Aspen ===== Current Keywords: LOW, MODERATE, avalanche danger, convective, crown, facets, human triggered, low-pressure, precipitation , settle, slab, slabs, surface hoar, trough, weak layer, Mountain Weather and Avalanche Forecast for the Aspen Zone Forecast Issued on 2/21/2008 6:41:19 AM Forecaster: Brian McCall Weather Synopsis A low-pressure circulation is moving through the Four Corners region this morning. This system will track along the Colorado/New Mexico boarder today pushing clouds and precipitation into the southern and central mountains. Snow totals this morning are in the 5-9 inch range on the west side of the San Juan zones, and 2-4 inches in other parts of the southern and central mountain zones. Expect mostly cloudy to overcast skies today with light winds that shift from southerly to easterly. The winds are not very strong with this system, but there is enough instability to produce nice convective showers. Snowfall will be greatest in the southern mountains and decrease as you move north trough the state. Snow showers will linger into the evening, but decrease after midnight. The next system moves in on Friday, bringing unsettled weather to most mountain areas through Saturday. A third and strong system is forecast to move into Colorado Sunday night. Weather Thursday Thursday Night Friday Temperature(°F) 22-27 12-17 20-25 Wind Speed(mph) 5-15 5-15 5-15 Wind Direction Sly->Ely NNW W Sky Cover Overcast Mostly Cloudy Mostly Cloudy Snow(in) 2-4 2-4 0-2 Snowpack Discussion Light snow around the Aspen zone yesterday and overnight has added up to 1-2" during the last 24 hours. Winds with this storm were also light, coming out of the South and Southeast. Such mild weather will have little effect on our avalanche danger for today. Time, some mild temperatures, and a break from the heavy early season snows have helped to settle our snowpack and decrease the avalanche activity that was so frequent for the first few months of the winter. Avalanches can still be triggered though from the right location or with a large enough load. Snowmobilers triggered two deep slabs, just outside the Aspen Zone, over on the East side of Independence Pass on Tuesday. Our forecaster in the area visited the site, which is in the Mountain Boy Park area, and found the avalanche to have a crown that averaged 5-7 feet deep and running about 360 vertical feet. One rider was caught, though not in the main flow and luckily walked away uninjured. These slides remind us that deep slabs remain a very real problem in some areas of the Aspen zone. These will most likely occur in areas with shallower snowpacks, such as Independence Pass and the upper Castle Creek valley. It may take just the right trigger to release such a slide, but the resulting avalanche could be large and destructive. This is a tricky time because while we are not seeing many slides, but the ones that are running have been large, deep slab avalanches. Clear skies and mild temperatures during the last few days have changed the snow surface. Crusts have formed on most sunny aspects and at lower elevations. In the shadier areas we are starting to see some facets and surface hoar forming on top of the snowpack as well. While none of the layers pose a danger today, do take note of their location and distribution as the next couple storms approach. Today's surface is tomorrow's weak layer. Avalanche Danger Avalanche danger for the Aspen zone today is MODERATE on all aspects near and above treeline. Danger below treeline is LOW. Human triggered avalanches remain possible. The CAIC Aspen office needs your avalanche, snowpack, or weather observations. Drop us and e-mail at [57]caic@qwest.net with any Front Range =========== Current Keywords: LOW, MODERATE, avalanche danger, convective, low-pressure, precipitation , settle, slab, trough, wind slab, windloaded, Mountain Weather and Avalanche Forecast for the Front Range Zone Forecast Issued on 2/21/2008 7:29:12 AM Forecaster: Ethan Greene Weather Synopsis A low-pressure circulation is moving through the Four Corners region this morning. This system will track along the Colorado/New Mexico boarder today pushing clouds and precipitation into the southern and central mountains. Snow totals this morning are in the 5-9 inch range on the west side of the San Juan zones, and 2-4 inches in other parts of the southern and central mountain zones. Expect mostly cloudy to overcast skies today with light winds that shift from southerly to easterly. The winds are not very strong with this system, but there is enough instability to produce nice convective showers. Snowfall will be greatest in the southern mountains and decrease as you move north trough the state. Snow showers will linger into the evening, but decrease after midnight. The next system moves in on Friday, bringing unsettled weather to most mountain areas through Saturday. A third and strong system is forecast to move into Colorado Sunday night. Weather Thursday Thursday Night Friday Temperature(°F) 20-25 8-13 