forecast, look for changing conditions and reevaluate the snowpack through out the day on Friday. The danger could rise if forecasted snow amounts are met or exceeded. Riding conditions are excellent, but you will need to temper powder fever with careful route finding and terrain management. Terrain choices are very important. Watch your slope angles carefully, and avoid traveling on or below slopes steeper than 30 degrees on the problematic aspects. It's a great time to use your clinometers and compasses. Avalanche Danger The avalanche danger in the Aspen Zone is CONSIDERABLE on northwest, north, northeast, and east aspects above treeline. Pockets of CONSIDERABLE danger can be found on steeper slopes facing northwest, north, northeast, and east near treeline. The danger is MODERATE on those aspects below treeline, where unstable slabs are possible in steep terrain. On southeast, south, southwest, and west aspects, the danger is MODERATE above treeline, and LOW near and below treeline. Your backcountry observations are VERY important to us. Observations can be sent to caic@qwest.net Front Range =========== Current Keywords: CONSIDERABLE, MODERATE, avalanche danger, collapses, cornice, density, drifted, facets, human triggered, human triggered avalanches, natural, powder , slab, start zones, wind loading, Mountain Weather and Avalanche Forecast for the Front Range Zone Forecast Issued on 12/13/2007 3:24:26 PM Forecaster: Ann Mellick Weather Synopsis Increasing cloud cover and backing winds indicate the approach of the next weather system. Clouds will continue to build through the remainder of day with light snow beginning late this afternoon in the Northern Mountains, spreading southward overnight. The bulk of the moisture looks to come between midnight tonight through noon on Friday, though showers will linger over the high country through Friday evening. Expect clearing skies and quite cold temperatures by Saturday morning. A few weak ripples roll through on northwesterly flow bringing a slight chance of showers to the Northern Mountains this weekend. Otherwise, look for dry conditions as a ridge builds into the area. Weather Thursday Night Friday Friday Night Temperature(°F) 5-10 2-7 0-5 Wind Speed(mph) 10-20 10-20 15-25 Wind Direction WSW NW N Sky Cover Overcast Overcast Decreasing Snow(in) 2-5 1-4 0-1 Snowpack Discussion Avalanche activity has slowed down, though has not halted altogether. An observer reported 2 fresh natural slides near Loveland Pass on Thursday morning. Both slides ran on easterly aspects above treeline in the new snow. Crowns appeared roughly 1 foot in depth and slid due to wind loading. Observers also continue to report large, "impressive" collapses on low angled slopes below treeline. The snowpack still has a very weak foundation of facets on northwest, north, northeast, and east aspects. We have all the ingredients for human triggered avalanches--a really weak foundation, a strengthening slab to lure you into a false sense of security, and light powder on the surface. Human triggered slides are still probable on steep slopes. Do not let your guard down. Where snowfall was not on the ground prior to last weekend's storm the snowpack stability is good. That is generally on southeast, south, southwest and west aspects. Without that old, weak snow, the signs of instability have been minimal. As evidenced by the recent natural releases, a new complication has developed at the snow surface. Winds picked up on Wednesday, both above treeline and down canyon. The winds easily drifted and loaded the abundant light-density storm snow. Observers noted big pillows well down into start zones though little cornice development. This means you may get lured lower down on slopes before triggering a slide, so watch out. With more snow and wind on the way, the avalanche danger in near and above treeline areas will not decrease just yet. Riding conditions are good, but you will need to temper powder fever with careful route finding and terrain management. Terrain choices are very important. Watch your slope angles carefully, and avoid traveling on or below slopes steeper than 30 degrees on the problematic aspects. It's a great time to use your clinometers and compasses. Also be aware of unusual loading and patterns. Avalanche Danger The avalanche danger for the Front Range zone is CONSIDERABLE on all slopes above treeline and on northwest, north, northeast, and east aspects near and below treeline. Human triggered avalanches are probable on steep slopes that have a weak base layer or are wind loaded. On southeast, south, southwest and west aspects the danger is MODERATE near and below treeline. Grand Mesa ========== Current Keywords: LOW, MODERATE, avalanche danger, natural avalanche, settled, slabs, sluffing, Mountain Weather and Avalanche Forecast for the Grand Mesa Zone Forecast Issued on 12/13/2007 4:23:55 PM Forecaster: Ann Mellick Weather Synopsis Increasing cloud cover and backing winds indicate the approach of the next weather system. Clouds will continue to build through the remainder of day with light snow beginning late this afternoon in the Northern Mountains, spreading southward overnight. The bulk of the