Aspen ===== Current Keywords: CONSIDERABLE, MODERATE, avalanche danger, collapses, cross loaded, cross loading, density, drifts, faceted, facets, high pressure, human triggered avalanches, loose snow avalanches, natural, slab, slabs, sluffing, surface hoar, temperature gradients, unconsolidated, weak layers, wind loading, Mountain Weather and Avalanche Forecast for the Aspen Zone Forecast Issued on 12/28/2007 3:47:32 PM Forecaster: Spencer Logan Weather Synopsis Clouds are returning to Colorado Friday night. They have moved into western Colorado Friday afternoon, and will spread across the state overnight. The clouds bring light, scattered snow. Upper level flow is northwesterly, which favors the Steamboat, northern Front Range, Aspen, and North San Juan zones. Shortwaves are coming through over the next few days. The shortwaves are hard to time, but it looks like stronger pulses and heavier snow will come Saturday and Sunday nights. The accumulations will be nickel and dime amounts, but a few inches every 12 hours will eventually add up. Winds will be increasing through Sunday. Snow continues through Monday, followed by a high pressure ridge for the middle part of the week. Weather Friday Night Saturday Saturday Night Temperature(°F) -5 to 0 10-15 0-5 Wind Speed(mph) 15-25 15-25 G40 15-25 G50 Wind Direction NW W W Sky Cover Mostly Cloudy Mostly Cloudy Overcast Snow(in) 0-1 1-4 3-6 Snowpack Discussion 3-4" of low density new snow accumulated Thursday and Friday. A few new avalanches have been reported, too. An observer noted a couple small natural loose snow avalanches on steeper east facing slopes in the Maroon Creek valley on Thursday. Visibility was limited so not too many details were available. On Wednesday in Gold Dust Basin near the Peter Estin hut there was a small natural avalanche on a west aspect at about 12,200 ft. Also observed on Wednesday was another natural on a NW aspect of Richmond Ridge at around 10500. This one occurred in steep terrain and looked to have run in old snow layers, deeper in the snowpack. Changing wind directions during the past week have resulted in areas of wind loading and cross loading on a variety of aspects near and above treeline. Some collapses and shooting cracks were observed around the Estin Hut above treeline in areas where these fresh wind drifts are resting on a layer of faceted snow below. Any steep wind loaded or cross loaded slope above treeline should be treated with caution right now. Human triggered avalanches will be probable in these areas. This variability will be tough to pick up on this morning as snow that fell in the last two days came with lighter winds and will give things a more uniform look. Frequent probing and digging will help you sort out where these slabs exist. Winds are forecasted to increase again out of the N and NW later in the day today. Low density new snow will be easily transported by this wind so look out for some new slab formation as we move into the evening hours. A big player driving changes in the snowpack has been the cold temperatures during the last couple weeks. Cold clear nights like the one we just had will result in some strong temperature gradients in the snowpack. Changes will be most evident in the upper snowpack where small facets and surface hoar can form in a matter of hours. This process will keep the upper 10-12 inches of the snowpack loose and unconsolidated. Keep an eye out for some sluffing of this layer in steeper terrain for the next few days. Prolonged colder weather has an effect on the mid and lower portions of the snowpack as well. Our generally stronger midpack from all the early December snow is starting to lose strength from strong temperature gradients as well. Small faceted snow grains are starting to replace the rounded ones we like so much. This is most evident in areas of the zone where the snowpack is shallower. Multiple weak layers in the snowpack and a high degree of variability from one slope to the next require a cautious approach to backcountry travel. Frequent snowpack, weather, and avalanche observations will help you sort out the current conditions. Avalanche Danger Above treeline, there are pockets of CONSIDERABLE danger on steep wind loaded or cross loaded slopes facing north, northeast, east, and southeast. The danger is MODERATE on other