Aspen ===== Current Keywords: CONSIDERABLE, HIGH, avalanche danger, collapses, depth hoar, drifts, faceted, human triggered, lee , low pressure, natural, natural avalanches, orographic, slabs, trough, weak layer, weak layers, wind transported, Mountain Weather and Avalanche Forecast for the Aspen Zone Forecast Issued on 1/6/2008 7:19:31 AM Forecaster: John Snook Weather Synopsis Heavy snow and strong southwest winds since Saturday have created high avalanche danger for the San Juan Mountain and Gunnison zones where an avalanche warning has been issued. A broad trough of low pressure is slowly pushing into the western US. Southwest flow ahead of the trough continues to carry abundant moisture into the state. Moderate to heavy snow will continue for favored southwest mountain aspects including the San Juans, West Elks, and Flat Tops. Wind gusts will remain on the strong side into Monday morning. Less intense snow will linger through Monday. The slow moving low pressure trough is expected to cross the state Monday night which will bring colder temperatures. Monday night winds will shift to west and northwest shifting the focus of light snow to the central and northern mountains. Tuesday will bring a break from the unsettled weather. Favorable orographic west to northwest flow continues for the remainder of the week with the next chance for mountain snow on Wednesday. Weather Sunday Night Monday Monday Night Temperature(°F) 22-27 5-10 10-15 Wind Speed(mph) 15-25 G45 15-25 G40 15-25 G40 Wind Direction WSW WSW W Sky Cover Overcast Overcast Overcast Snow(in) 4-6 3-5 1-3 Snowpack Discussion Winter has returned to the Aspen zone. Strong winds from the west-southwest are combining with new storm snow to create fresh drifts on north through southeast aspects. The new load will be piling on a highly variable older snowpack. Last week's strong winds already created hard and soft slabs on most aspects in both lee and cross loaded zones. This wind transported snow has set us up with the classic Colorado strong over weak layering in the snowpack. These wind loaded pockets on Friday proved to be very tender around Independence Pass with several large collapses and some shooting crack observed on E and SE aspects near treeline. Tests revealed some high energy failures in the snowpack in these zones. It won't take much more of a load to bring natural avalanches back into the picture. The Aspen area reported 15-18" of new snow Sunday morning with around 1.5" of water content, which is a significant new load on the snowpack. Although wind speeds have slowed Sunday morning, there were periods of very strong winds from the west-southwest. Numerous shallow slabs up to one foot deep have been reported. New snow, strong winds and multiple weak layers in the snowpack will combine to create avalanches on a variety of aspects and elevations. Some of the avalanches could be large events, failing at the base of the snowpack. Weak faceted snow and depth hoar at the ground in many areas has sat quietly for some time. Increasing load on that layer as well as a weakening of the middle of the snowpack due to recent colder weather could bring it into play again. Slopes facing N-NE-E-SE have gained the greatest new load and have the potential for the largest avalanches at this time. The avalanche danger has been raised to HIGH on these aspects near and above treeline where natural and human triggered slides are likely. Elsewhere the danger is CONSIDERABLE. Avalanche Danger The avalanche danger for the Aspen zone is HIGH on N-NE-E-SE aspects near and above treeline where natural and human triggered slides are likely. Elsewhere the danger is CONSIDERABLE. Avalanche forecasting is a community effort. Help out your fellow backcountry travelers (and forecasters) by dropping us a quick e-mail at caic@qwest.net with any avalanche, snowpack, or weather observations you might have. Front Range =========== Current Keywords: CONSIDERABLE, MODERATE, avalanche danger, cross loaded, crust, drifts, facets, human triggered, human triggered avalanches, low pressure, orographic, stabilize, start zone, trough, wind slab, wind slabs, windslabs, Mountain Weather and Avalanche Forecast for the Front Range Zone Forecast Issued on 1/6/2008 7:05:01 AM Forecaster: John Snook Weather Synopsis Heavy snow and strong southwest winds since Saturday have created high avalanche danger for the San Juan Mountain and Gunnison zones where an avalanche warning has been issued. A broad trough of low pressure is slowly pushing into the western US. Southwest flow ahead of the trough continues to carry abundant moisture