Aspen ===== Current Keywords: CONSIDERABLE, avalanche danger, human triggered avalanches, low pressure, natural, natural avalanches, path, paths, settle, trough, Mountain Weather and Avalanche Forecast for the Aspen Zone Forecast Issued on 1/9/2008 6:51:37 AM Forecaster: John Snook Weather Synopsis A fast-moving low pressure trough embedded within zonal west to east flow will cross the state today. Light to moderate snow will fall onto most mountain locations into tonight. Snow is expected to end by Thursday morning with the exception of a few lingering flakes over the northern mountains. Persistent northwest flow will generate more periods of mountain snow favoring the northern and central mountains. Light snow will regenerate Thursday night and last into early Saturday. Snowfall intensities are not expected to be heavy, but moderate accumulations could add up by Saturday on favored northwest aspects. Somewhat drier northwest flow is expected for the remainder of the weekend. Weather Wednesday Wednesday Night Thursday Temperature(°F) 15-20 0-5 10-15 Wind Speed(mph) 10-20 G30 15-25 G35 15-25 G40 Wind Direction W WNW WNW Sky Cover Overcast Overcast Mostly Cloudy Snow(in) 2-4 2-4 0-1 Snowpack Discussion Widespread avalanche activity has occurred around the Aspen Zone during the last couple days. It will take us quite a while to gather all these observations. Some of the more significant events include a large cycle on the Highlands Ridge. Most of the paths facing E, SE, and NE on the ridge from South Highlands Bowl, Five Fingers, and the K Chutes had avalanches in them. Our observer got a good look at the avalanche reported in the S Kellogg path in Ashcroft on Sunday. This one occurred on a SE aspect at about 12,600' and ran full track filling Castle Creek with snow. It was over 300' wide, destroying groves of aspen trees and breaking through 2' thick ice on a small pond in the area. Thanks to Ashcroft Ski Touring for the help with this observation. Also observed in the Castle Creek Valley were numerous avalanches near and below treeline on the west facing aspects of Richmond Ridge. Near Snowmass, a large natural was observed on an E aspect of Garrett Peak. This one occurred near 12,000' and was over 600' wide. Warmer temperatures and a brief period of sunshine has helped the snowpack to settle a little. Reports of natural avalanches are slowing. We are lowering the avalanche danger to overall CONSIDERABLE. This does not mean you can let your guard down. Natural avalanches are still possible and human triggered avalanches are probable on steep slopes. More light snow is the forecast. The snowpack is still tender and reactive, and will stay that way for a few more days at least. Think about the consequences of your route selection. It's a long winter. Stay safe and enjoy it. Avalanche Danger The avalanche danger in the Aspen Zone is overall CONSIDERABLE. Natural slides are possible and human triggered avalanches are probable. You can expect avalanches on a variety of aspects, elevations, and slope angles. The snowpack is still tender and recative, and will stay that way for a few more days at least. Thanks to everyone who has submitted observations in the last few days. These are a huge help to the forecasts. Any avalanche, weather, or snowpack information can be e-mailed to us at caic@qwest.net. Front Range =========== Current Keywords: CONSIDERABLE, MODERATE, avalanche danger, drifts, human triggered avalanches, low pressure, path, paths, slab, trough, windslabs, Mountain Weather and Avalanche Forecast for the Front Range Zone Forecast Issued on 1/9/2008 6:27:09 AM Forecaster: John Snook Weather Synopsis A fast-moving low pressure trough embedded within zonal west to east flow will cross the state today. Light to moderate snow will fall onto most mountain locations into tonight. Snow is expected to end by Thursday morning with the exception of a few lingering flakes over the northern mountains. Persistent northwest flow will generate more periods of mountain snow favoring the northern and central mountains. Light snow will regenerate Thursday night and last into early Saturday. Snowfall intensities are not expected to be heavy, but moderate accumulations could add up by Saturday on favored northwest aspects. Somewhat drier northwest flow is expected for the remainder of the weekend. Weather