Aspen ===== Current Keywords: LOW, MODERATE, avalanche danger, cross loaded, density, drifts, facets, recrystallized, slabs, stabilizing, trough, weak layer, whumpfing, windloaded, windslabs, Mountain Weather and Avalanche Forecast for the Aspen Zone Forecast Issued on 12/17/2007 2:56:46 PM Forecaster: Ann Mellick Weather Synopsis Southwest flow has allowed warmer air to seep into the state, with early morning temperatures averaging 5 to 10 degrees warmer than yesterday morning. A series of disturbances will move through the region this week, getting stronger as we head into the weekend. Increasing moisture will move into the state today as the first of several shortwaves ripples through. Expect gusty winds and a chance of snow showers in the Northern and Central Mountains today into tonight. The next upper trough pushes through Tuesday night into Wednesday, bringing measurable snowfall to all mountains. Brief clearing occurs Wednesday night before the strongest in the series of systems digs across the Great Basin late Thursday. Weather Monday Night Tuesday Tuesday Night Temperature(°F) 15-20 22-27 17-22 Wind Speed(mph) 15-25 15-25 10-20 Wind Direction WSW W SW Sky Cover Partly Cloudy Increasing Overcast Snow(in) 0 0 1-3 Snowpack Discussion Observers report a generally stabilizing snowpack, though don't let this make you complacent. Winds from the northeast, north, west, and southwest have redistributed last week's storm snow. Expect to find fresh windslabs, sensitive drifts, and cross loaded terrain features on a variety of aspects on higher elevation slopes as well as on exposed areas below treeline. These slabs can be reactive on steep slopes where they are sitting on low-density powder. Avalanche activity and reports of cracking and whumpfing have decreased in the Aspen Zone. The snowpack has generally adjusted to the December snow. Avalanches are becoming harder to trigger, but the structure of the snowpack still dictates a cautious approach to backcountry travel. The two large snow storms that fell in December have given us a fairly strong middle and upper portion of the snowpack. Unfortunately, basal facets have not gone away on higher elevation slopes facing NW, N, NE, and E. Observers in the Ashcroft area this weekend found this weak layer to be reactive in snow stability tests. The presence and thickness of this weak layer varies throughout the zone. Your snowpack observations should include a careful look for this persistent weak layer before you commit to steeper terrain, especially on higher elevation, shady aspects. Another round of storms will move through this week. Now is the time to think about what this new snow will be falling on and how it will bond. Cold weather has encouraged the growth of near-surface facets on most aspects and at most elevations. These small, angular, recrystallized surface grains do not currently pose a problem. However, these grains tend to bond poorly and will become reactive with the addition of new snow load in the future. Keep this in mind as snow piles up this week. Avalanche Danger Above treeline the avalanche danger is MODERATE on all aspects. Near and below treeline, danger is MODERATE on slopes facing west, northwest, north, northeast, and east. The danger is LOW on other aspects. Unstable windloaded slabs are possible eon most steep slopes. High elevation, shady slopes may have a weak layer at the bottom of the snowpack at a perfect depth for human-triggering. Your backcountry observations are very helpful to our forecasts. If you are traveling around Aspen Zone, we would love to know what you're seeing. Drop us a quick [57]e-mail with your observations from this area or any other. Front Range =========== Current Keywords: CONSIDERABLE, HIGH, MODERATE, avalanche danger, collapsing,, cross loaded, crown, drifted, drifting, drifts, facets, human triggered, human triggered avalanches, natural, natural avalanches, slabs, start zones, stress, trough, whumpfing, wind loaded, wind loading, windloaded, windslabs, Mountain Weather and Avalanche Forecast for the Front Range Zone Forecast Issued on 12/17/2007 2:43:57 PM Forecaster: Ann Mellick Weather Synopsis Southwest flow has allowed warmer air to seep into the state, with early morning temperatures averaging 5 to 10 degrees warmer than yesterday morning. A series of disturbances will move through the region this week, getting stronger