Aspen ===== Current Keywords: LOW, MODERATE, avalanche danger, crossloading, density, drifting, facets, powder. , slabs, weak layer, whumpfing, windloaded, windslab, Mountain Weather and Avalanche Forecast for the Aspen Zone Forecast Issued on 12/16/2007 3:14:27 PM Forecaster: Spencer Logan Weather Synopsis Sunday turned into a nice Colorado day. Monday will be another--mostly clear, breezy, and near seasonal temperatures. Valley bottoms will stay cool. Cold air as pooled in them, and a stable airmass overhead will inhibit mixing. The stable air is part of a low-amplitude ridge that will be overhead through Monday. Winds will be westerly and strong over the Front Range, Divide, and Sawatch. Clouds come in Monday night. Tuesday begins another period of unsettled weather, with some promising looking storms towards the end of the week. Stay tuned... Weather Sunday Night Monday Monday Night Temperature(°F) 10-15 22-27 10-15 Wind Speed(mph) 10-20 15-25 15-25 Wind Direction WSW WSW W Sky Cover Mostly Clear Mostly Clear Partly Cloudy Snow(in) 0 0 0 Snowpack Discussion Friday's snow storm fell on low density powder. Since then, winds have blown from the northeast, north, west, and southwest. There has been lots of drifting and transport of snow above treeline. Expect crossloading and windslab on most aspects above treeline and in openings near treeline. Many of the new slabs will be formed on top of the older powder. Strong over weak, and we're back to an avalanche problem. Keep your eyes open, and avoid steep, loaded slopes. At least the avalanche problem on the surface is a change from the deep facets. Unfortunately, the facets have not gone away. Avalanche activity and reports of instability indications (cracking and whumpfing) have decreased in the Aspen Zone. The snowpack has mostly adjusted to all 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. 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 a very weak foundation. 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. In many areas of the zone, the snowpack is a perfect depth for human triggering. 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 fro 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 , crossloaded, crossloading, drift, drifting, facets, human triggered avalanches, natural, powder. , slabs, stress, windloaded, windloading, windslab, windslabs, Mountain Weather and Avalanche Forecast for the Front Range Zone Forecast Issued on 12/16/2007 3:12:51 PM Forecaster: Spencer Logan Weather Synopsis Sunday turned into a nice Colorado day. Monday will be another--mostly clear, breezy, and near seasonal temperatures. Valley bottoms will stay cool. Cold air as pooled in them, and a stable airmass overhead will inhibit mixing. The stable air is part of a low-amplitude ridge that will be overhead through Monday. Winds will be westerly and strong over the Front Range, Divide, and Sawatch. Clouds come in Monday night. Tuesday begins another period of unsettled weather, with some promising looking storms towards the end of the week. Stay tuned... Weather Sunday Night Monday Monday Night Temperature(°F) 10-15 18-23 10-15 Wind Speed(mph) 10-20 25-35 G50 15-25 Wind Direction SW W W Sky Cover Mostly Clear Mostly Clear Partly Cloudy Snow(in) 0 0 0 Snowpack Discussion News of fresh natural and triggered avalanche activity continues to come in. Natural avalanches ran Saturday night near Loveland Pass, from heavily crossloaded north, east, and southeast aspects near and above treeline. Control work on Sunday triggered more, on the same aspects. Saturday morning, observers found several large avalanches on Diamond Peak, near Cameron Pass. The slides ran on northeast aspects above treeline, and were more than 2 feet deep and up to 800 feet wide. On Friday a snowboarder triggered a 3 foot deep avalanche on a north aspect below treeline in Current Creek near Berthoud Pass. Near treeline observers still report some collapsing and shooting cracks. Winds have blown from the northeast, north, west, and southwest. There has been lots of drifting and transport of snow above treeline. Expect crossloading and windslab on most aspects above treeline and in openings below treeline. Many of the new slabs will be formed on top of the older powder. Strong over weak means we have an avalanche problem. Mid-day Sunday obervers described hard windslabs on some