aspects above treeline. The avalanche danger is MODERATE on all aspects near and below treeline. Please send us a quick e-mail to caic@qwest.net with your avalanche, snowpack, or weather observations from this area or any other. Those observations are very valuable to our forecasts. Front Range =========== Current Keywords: CONSIDERABLE, LOW, MODERATE, avalanche danger, depth hoar, drifted, drifts, faceted, high pressure, human triggered, ski cut, slabs, wind scoured, wind slabs, Mountain Weather and Avalanche Forecast for the Front Range Zone Forecast Issued on 12/28/2007 3:44:48 PM Forecaster: Spencer Logan Weather Synopsis Clouds are returning to Colorado Friday night. They have moved into western Colorado Friday afternoon, and will spread across the state overnight. The clouds bring light, scattered snow. Upper level flow is northwesterly, which favors the Steamboat, northern Front Range, Aspen, and North San Juan zones. Shortwaves are coming through over the next few days. The shortwaves are hard to time, but it looks like stronger pulses and heavier snow will come Saturday and Sunday nights. The accumulations will be nickel and dime amounts, but a few inches every 12 hours will eventually add up. Winds will be increasing through Sunday. Snow continues through Monday, followed by a high pressure ridge for the middle part of the week. Weather Friday Night Saturday Saturday Night Temperature(°F) -5 to 0 8-13 0-5 Wind Speed(mph) 20-30 G40 15-25 G50 20-30 G50 Wind Direction NW NW W Sky Cover Mostly Cloudy Mostly Cloudy Overcast Snow(in) 0-2 1-4 3-6 Snowpack Discussion Another inch or two of new snow was added to the snowpack without much wind on Thursday. In Butler Gulch, an observer found a mostly supportable snow surface below treeline. Above treeline he found 1-3" of new snow on top of ugly wind slabs. The old Christmas snow was still breaking out in a few locations. Conditions were extremely variable above treeline with some areas wind scoured down to rock and other regions loaded with thick wind slabs. Increasing west winds on Friday moved the new snow to easterly aspects. Expect to find new, reactive soft slabs on east through southeast aspects above treeline. These slabs will be getting deeper and more extensive through the weekend as bits of snow and winds continue. Fragile depth hoar continues to grow near the ground. The layer becomes weaker as the grains grow larger. The potential for full depth avalanches is slowly increasing. An observer on the west side of Cameron Pass was able to trigger two slides with ski cuts that went to the ground on steep north facing aspects below treeline. The most suspect slopes continue to be north through east where the snowpack is most complicated with a combination of new snow, new and old wind slabs, and a weak, faceted base layer. Human triggered slides remain probable on north through east aspects especially where freshly drifted storm snow will not bond well with the older snow surface. The snowpack is highly variable. Respect the snowpack and do not take it for granted! Get out there, but always use good route finding skills and smart backcountry protocols. Avalanche Danger There are pockets of CONSIDERABLE avalanche danger on north, northeast, east, and southeast aspects near and above treeline. Human triggered avalanches are probable on steep slopes with wind slabs, drifts, or pillows. Winds have worked the snowpack over, leaving plenty of scoured, bare ground adjacent to the heavily loaded slopes. On northwest, west, southwest, and south aspects near and above treeline the danger is MODERATE. Below treeline the danger is MODERATE on north to southeast aspects and otherwise LOW. Grand Mesa ========== Current Keywords: CONSIDERABLE, avalanche danger, drifting, faceted, high pressure, human triggered avalanches, slabs, surface hoar, weak layer, whumpfing, Mountain Weather and Avalanche Forecast for the Grand Mesa Zone Forecast Issued on 12/28/2007 3:53:01 PM Forecaster: Spencer Logan Weather Synopsis Clouds are returning to Colorado Friday night. They have moved into western Colorado Friday afternoon, and will spread across the state overnight. The clouds bring light, scattered snow. Upper level flow is northwesterly, which favors the Steamboat, northern Front Range, Aspen, and North San Juan zones. Shortwaves are coming