moisture looks to come between midnight tonight through noon on Friday, though showers will linger over the high country through Friday evening. Expect clearing skies and quite cold temperatures by Saturday morning. A few weak ripples roll through on northwesterly flow bringing a slight chance of showers to the Northern Mountains this weekend. Otherwise, look for dry conditions as a ridge builds into the area. Weather Thursday Night Friday Friday Night Temperature(°F) 7-12 5-10 0-5 Wind Speed(mph) 5-15 5-15 5-15 Wind Direction SW NW NNW Sky Cover Overcast Overcast Decreasing Snow(in) 1-4 1-4 0-1 Snowpack Discussion We have received no recent observations from the Grand Mesa Zone. Observers noted natural avalanche activity Grand Mesa last Friday, some of the avalanches bringing down quite a bit of snow. All of the reported activity came from steep northerly slopes. The weekend snow fell with warm temperatures and settled well. A few inches of new snow are now sitting on top. This makes a pretty good snowpack--weak over strong snow. Expect some sluffing off very steep slopes. You may find a few pockets where old, very weak snow sits underneath the snow from the last few storms. You may trigger avalanches fairly easily in these pockets. Watch out for these exceptions to the generally stable snowpack. Beware of changing conditions on Friday, especially if snow totals meet or exceed forecasted amounts. If you're out on Friday, continually check the snowpack and how the new snow is bonding to the old snow surface. Avalanche Danger There are pockets of MODERATE avalanche danger on high elevation northwest, north, and northeast aspects. Unstable slabs are possible on steep slopes where there is old, weak snow at the base of the snowpack. The danger is LOW elsewhere. Your backcountry observations are VERY important to us. Observations can be submitted to [57]caic@qwest.net. San Juan North ============== Current Keywords: CONSIDERABLE, LOW, MODERATE, avalanche danger, consolidating, cross-loading, density, drifts, faceted, facets, natural, natural avalanches, powder , settles, slabs, suncrusts, windloaded, Mountain Weather and Avalanche Forecast for the Northern San Juan Mountain Zone Forecast Issued on 12/13/2007 6:22:35 AM Forecaster: Mark Rikkers Weather Synopsis Increasing cloud cover and backing winds indicate the approach of the next weather system. Clouds will continue to build through the remainder of day with light snow beginning late this afternoon in the Northern Mountains, spreading southward overnight. The bulk of the moisture looks to come between midnight tonight through noon on Friday, though showers will linger over the high country through Friday evening. Expect clearing skies and quite cold temperatures by Saturday morning. A few weak ripples roll through on northwesterly flow bringing a slight chance of showers to the Northern Mountains this weekend. Otherwise, look for dry conditions as a ridge builds into the area. Weather Thursday Thursday Night Friday Temperature(°F) 18-23 5-10 5-10 Wind Speed(mph) 5-15 10-20 10-20 Wind Direction WSW W NNW Sky Cover Increasing Overcast Mostly Cloudy Snow(in) 0-1 1-4 3-6 Snowpack Discussion New reports of fresh avalanche activity have come to a standstill, but as backcountry travelers are getting farther out in the field they are also returning with reports of significant avalanches that occurred during our last storm cycle. Near Red Mt. Pass, an observer noted with awe that the north side of Red #2 ran from 12,000' into Corkscrew Gulch - the fracture line width is estimated at ¾ of a mile! Lower in the basin four smaller slides on northerly aspects were also reported. Backcountry skiers reported another relatively large avalanche on Sheep Mt. near Lizard Head Pass. Again a north-facing slope from above treeline, this fracture line width was estimated to be 400 feet wide. Both natural and triggered avalanches were reported from near Telluride Tuesday - these were on northerly slopes and one fracture line was 4 feet deep. Backcountry observers spotted some fresh, relatively small natural avalanches on windloaded north aspects Tuesday afternoon. Ridgetop winds have slowed down in the past 24 hours and hourly averages are generally near 10mph. The interesting thing is the direction - if you look at the data from our various local weather stations, directions have been circling around the compass on some sensors, and each station is reporting winds from different directions. Accordingly, snow transport above treeline has slowed with the wind speeds. While we have been getting a fairly steady flow of avalanche reports lately, backcountry travelers are also reporting great powder conditions and a snowpack that feels "pretty stout." Our recent storm cycles have been unusual for Colorado, coming in with very warm temperatures and high-density snow. As it settles out it is consolidating and making a good foundation for our snowpack. Add to that a turn toward colder temperatures and new, light-density snow over the past few days, and those who are traveling wisely are getting some great turns in. With fresh powder all around, it will be tempting for many backcountry travelers to start