Wednesday Wednesday Night Thursday Temperature(°F) 17-22 3-8 13-18 Wind Speed(mph) 15-25 G45 15-25 G45 20-30 G50 Wind Direction W WNW W Sky Cover Overcast Overcast Mostly Cloudy Snow(in) 1-3 2-4 0-2 Snowpack Discussion CDOT had some very impressive results along the Berthoud and Loveland Passes plus the I-70 corridor. The beauty of this day was the results mainly stopped right at the edge of roads. Faster clean-up. The bad part is it continues to show there is some deep instability in the backcountry of the Front Range. The strong winds from Tuesday did not ease the problem at all, and may have loaded slab further down slope than we normally expect. Many of the results today came on southerly aspects, but also around to the northeast. Try as I might I just cannot lower the danger. Another near miss today just south of Abasin. Two skiers remotely triggered a large slab in the Daves Wave area. This sympathetically triggered further south into what is called the Ironing Board, a notorious path. These slides were big and to the ground. Apparently a dog has been buried in one of these slides and at last word they were still probing to try to find it. We are in a classic Colorado scenario. There are deep slab instabilities lurking in the backcountry. Several people can cross paths, even over several days. The weakness may be there, but you have to hit it just right. When you do, you will probably be dealing with a very big problem. One that is difficult or impossible to fix, with tragic outcomes. It is not an easy issue to address. And there is no easy answer, except to really evaluate your terrain, the consequences and your own take on what level of risk you are willing to accept. Remember that the bottom line of risk is death. That is a pretty permanent problem. Winds calmed down this morning, but they are expected to increase again on Wednesday from the west, and light snow is expected. We will hold the avalanche danger steady for now. Avalanche Danger The danger is CONSIDERABLE on N-NE-E-SE-S-SW aspects all elevations. Human triggered avalanches are probable on slopes with windslabs, drifts, or pillows. There are pockets of CONSIDERABLE danger on cross loaded terrain features on W-NW aspects near and above treeline. Below treeline the danger is MODERATE on SW-W-NW aspects. Grand Mesa ========== Current Keywords: MODERATE, avalanche danger, human triggered avalanches, low pressure, natural, settle, trough, Mountain Weather and Avalanche Forecast for the Grand Mesa Zone Forecast Issued on 1/9/2008 6:31:34 AM Forecaster: John Snook Weather Synopsis A fast-moving low pressure trough embedded within zonal west to east flow will cross the state today. Light to moderate snow will fall onto most mountain locations into tonight. Snow is expected to end by Thursday morning with the exception of a few lingering flakes over the northern mountains. Persistent northwest flow will generate more periods of mountain snow favoring the northern and central mountains. Light snow will regenerate Thursday night and last into early Saturday. Snowfall intensities are not expected to be heavy, but moderate accumulations could add up by Saturday on favored northwest aspects. Somewhat drier northwest flow is expected for the remainder of the weekend. Weather Wednesday Wednesday Night Thursday Temperature(°F) 18-23 5-10 15-20 Wind Speed(mph) 10-20 5-15 5-15 Wind Direction WSW NW W Sky Cover Overcast Overcast Mostly Cloudy Snow(in) 3-5 1-3 0-1 Snowpack Discussion Warmer temperatures and a brief period of sunshine allowed the snowpack across the Grand Mesa to settle and gain some strength on Tuesday. It has been awhile since we have gotten observations from the Mesa but we suspect that natural activity has all but ended. Human triggered avalanches will still be possible, especially in terrain 35 degrees and steeper. With light snow in the forecast, I will hold the avalanche danger steady for now. Avalanche Danger The avalanche danger for the Grand Mesa zone is MODERATE on all aspects and elevations. Please send observations from this or any other zone to [57]caic@qwest.net San Juan North ============== Current Keywords: CONSIDERABLE, avalanche danger, crown, faceted, human triggered, low pressure, natural, slab, trough, wind-loaded, windslab, Mountain Weather and Avalanche Forecast for the Northern San Juan