through over the next few days. The shortwaves are hard to time, but it looks like stronger pulses and heavier snow will come Saturday and Sunday nights. The accumulations will be nickel and dime amounts, but a few inches every 12 hours will eventually add up. Winds will be increasing through Sunday. Snow continues through Monday, followed by a high pressure ridge for the middle part of the week. Weather Friday Night Saturday Saturday Night Temperature(°F) -4 to 1 15-20 5-10 Wind Speed(mph) 5-15 5-15 G30 10-20 G30 Wind Direction W W WSW Sky Cover Partly Cloudy Overcast Overcast Snow(in) 0-2 1-3 1-4 Snowpack Discussion Winds have picked up across the Mesa. Recent snow is blowing and drifting, creating soft slabs more than a foot thick. An observer found a buried surface hoar layer about 8-12" underneath the recent storm snow. He was surprised to find no failures on this layer with column tests in several hasty pits. Nonetheless, he remained quite concerned about this layer and said that he would not trust it. With cold temperatures and brisk winds in the forecast, it remains probable to start a slide on a weak layer. You need to approach steep slopes with caution and watch for signs of instability such as avalanches, cracking in the snow, or whumpfing sounds. Avalanche Danger The avalanche danger in the Grand Mesa zone is CONSIDERABLE. Natural avalanches are possible and human triggered avalanches are probable on steep terrain. The most problematic areas are probably steep slopes that have surface hoar or weak faceted snow under new snow. If you have any observations or data to share, please send them to [57]caic@qwest.net. San Juan North ============== Current Keywords: LOW, MODERATE, avalanche danger, collapsing,, cross-loaded, drifted, facets, high pressure, human triggered, slab, slabs, sluff, wind slabs, windloaded, Mountain Weather and Avalanche Forecast for the Northern San Juan Mountain Zone Forecast Issued on 12/28/2007 3:55:28 PM Forecaster: Spencer Logan Weather Synopsis Clouds are returning to Colorado Friday night. They have moved into western Colorado Friday afternoon, and will spread across the state overnight. The clouds bring light, scattered snow. Upper level flow is northwesterly, which favors the Steamboat, northern Front Range, Aspen, and North San Juan zones. Shortwaves are coming through over the next few days. The shortwaves are hard to time, but it looks like stronger pulses and heavier snow will come Saturday and Sunday nights. The accumulations will be nickel and dime amounts, but a few inches every 12 hours will eventually add up. Winds will be increasing through Sunday. Snow continues through Monday, followed by a high pressure ridge for the middle part of the week. Weather Friday Night Saturday Saturday Night Temperature(°F) -5 to 0 10-15 5-10 Wind Speed(mph) 15-25 15-25 G40 15-25 G40 Wind Direction WSW WSW W Sky Cover Mostly Cloudy Overcast Overcast Snow(in) 0-2 0-3 1-4 Snowpack Discussion Observers are spotting almost no new avalanche activity. There was one 400 vertical foot loose sluff spotted Friday afternoon, so I cannot say "no activity." Observers are noting that the older, lower portion of the snowpack is very strong. One observer even noted slow strengthening of the base layer. This is Colorado and we should never ignore the possibility of deep slab instability, the potential for full depth avalanches is decreasing near and below treeline. Recent periods of wind, cold, and snow, however, have increased the complexity of the upper snowpack. Layers of storm snow, wind slabs, and buried facets all require paying close attention to the upper portion of the snowpack. Human triggered slides remain possible within these upper snowpack layers. Over the weekend bits of snow and increasing winds will form another layer of slabs to the stack. For now, as you travel through the backcountry, continue to monitor for signs of instability in the upper snowpack like cracking, collapsing, or recent slide activity. Remember to respect the snowpack and do not take it for granted! Get out there, but always use good route finding skills and smart backcountry protocols. Avalanche Danger The avalanche danger for the Northern San Juan is MOSERATE on all slopes that are near and above treeline. Some areas are scoured from recent winds, but next to them you