pushing things a bit. It is important to remember that instabilities remain in the snowpack, particularly deep down on those tempting high northerly slopes. Temper your powder lust with a healthy dose of caution - and prepare for another round of fresh snow! The areas that have been most active and continue to be of particular concern are northwest, north and northeast aspects. These slopes have a combination of new drifts and loading above treeline and heavy slabs from the last two storms sitting on top of relatively weak, faceted snow grains from early in the season - they have the potential to run big. East and west aspects developed suncrusts and associated near-surface facets between storms, and fresh slabs are testing those interfaces. Southerly aspects have relatively little snow on them, though there has been some cross-loading above treeline, leaving areas of unstable slabs. Avalanche Danger The avalanche danger is CONSIDERABLE on northwest, north, and northeast aspects at all elevations. On east and west aspects the danger is MODERATE at all elevations. On southeast, south, and southwest aspects the danger is MODERATE above treeline and LOW near and below treeline. The snowpack requires respect and continual evaluation as you tour in the backcountry - have fun out there, but be careful. Thanks to those that contributed to and attended last night's very successful fundraiser in Telluride! San Juan South ============== Current Keywords: CONSIDERABLE, avalanche danger, drifted, naturals, powder, , settling, slabs, stabilizing, suncrusts, surface hoar, Mountain Weather and Avalanche Forecast for the Southern San Juan Mountain Zone Forecast Issued on 12/13/2007 6:42:06 AM Forecaster: Ann Mellick Weather Synopsis Increasing cloud cover and backing winds indicate the approach of the next weather system. Clouds will continue to build through the remainder of day with light snow beginning late this afternoon in the Northern Mountains, spreading southward overnight. The bulk of the moisture looks to come between midnight tonight through noon on Friday, though showers will linger over the high country through Friday evening. Expect clearing skies and quite cold temperatures by Saturday morning. A few weak ripples roll through on northwesterly flow bringing a slight chance of showers to the Northern Mountains this weekend. Otherwise, look for dry conditions as a ridge builds into the area. Weather Thursday Thursday Night Friday Temperature(°F) 15-20 8-13 7-12 Wind Speed(mph) 5-15 10-20 5-15 Wind Direction WSW W WNW Sky Cover Increasing Mostly Cloudy Decreasing Snow(in) 0-1 0-3 0-3 Snowpack Discussion The official snow total from the last storm to grace the Southern San Juan comes to 46 inches on Wolf Creek Pass and 20.5 inches on Coal Bank Pass where a skier triggered an avalanche Tuesday afternoon. The slide was on a sparsely treed east aspect, and failed on a layer of surface hoar about 18 inches below the surface. Control work along Highway 160 produced a few avalanches 1 to 3 feet deep Wednesday morning. Observers spotted a few naturals along the highway, too. The snowpack is settling and stabilizing, but there are things to watch for. The storm snow, obviously, was a significant load. It will take a few more days before the snowpack fully adjusts. The old snow surface will be key, whether it was powder, thin suncrusts, or surface hoar. Carefully evaluate the bond at the bottom of the storm snow. Keep in mind that the distribution of surface hoar, especially, can be patchy and change over short distances. With fresh powder all around, it will be tempting to push things a bit. Temper your powder lust with a healthy dose of caution, terrain management, and good route finding. Work into steeper terrain gradually, and reevaluate snowpack instability frequently as you go. Avalanche Danger The avalanche danger is CONSIDERABLE on all aspects and at all elevations. Ustable slabs are probable on steep slopes. A slab can be powder snow, if there is an even weaker layer buried underneath. Steer clear of recently drifted areas, too. Sangre de Christo ================= Current Keywords: avalanche danger, collapsing,, drifted, drifts, faceted, wind slabs, Mountain Weather and Avalanche Forecast for the Sangre De Cristo Zone Forecast Issued on 12/13/2007 6:49:07 AM Forecaster: Ann Mellick Weather Synopsis Increasing cloud cover and backing winds indicate the approach of the next weather system. Clouds will continue to build through the remainder of day with light snow beginning late this afternoon in the Northern Mountains, spreading southward overnight. The bulk of the moisture looks to come between midnight tonight through noon on Friday, though showers will linger over the high country through Friday evening. Expect clearing skies and quite cold temperatures by Saturday morning. A few weak ripples roll through on northwesterly flow bringing a slight chance of showers to the Northern Mountains this weekend. Otherwise, look for dry conditions as a ridge builds into the area. Weather Thursday Thursday Night Friday Temperature(°F) 29-34 6-11 20-25 Wind Speed(mph) 7-17 17-27 8-18 Wind Direction SSW SW NNW Sky Cover Mostly Cloudy Mostly