into the state. Moderate to heavy snow will continue for favored southwest mountain aspects including the San Juans, West Elks, and Flat Tops. Wind gusts will remain on the strong side into Monday morning. Less intense snow will linger through Monday. The slow moving low pressure trough is expected to cross the state Monday night which will bring colder temperatures. Monday night winds will shift to west and northwest shifting the focus of light snow to the central and northern mountains. Tuesday will bring a break from the unsettled weather. Favorable orographic west to northwest flow continues for the remainder of the week with the next chance for mountain snow on Wednesday. Weather Sunday Night Monday Monday Night Temperature(°F) 25-30 10-15 15-20 Wind Speed(mph) 15-25 G50 15-25 G40 15-25 G40 Wind Direction WSW WSW W Sky Cover Overcast Overcast Mostly Cloudy Snow(in) 2-4 1-3 1-3 Snowpack Discussion Early reports Sunday morning indicate 4-6" of new snow with periods of very strong west-southwest winds The last slides reported in the Front Range zone were on Thursday. Recent slide activity has been primarily on south to southeast aspects near and above treeline. Observers continue to remark about how complicated the snow pack is especially near and just above treeline where a variety of wind slabs sit on top of a weaker base layer of facets. The recent warm weather has helped to stabilize the upper snow pack, but has had little effect on the already weak lower snow pack. An observer on Thursday noted a bulletproof wind slab near and just above treeline and a variable trap crust down lower. This supportable wind slab might fool you into thinking that a slope is safe, but as you travel downhill the snow surface becomes weaker where you could trigger an avalanche. Consistent with these observations is that recent slide activity is being initiated below the start zone. Additional light snowfall and continued strong winds from the west-southwest are expected to create fresh drifts on north through southeast aspects. This is going to add weight to the snow. And if you add your own weight, it may be enough to tip the balance where snow pack strength can no longer hold the load. Human triggered slides remain possible to probable. Watch for changing conditions as additional snow and strong winds continue to add load to the snow pack. Avalanche Danger The danger is CONSIDERABLE on N-NE-E-SE-S aspects near and above treeline. Human triggered avalanches are probable on steep slopes with windslabs, drifts, or pillows. There are pockets of CONSIDERABLE danger on cross loaded terrain features on SW-W-NW aspects near and above treeline. Below treeline the danger is MODERATE. Grand Mesa ========== Current Keywords: CONSIDERABLE, avalanche danger, dense, drifts, human triggered avalanches, low pressure, orographic, trough, weak layer, wind drifted, Mountain Weather and Avalanche Forecast for the Grand Mesa Zone Forecast Issued on 1/6/2008 7:21:07 AM Forecaster: John Snook Weather Synopsis Heavy snow and strong southwest winds since Saturday have created high avalanche danger for the San Juan Mountain and Gunnison zones where an avalanche warning has been issued. A broad trough of low pressure is slowly pushing into the western US. Southwest flow ahead of the trough continues to carry abundant moisture into the state. Moderate to heavy snow will continue for favored southwest mountain aspects including the San Juans, West Elks, and Flat Tops. Wind gusts will remain on the strong side into Monday morning. Less intense snow will linger through Monday. The slow moving low pressure trough is expected to cross the state Monday night which will bring colder temperatures. Monday night winds will shift to west and northwest shifting the focus of light snow to the central and northern mountains. Tuesday will bring a break from the unsettled weather. Favorable orographic west to northwest flow continues for the remainder of the week with the next chance for mountain snow on Wednesday. Weather Sunday Night Monday Monday Night Temperature(°F) 27-32 13-18 15-20 Wind Speed(mph) 15-25 G40 10-20 G30 10-20 Wind Direction SW SW WNW Sky Cover Overcast Overcast Mostly Cloudy Snow(in) 4-6 4-6 1-3 Snowpack Discussion Winter has returned to the Grand Mesa zone. Strong winds from the west-southwest are combining with storm snow to create fresh drifts on north through southeast aspects. The new load is falling on a classic Colorado strong over weak layering in the snowpack. We are starting to get reports that the new snow storm snow is rather dense and is not bonding well with old