as we head into the weekend. Increasing moisture will move into the state today as the first of several shortwaves ripples through. Expect gusty winds and a chance of snow showers in the Northern and Central Mountains today into tonight. The next upper trough pushes through Tuesday night into Wednesday, bringing measurable snowfall to all mountains. Brief clearing occurs Wednesday night before the strongest in the series of systems digs across the Great Basin late Thursday. Weather Monday Night Tuesday Tuesday Night Temperature(°F) 10-15 18-23 10-15 Wind Speed(mph) 15-25 15-25 15-25 Wind Direction W W WSW Sky Cover Partly Cloudy Increasing Mostly Cloudy Snow(in) 0-1 0 0-2 Snowpack Discussion News of fresh natural and triggered avalanche activity continues to roll in. Observers noted both human triggered and natural avalanches in the Cameron Pass area over the weekend. Backcountry skiers on Seven Utes Mountain on Sunday remotely triggered a slide on a north facing aspect below treeline from roughly 200 feet away. The crown measured 2 feet deep by 300 feet wide and ran 150 feet on a 32 degree slope. A group near Clark Peak also remotely triggered a slide, running on a northwest aspect near 11,000'. This slide broke 1-3' deep, 300 feet wide and ran 1000'. Observers noted natural avalanches above treeline on the NE aspects of the Diamond Peaks and the W aspect of Clark Peak as well. Natural avalanches ran Saturday night near Loveland Pass, from heavily cross loaded north, east, and southeast aspects near and above treeline. Control work on Sunday triggered more, on the same aspects. Backcountry travelers across the zone still report some collapsing, impressive whumpfing and shooting cracks near and below treeline. Winds have blown from the northeast, north, west, and southwest. There has been lots of drifting and transport of snow above treeline. Expect to find fresh windslabs, sensitive drifts, and cross loaded terrain features on higher elevation slopes as well as on exposed areas below treeline. Many of the new slabs formed on top of the older powder. This strong over weak configuration can be easily triggered by the additional weight of a backcountry traveler. Strong winds have drifted snow well down on slopes and into start zones. This means you may get lured farther down a slope before triggering a slide. Persistent wind loading is further stressing the weak foundation of facets on northwest, north, northeast, and east aspects. These slopes are getting closer and closer to the breaking point. A traveler may be the final stress. Don't be the straw; travel smart, and avoid crossing on or below wind loaded slopes. Avalanche Danger The avalanche danger for the Front Range zone is HIGH on northwest, north, northeast, east, and southeast aspects above treeline. Natural and human triggered avalanches are likely. On south, southwest, and west aspects there are pockets of CONSDIERABLE danger on steep, windloaded slopes. Near treeline the danger is CONSIDERABLE on northwest, north, northeast, east, and southeast aspects. On south, southwest, and west aspects there are pockets of CONSDIERABLE danger on steep, windloaded slopes. Below treeline the danger is MODERATE. Unstable slabs are possible on steep slopes. Grand Mesa ========== Current Keywords: avalanche danger, crusts, drifting, drifts, facets, slabs, trough, wind slabs, Mountain Weather and Avalanche Forecast for the Grand Mesa Zone Forecast Issued on 12/17/2007 2:58:06 PM Forecaster: Ann Mellick Weather Synopsis Southwest flow has allowed warmer air to seep into the state, with early morning temperatures averaging 5 to 10 degrees warmer than yesterday morning. A series of disturbances will move through the region this week, getting stronger as we head into the weekend. Increasing moisture will move into the state today as the first of several shortwaves ripples through. Expect gusty winds and a chance of snow showers in the Northern and Central Mountains today into tonight. The next upper trough pushes through Tuesday night into Wednesday, bringing measurable snowfall to all mountains. Brief clearing occurs Wednesday night before the strongest in the series of systems digs across the Great Basin late Thursday. Weather Monday Night Tuesday Tuesday Night Temperature(°F) 15-20 27-32 17-22 Wind Speed(mph) 5-15 5-15 5-15 Wind Direction SW SW SW Sky Cover Partly Cloudy Mostly Cloudy