Cloudy Mostly Clear Snow(in) 0 0-1 0-1 Snowpack Discussion Soft surface snow will be easily transported, drifted, and loaded by the winds. Watch for new drifts, and check out the older snow underneath.The old snow surface will determine the strength of bonding with new snow, so dig down and check it out! Around the state, north and easterly aspects continue to show the most signs of instability. These are the areas that have old faceted snow at the ground. This weak snow makes a poor foundation, for overlying snow. Remain watchful for the signs of instability including cracking, collapsing, and recent avalanching. Keep your guard up on north, northeast, and east aspects where wind slabs overlying weak base layers may exist. Avalanche Danger We have insufficient data to rate the avalanche danger in the Sangre de Cristo Zone. Please send observations from this or any other zone to [57]caic@qwest.net Sawatch ======= Current Keywords: CONSIDERABLE, LOW, MODERATE, avalanche danger, collapses, faceted, human triggered avalanches, natural avalanches, slab, slabs, sugar snow, windloading, Mountain Weather and Avalanche Forecast for the Sawatch Range Zone Forecast Issued on 12/13/2007 6:46:09 AM Forecaster: Brad Sawtell Weather Synopsis Increasing cloud cover and backing winds indicate the approach of the next weather system. Clouds will continue to build through the remainder of day with light snow beginning late this afternoon in the Northern Mountains, spreading southward overnight. The bulk of the moisture looks to come between midnight tonight through noon on Friday, though showers will linger over the high country through Friday evening. Expect clearing skies and quite cold temperatures by Saturday morning. A few weak ripples roll through on northwesterly flow bringing a slight chance of showers to the Northern Mountains this weekend. Otherwise, look for dry conditions as a ridge builds into the area. Weather Thursday Thursday Night Friday Temperature(°F) 15-20 7-12 3-8 Wind Speed(mph) 10-20 10-20 10-20 Wind Direction WSW W WNW Sky Cover Increasing Mostly Cloudy Mostly Cloudy Snow(in) 0-1 0-3 1-4 Snowpack Discussion Yesterday in the Independence Pass area I found the snowpack showed more signs of instability than what can be found in the Southern part of the zone. Large collapses near treeline and some cracking above treeline, especially near ridgelines. Natural avalanche activity throughout the zone is tapering down but still occurring. I observed one very large slide on the NE face of Star Mountain that ran 2000' vertical feet. We also received a report of 2 natural avalanches on the SE aspect of Taylor peak near Monarch Pass. The big difference with the snowpack that I found near Independence Pass compared with the Monarch Pass area was the presence of faceted or sugar snow near the ground. I suspect this is also a problem further south in the Collegiate Peaks as well. Sugar snow at the ground is our enemy. As the weight of the load above this layer increases, human triggered avalanches will remain an issue. Reports of moderate to strong winds yesterday throughout the zone from Monarch Pass all the way North will become another issue forming new soft and hard slab conditions especially at and above treeline on NE-SE-S aspects. Riding on steep terrain will become less likely as loading continues to occur and new snow falls expect these slabs to grow and become more tender. Terrain choice and route finding will be key for the next few days. Be mindful of where you are and approach all slopes steeper than 30 degrees with caution. Avoid avalanche run out zones, ride one at a time and have escape routes planned. Avalanche Danger The avalanche danger is MODERATE with pockets of CONSIDERABLE on northwest, north, northeast, east and southeast aspects above treeline and MODERATE near and below treeline. Watch for areas with fresh windloading, or that have old, weak snow at the ground. On south, and southwest aspects, the danger is MODERATE above treeline and LOW below treeline. The danger is MODERATE at all elevations on west aspects. Steamboat ========= Current Keywords: avalanche danger, collapsing , faceted, facets, human triggered avalanches, slabs, sugary, wind slabs, Mountain Weather and Avalanche Forecast for the Steamboat and Parks Range Zone Forecast Issued on 12/13/2007 2:59:35 PM Forecaster: Ann Mellick Weather Synopsis Increasing cloud cover and backing winds indicate the approach of the next weather system. Clouds will continue to build through the remainder of day with light snow beginning late this afternoon in the Northern Mountains, spreading southward overnight. The bulk of the moisture looks to come between midnight tonight through noon on Friday, though showers will linger over the high country through Friday evening. Expect clearing skies and quite cold temperatures by Saturday morning. A few weak ripples roll through on northwesterly flow bringing a slight chance of showers to the Northern Mountains this weekend. Otherwise, look for dry conditions as a ridge builds into the area. Weather Thursday Night Friday Friday Night Temperature(°F) 3-8 5-10 -3 to 2 Wind Speed(mph) 15-25 10-20 15-25 Wind Direction NW NW N