snow surface. The new storm and wind drifted snow could react to the weight of a backcountry traveler. We have not received any reports of new snow as of Sunday morning, but radar data suggests that it has been heavy. With more snow in the forecast, we feel that the probability of human triggered avalanches has increased to probable. As a result, the avalanche danger has been rated as CONSIDERABLE on all aspects and elevations. Stay tuned to changing conditions this weekend and choose your routes accordingly. Avalanche Danger The avalanche danger for the Grand Mesa zone is CONSIDERABLE on all aspects and elevations. Please send observations from this or any other zone to [57]caic@qwest.net San Juan North ============== Current Keywords: HIGH, avalanche danger, drifts, faceted, faceting, graupel, low pressure, natural, orographic, slabs, trough, wind slab, Mountain Weather and Avalanche Forecast for the Northern San Juan Mountain Zone Avalanche Warning in Effect through 1/7/2008 5:00:00 AM Forecast Issued on 1/6/2008 6:52:26 AM Forecaster: John Snook Weather Synopsis Heavy snow and strong southwest winds since Saturday have created high avalanche danger for the San Juan Mountain and Gunnison zones where an avalanche warning has been issued. A broad trough of low pressure is slowly pushing into the western US. Southwest flow ahead of the trough continues to carry abundant moisture into the state. Moderate to heavy snow will continue for favored southwest mountain aspects including the San Juans, West Elks, and Flat Tops. Wind gusts will remain on the strong side into Monday morning. Less intense snow will linger through Monday. The slow moving low pressure trough is expected to cross the state Monday night which will bring colder temperatures. Monday night winds will shift to west and northwest shifting the focus of light snow to the central and northern mountains. Tuesday will bring a break from the unsettled weather. Favorable orographic west to northwest flow continues for the remainder of the week with the next chance for mountain snow on Wednesday. Weather Sunday Sunday Night Monday Temperature(°F) 22-27 7-12 10-15 Wind Speed(mph) 15-25 G45 15-25 G45 10-20 G30 Wind Direction SW SW WNW Sky Cover Overcast Overcast Mostly Cloudy Snow(in) 6-8 5-7 2-4 Snowpack Discussion Winter has returned to the Northern San Juan zone. Strong winds from the southwest are combining with storm snow to create fresh drifts on north through southeast aspects. As would be expected with southwest flow, snow is heavier in the southern portion of the zone. Saturday afternoon reports indicate heavy snow falling with up to 8" new on Red Mountain Pass. Early reports Sunday morning indicate 24 hour snowfall of around 18" with high water content. A lot of graupel has also been noted which is not good. The new snow is not bonding well with the old snow surface, and it has been described as very, very reactive. The new load is piling up on firm wind slab that sits on top of cold, faceted snow on most aspects. This is testing the snowpack, particularly near and above treeline on northerly through easterly aspects. Many of the old slabs will be able to take quite a bit of weight, but they also have the potential to propagate over long distances once they fail. We have had some relatively large avalanches, both natural and triggered, near treeline recently - this elevation zone is perhaps the most complex right now due to variable wind-effects and significant faceting that occurred during the recent spell of cold weather. Both near and above treeline, deep instabilities persist, particularly on northerly and easterly terrain, and the potential for avalanches to fail to the ground during the course of this storm is becoming increasingly real. Below treeline, the main concern is that recent cold temperatures have faceted and weakened grains deep in the snowpack, particularly on cold northerly slopes. These cohesionless grains will not be a strong foundation for a heavy load. Highway crews have reported numerous natural slides. Natural and human triggered slides are likely on all aspects and all elevations. As a result, the avalanche danger has been raised to overall HIGH and an avalanche warning has been issued. More heavy snow and strong winds are predicted for Sunday. We recommend that you do not travel onto or underneath steep terrain anywhere in the backcountry. Avalanche Danger The avalanche danger for the Northern San Juan zone is HIGH on all aspects and elevations. Natural and human-triggered avalanches are likely. An avalanche warning has been issued for Sunday. Do not