slopes above treeline, and said the winds were having a serious effect on the snow. Strong winds drift snow well down on slopes and start zones. This means you may get lured low down on slopes before triggering a slide. The windslabs may support the stress of a traveler fairly well, but once they are overloaded they can rip big. The windloading 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 beign on or underneath windloaded 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, wind slabs, Mountain Weather and Avalanche Forecast for the Grand Mesa Zone Forecast Issued on 12/16/2007 3:16:59 PM Forecaster: Spencer Logan Weather Synopsis Sunday turned into a nice Colorado day. Monday will be another--mostly clear, breezy, and near seasonal temperatures. Valley bottoms will stay cool. Cold air as pooled in them, and a stable airmass overhead will inhibit mixing. The stable air is part of a low-amplitude ridge that will be overhead through Monday. Winds will be westerly and strong over the Front Range, Divide, and Sawatch. Clouds come in Monday night. Tuesday begins another period of unsettled weather, with some promising looking storms towards the end of the week. Stay tuned... Weather Sunday Night Monday Monday Night Temperature(°F) 15-20 25-30 15-20 Wind Speed(mph) 5-15 5-15 5-15 Wind Direction S SW SW Sky Cover Partly Cloudy Mostly Clear Partly Cloudy Snow(in) 0 0 0 Snowpack Discussion 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. The snow and 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, crossloading, density, drift, faceted, facets, powder. , settled, slab, slabs, stress, windloading, windslab, windslabs, Mountain Weather and Avalanche Forecast for the Northern San Juan Mountain Zone Forecast Issued on 12/16/2007 3:20:32 PM Forecaster: Spencer Logan Weather Synopsis Sunday turned into a nice Colorado day. Monday will be another--mostly clear, breezy, and near seasonal temperatures. Valley bottoms will stay cool. Cold air as pooled in them, and a stable airmass overhead will inhibit mixing. The stable air is part of a low-amplitude ridge that will be overhead through Monday. Winds will be westerly and strong over the Front Range, Divide, and Sawatch. Clouds come in Monday night. Tuesday begins another period of unsettled weather, with some promising looking storms towards the end of the week. Stay tuned... Weather Sunday Night Monday Monday Night Temperature(°F) 10-15 23-28 10-15 Wind Speed(mph) 10-20 10-20 5-15 Wind Direction NW SW W Sky Cover Mostly Clear Partly Cloudy Partly Cloudy Snow(in) 0 0 0 Snowpack Discussion Reports of fresh avalanche activity have slowed to a drip. There was a small skier-triggered avalanche in Bear Creek, near Telluride, on Friday. It was on a northerly aspect above treeline, and about 1 foot deep. Observers report a strengthening and less reactive snowpack. Folks are pushing into steeper lines, though most are wisely avoiding the northerly aspects. Winds are starting to change the snowpack, though, by building a new layer of windslabs on the snow surface. Winds have been from the north to the west over the past few days and strong enough to drift snow. Expect crossloading and windslab formation above treeline. The slabs will be sensitive where they are sitting on low-density powder. Keep your eyes open, and avoid steep, loaded slopes. The big December storms formed beefy slabs in the middle of the snowpack. These have settled in, and would be "almost bomber" if it were not for the foundation. The slabs are sitting on weak, faceted grains that are hiding at the bottom of the snowpack, particularly on high elevation northerly and easterly aspects. The slabs may support the stress of a traveler fairly well, but once they are overloaded they can rip big. 