will find heavily windloaded slopes. Unstable slabs are possilbe on steep drifted and cross-loaded slopes. Below treeline the danger is MODERATE on west throguh north to east aspects, and LOW on southeast, south, and southwest aspects. San Juan South ============== Current Keywords: LOW, MODERATE, avalanche danger, density, drifting, faceting, high pressure, human triggered, slabs, weak layers, Mountain Weather and Avalanche Forecast for the Southern San Juan Mountain Zone Forecast Issued on 12/28/2007 3:58:50 PM Forecaster: Spencer Logan Weather Synopsis Clouds are returning to Colorado Friday night. They have moved into western Colorado Friday afternoon, and will spread across the state overnight. The clouds bring light, scattered snow. Upper level flow is northwesterly, which favors the Steamboat, northern Front Range, Aspen, and North San Juan zones. Shortwaves are coming through over the next few days. The shortwaves are hard to time, but it looks like stronger pulses and heavier snow will come Saturday and Sunday nights. The accumulations will be nickel and dime amounts, but a few inches every 12 hours will eventually add up. Winds will be increasing through Sunday. Snow continues through Monday, followed by a high pressure ridge for the middle part of the week. Weather Friday Night Saturday Saturday Night Temperature(°F) -5 to 0 15-20 5-10 Wind Speed(mph) 10-20 15-25 15-25 Wind Direction SW SW SW Sky Cover Partly Cloudy Mostly Cloudy Overcast Snow(in) 0-2 0-2 0-3 Snowpack Discussion There are no reports of recent avalanche activity. An observer on Wolf Creek Pass described the bottom portion of the snowpack as bomber. The upper snowpack is more interesting. Low density snow, faceting driven by the cold temperatures, and wind drifting have created a variety of layers in the upper snowpack. These include some buried weak layers, but without a significant new load they have not been causing large problems. Human triggered slides remain possible near and above treeline where the newer snow could move on top of the older stable layer. Most areas will remain stable, but you do not want to let your guard down and wander onto a slope with unstable slabs. Avalanche Danger The avalanche danger is MODERATE on all aspects near and above treeline. Unstable slabs are possible on steep terrain. Below treeline the danger is LOW. Sangre de Christo ================= Current Keywords: avalanche danger, density, drifting, high pressure, human triggered, slab, slabs, wind slabs, Mountain Weather and Avalanche Forecast for the Sangre De Cristo Zone Forecast Issued on 12/28/2007 4:00:37 PM Forecaster: Spencer Logan Weather Synopsis Clouds are returning to Colorado Friday night. They have moved into western Colorado Friday afternoon, and will spread across the state overnight. The clouds bring light, scattered snow. Upper level flow is northwesterly, which favors the Steamboat, northern Front Range, Aspen, and North San Juan zones. Shortwaves are coming through over the next few days. The shortwaves are hard to time, but it looks like stronger pulses and heavier snow will come Saturday and Sunday nights. The accumulations will be nickel and dime amounts, but a few inches every 12 hours will eventually add up. Winds will be increasing through Sunday. Snow continues through Monday, followed by a high pressure ridge for the middle part of the week. Weather Friday Night Saturday Saturday Night Temperature(°F) -5 to 0 10-15 2-7 Wind Speed(mph) 15-25 15-25 G40 20-30 Wind Direction W W W Sky Cover Partly Cloudy Partly Cloudy Mostly Cloudy Snow(in) 0-1 0-1 0-1 Snowpack Discussion We have received no observations from the Sangre zone. A few inches of recent snow and increasing winds means blowing and drifting snow. It will not take much to move the recently fallen low-density snow. You should watch for fresh wind pillows that could be covering older wind slabs on steep exposed slopes. Human triggered slides within the more recent storm snow layers are probable. You should also be aware of the possibilities for deep slab instabilities on N-NE-E aspects. A combination of fresh wind pillows, older wind slabs, and a weak base layer could avalanche large with a sufficient trigger. You should constantly evaluate the snowpack for changing conditions. 