Mountain Zone Forecast Issued on 1/9/2008 6:33:12 AM Forecaster: Mark Rikkers Weather Synopsis A fast-moving low pressure trough embedded within zonal west to east flow will cross the state today. Light to moderate snow will fall onto most mountain locations into tonight. Snow is expected to end by Thursday morning with the exception of a few lingering flakes over the northern mountains. Persistent northwest flow will generate more periods of mountain snow favoring the northern and central mountains. Light snow will regenerate Thursday night and last into early Saturday. Snowfall intensities are not expected to be heavy, but moderate accumulations could add up by Saturday on favored northwest aspects. Somewhat drier northwest flow is expected for the remainder of the weekend. Weather Wednesday Wednesday Night Thursday Temperature(°F) 15-20 0-5 15-20 Wind Speed(mph) 10-20 G30 10-20 G30 10-20 Wind Direction W NW NW Sky Cover Overcast Overcast Mostly Cloudy Snow(in) 4-6 2-4 0-1 Snowpack Discussion There have been a lot of observations recently from forecasters doing avalanche mitigation work on state highways and county roads, as well as natural activity that affected those roads. Yesterday was no exception as everyone got great visibility for the first time in a while - highway and helicopter crews reported remarkable results and natural activity from areas near Ophir, Telluride, Rico, Ouray and Silverton. There is an overwhelming amount of information to sort through. The bottom line is that significant avalanche activity has been occurring over the past four days on all aspects and at all elevations. While observers generally agree that the natural cycle is largely over for now, the snowpack proved to be very reactive to mitigation efforts yesterday, which caused many large, destructive avalanches to come down. Some of these slides ran full-track and to the ground, with crown lines estimated at up to seven feet deep. Forecasters also report wide propagation with many of the slab releases, as well as multiple releases in close proximity. Debris across closed roads ranged from a dusting to an estimated 40-feet deep on the south side of Red Mt. Pass. While reports confirm fairly widespread activity with no significant bias to elevation or aspect, some observers noted less natural activity above treeline than expected. There are likely two reasons for this. First, we know that the natural cycle really began to happen on Saturday late afternoon as the storm produced its first inch of water-equivalence - there was so much more new snow and high winds through Sunday and into Monday that some natural activity that occurred early on is now covered up. Also, very strong winds over the previous holiday week formed very firm windslab near and above treeline that can support a significant amount of weight. Below treeline, extensive natural activity has been reported. The relatively thin snowpack below treeline was faceted and weakened during the week or so of cold temperatures around the holidays, creating a weak and cohesionless foundation for the new snow load in many areas. There have been several avalanche related incidents lately, both around the Western US and very close to home. This is a time to consider the snowpack and your backcountry agenda very seriously. If you do travel in the backcountry today, practice strict protocol and conservative terrain management. Avalanche Danger The avalanche danger for the Northern San Juan zone is CONSIDERABLE on all aspects and elevations. Natural avalanches remain possible. Human-triggered avalanches are probable and large human triggered avalanches possible, particularly on steep, convex, wind-loaded slopes. THINK SAFETY! San Juan South ============== Current Keywords: CONSIDERABLE, avalanche danger, human triggered, human triggered avalanches, lee , low pressure, settle, slabs, trough, Mountain Weather and Avalanche Forecast for the Southern San Juan Mountain Zone Forecast Issued on 1/9/2008 6:34:13 AM Forecaster: John Snook Weather Synopsis A fast-moving low pressure trough embedded within zonal west to east flow will cross the state today. Light to moderate snow will fall onto most mountain locations into tonight. Snow is expected to end by Thursday morning with the exception of a few lingering flakes over the northern mountains. Persistent