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, facets, natural, settle, stabilize, surface hoar, weak layers, Mountain Weather and Avalanche Forecast for the Southern San Juan Mountain Zone Forecast Issued on 12/16/2007 3:21:05 PM Forecaster: Spencer Logan Weather Synopsis Sunday turned into a nice Colorado day. Monday will be another--mostly clear, breezy, and near seasonal temperatures. Valley bottoms will stay cool. Cold air as pooled in them, and a stable airmass overhead will inhibit mixing. The stable air is part of a low-amplitude ridge that will be overhead through Monday. Winds will be westerly and strong over the Front Range, Divide, and Sawatch. Clouds come in Monday night. Tuesday begins another period of unsettled weather, with some promising looking storms towards the end of the week. Stay tuned... Weather Sunday Night Monday Monday Night Temperature(°F) 10-15 25-30 12-17 Wind Speed(mph) 5-15 5-15 5-15 Wind Direction SW SW SW Sky Cover Mostly Clear Partly Cloudy Partly Cloudy Snow(in) 0 0 0 Snowpack Discussion Reported avalanche activity has stopped. There are several old natural avalanches visible, including a a deep avalanche on a north aspect below treeline. The last triggered avalanches were on Wednesday, and a skier triggered an avalanche on a layer of buried surface hoar on Tuesday. Recent mild weather helped the snowpack to settle and stabilize. Observers reported that "ski tests were negative, but skiing was very positive." They found no signs of instability and no weak layers. There are a few weak layers out there, though, including buried surface hoar or surface facets snow on north to easterly aspects. Poke around the snowpack carefully before you move onto steeper terrain, because the distribution of surface hoar, especially, can be patchy and change over short distances. This is a great time to enjoy conditions, but do it safely. Work into steeper terrain gradually, reevaluating the snowpack often. Keep the consequences of an avalanche in mind, because there are isolated areas that you could trigger one. Most likely very steep terrain, where the consequences would be worse. 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, collapsing , faceted, facets, human triggered avalanches, slabs, sugary, Mountain Weather and Avalanche Forecast for the Sangre De Cristo Zone Forecast Issued on 12/16/2007 3:21:38 PM Forecaster: Spencer Logan Weather Synopsis Sunday turned into a nice Colorado day. Monday will be another--mostly clear, breezy, and near seasonal temperatures. Valley bottoms will stay cool. Cold air as pooled in them, and a stable airmass overhead will inhibit mixing. The stable air is part of a low-amplitude ridge that will be overhead through Monday. Winds will be westerly and strong over the Front Range, Divide, and Sawatch. Clouds come in Monday night. Tuesday begins another period of unsettled weather, with some promising looking storms towards the end of the week. Stay tuned... Weather Sunday Night Monday Monday Night Temperature(°F) 10-15 18-23 10-15 Wind Speed(mph) 15-25 20-30 20-30 Wind Direction WSW WSW SW Sky Cover Mostly Clear Partly Cloudy Partly Cloudy Snow(in) 0 0 0 Snowpack Discussion Steep slopes that have wind affected slabs sitting on top of sugary facets are the most likely place to trigger an avalanche. 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. 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 December 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. 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, crossloading, density, drifting, facets, powder. , slabs, stress, wind drifting, windslab, Mountain Weather and Avalanche Forecast for the Sawatch Range Zone Forecast Issued on 12/16/2007 3:18:26 PM Forecaster: Spencer Logan Weather Synopsis Sunday turned into a nice Colorado day. Monday will be another--mostly clear, breezy, and near seasonal temperatures. Valley bottoms will stay cool. Cold air as pooled in them, and a stable airmass overhead will inhibit mixing. The stable air is part of a low-amplitude ridge that will be overhead through Monday. Winds will be westerly and strong over the Front Range, Divide, and Sawatch. Clouds come in Monday night. Tuesday begins another period of unsettled weather, with some promising looking storms towards the end of the week. Stay tuned... Weather Sunday Night Monday Monday Night Temperature(°F) 10-15 15-20 12-17 Wind Speed(mph) 10-20 20-30 20-30 Wind Direction W WSW WNW Sky Cover Mostly Clear Partly Cloudy Partly Cloudy Snow(in) 0 0 0 Snowpack Discussion Friday's snow storm fell on low density powder. Since then, winds have blown from the northeast, north, west, and southwest. There has been lots of drifting and transport of snow above treeline. Expect crossloading and windslab on most aspects above treeline and in openings below treeline. Many of the new slabs will be formed on top of the older powder. Strong over weak, and we're back to an avalanche problem. Keep your eyes open, and avoid steep, loaded slopes. On high, shady slopes you can find areas with very weak snow at the bottom of the snowpack. There is potential to trigger large, deep avalanches in these spots. We got 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 there are still big facets at the ground, with hard slabs underneath. The slabs may support the stress of a traveler fairly well, but once they are overloaded they can rip big. Winds have added an additional load to these slopes, pushing them closer to the breaking point. 