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, collapsing , cross-loading, density, drifting, faceted, high pressure, sastrugi, shears, slabs, surface hoar, weak layer, wind slabs, windslabs, Mountain Weather and Avalanche Forecast for the Sawatch Range Zone Forecast Issued on 12/28/2007 4:01:41 PM Forecaster: Spencer Logan Weather Synopsis Clouds are returning to Colorado Friday night. They have moved into western Colorado Friday afternoon, and will spread across the state overnight. The clouds bring light, scattered snow. Upper level flow is northwesterly, which favors the Steamboat, northern Front Range, Aspen, and North San Juan zones. Shortwaves are coming through over the next few days. The shortwaves are hard to time, but it looks like stronger pulses and heavier snow will come Saturday and Sunday nights. The accumulations will be nickel and dime amounts, but a few inches every 12 hours will eventually add up. Winds will be increasing through Sunday. Snow continues through Monday, followed by a high pressure ridge for the middle part of the week. Weather Friday Night Saturday Saturday Night Temperature(°F) -8 to -3 5-10 0-5 Wind Speed(mph) 15-25 20-30 G50 25-35 G50 Wind Direction W W W Sky Cover Partly Cloudy Mostly Cloudy Overcast Snow(in) 0-2 1-3 1-4 Snowpack Discussion Some surface hoar grew on the snow surface Thrusday night in wind protected areas. Surface hoar is pretty and makes a cool sound when you ride through it, but if gets buried it becomes a very persistent weak layer. It is worth poking around under the new snow to see if there are surface hoar feathers. Recent snow was very low density. As winds pick up this weekend, be aware of how quickly new slabs can form. Winds will be from the west and northwest, easily redistributing snow to east through south aspects. Cross loading has also occurred on northeast and southwest aspects. The new wind slabs are bonding poorly to the older snow. There pockets of older slabs, too, on most aspects above treeline. Observers have found clean shears The older snow underneath has rapidly faceted in the cold temperatures we have had. The middle and bottom of the snowpack is weakening. REcent windsalbs on a weakening snowpakc does not make for a good combination. You will find pockets of unstable windslabs on most aspects near and above treeline. Watch for clues like wind etching, sastrugi, hollow drum-like snow, and thick wind pillows. Cracking and collapsing are good indicators of unstable snow. Avalanche Danger The avalanche danger is MODERATE with pockets of CONSIDERABLE on northwest, north, northeast, east, southeast and south aspects near and above treeline. The danger is MODERATE on other aspects near and above treeline. Be especially cautious on steep slopes with cross-loading or drifting. Below treeline the danger is LOW on all aspects. Steamboat ========= Current Keywords: LOW, MODERATE, avalanche danger, cross loaded, facets, high pressure, human triggered, lee , natural, naturals, slabs, wind slabs, Mountain Weather and Avalanche Forecast for the Steamboat and Parks Range Zone Forecast Issued on 12/28/2007 3:40:50 PM Forecaster: Spencer Logan Weather Synopsis Clouds are returning to Colorado Friday night. They have moved into western Colorado Friday afternoon, and will spread across the state overnight. The clouds bring light, scattered snow. Upper level flow is northwesterly, which favors the Steamboat, northern Front Range, Aspen, and North San Juan zones. Shortwaves are coming through over the next few days. The shortwaves are hard to time, but it looks like stronger pulses and heavier snow will come Saturday and Sunday nights. The accumulations will be nickel and dime amounts, but a few inches every 12 hours will eventually add up. Winds will be increasing through Sunday. Snow continues through Monday, followed by a high pressure ridge for the middle part of the week. Weather Friday Night Saturday Saturday Night Temperature(°F) -5 to 0 8-13 5-10 Wind Speed(mph) 15-25 15-25 G40 15-25 G40 Wind Direction W W W Sky Cover Mostly Cloudy Overcast Overcast Snow(in) 1-4 1-4 3-6 Snowpack Discussion An observer spotted several natural slides on west aspects of Hahns Peak several days ago, but no naturals have been reported since. With careful route selection, a number of lines have been ridden and folks are venturing into steeper terrain. Near the ski area, one