travel San Juan South ============== Current Keywords: HIGH, avalanche danger, drifts, low pressure, natural, orographic, stress, surface hoar, test slopes, trough, Mountain Weather and Avalanche Forecast for the Southern San Juan Mountain Zone Avalanche Warning in Effect through 1/7/2008 5:00:00 AM Forecast Issued on 1/6/2008 6:52:49 AM Forecaster: John Snook Weather Synopsis Heavy snow and strong southwest winds since Saturday have created high avalanche danger for the San Juan Mountain and Gunnison zones where an avalanche warning has been issued. A broad trough of low pressure is slowly pushing into the western US. Southwest flow ahead of the trough continues to carry abundant moisture into the state. Moderate to heavy snow will continue for favored southwest mountain aspects including the San Juans, West Elks, and Flat Tops. Wind gusts will remain on the strong side into Monday morning. Less intense snow will linger through Monday. The slow moving low pressure trough is expected to cross the state Monday night which will bring colder temperatures. Monday night winds will shift to west and northwest shifting the focus of light snow to the central and northern mountains. Tuesday will bring a break from the unsettled weather. Favorable orographic west to northwest flow continues for the remainder of the week with the next chance for mountain snow on Wednesday. Weather Sunday Sunday Night Monday Temperature(°F) 23-28 12-17 13-18 Wind Speed(mph) 15-25 G45 15-26 G40 10-20 G30 Wind Direction SW SW WSW Sky Cover Overcast Overcast Mostly Cloudy Snow(in) 8-12 6-8 2-4 Snowpack Discussion Winter has returned to the Southern San Juan zone. Strong winds from the southwest are combining with storm snow to create fresh drifts on north through southeast aspects. As of Sunday morning, 24 hour snowfall has exceeded well over a foot. Our observer Saturday afternoon noted major cracking on test slopes within the new snow. The new snow load is piling up on a couple of surface hoar layers that are buried about a foot deep and around a foot and a half deep. This is likely stressing these layers. Highway crews have reported numerous natural slides. Natural and human triggered slides are likely on all aspects and all elevations. As a result, the avalanche danger has been raised to overall HIGH and an avalanche warning has been issued. More heavy snow and strong winds are predicted for Sunday. We recommend that you do not travel onto or underneath steep terrain anywhere in the backcountry. Avalanche Danger The avalanche danger for the Southern San Juan zone is HIGH on all aspects and elevations. Natural and human-triggered avalanches are likely. An avalanche warning has been issued for Sunday. Do not travel Sangre de Christo ================= Current Keywords: avalanche danger, low pressure, orographic, trough, whumpfing, wind drifted, Mountain Weather and Avalanche Forecast for the Sangre De Cristo Zone Forecast Issued on 1/6/2008 7:22:02 AM Forecaster: John Snook Weather Synopsis Heavy snow and strong southwest winds since Saturday have created high avalanche danger for the San Juan Mountain and Gunnison zones where an avalanche warning has been issued. A broad trough of low pressure is slowly pushing into the western US. Southwest flow ahead of the trough continues to carry abundant moisture into the state. Moderate to heavy snow will continue for favored southwest mountain aspects including the San Juans, West Elks, and Flat Tops. Wind gusts will remain on the strong side into Monday morning. Less intense snow will linger through Monday. The slow moving low pressure trough is expected to cross the state Monday night which will bring colder temperatures. Monday night winds will shift to west and northwest shifting the focus of light snow to the central and northern mountains. Tuesday will bring a break from the unsettled weather. Favorable orographic west to northwest flow continues for the remainder of the week with the next chance for mountain snow on Wednesday. Weather Sunday Night Monday Monday Night Temperature(°F) 25-30 10-15 13-18 Wind Speed(mph) 15-25 G40 10-20 G35 10-20 G30 Wind Direction SW SW W Sky Cover Overcast Mostly Cloudy Mostly Cloudy Snow(in) 0-2 0-2 0-2 Snowpack Discussion The current winter storm is having less effect on the Sangre zone. Nonetheless, new snow with strong southwest winds is expected. The new snow load will fall onto wind drifted slopes with northeast, east, and southeast aspects. Evaluate the snowpack frequently and look for obvious signs of instability including whumpfing, cracking, or recent avalanching. This avalanche danger will slowly rise during the next 24 hours. 