20-25 Wind Speed(mph) 5-15 5-15 5-15 Wind Direction NE W WNW Sky Cover Increasing Mostly Cloudy Increasing Snow(in) 1-3 0-2 0-2 Snowpack Discussion No new slides have been reported in the Front Range Zone since the weekend. Mild weather and time have helped settle the upper snowpack, but you can still trigger a wind slab, especially on east, southeast and south aspects near and above treeline. Take the time to poke around as you cross onto a new aspect or approach the next snow roll. Remember these tend to break on the convex portion of a slope where there is more tension on the snowpack. Deep slab avalanches continue to be a possibility as well. It may take a trigger in just the right spot to release the slab, but the resulting avalanche could be VERY large and destructive. A skier triggered a deep-slab avalanche on an easterly aspect in Summit County last weekend, but luckily no one was caught. These are tricky conditions because we are not seeing many avalanches, but the ones that are running are quite large and dangerous. Use extra caution in exposed terrain that is near and above treeline. Avalanche Danger The avalanche danger in the Front Range is MODERATE on all aspects near and above treeline and LOW on all aspects below treeline. Human triggered avalanches are possible on steep, windloaded slopes, and have the potential to break into snow layers near the ground. Grand Mesa ========== Current Keywords: LOW, avalanche danger, convective, low-pressure, precipitation , settle, sluffing, trough, whumpfing, wind loaded, Mountain Weather and Avalanche Forecast for the Grand Mesa Zone Forecast Issued on 2/21/2008 7:29:43 AM Forecaster: Ethan Greene Weather Synopsis A low-pressure circulation is moving through the Four Corners region this morning. This system will track along the Colorado/New Mexico boarder today pushing clouds and precipitation into the southern and central mountains. Snow totals this morning are in the 5-9 inch range on the west side of the San Juan zones, and 2-4 inches in other parts of the southern and central mountain zones. Expect mostly cloudy to overcast skies today with light winds that shift from southerly to easterly. The winds are not very strong with this system, but there is enough instability to produce nice convective showers. Snowfall will be greatest in the southern mountains and decrease as you move north trough the state. Snow showers will linger into the evening, but decrease after midnight. The next system moves in on Friday, bringing unsettled weather to most mountain areas through Saturday. A third and strong system is forecast to move into Colorado Sunday night. Weather Thursday Thursday Night Friday Temperature(°F) 25-33 15-20 28-33 Wind Speed(mph) 0-10 0-10 0-10 Wind Direction S WNW SW Sky Cover Overcast Mostly Cloudy Mostly Cloudy Snow(in) 1-3 0-2 0-2 Snowpack Discussion Time and warm temperatures have helped the snowpack settle and gain strength. There have been no new avalanches reported from the Grand Mesa area in several weeks. The greatest danger on the Grand Mesa continues to be the many small, steep wind loaded slopes and terrain traps. Be sure to evaluate steep slopes before you cross. Watch for signs of instability such as whumpfing noises, shooting cracks, or recent slide activity. The avalanche danger will be on the rise once again as snow piles up later this week. Be aware of changing conditions and plan accordingly. Avalanche Danger The avalanche danger for the Grand Mesa is LOW on all aspects and elevations. Watch for sluffing in the new snow and areas of unstable snow on very steep slopes and terrain traps. Please send observations from this or any other zone to [57]caic@qwest.net San Juan North ============== Current Keywords: MODERATE, avalanche danger, consolidated, convective, drifting, explosives, low-pressure, natural, precipitation , slab, slabs, trough, Mountain Weather and Avalanche Forecast for the Northern San Juan Mountain Zone Forecast Issued on 2/21/2008 7:28:44 AM Forecaster: Ethan Greene Weather Synopsis A low-pressure circulation is moving through the Four Corners region this morning. This system will track along the Colorado/New Mexico boarder today pushing clouds and precipitation into the southern and central mountains. Snow totals this morning are in the 5-9 inch range on the west side of the San Juan zones, and 2-4 inches in other parts of the southern and central mountain zones. Expect mostly cloudy to overcast skies today with light winds that shift from southerly to easterly. The winds are not very strong with this system, but there is enough instability to produce nice convective showers. Snowfall will be greatest in the southern mountains and decrease as you move north trough the state. Snow showers will linger into the evening, but decrease after midnight. The next system moves in on Friday, bringing unsettled weather to most mountain areas through Saturday. A third and strong system is forecast to move into Colorado Sunday night. Weather Thursday Thursday Night