of our forecasters found "big strong slabs sitting on the ubiquitous weak facets on northerly aspects." The slabs though, are strong enough that the facets are hard to trigger. The potential for full depth avalanches remains, but it is getting more and more unlikely. Recent storm snow has amounted to a few inches, and each of the next couple days will bring a few more. The snow is not a significant load by itself. With increasing winds, though, you can expect to find some new, reactive soft slabs forming on northeast through southeast aspects. Fresh wind pillows on top of the snowpack should keep you on your toes. You will find pockets of unstable slabs on north, northeast, east, southeast, and south aspects near and above treeline. Do not jump blindly onto steep slopes. Spend a bit of time checking the layering, and how well those old slabs want to stick together. For now, the most suspect slopes are on lee and cross loaded aspects near and above treeline where new snow and older wind slabs have combined to create areas of instability. Avalanche Danger The avalanche danger in the Steamboat zone is MODERATE on all northwest, north, northeast, east, and southeast aspects at all elevations. Human triggered slides are possible on steep slopes with fresh wind pillows. The danger is LOW on other aspects. If you have any observations or data to share, please send them to [57]caic@qwest.net. Vail ==== Current Keywords: CONSIDERABLE, LOW, MODERATE, avalanche danger, faceted, faceting, high pressure, human triggered avalanches, slab, sugar snow, windslabs, Mountain Weather and Avalanche Forecast for the Vail and Summit County Zone Forecast Issued on 12/28/2007 3:46:19 PM Forecaster: Spencer Logan Weather Synopsis Clouds are returning to Colorado Friday night. They have moved into western Colorado Friday afternoon, and will spread across the state overnight. The clouds bring light, scattered snow. Upper level flow is northwesterly, which favors the Steamboat, northern Front Range, Aspen, and North San Juan zones. Shortwaves are coming through over the next few days. The shortwaves are hard to time, but it looks like stronger pulses and heavier snow will come Saturday and Sunday nights. The accumulations will be nickel and dime amounts, but a few inches every 12 hours will eventually add up. Winds will be increasing through Sunday. Snow continues through Monday, followed by a high pressure ridge for the middle part of the week. Weather Friday Night Saturday Saturday Night Temperature(°F) -5 to 0 5-10 0-5 Wind Speed(mph) 20-30 G40 15-25 G50 20-30 G50 Wind Direction NW W W Sky Cover Mostly Cloudy Mostly Cloudy Overcast Snow(in) 0-2 1-3 2-5 Snowpack Discussion Brrrrr! Temperature have been really cold. The cold temperatures have really put the faceting process in warp speed - a process that is progressively weakening the snowpack. If you poke around in the snow you will find two main issues in the older snow. The first is in the upper half of the snowpack where a grain size difference exists from one layer of sugar snow to the next. You will find easy, clean shaers when you test it. The second is the growing concern of larger faceted grains near the ground. The layer becomes weaker as the grains grow larger. The potential for full depth avalanches is coming back. On the snow surface are new windslabs formed from recent snow. These poeckts will be getting deeper and more extensive through the weekend as bits of snow ans strenghtening winds continue. So the picture is new snow and growing wind pillows sitting on a weakening mid-pack sitting above a weakening deep slab instability issue. Not a pretty picture, if you dig below the surface. The snowpack is becoming much more variable. Respect the snowpack and do not take it for granted! Get out there, but always use good route finding skills and smart backcountry protocols. Avalanche Danger The avalanche danger for the Vail-Summit zone is MODERATE with pockets of CONSIDERABLE on north, northeast, east, southeast and south aspects near and above treeline. Human triggered avalanches are possible to probable on steep slopes with freshly loaded wind pillows. On northwest, west, southwest, and south aspects near and above treeline the danger is MODERATE. Below treeline the danger is MODERATE on north to southeast aspects and otherwise LOW.