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, MODERATE, avalanche danger, beacons, crossloaded, drifts, human triggered, low pressure, orographic, probe, shears, shovels, slabs, trough, weak layer, wind loaded, Mountain Weather and Avalanche Forecast for the Sawatch Range Zone Forecast Issued on 1/6/2008 7:26:22 AM Forecaster: John Snook Weather Synopsis Heavy snow and strong southwest winds since Saturday have created high avalanche danger for the San Juan Mountain and Gunnison zones where an avalanche warning has been issued. A broad trough of low pressure is slowly pushing into the western US. Southwest flow ahead of the trough continues to carry abundant moisture into the state. Moderate to heavy snow will continue for favored southwest mountain aspects including the San Juans, West Elks, and Flat Tops. Wind gusts will remain on the strong side into Monday morning. Less intense snow will linger through Monday. The slow moving low pressure trough is expected to cross the state Monday night which will bring colder temperatures. Monday night winds will shift to west and northwest shifting the focus of light snow to the central and northern mountains. Tuesday will bring a break from the unsettled weather. Favorable orographic west to northwest flow continues for the remainder of the week with the next chance for mountain snow on Wednesday. Weather Sunday Night Monday Monday Night Temperature(°F) 23-28 8-13 10-15 Wind Speed(mph) 15-25 G40 15-25 G40 15-25 G40 Wind Direction WSW WSW W Sky Cover Overcast Overcast Overcast Snow(in) 5-7 2-4 1-3 Snowpack Discussion Winter has returned to the Sawatch zone. Strong winds from the west-southwest are combining with storm snow to create fresh drifts on north through southeast aspects. Sunday morning reports indicate about a foot and a half of new snow on Monarch Pass. The southern portion of the zone received more new snow than the north. An observer noted easy shears under the new snow but not much tension. Wind drifts are up to a couple of feet deep. The new load is being added to a classic Colorado strong over weak layering in the snowpack. And when you add your own weight, it may be enough to tip the balance where snowpack strength can no longer hold the load. More snow and strong west-southwest winds are in the forecast. The avalanche danger has risen such that human triggered slides are possible to probable on all aspects and elevations, especially over the southern portion of the zone. Avalanches will occur and may be large. Steep, wind loaded terrain at and above treeline should be avoided. Expect to find fresh slabs forming on north through east and southeast aspects. The strong winds will also carry snow much further down slopes, making trigger points farther away from traditional start zones. Skilled route finding is in order as well as smart travel practices. Know how to use and carry beacons, shovels and probe poles. Avalanche Danger The avalanche danger in the Sawatch Zone is CONSIDERABLE near and above treeline on steep wind loaded and crossloaded slopes facing north, northeast, east, and southeast. Elsewhere, the danger is MODERATE. . Steamboat ========= Current Keywords: CONSIDERABLE, avalanche danger, human triggered, low pressure, orographic, trough, weak layer, weak layers, whumpfing, wind drifted, wind drifts, wind loaded, Mountain Weather and Avalanche Forecast for the Steamboat and Parks Range Zone Forecast Issued on 1/6/2008 7:01:49 AM Forecaster: John Snook Weather Synopsis Heavy snow and strong southwest winds since Saturday have created high avalanche danger for the San Juan Mountain and Gunnison zones where an avalanche warning has been issued. A broad trough of low pressure is slowly pushing into the western US. Southwest flow ahead of the trough continues to carry abundant moisture into the state. Moderate to heavy snow will continue for favored southwest mountain aspects including the San Juans, West Elks, and Flat Tops. Wind gusts will remain on the strong side into Monday morning. Less intense snow will linger through Monday. The slow moving low pressure trough is expected to cross the state Monday night which will bring colder temperatures. Monday night winds will shift to west and northwest shifting the focus of light snow to the central and northern mountains. Tuesday will bring a break from the unsettled weather. Favorable orographic west to northwest flow continues for the remainder of the week with the next chance for mountain snow on Wednesday. Weather Sunday Sunday Night Monday Temperature(°F) 25-30 12-17 15-20 