Aspen ===== Current Keywords: CONSIDERABLE, MODERATE, avalanche cycle, avalanche danger, cornice, faceted, front, high pressure, human triggered avalanches, low-pressure, natural, natural avalanches, settle, stresse, sugar snow, trough, weak layer, weak layers, wind loaded, Mountain Weather and Avalanche Forecast for the Aspen Zone Forecast Issued on 2/12/2008 4:16:02 PM Forecaster: Ethan Greene Weather Synopsis Clouds continue to stream into the state from the north. Light to moderate snow showers cover much of the northern mountains and strong winds continue to blow from the north and northwest at ridecrest. The weather is mild by comparison as you move southward into the central and southern mountains. The back edge of the low-pressure trough, currently over the eastern half of Colorado, is moving eastward and high pressure is building in from the southwest. On Wednesday the flow will shift to the west and southwest as the high pressure ridge briefly covers the state. A strong cold front will approach from the northwest on Wednesday afternoon/evening bringing snow to most mountain areas on Thursday. Weather Tuesday Night Wednesday Wednesday Night Temperature(°F) 6-11 25-30 -5 to 0 Wind Speed(mph) 5-15 10-20 15-25 Wind Direction W WSW WSW Sky Cover Mostly Cloudy Mostly Cloudy Overcast Snow(in) 0 0-2 4-8 Snowpack Discussion We are on tail end of a larger avalanche cycle in the Aspen zone. The period from late Friday into Saturday saw some large natural avalanches running on most aspects and elevations near and above treeline. This natural cycle has slowed in the last couple days but we continue to get reports of human triggered avalanches. The most recent came yesterday in the Marble Peak area. A group of skiers here kicked off a large chunk of cornice on the North aspect of the peak above Mud Gulch. This cornice triggered an avalanche in the upper snowpack that became about 50 ft wide and ran a couple hundred yards down the slope. Some milder temperatures and a break from the heavy snowfall are slowly allowing the snowpack to settle and gain some strength but we are still in a time when human triggered avalanches are probable on many slopes. The snowpack around the Aspen zone is developing this season with a high degree of variability from one valley to the next. This variability showed itself with our last avalanche cycle. Areas with shallower and weaker snow, like Independence Pass, the Divide, and the Ashcroft area, all had avalanches running in old snow layers or near the ground this past weekend. Recent storm snow and wind deposited snow stressed these deep weak layers to the breaking point. As you head further to the Southwest towards Marble and McClure Pass, most avalanches have occurred in just the upper snowpack. A deeper and stronger snow cover in these zones can be found without the weaker faceted sugar snow at the base of the snowpack that has failed in other areas. If you are traveling in an area with a shallower snowpack, take a careful look at the structure of the snow. Weak layers near the ground could be triggered in these zone creating large avalanches. Check the Crested Butte Avalanche Center website for some details on large human triggered avalanches that have occurred in the last couple days in our neighboring zone to the South.[57]Crested Butte Avalanche Center Below treeline, the mild weather has allowed the snowpack to gain a little strength in the last few days. You still need to be careful on SW-S-SE aspects below treeline where a weak layer near the mid-pack could pose problems. Recent avalanches below treeline have been largest on these aspects. Avalanche Danger The avalanche danger for the Aspen Zone is rated CONSIDERABLE on slopes facing North through East through South near and above treeline. You will find pockets of CONSIDERABLE danger in steep cross loaded or wind loaded areas of slopes facing Northwest, West, and Southwest at these higher elevations. Below treeline today expect to find MODERATE avalanche danger on all aspects. Extra caution will be required on those slopes facing Southwest, South, and Southeast where triggered avalanches have the potential to fail in deeper weak layers. The CAIC Aspen office needs your avalanche, snowpack, or weather observations. Drop us and e-mail at [58]caic@qwest.net with any observations you have from today. Front Range =========== Current Keywords: CONSIDERABLE, HIGH, avalanche danger, cornice, drifts, explosive, front, high pressure, human triggered avalanches, low-pressure, natural, natural avalanches, slab, slabs, trough, Mountain Weather and Avalanche Forecast for the Front Range Zone Forecast Issued on 2/12/2008 8:10:32 AM Forecaster: Ethan Greene Weather Synopsis Clouds continue to stream into the state from the north. Light to moderate snow showers cover much of the northern mountains and strong winds continue to blow from the north and northwest at ridecrest. The weather is mild by comparison as you move southward into the central and southern mountains. The back edge of the low-pressure trough, currently over the eastern half of Colorado, is moving eastward and high pressure is building in from the southwest. On Wednesday the flow will shift to the west and southwest as the high pressure ridge briefly covers the state. A strong cold front will approach from the northwest on Wednesday afternoon/evening bringing snow to most mountain areas on Thursday. Weather Tuesday Night Wednesday Wednesday Night Temperature(°F) 17-22 2-7 21-26 Wind Speed(mph) 20-30 20-30 20-30 G 60 Wind Direction NW W WSW Sky Cover Mostly Cloudy Mostly Cloudy Mostly Cloudy Snow(in) 1-4 0-2 1-3 Snowpack Discussion Winter took a small break over the weekend, but could not rest for long. Overnight the Front Range zone picked up 2-8 inches of new snow with more as you head north. It looks like closer to 10-16" fell in the Cameron Pass area where some natural avalanches released overnight. The winds have been from the northwest in the 20-30 mph range with gusts in the 60's, and temperatures dipped into the single digits. Reports of natural and triggered avalanches continue to roll into our office. During the last 5 days, natural avalanches have released from slopes that face the east half of the compass and are near and above treeline. There have also been some explosive triggered avalanches in both above and below-treeline areas. The new snow and wind will create some sensitive slabs this morning. Watch for cracking in the fresh drifts and stay out from under steep slopes near exposed ridgelines. Natural and human triggered avalanches in the new snow layers will be likely this morning and gradually decrease as snowfall rates decrease in the afternoon. Sunday morning at about 10am, a snowmobiler triggered a slide on Gravel Mountain, which is north of Granby. The slide broke at the cornice on top of the ridge taking out numerous snowmobile tracks when it slid. The avalanche broke into old snow layers, talking snow out all the way to the ground. Although many of the recent avalanches have been breaking within the new snow layers, this is a reminder that deep slab avalanches are still possible. Avalanche Danger The avalanche danger for the Front Range zone is currently HIGH on NW-NE-SE-S aspects all elevations, and it is CONSIDERABLE elsewhere. Grand Mesa ========== Current Keywords: LOW, avalanche danger, front, high pressure, low-pressure, trough, whumpfing, Mountain Weather and Avalanche Forecast for the Grand Mesa Zone Forecast Issued on 2/12/2008 4:16:17 PM Forecaster: Ethan Greene Weather Synopsis Clouds continue to stream into the state from the north. Light to moderate snow showers cover much of the northern mountains and strong winds continue to blow from the north and northwest at ridecrest. The weather is mild by comparison as you move southward into the central and southern mountains. The back edge of the low-pressure trough, currently over the eastern half of Colorado, is moving eastward and high pressure is building in from the southwest. On Wednesday the flow will shift to the west and southwest as the high pressure ridge briefly covers the state. A strong cold front will approach from the northwest on Wednesday afternoon/evening bringing snow to most mountain areas on Thursday. Weather Tuesday Night Wednesday Wednesday Night Temperature(°F) 15-20 32-37 2-7 Wind Speed(mph) 5-15 5-15 10-20 Wind Direction SW SW W Sky Cover Partly Cloudy Increasing Overcast Snow(in) 0 0-2 3-6 Snowpack Discussion There have been no new avalanches reported from the Grand Mesa area in the last two weeks. Although there has been new snow and wind from the last few storms, this has not been enough to produce significant avalanche activity. Two of our staff visited the zone today and found mostly stable snow. They said the