Overcast Snow(in) 0 0-1 2-5 Snowpack Discussion We have received no new observations from the Grand Mesa area since Powderhorn Ski Area reported a little over 10 inches of storm snow on Friday. Winds have been light to moderate since, capable of drifting some snow around. Expect soft slabs and drifts in openings and on exposed slopes. Fresh drifts are sitting on a variety of snow surfaces and will have trouble sticking to older, slick wind slabs or crusts. Check the snow while you are traveling in the backcountry and be aware of small changes in aspect and slope angle. You will likely find surface instabilities, but slides are not likely to step down into deeper layers. There are pockets where the snowpack still has a weak foundation of facets on high elevation northwest, north, northeast, and east aspects. Avalanche Danger We have insufficient data to rate the avalanche danger in the Grand Mesa Zone. Please send observations from this or any other zone to [57]caic@qwest.net San Juan North ============== Current Keywords: LOW, MODERATE, avalanche danger, cross loaded, density, drifts, facets, powder , recrystallized, slab, slabs, stabilizing, trough, wind slabs, windloading, Mountain Weather and Avalanche Forecast for the Northern San Juan Mountain Zone Forecast Issued on 12/17/2007 3:04:14 PM Forecaster: Ann Mellick Weather Synopsis Southwest flow has allowed warmer air to seep into the state, with early morning temperatures averaging 5 to 10 degrees warmer than yesterday morning. A series of disturbances will move through the region this week, getting stronger as we head into the weekend. Increasing moisture will move into the state today as the first of several shortwaves ripples through. Expect gusty winds and a chance of snow showers in the Northern and Central Mountains today into tonight. The next upper trough pushes through Tuesday night into Wednesday, bringing measurable snowfall to all mountains. Brief clearing occurs Wednesday night before the strongest in the series of systems digs across the Great Basin late Thursday. Weather Monday Night Tuesday Tuesday Night Temperature(°F) 10-15 23-28 12-17 Wind Speed(mph) 15-25 10-20 15-25 Wind Direction SW WSW SSW Sky Cover Partly Cloudy Increasing Mostly Cloudy Snow(in) 0 0-1 0-3 Snowpack Discussion Reports of fresh avalanche activity in the NSJ Zone have all but stopped. Observers report a generally stabilizing snowpack with backcountry travelers pushing out into steeper, bolder lines, for the most part, without incident. Don't let this make you complacent though. Weak layers still lurk on north and easterly aspects. Additionally, winds have changed the snowpack, stripping snow from some areas while depositing it in others. Winds have blown from the southwest to west to north and back again. This means that you can expect to find fresh wind slabs, drifts, and cross loaded terrain features on a variety of aspects on higher elevation slopes as well as on exposed areas below treeline. These slabs may be reactive on steep slopes where they are sitting on low-density powder or facets. Recent weather has changed the snow surface in other ways as well. Observers report the formation of near-surface facets on most aspects and at most elevations. These small, angular, recrystallized surface grains do not currently pose a problem. However, these grains tend to bond poorly and will become reactive with the addition of new snow load in the future. Keep this in mind as snow piles up this week. Avalanche Danger The avalanche danger for the Northern San Juan is MODERATE on all aspects and elevations except SE-S-SW aspects near and below treeline where the danger is LOW. Unstable slabs are possible on steep terrain. The slab can be recent windloading near the surface, or the full depth of the snowpack when there are weak facets underneath. San Juan South ============== Current Keywords: LOW, avalanche danger, crusts, faceting, settle, stabilize, surface hoar, trough, Mountain Weather and Avalanche Forecast for the Southern San Juan Mountain Zone Forecast Issued on 12/17/2007 3:09:44 PM Forecaster: Ann Mellick Weather Synopsis Southwest flow has allowed warmer air to seep into the state, with early morning temperatures averaging 5 to 10 degrees warmer than yesterday morning. A series of disturbances will move through the region this week, getting stronger as we head into the weekend. Increasing