Wind Speed(mph) 10-20 G35 10-20 15-25 Wind Direction WSW WSW W Sky Cover Overcast Overcast Mostly Cloudy Snow(in) 6-8 3-6 1-3 Snowpack Discussion Winter has returned to the Steamboat zone, and you need to be thinking about winter-time avalanche conditions. Automated weather stations indicate that winds from the west-southwest have been strong. Early reports Sunday morning indicate around 9" of new snow. The wind is likely creating fresh wind drifts on north through southeast aspects. The newly fallen and wind drifted snow is piling up on a recently developed weak layer of surface snow. It will be critical to watch for a point where new snow overwhelms the strength of the older underlying snow. This can be tricky as the onset can be rapid. Watch for new avalanche activity, cracking and whumpfing sounds. The other issue is buried weak layers deep down in the snowpack. These can be potentially more dangerous as they can involve the entire winter snowpack. Additional snow is in the forecast that may be enough additional weight to start affecting those layers, and the addition of humans could be the trigger. Human triggered slides remain probable. The most likely place for you to trigger a slide will be on steep, wind loaded slopes with north, northeast, east, and southeast aspects. Avalanche Danger The avalanche danger in the Steamboat Zone is CONSIDERABLE on all aspects and elevations. Human triggered slides are probable. If you have any observations or data to share, please send them to [57]caic@qwest.net. Vail ==== Current Keywords: MODERATE, avalanche danger, drifts, facets, human triggered, low pressure, orographic, path, slab, slabs, start zone, stress, trough, wind drifts, Mountain Weather and Avalanche Forecast for the Vail and Summit County Zone Forecast Issued on 1/6/2008 7:09:39 AM Forecaster: John Snook Weather Synopsis Heavy snow and strong southwest winds since Saturday have created high avalanche danger for the San Juan Mountain and Gunnison zones where an avalanche warning has been issued. A broad trough of low pressure is slowly pushing into the western US. Southwest flow ahead of the trough continues to carry abundant moisture into the state. Moderate to heavy snow will continue for favored southwest mountain aspects including the San Juans, West Elks, and Flat Tops. Wind gusts will remain on the strong side into Monday morning. Less intense snow will linger through Monday. The slow moving low pressure trough is expected to cross the state Monday night which will bring colder temperatures. Monday night winds will shift to west and northwest shifting the focus of light snow to the central and northern mountains. Tuesday will bring a break from the unsettled weather. Favorable orographic west to northwest flow continues for the remainder of the week with the next chance for mountain snow on Wednesday. Weather Sunday Night Monday Monday Night Temperature(°F) 22-27 5-10 10-15 Wind Speed(mph) 15-25 G45 10-20 G35 10-20 G35 Wind Direction WSW SW W Sky Cover Overcast Overcast Overcast Snow(in) 3-5 1-3 1-3 Snowpack Discussion Observers are noting that the snowpack is most complicated near and just above treeline where a variety of hard layers including wind slabs and storm snow sit on top of a weaker base layer of facets. Most recent slide activity has been occurring in this same elevation zone on steep northeast through south aspects. The human triggered slides have a common theme...they were triggered from below the start zone. Imagine blowing and loading snow shaped like a saucer or a contact lens, covering the entire start zone of a slide path. Near the top, the slab is very thick and very strong. As you descend the slope the slab thickness decreases and therefore is more susceptible to the added stress of you. The slope then fractures and you are caught in the middle of a hard slab avalanche. Early reports Sunday morning indicate about 5-8" of new snow and periods of very strong west-southwest winds since Saturday resulting in fresh drifts on north through southeast aspects. This is going to add weight to the snow. And if you add your own weight, it may be enough to tip the balance where snow pack strength can no longer hold the load. Human triggered slides remain possible to probable. Watch for changing conditions as additional snow and strong winds continue to add load to the snow pack. Avalanche Danger The avalanche danger in the Vail Summit Zone is CONSIDERABE near and above treeline on NW-N-NE-E-SE aspects where new snow and strong winds have created fresh wind drifts and slabs. Other aspects and elevations are at MODERATE.