greatest danger was in the many small, but still steep slopes. Be sure to evaluate each slope before you cross. As always, you should watch for signs of instability such as whumpfing noises, propagating cracks, or recent slide activity. If you observe these signs, then avoid traveling on or under steep slopes. Avalanche Danger The avalanche danger for the Grand Mesa zone is LOW overall. Please send observations from this or any other zone to [57]caic@qwest.net San Juan North ============== Current Keywords: CONSIDERABLE, MODERATE, avalanche danger, explosive, explosives, front, high pressure, low-pressure, natural, settle, trough, weak layers, Mountain Weather and Avalanche Forecast for the Northern San Juan Mountain Zone Forecast Issued on 2/12/2008 4:16:38 PM Forecaster: Ethan Greene Weather Synopsis Clouds continue to stream into the state from the north. Light to moderate snow showers cover much of the northern mountains and strong winds continue to blow from the north and northwest at ridecrest. The weather is mild by comparison as you move southward into the central and southern mountains. The back edge of the low-pressure trough, currently over the eastern half of Colorado, is moving eastward and high pressure is building in from the southwest. On Wednesday the flow will shift to the west and southwest as the high pressure ridge briefly covers the state. A strong cold front will approach from the northwest on Wednesday afternoon/evening bringing snow to most mountain areas on Thursday. Weather Tuesday Night Wednesday Wednesday Night Temperature(°F) 10-15 30-35 -2 to 3 Wind Speed(mph) 5-15 10-20 15-25 Wind Direction W SW W Sky Cover Partly Cloudy Increasing Overcast Snow(in) 0 0-2 6-10 Snowpack Discussion After an active week, some calm weekend weather allowed the snow to settle and gain some strength. The mild weather gave people a chance to get out and seen some of the activity that occurred towards the end of the natural cycle, and highway work crews were also able to trigger some avalanche with explosives. Recent natural and triggered avalanche activity has mostly been on slopes that face the east side of the compass. There were also some avalanches on NW and SW facing slopes. Elevation does not seem to be a limiting factor, as slides have released from both above and below treeline areas. Most of the explosive activity has been on slopes that tip towards the south side of the compass, and we have been seeing repeaters, slopes avalanching that have avalanched in one of the last few cycles. This indicates that the weak layers are not getting destroyed and can reactivate once a new load snows or blow back in on top. Enjoy our current break in the weather as it won't last too long. The next system is headed our way and should impact the southern mountains on early Thursday morning. Avalanche Danger The avalanche danger is CONSIDERABLE on southeast and south aspects at all elevations; the danger is MODERATE on other aspects and elevations. Human-triggered avalanches remain possible to probable on slopes 35 degrees and steeper - be wise out there! [57]Please let us know if you see any avalanche activity or signs of instability. San Juan South ============== Current Keywords: LOW, MODERATE, avalanche danger, front, high pressure, low-pressure, settle, trough, Mountain Weather and Avalanche Forecast for the Southern San Juan Mountain Zone Forecast Issued on 2/12/2008 4:16:58 PM Forecaster: Ethan Greene Weather Synopsis Clouds continue to stream into the state from the north. Light to moderate snow showers cover much of the northern mountains and strong winds continue to blow from the north and northwest at ridecrest. The weather is mild by comparison as you move southward into the central and southern mountains. The back edge of the low-pressure trough, currently over the eastern half of Colorado, is moving eastward and high pressure is building in from the southwest. On Wednesday the flow will shift to the west and southwest as the high pressure ridge briefly covers the state. A strong cold front will approach from the northwest on Wednesday afternoon/evening bringing snow to most mountain areas on Thursday. Weather Tuesday Night Wednesday Wednesday Night Temperature(°F) 12-17 31-36 7-12 Wind Speed(mph) 0-10 10-20 10-20 Wind Direction SW SW SW Sky Cover Partly Cloudy Increasing Overcast Snow(in) 0 0-1 4-8 Snowpack Discussion A few