Friday Temperature(°F) 20-25 10-15 23-28 Wind Speed(mph) 0-10 5-10 10-20 Wind Direction Sly -> Ely Nly WSW Sky Cover Overcast Mostly Cloudy Mostly Cloudy Snow(in) 4-6 1-3 1-3 Snowpack Discussion Overnight the San Juan Mountains picked up 5-9 inches of new snow, with the greatest accumulation in the southwestern portion of the zone. The winds have been from a lot of different directions, but generally from the south in the 10-20 mph range. On the north and west sides of the zone the flow is shifting to the northeast. Yesterday, avalanche workers triggered a hard slab avalanche with explosives on an east-facing slope near 12,000' south of the Town of Telluride. The slide was 5 feet deep, 200 feet wide and ran about 250 feet down the slope. One of our forecasters also observed some natural avalanche activity over the past few days in the Silverton area. One was a slab avalanche, 4-6' deep on a SE aspect above treeline that broke down to the ground, and there was some wet loose avalanches on westerly slopes above treeline. The new snow is fairly light stuff and could slide easily off of some of the hard surfaces, especially on southerly aspects. Without much wind, loose-snow and soft slab avalanches shouldn't be too large, but watch out for areas where the wind is drifting the new snow into a consolidated slab. The recent activity is a good reminder that while new snow avalanches will be shallow, deep-slab avalanches are still possible. These slab avalanches will be difficult to trigger. But if you find the right spot you could start a fracture that breaks down into layers near the ground producing a very dangerous avalanche. Avalanche Danger The avalanche danger in the Northern San Juan is MODERATE on all aspects and elevations. You may find reactive slabs on slopes 35 degrees and steeper, particularly on sunny aspects above treeline. [57]Please let us know if you see any avalanche activity or signs of instability. San Juan South ============== Current Keywords: MODERATE, avalanche danger, convective, facets, low-pressure, precipitation , settled, trough, windslabs, Mountain Weather and Avalanche Forecast for the Southern San Juan Mountain Zone Forecast Issued on 2/21/2008 7:31:04 AM Forecaster: Ethan Greene Weather Synopsis A low-pressure circulation is moving through the Four Corners region this morning. This system will track along the Colorado/New Mexico boarder today pushing clouds and precipitation into the southern and central mountains. Snow totals this morning are in the 5-9 inch range on the west side of the San Juan zones, and 2-4 inches in other parts of the southern and central mountain zones. Expect mostly cloudy to overcast skies today with light winds that shift from southerly to easterly. The winds are not very strong with this system, but there is enough instability to produce nice convective showers. Snowfall will be greatest in the southern mountains and decrease as you move north trough the state. Snow showers will linger into the evening, but decrease after midnight. The next system moves in on Friday, bringing unsettled weather to most mountain areas through Saturday. A third and strong system is forecast to move into Colorado Sunday night. Weather Thursday Thursday Night Friday Temperature(°F) 25-30 12-17 28-32 Wind Speed(mph) 0-10 5-15 10-20 Wind Direction SW SW W Sky Cover Overcast Mostly Cloudy Mostly Cloudy Snow(in) 4-6 0-2 0-2 Snowpack Discussion The Southern San Juan zone picked up 1-5 inches of snow overnight. The winds have generally been light and from the south. The upper snowpack has settled and strengthened over the last days of mild weather and no fresh slides have been reported since the weekend. With a new round of storms coming in, our attention turns to the snow surface. Crusts have formed on sunny aspects and at lower elevations. Cooler, shadier slopes have developed pronounced layers of near surface facets. While neither of the layers poses a danger today, both act as potential weak interfaces for future snowfall. Take note of the location and distribution of them as this will be important information as the snow piles up. Expect changing conditions in the backcountry on Thursday. Light winds will mean fairly uniform distributions of new snow. With our increasingly deep snowpack, the upper layers continue to be the area of primary concern. Check the bond between upper snowpack layers before venturing onto exposed terrain. Avalanche Danger The avalanche danger in the Southern San Juan is MODERATE on all aspects and elevations. You may find reactive windslabs on slopes 35 degrees and steeper, particularly on south and easterly aspects above treeline. [57]Please let us know if you see any avalanche activity or signs of instability. Sangre de Christo ================= Current Keywords: avalanche danger, convective, crusts, facets, low-pressure, precipitation , trough, windslabs, Mountain Weather and Avalanche Forecast for the Sangre De Cristo Zone Forecast Issued on 2/21/2008 7:33:35 AM Forecaster: Ethan Greene