Sky Cover Overcast Overcast Decreasing Snow(in) 2-5 1-4 0-1 Snowpack Discussion We have received no recent observations from the Steamboat Zone. On Sunday an observer near Buffalo Pass noted lots of collapsing but not much cracking. The most likely place to trigger an avalanche today is on steep slopes that have wind affected slabs sitting on top of sugary facets. This combination can generally be found on higher elevation north and easterly slopes. Southerly and westerly aspects tend to not have the weak base layer and just have less snow. However, the winds blew out of the northeast for a 12 hour period Wednesday night into Thursday so watch for unusual loading patterns and fresh wind slabs on high elevation areas on south and westerly aspects as well. Watch for signs of instability, such as collapsing and cracking while traveling in the backcountry today. Human triggered avalanches remain possible on steep slopes where slabs over lie facets. The old snow was patchy prior to the last couple storms, meaning weak snow is unevenly distributed. You can move from relatively stable snow, lacking the faceted basal layer, to unstable snow over a short distance. Re-evaluate the snowpack often, and do not get complacent. Conditions will be changing with fresh snow expected Thursday night into Friday. Be aware of changing conditions, including a rising danger, as the snow piles up. Avalanche Danger We have insufficient data to rate the avalanche danger in the Steamboat Zone. The most problematic areas are probably steep north, northeast, and east facing slopes that have old, weak snow underneath. If you have any observations or data to share, please send them to [57]caic@qwest.net. Vail ==== Current Keywords: CONSIDERABLE, MODERATE, avalanche danger, faceted, human triggered, powder , slabby, wind loaded, windloaded, Mountain Weather and Avalanche Forecast for the Vail and Summit County Zone Forecast Issued on 12/13/2007 3:45:16 PM Forecaster: Ann Mellick Weather Synopsis Increasing cloud cover and backing winds indicate the approach of the next weather system. Clouds will continue to build through the remainder of day with light snow beginning late this afternoon in the Northern Mountains, spreading southward overnight. The bulk of the moisture looks to come between midnight tonight through noon on Friday, though showers will linger over the high country through Friday evening. Expect clearing skies and quite cold temperatures by Saturday morning. A few weak ripples roll through on northwesterly flow bringing a slight chance of showers to the Northern Mountains this weekend. Otherwise, look for dry conditions as a ridge builds into the area. Weather Thursday Night Friday Friday Night Temperature(°F) 5-10 3-8 -5 to 0 Wind Speed(mph) 10-20 10-20 15-25 Wind Direction WSW NW N Sky Cover Overcast Overcast Decreasing Snow(in) 3-6 2-5 0-2 Snowpack Discussion We have received no new reports of fresh avalanche activity since Monday. Unfortunately, the snowpack throughout the zone still has a weak foundation of faceted snow on high elevation north and easterly slopes. While faceted snow can never be fully trusted, forecasters in the field have noted that the snowpack has become less reactive and signs of instability are decreasing. However, recent strong winds have created some very large convex pregnant pillows at the above treeline north facing ridges in the south end of the Tenmile Range. These windloaded convexities are the most likely place to trigger an avalanche today. New snow and continued winds will continue to load easterly slopes through Friday. So bottom line, while the snowpack is adjusting to its new load, more is being added so we will not lower the danger just yet. Look for changing conditions in the backcountry on Friday as the snow piles up. You will likely find slabby conditions and surface instabilities, but slides are not likely to step down into deeper layers. Human triggered slides are still possible to probable on steep slopes. Do not let your guard down. Where snowfall was not on the ground prior to last weekend's storm the snowpack stability is good. That is generally on southeast, south, southwest and west aspects. Without that old, weak snow, the signs of instability have been minimal. Although riding conditions have been good, you will need to temper powder fever with careful route finding and terrain management. Terrain choices are very important. Measure your slope angles carefully, and avoid traveling on or below slopes steeper than 30 degrees on the problematic aspects. It's a great time to use your inclinometers and compasses. Test all slopes as loading patterns will vary. Do not trust that stability will be the same from one slope to the next. More snow and wind is on the way, so keep your head tuned into the snowpack stability. Avalanche Danger The avalanche danger is CONSIDERABLE on all slopes above treeline and on northwest, north, northeast, and east aspects near treeline. Human triggered avalanches are probable on steep slopes that have a weak base layer or are wind loaded. On southeast, south, southwest and west aspects the danger is MODERATE near treeline, and MODERATE on all aspects below treeline.