days of calm weather has allowed the snowpack in the Southern San Juan zone to settle and gain some strength. There have been no new avalanches reported since last week, with the exception of a roof avalanche. As temperatures begin to warm, remember to take a look at the deep snow on your roof. Snow sliding off of buildings can be very dangerous in years like this one. The next storm system is forecast to arrive early on Thursday. This system is forecast to form a cut off low in southern Colorado. Although it is coming from the Pacific Northwest, it could bring another dose of snow to the Southern San Juan. Avalanche Danger The avalanche danger for the Southern San Juan zone is MODERATE near and above treeline on NW-NE-SE aspects, and LOW elsewhere. [57]Please let us know if you see any avalanche activity or experienced signs of instability. Sangre de Christo ================= Current Keywords: LOW, MODERATE, avalanche danger, dense, drifts, front, high pressure, low-pressure, sastrugi, slab, slabs, trough, Mountain Weather and Avalanche Forecast for the Sangre De Cristo Zone Forecast Issued on 2/12/2008 4:17:14 PM Forecaster: Ethan Greene Weather Synopsis Clouds continue to stream into the state from the north. Light to moderate snow showers cover much of the northern mountains and strong winds continue to blow from the north and northwest at ridecrest. The weather is mild by comparison as you move southward into the central and southern mountains. The back edge of the low-pressure trough, currently over the eastern half of Colorado, is moving eastward and high pressure is building in from the southwest. On Wednesday the flow will shift to the west and southwest as the high pressure ridge briefly covers the state. A strong cold front will approach from the northwest on Wednesday afternoon/evening bringing snow to most mountain areas on Thursday. Weather Tuesday Night Wednesday Wednesday Night Temperature(°F) 12-17 31-36 0-5 Wind Speed(mph) 8-18 22-32 20-30 Wind Direction NNW WSW W Sky Cover Partly Cloudy Increasing Overcast Snow(in) 0 0-1 3-6 Snowpack Discussion The terrain in the Sangre de Cristo range has been wind hammered. The snow has been stripped from most areas and deposited into hard drifts. Fresh snow seems to only remain in the densest stands of trees. The snow surface conditions are quite variable, with some soft snow and lots of sastrugi and firm surfaces. There is about 4' of snow in loaded areas at 10,000'. The new snow has been blown around and does not pose too much of a threat this morning. Deep slab avalanches are still possible in localized areas. Watch out for deep slabs on very steep slopes that have been loaded by wind over the last few weeks. Although you are likely to find them in near and above treeline areas, they could exist on any aspect. Avalanche Danger The avalanche danger for the Sawatch zone is MODERATE on all aspects below treeline where the snowpack is the deepest and deep slab instabilities are a concern. Near and above treeline the danger is MODERATE on NE-E-SE aspects, and is LOW elsewhere where the wind has essentially stripped all snow from these locations. Please send observations from this or any other zone to [57]caic@qwest.net Sawatch ======= Current Keywords: CONSIDERABLE, MODERATE, avalanche danger, crown, front, high pressure, lee , low-pressure, natural, path, slab, slabs, trough, wind loading, wind slab, wind slabs, Mountain Weather and Avalanche Forecast for the Sawatch Range Zone Forecast Issued on 2/12/2008 4:17:28 PM Forecaster: Ethan Greene Weather Synopsis Clouds continue to stream into the state from the north. Light to moderate snow showers cover much of the northern mountains and strong winds continue to blow from the north and northwest at ridecrest. The weather is mild by comparison as you move southward into the central and southern mountains. The back edge of the low-pressure trough, currently over the eastern half of Colorado, is moving eastward and high pressure is building in from the southwest. On Wednesday the flow will shift to the west and southwest as the high pressure ridge briefly covers the state. A strong cold front will approach from the northwest on Wednesday afternoon/evening bringing snow to most mountain areas on Thursday. Weather Tuesday Night Wednesday Wednesday Night Temperature(°F) 6-11 24-29 3-8 Wind Speed(mph) 7-17 16-26 20-30 Wind Direction NW W W