moisture will move into the state today as the first of several shortwaves ripples through. Expect gusty winds and a chance of snow showers in the Northern and Central Mountains today into tonight. The next upper trough pushes through Tuesday night into Wednesday, bringing measurable snowfall to all mountains. Brief clearing occurs Wednesday night before the strongest in the series of systems digs across the Great Basin late Thursday. Weather Monday Night Tuesday Tuesday Night Temperature(°F) 12-17 25-30 13-18 Wind Speed(mph) 10-20 10-20 15-25 Wind Direction W WSW SW Sky Cover Partly Cloudy Increasing Overcast Snow(in) 0 0 0-3 Snowpack Discussion Reported avalanche activity has stopped. Recent mild weather helped the snowpack to settle and stabilize. This is a great time to enjoy conditions, but do it safely. Work into steeper terrain gradually, reevaluating the snowpack often. Low avalanche danger does not mean no avalanche danger, so make decisions accordingly. Another round of storms will move through this week. Now is the time to think about what this new snow will be falling on and how it will bond. Observers in the Purgatory area noted widespread surface hoar development on the northern half of the compass while on the southern half, angled slopes have formed surface crusts. Observers have also noted near surface faceting in cool areas. Currently, none of these layers pose a problem. However, they do tend to bond poorly with fresh snow and will become reactive with the addition of new snow load in the future. Keep this in mind as snow piles up this week. Avalanche Danger The avalanche danger is LOW on all aspects and at all elevations. There are isolated areas where you could trigger avalanches on steep slopes. You will want to examine the snowack carefully before committing to steep terrain. Sangre de Christo ================= Current Keywords: avalanche danger, density, drifts, facets, settle, slabs, stabilize, trough, wind slabs, Mountain Weather and Avalanche Forecast for the Sangre De Cristo Zone Forecast Issued on 12/17/2007 3:10:58 PM Forecaster: Ann Mellick Weather Synopsis Southwest flow has allowed warmer air to seep into the state, with early morning temperatures averaging 5 to 10 degrees warmer than yesterday morning. A series of disturbances will move through the region this week, getting stronger as we head into the weekend. Increasing moisture will move into the state today as the first of several shortwaves ripples through. Expect gusty winds and a chance of snow showers in the Northern and Central Mountains today into tonight. The next upper trough pushes through Tuesday night into Wednesday, bringing measurable snowfall to all mountains. Brief clearing occurs Wednesday night before the strongest in the series of systems digs across the Great Basin late Thursday. Weather Monday Night Tuesday Tuesday Night Temperature(°F) 10-15 25-30 13-18 Wind Speed(mph) 20-30 20-30 25-35 Wind Direction W W WSW Sky Cover Partly Cloudy Increasing Overcast Snow(in) 0 0 0-1 Snowpack Discussion Recent mild weather helped the snowpack to settle and stabilize. Don't let this make you complacent though. Weak layers still lurk on north and easterly aspects. Additionally, winds have changed the snowpack, stripping snow from some areas while depositing it in others. Winds have blown from the southwest to west to north and back again. This means that you can expect to find fresh wind slabs, drifts, and cross loaded terrain features on a variety of aspects on higher elevation slopes as well as on exposed areas below treeline. These slabs may be reactive on steep slopes where they are sitting on low-density powder or facets. Work into steeper terrain gradually, reevaluating the snowpack often. 