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 , crossloaded, crossloading, drifts, faceted, facets, human triggered avalanches, slabs, sugary, windslabs, Mountain Weather and Avalanche Forecast for the Steamboat and Parks Range Zone Forecast Issued on 12/16/2007 3:11:31 PM Forecaster: Spencer Logan Weather Synopsis Sunday turned into a nice Colorado day. Monday will be another--mostly clear, breezy, and near seasonal temperatures. Valley bottoms will stay cool. Cold air as pooled in them, and a stable airmass overhead will inhibit mixing. The stable air is part of a low-amplitude ridge that will be overhead through Monday. Winds will be westerly and strong over the Front Range, Divide, and Sawatch. Clouds come in Monday night. Tuesday begins another period of unsettled weather, with some promising looking storms towards the end of the week. Stay tuned... Weather Sunday Night Monday Monday Night Temperature(°F) 8-13 18-23 10-15 Wind Speed(mph) 10-20 15-25 10-20 Wind Direction SW SW WSW Sky Cover Mostly Clear Partly Cloudy Mostly Cloudy Snow(in) 0 0 0-1 Snowpack Discussion The north to west to southwest winds on Friday and Saturday moved quite a bit of snow around in other Zones. Expect to find some fresh windslabs, sensitive drifts, and crossloading on higher elevation slopes in the Steamboat Zone. The last observation, on Friday, mentioned signs of instability were on the decrease. 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 tend to not have the weak base layer and just have less snow. 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. 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 , crossloaded, crossloading, drift, drifting, facets, human triggered avalanches, natural, powder. , slabs, stress, windloaded, windloading, windslab, windslabs, Mountain Weather and Avalanche Forecast for the Vail and Summit County Zone Forecast Issued on 12/16/2007 3:09:38 PM Forecaster: Spencer Logan Weather Synopsis Sunday turned into a nice Colorado day. Monday will be another--mostly clear, breezy, and near seasonal temperatures. Valley bottoms will stay cool. Cold air as pooled in them, and a stable airmass overhead will inhibit mixing. The stable air is part of a low-amplitude ridge that will be overhead through Monday. Winds will be westerly and strong over the Front Range, Divide, and Sawatch. Clouds come in Monday night. Tuesday begins another period of unsettled weather, with some promising looking storms towards the end of the week. Stay tuned... Weather Sunday Night Monday Monday Night Temperature(°F) 8-13 18-23 10-15 Wind Speed(mph) 10-20 20-30 15-25 Wind Direction SW WSW W Sky Cover Mostly Clear Mostly Clear Partly Cloudy Snow(in) 0 0 0 Snowpack Discussion 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 crossloaded 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. Winds have blown from the northeast, north, west, and southwest. There has been lots of drifting and transport of snow above treeline. Expect crossloading and windslab on most aspects above treeline and in openings below treeline. Many of the new slabs will be formed on top of the older powder. Strong over weak means we have an avalanche problem. Mid-day Sunday obervers described hard windslabs on some slopes above treeline, and said the winds were having a serious effect on the snow. Strong winds drift snow well down on slopes and start zones. This means you may get lured low down on slopes before triggering a slide. The windslabs may support the stress of a traveler fairly well, but once they are overloaded they can rip big. The windloading 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 being on or underneath windloaded slopes. Reports from the western side of the zone mention much less wind. Less wind mean 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.