northwest flow will generate more periods of mountain snow favoring the northern and central mountains. Light snow will regenerate Thursday night and last into early Saturday. Snowfall intensities are not expected to be heavy, but moderate accumulations could add up by Saturday on favored northwest aspects. Somewhat drier northwest flow is expected for the remainder of the weekend. Weather Wednesday Wednesday Night Thursday Temperature(°F) 15-20 5-10 23-28 Wind Speed(mph) 10-20 10-20 10-20 Wind Direction SW NW W Sky Cover Overcast Mostly Cloudy Mostly Cloudy Snow(in) 1-3 0-1 0 Snowpack Discussion Warmer temperatures on Tuesday and a brief period of sunshine helped to settle the snowpack and gain some strength. Natural avalanches will be possible, and human triggered slides will be probable. A couple things to watch for. Winds from the west to southwest the next few days will be strong enough to move snow onto lee slopes, so fresh shallow slabs will be building. If you get a slide started it could dig into some of the older layers. So pay attention to terrain traps. With all the new snow it will be tempting to push the bigger terrain. It is a good idea to slowly work your way into this as that is a good way to get a feel for how the snowpack is going to behave. With light snow in the forecast, I will hold the avalanche danger at current levels. Avalanche Danger The avalanche danger is CONSIDERABLE on all aspects and elevations. Natural avalanches are possible and human triggered avalanches are probable. Sangre de Christo ================= Current Keywords: avalanche danger, low pressure, slab, trough, Mountain Weather and Avalanche Forecast for the Sangre De Cristo Zone Forecast Issued on 1/9/2008 6:34:34 AM Forecaster: John Snook Weather Synopsis A fast-moving low pressure trough embedded within zonal west to east flow will cross the state today. Light to moderate snow will fall onto most mountain locations into tonight. Snow is expected to end by Thursday morning with the exception of a few lingering flakes over the northern mountains. Persistent northwest flow will generate more periods of mountain snow favoring the northern and central mountains. Light snow will regenerate Thursday night and last into early Saturday. Snowfall intensities are not expected to be heavy, but moderate accumulations could add up by Saturday on favored northwest aspects. Somewhat drier northwest flow is expected for the remainder of the weekend. Weather Wednesday Wednesday Night Thursday Temperature(°F) 17-22 5-10 20-25 Wind Speed(mph) 10-20 G30 10-20 10-20 Wind Direction WSW WNW W Sky Cover Overcast Partly Cloudy Mostly Cloudy Snow(in) 0-2 0 0 Snowpack Discussion The current winter storm is having less effect on the Sangre zone. We have gotten in touch with a potential observer in Westcliffe, so hoping to get a few more observations from this zone soon. For now, the Sangres have not gotten the snow that other zones have. They have likely gotten the wind so shallow slab development could be expected 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, crossloaded, crust, facets, human triggered, lee , low pressure, natural avalanche, path, settle, slab, slabs, starting zone, sugar snow, trough, weak layer, wind loaded, Mountain Weather and Avalanche Forecast for the Sawatch Range Zone Forecast Issued on 1/9/2008 6:36:26 AM Forecaster: John Snook Weather Synopsis A fast-moving low pressure trough embedded within zonal west to east flow will cross the state today. Light to moderate snow will fall onto most mountain locations into tonight. Snow is expected to end by Thursday morning with the exception of a few lingering flakes over the northern mountains. Persistent northwest flow will generate more periods of mountain snow favoring the northern and central mountains. Light snow will regenerate Thursday night and last into early Saturday. Snowfall intensities are not expected to be heavy, but moderate accumulations could add up by Saturday on favored northwest aspects. Somewhat drier northwest flow is expected for the remainder of the weekend. Weather Wednesday Wednesday Night Thursday Temperature(°F) 15-20 0-5 13-18 Wind Speed(mph) 10-20 G35 10-20 G35 15-25 G45 Wind Direction W WNW WNW Sky Cover Overcast Overcast Mostly Cloudy Snow(in) 2-4 0-2 0-1 Snowpack Discussion The last storm cycle brought close to