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, cross loaded, crossloading, drifting, drifts, faceted, facets, powder. , slabs, trough, wind drifting, wind slabs, Mountain Weather and Avalanche Forecast for the Sawatch Range Zone Forecast Issued on 12/17/2007 3:06:35 PM Forecaster: Ann Mellick Weather Synopsis Southwest flow has allowed warmer air to seep into the state, with early morning temperatures averaging 5 to 10 degrees warmer than yesterday morning. A series of disturbances will move through the region this week, getting stronger as we head into the weekend. Increasing moisture will move into the state today as the first of several shortwaves ripples through. Expect gusty winds and a chance of snow showers in the Northern and Central Mountains today into tonight. The next upper trough pushes through Tuesday night into Wednesday, bringing measurable snowfall to all mountains. Brief clearing occurs Wednesday night before the strongest in the series of systems digs across the Great Basin late Thursday. Weather Monday Night Tuesday Tuesday Night Temperature(°F) 10-15 20-25 10-15 Wind Speed(mph) 15-25 15-25 15-25 Wind Direction W W W Sky Cover Partly Cloudy Increasing Overcast Snow(in) 0 0-1 1-4 Snowpack Discussion Since our last storm, winds have blown from the northeast, north, west, and southwest. There has been lots of drifting and transport of snow above treeline. Expect to find fresh wind slabs, sensitive drifts, and cross loaded terrain features on higher elevation slopes as well as on exposed areas below treeline. Many of the new slabs formed on top of the older powder. This strong over weak configuration can be easily triggered by the additional weight of a backcountry traveler. On high, shady slopes you can still find areas with very weak snow at the bottom of the snowpack. There remains potential to trigger large, deep avalanches in these spots. We received a report of a large avalanche that ran Friday night, on a northeast aspect near or just above treeline. The slide broke 3 feet deep, 300 feet wide, and took out some trees. It's a good reminder that wind slabs remain perched atop large faceted grains that are hiding at the bottom of the snowpack. Winds have added an additional load to these slopes, pushing them closer to the breaking point. Avalanches are becoming more difficult to trigger, but the structure of the snowpack still dictates a cautious approach to backcountry travel. Use caution and sound decision making while traveling in the backcountry today. Avalanche Danger The avalanche danger is MODERATE with pockets of CONSIDERABLE on northwest, north, northeast, east, and southeast aspects above treeline. Watch for steep slopes that have recent wind drifting and loading. There are also areas where weak facets are at the bottom of the snowpack. If the facets fail, a large avalanche could result. The danger is MODERATE on all aspects at treeline and other aspects above treeline. Again, watch for steep slopes with crossloading or drifting. Below treeline the danger is MODERATE on west, northwest, north, northeast, east and southeast aspects, and LOW on other aspects. Steamboat ========= Current Keywords: avalanche danger, collapsing , cross loaded, crossloaded, drifts, faceted, facets, human triggered avalanches, slabs, sugary, trough, whumpfing, windslabs, Mountain Weather and Avalanche Forecast for the Steamboat and Parks Range Zone Forecast Issued on 12/17/2007 2:33:07 PM Forecaster: Ann Mellick Weather Synopsis Southwest flow has allowed warmer air to seep into the state, with early morning temperatures averaging 5 to 10 degrees warmer than yesterday morning. A series of disturbances will move through the region this week, getting stronger as we head into the weekend. Increasing moisture will move into the state today as the first of several shortwaves ripples through. Expect gusty winds and a chance of snow showers in the Northern and Central Mountains today into tonight. The next upper trough pushes through Tuesday night into Wednesday, bringing measurable snowfall to all mountains. Brief clearing occurs Wednesday night before the strongest in the series of systems digs across the Great Basin late Thursday. Weather Monday Night Tuesday Tuesday Night Temperature(°F) 10-15 23-28 12-17 Wind Speed(mph) 15-25 15-25 10-20 Wind Direction W WSW SW Sky Cover Mostly Cloudy Mostly Cloudy Overcast Snow(in) 0-1 0-2 PM 1-4 Snowpack Discussion The north to west to southwest winds over the weekend moved quite a bit of snow around. Expect to find fresh windslabs, sensitive drifts, and cross loaded terrain features on exposed higher elevation slopes in the Steamboat Zone. Observers on Buffalo Pass last weekend noted lots of whumpfing as well as a couple recent avalanches. These slid below treeline on steep north facing slopes off the Camel's Hump. Steep slopes that have wind affected slabs sitting on top of sugary facets continue to be the most likely place to trigger a slide today. This combination can be found on higher elevation northwest, north, northeast, and east aspects. 