Sky Cover Partly Cloudy Increasing Overcast Snow(in) 0 0-1 3-6 Snowpack Discussion New snow totals in the Sawatch have been just a skiff. Winds continue to be quite breezy and mostly from the west and north west. Reports of natural slide activity are slowing. It appears that natural slide activity peaked Friday night into Saturday, although a probable natural slide on the peak just north of Buckeye in the Chicago Ridge area - size 3, SSE aspect from 12,200'. The warmer weekend weather helped the snowpack to gain some strength, but reports of artificially triggered slides continue to come in. On Sunday there was a report of snowmobiler triggered slide above Upper Hancock Lake near St. Elmo. Two more slides, most likely snowmobile triggered, were noted on the east side of Cottonwood Pass. The larger one had a fracture line of 3-8', about 700' wide, and ran 350' with deposition 15' deep. This path has slid multiple times this season. There was also a snowmobile triggered avalanche on a NE facing slope near Freemont Pass on Sunday. The slide was reported as 2-20' deep and breaking to the ground. The frature was 450' wide and the rider was caught and partially buried. Fortunately he was not seriously hurt. Several recent slides have been quite large with deep crown lines and running to the ground. Deep slab instability remains a real issue as they are becoming harder to trigger, but still quite large and distructive. Hard wind slabs near and above treeline on lee N-E-S aspects are the most suspect areas. Terrain choices should be at the forefront of your decision making process. Avoid slopes steeper than 35 degrees, especially if they are freshly loaded. The combination of wind loading over the past several weeks and last weekends warm temperatures have created some very stiff slabs. Stiff slabs can give you a false sense of stability. You will find good riding at and below tree line slopes where less wind loading has occurred. Do not let yourself get caught out on an easterly facing slope above tree line, steeper than 30 degrees with hard wind slab that weakens as you ride downhill. If you punch through, you could start a large hard slab slide. Avalanche Danger The avalanche danger for the Sawatch zone is CONSIDERABLE on N-E-SW aspects, all elevations. It is MODERATE elsewhere. [57]Please let us know if you see any avalanche activity or experienced signs of instability. Your observations are very important to us! Thanks to those who have sent us in observations. It's great to get multiple reports of the same avalanche activity. Steamboat ========= Current Keywords: CONSIDERABLE, MODERATE, avalanche danger, drifts, front, high pressure, human triggered avalanches, low-pressure, natural avalanche, settling, trough, wind drifts, wind-loaded, Mountain Weather and Avalanche Forecast for the Steamboat and Parks Range Zone Forecast Issued on 2/12/2008 4:15:33 PM Forecaster: Ethan Greene Weather Synopsis Clouds continue to stream into the state from the north. Light to moderate snow showers cover much of the northern mountains and strong winds continue to blow from the north and northwest at ridecrest. The weather is mild by comparison as you move southward into the central and southern mountains. The back edge of the low-pressure trough, currently over the eastern half of Colorado, is moving eastward and high pressure is building in from the southwest. On Wednesday the flow will shift to the west and southwest as the high pressure ridge briefly covers the state. A strong cold front will approach from the northwest on Wednesday afternoon/evening bringing snow to most mountain areas on Thursday. Weather Tuesday Night Wednesday Wednesday Night Temperature(°F) 13-18 27-32 4-9 Wind Speed(mph) 15-25 15-25 15-25 Wind Direction W W -> SW W Sky Cover Mostly Cloudy Mostly Cloudy Overcast Snow(in) 0-2 1-3 4-8 Snowpack Discussion Warmer weather over the weekend gave the snowpack and a few avalanche forecasters a bit of a break. The snow took advantage of this period by settling and gain some strength. Reports of natural avalanche activity dropped off over the weekend. Winter returned to the zone on Monday and overnight 4-7 inches of new snow fell. The winds have been from the northwest in the 20 mph range. This weather pattern will produce some soft and sensitive drifts by this morning, especially on slopes that face the east and south sides of the compass. Approach