two feet of snow to the Sawatch zone. Winds have also been quite breezy at times. Although winds have been primarily from the west, they at times have come from the northeast, southeast and northwest. Loading patterns will be inconsistent. New and loaded snow has fallen on a variety of snow surfaces too. On northerly and easterly aspects, it has fallen on both soft and hard slab surfaces. Hard slabs can give you a false sense of security. The problem with hard slabs is that although they can support a fair bit of weight in thick areas, they tend to break easily and propagate far very quickly. Yesterday in the Cottonwood Pass area Brad went in to investigate the natural avalanche that injured a snowmobiler on Sunday. The slide ran over 1,200' on a south aspect. The fracture line was nearly 400' wide and 2-5 feet deep. The path has run in previous years but was hidden well due to several stands of aspen trees that have now lost the fight once again. The culprit was a buried sun crust that had small grained sugar snow above and large sized grains below. Sugar snow, or facets, are a very persistent grain type, meaning they will be there for the rest of the winter. Layers of both soft and hard slabs sat above the sun crust/weak layer sandwich. As we have been noting for a while. the snowpack is a bit complicated and is only a small part of the current avalanche picture. The weather over the past two to three weeks has also been a big player. Backcountry users need to carefully evaluate terrain and what the weather has done. Be suspicious of convex rolls on terrain 30 degrees and steeper. If you see rock bands and vegetation sticking out of the snow surface below the suspected starting zone be thinking deep slab instability. Fresh avalanche activity is bulls-eye information. If avalanches have been running, expect to find instabilities on similar aspects and elevations. Snowpit data and stability tests may give you false stable signs. So look at the big picture and always think about the consequences of getting caught. Being caught in an avalanche can really ruin your day if not worse. If you are traveling through avalanche terrain on foot or machine, be aware of what both above and below you and your party. If the terrain is capable of sliding, spread your party out. If you venture into the backcountry, it really is okay to just look and feel lucky to just be out there instead of pushing the limit. Warmer temperatures and a brief period of sunshine on Tuesday has allowed the snowpack to slowly settle a little. Natural slides are becoming less likely, but human triggered slides remain possible to probable. Light snow is in the forecast. The most suspect slopes will be steep, lee aspects where fresh wind pillows could build on Wednesday. Avalanche Danger The avalanche danger in the Sawatch Zone is CONSIDERABLE near and above treeline on wind loaded and crossloaded slopes facing north, northeast, east, southeast to south. Elsewhere, the danger is MODERATE. Please let us now if you saw any avalanche activity or experienced signs of instability. Email us at caic@qwest.net. Steamboat ========= Current Keywords: CONSIDERABLE, MODERATE, avalanche danger, lee , low pressure, slab, slabs, trough, weak layer, weak layers, Mountain Weather and Avalanche Forecast for the Steamboat and Parks Range Zone Forecast Issued on 1/9/2008 6:26:26 AM Forecaster: John Snook Weather Synopsis A fast-moving low pressure trough embedded within zonal west to east flow will cross the state today. Light to moderate snow will fall onto most mountain locations into tonight. Snow is expected to end by Thursday morning with the exception of a few lingering flakes over the northern mountains. Persistent northwest flow will generate more periods of mountain snow favoring the northern and central mountains. Light snow will regenerate Thursday night and last into early Saturday. Snowfall intensities are not expected to be heavy, but moderate accumulations could add up by Saturday on favored northwest aspects. Somewhat drier northwest flow is expected for the remainder of the weekend. Weather Wednesday Wednesday Night Thursday Temperature(°F) 15-20 3-8 13-18 Wind Speed(mph) 10-20 G35 10-20 G35 15-25 G40 Wind Direction WSW WNW W Sky Cover Overcast Overcast Mostly Cloudy Snow(in) 4-6 1-3 0-2 Snowpack Discussion No observations for several days now. I suspect people have been out and about, so if you have seen anything, please feel free to send us the news. Expect to find some fresh shallow slab on the lee aspects to recent southwest winds. 