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, early season snow was patchy, meaning weak snow is unevenly distributed. Southerly and westerly aspects generally have less snow and lack the weak faceted layer at the bottom of the snowpack. 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 practice conservative decision making. 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. Expect some crossloaded soft slabs on high elevation slopes. If you have any observations or data to share, please send them to [57]caic@qwest.net. Vail ==== Current Keywords: CONSIDERABLE, MODERATE, avalanche danger, collapsing , cross loaded, density, drifted, drifting, drifts, entrained, facets, human triggered avalanches, natural, powder. , slabs, start zones, stress, trough, wind loaded, wind loading, wind slab, wind slabs, windloaded, Mountain Weather and Avalanche Forecast for the Vail and Summit County Zone Forecast Issued on 12/17/2007 2:47:44 PM Forecaster: Ann Mellick Weather Synopsis Southwest flow has allowed warmer air to seep into the state, with early morning temperatures averaging 5 to 10 degrees warmer than yesterday morning. A series of disturbances will move through the region this week, getting stronger as we head into the weekend. Increasing moisture will move into the state today as the first of several shortwaves ripples through. Expect gusty winds and a chance of snow showers in the Northern and Central Mountains today into tonight. The next upper trough pushes through Tuesday night into Wednesday, bringing measurable snowfall to all mountains. Brief clearing occurs Wednesday night before the strongest in the series of systems digs across the Great Basin late Thursday. Weather Monday Night Tuesday Tuesday Night Temperature(°F) 8-13 17-22 10-15 Wind Speed(mph) 15-25 15-25 15-25 Wind Direction W W WSW Sky Cover Partly Cloudy Increasing Mostly Cloudy Snow(in) 0-1 0 0-2 Snowpack Discussion Conditions vary quite a bit across the Vail/Summit Zone. News of fresh natural and triggered avalanche activity continues to come in from the eastern part of the Zone. Natural avalanches ran Saturday night near Loveland Pass, from heavily cross loaded north, east, and southeast aspects near and above treeline. Control work on Sunday triggered more, on the same aspects. Near treeline observers still report some collapsing and shooting cracks. On the western side of the zone, backcountry skiers triggered several loose slides on northerly slopes near 11, 500' that ran up to 800 feet and entrained a fair amount of snow. Winds have blown from the northeast, north, west, and southwest. There has been lots of drifting and transport of snow above treeline. Expect to find fresh wind slabs, sensitive drifts, and cross loaded terrain features on a variety of aspects on higher elevation slopes as well as on exposed areas below treeline. These slabs can be reactive on steep slopes where they are sitting on low-density powder. Observers on Monday noted that fresh wind slabs 20-30cm deep are not bonding well with the underlying wind slab. Strong winds have drifted snow well down on slopes and into start zones. This means you may get lured farther down a slope before triggering a slide, so look before you leap. Persistent wind loading is further stressing the weak foundation of facets on northwest, north, northeast, and east aspects. These slopes are getting closer to the breaking point. A traveler may be the final stress. Don't be the straw; travel smart, and avoid crossing on or below wind loaded slopes. Reports from the western side of the zone mention much less wind. Less wind means a lower avalanche danger. Observers in the southern Gore on Saturday reported few reactive slabs near and below treeline. They did complain about good snow. Find wind sheltered valleys, evaluate the snowpack, and enjoy. Avalanche Danger The avalanche danger for the Vail Summit zone is CONSIDERABLE on northwest, north, northeast, east, and southeast aspects near and above treeline. Human triggered avalanches are probable. On south, southwest, and west aspects near and above treeline there are pockets of CONSDIERABLE danger on steep, windloaded slopes.Below treeline the danger is MODERATE. Unstable slabs are possible on steep slopes. The danger is not as great in the western part of the zone where winds have been lighter and loading less.