recent wind drifts with caution and watch for cracking in the new snow layers. Human triggered avalanches will be probable to likely in steep wind-loaded areas. Avalanche Danger The avalanche danger for the Steamboat zone is CONSIDERABLE on NE-E-SE-S aspects near and above treeline. On other aspects and well below treeline, the danger is MODERATE. If you have any observations or data to share, please send them to [57]caic@qwest.net. Vail ==== Current Keywords: CONSIDERABLE, MODERATE, avalanche danger, cornices, crown, front, high pressure, human triggered, lee , low-pressure, natural, settle, slab, slabs, trough, wind loading, wind slab, wind slabs, windloaded, Mountain Weather and Avalanche Forecast for the Vail and Summit County Zone Forecast Issued on 2/12/2008 4:15:48 PM Forecaster: Ethan Greene Weather Synopsis Clouds continue to stream into the state from the north. Light to moderate snow showers cover much of the northern mountains and strong winds continue to blow from the north and northwest at ridecrest. The weather is mild by comparison as you move southward into the central and southern mountains. The back edge of the low-pressure trough, currently over the eastern half of Colorado, is moving eastward and high pressure is building in from the southwest. On Wednesday the flow will shift to the west and southwest as the high pressure ridge briefly covers the state. A strong cold front will approach from the northwest on Wednesday afternoon/evening bringing snow to most mountain areas on Thursday. Weather Tuesday Night Wednesday Wednesday Night Temperature(°F) 5-10 21-26 -2 to 3 Wind Speed(mph) 15-25 15-25 10-20G30 Wind Direction WNW WSW W Sky Cover Mostly Cloudy Mostly Cloudy Overcast Snow(in) 0-1 0-1 4-8 Snowpack Discussion In the last 24 hours the Vail/Summit zone picked up 2 to 6 inchs of new snow, with the north eastern part of the zone receiving the upper end. Winds have been moderate to strong from the northwest. This means you will find freshly loaded wind slabs on east through south aspects. We received several reports of avalanche activity from all around the zone. Most of the activity was natural and from a wide range of aspects, above tree line; north east, east, south east and even north west. Most of the activity was a result of cornices falling onto freshly loaded steep slopes. The human triggered slides were triggered by snowmobilers, north east of Breckenridge. Warm temperatures over last weekend has helped the snowpack settle and gain strength, but both human and natural triggered avalanches are still possible to probable. On Sunday a group of snowmobilers triggered a large avalanche near Freemont Pass. The side occurred on a NE facing slope that is just above treeline. The avalanche broke back into a very windloaded area. The crown face was reported as 2-20' deep and 450' wide. The avalanche broke into snow very near the ground. One rider was caught and partially buried in the avalanche. Fortunately he was not seriously injured. The avalanche near Freemont Pass is an unfortunate, but good example of one of the problems we are facing. It is getting more difficult to trigger deep-slab avalanches, but once you hit the right spot, the resulting avalanche could be huge. Several recent slides have been quite large with deep crown lines and running to the ground. Deep slab instability remains a real issue with hard wind slabs near and above treeline on lee N-E-S aspects. Terrain choices should be at the forefront of your decision making process. Avoid slopes steeper than 35 degrees, especially if they are freshly loaded. The combination of wind loading over the past several weeks and last weekends warm temperatures have created some very stiff slabs. Stiff slabs can give you a false sense of stability. You will find good riding at and below tree line slopes where less wind loading has occurred. Do not let yourself get caught out on an easterly facing slope above tree line, steeper than 30 degrees with hard wind slab that weakens as you ride downhill. If you punch through, you could start a large hard slab slide. Avalanche Danger The avalanche danger for the Vail-Summit zone is CONSIDERABLE on NW-NE-SE-S aspects all elevations, and MODERATE elsewhere. We have received many observations during the past several days. Thanks for all the observations and please keep the e-mails coming with what you are seeing.