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. They may be a little harder to trigger, and could come on backcountry terrain that has had some traffic thru the winter. Mostly this problem will involve hard slabs, so above and at treeline in the typical windy areas. Snowpits may not find a defined weak layer, so also look at the terrain, and the snow surface. Are there convex rolls with hard snow at the surface? Cornices? Are there nasty terrain features with perhaps exposed rock bands or small trees sticking through the snow? Think about consequences to go along with all your other decision processes. Light snow and moderate west wind is in the forecast. The avalanche danger is holding steady for now. Avalanche Danger The avalanche danger in the Steamboat Zone is CONSIDERABLE on N-E-S aspect near and above treeline. It is MODERATE elsewhere. Human triggered slides are probable especially on terrain over 35 degrees. If you have any observations or data to share, please send them to [57]caic@qwest.net. Vail ==== Current Keywords: MODERATE, avalanche danger, low pressure, path, paths, slab, slabs, trough, wind drifts, Mountain Weather and Avalanche Forecast for the Vail and Summit County Zone Forecast Issued on 1/9/2008 6:27:58 AM Forecaster: John Snook Weather Synopsis A fast-moving low pressure trough embedded within zonal west to east flow will cross the state today. Light to moderate snow will fall onto most mountain locations into tonight. Snow is expected to end by Thursday morning with the exception of a few lingering flakes over the northern mountains. Persistent northwest flow will generate more periods of mountain snow favoring the northern and central mountains. Light snow will regenerate Thursday night and last into early Saturday. Snowfall intensities are not expected to be heavy, but moderate accumulations could add up by Saturday on favored northwest aspects. Somewhat drier northwest flow is expected for the remainder of the weekend. Weather Wednesday Wednesday Night Thursday Temperature(°F) 15-20 0-5 10-15 Wind Speed(mph) 10-20 G35 10-20 G35 15-25 G40 Wind Direction W WNW W Sky Cover Overcast Overcast Mostly Cloudy Snow(in) 1-3 1-3 0-1 Snowpack Discussion CDOT had some very impressive results along the Berthoud and Loveland Passes plus the I-70 corridor. The beauty of this day was the results mainly stopped right at the edge of roads. Faster clean-up. The bad part is it continues to show there is some deep instability in the backcountry of the Summit county portion of the zone, and I would suspect in the Vail area as well. The strong winds from Tuesday did not ease the problem at all, and may have loaded slab further down slope than we normally expect. Many of the results today came on southerly aspects, but also around to the northeast. Another near miss on Tuesday just north of A-Basin. Two skiers remotely triggered a large slab in the Dave's Wave area. This sympathetically triggered further south into what is called the Ironing Board, a notorious path. These slides were big and to the ground. Apparently a dog has been buried in one of these slides and at last word they were still probing to try to find it. Ski patrols ski triggered some pretty large hard slabs in Summit County. We are in a classic Colorado scenario. There are deep slab instabilities lurking in the backcountry. Several people can cross paths, even over several days. The weakness may be there, but you have to hit it just right. When you do, you will probably be dealing with a very big problem. One that is difficult or impossible to fix, with tragic outcomes. It is not an easy issue to address. And there is no easy answer, except to really evaluate your terrain, the consequences and your own take on what level of risk you are willing to accept. I will hold the avalanche danger steady for now with light snow and strengtheng westerly winds in the forecast. Avalanche Danger The avalanche danger in the Vail Summit Zone is CONSIDERABE all elevations on N-NE-E-SE-S-SW aspects where new snow and strong winds have created fresh wind drifts and slabs. Other aspects and elevations are at MODERATE.