Weather Synopsis A low-pressure circulation is moving through the Four Corners region this morning. This system will track along the Colorado/New Mexico boarder today pushing clouds and precipitation into the southern and central mountains. Snow totals this morning are in the 5-9 inch range on the west side of the San Juan zones, and 2-4 inches in other parts of the southern and central mountain zones. Expect mostly cloudy to overcast skies today with light winds that shift from southerly to easterly. The winds are not very strong with this system, but there is enough instability to produce nice convective showers. Snowfall will be greatest in the southern mountains and decrease as you move north trough the state. Snow showers will linger into the evening, but decrease after midnight. The next system moves in on Friday, bringing unsettled weather to most mountain areas through Saturday. A third and strong system is forecast to move into Colorado Sunday night. Weather Thursday Thursday Night Friday Temperature(°F) 16-21 5-10 20-25 Wind Speed(mph) 0-10 5-15 5-15 Wind Direction NE NE W Sky Cover Mostly Cloudy Mostly Cloudy Mostly Cloudy Snow(in) 2-4 2-4 0-2 Snowpack Discussion Recent strong northwesterly winds moved available snow onto south and easterly faces. The snowpack has been getting pummeled with wind all winter, resulting in lots of windslabs in all exposed locations. Many of these windslabs sit on weak facets and may be reactive to the weight of a backcountry traveler. Recent warmer weather has created crusts at lower elevations and on southerly aspects. As we move back to a snowier, more unsettled regime, remember that new snow will not likely stick well to these recently formed slick crusts. Avoid steep terrain until you have checked it out thoroughly and use extra caution on steep slopes near and above treeline. Avalanche Danger We have insufficient information to make an avalanche danger rating for the Sangres at this time. Watch for windslabs on steep, open slopes. Please send observations from this or any other zone to [57]caic@qwest.net Sawatch ======= Current Keywords: LOW, MODERATE, avalanche danger, convective, crusts, facets, low-pressure, precipitation , settle, settled, slab, slabs, trough, windloaded, Mountain Weather and Avalanche Forecast for the Sawatch Range Zone Forecast Issued on 2/21/2008 6:55:24 AM Forecaster: Brad Sawtell Weather Synopsis A low-pressure circulation is moving through the Four Corners region this morning. This system will track along the Colorado/New Mexico boarder today pushing clouds and precipitation into the southern and central mountains. Snow totals this morning are in the 5-9 inch range on the west side of the San Juan zones, and 2-4 inches in other parts of the southern and central mountain zones. Expect mostly cloudy to overcast skies today with light winds that shift from southerly to easterly. The winds are not very strong with this system, but there is enough instability to produce nice convective showers. Snowfall will be greatest in the southern mountains and decrease as you move north trough the state. Snow showers will linger into the evening, but decrease after midnight. The next system moves in on Friday, bringing unsettled weather to most mountain areas through Saturday. A third and strong system is forecast to move into Colorado Sunday night. Weather Thursday Thursday Night Friday Temperature(°F) 23-28 8-13 20-25 Wind Speed(mph) 0-10 5-15 10-20 Wind Direction SW->Ely NNW W Sky Cover Overcast Mostly Cloudy Mostly Cloudy Snow(in) 2-4 1-3 0-2 Snowpack Discussion Overnight winds have been light and variable from the south west, west and north west. Temperatures were the only consistent reading low teens. Cottonwood Pass is reporting 3.5 inches of new snow. The warmer day time temperatures have helped the snowpack settle and strengthen quite a bit over the last week, however, they have also settled, forming very stiff slabs. We have entered the time of the season where you need to ask yourself what is under the stiff slab? On the surface you will find that most aspects have formed surface facets. Below tree line on southly aspects have formed stout crusts and you may see signs of wet loose activity. Yesterday, I toured in to the site where the snowmobile triggered slide occurred, near Independence Pass. Touring in, I observed signs of several avalanches that had occurred on north, east and south east aspects; probably occurring last weekend. It appears that the riders were doing some cliff hucking as there were three noticeable dents in the snow surface, just above the fracture line. I measured the fracture line to be between 3 and 8 feet deep, 300 yards long, running between 360 and 400 vertical feet. It occurred on an east aspect above tree line and slid on the old snow-new snow interface, stepping down to the ground in some places. The slope angle measured a consistent 40 degrees and ended abruptly in a terrain trap. I classified the avalanche as a HS-AM-R4D2-I/O/G. We received reports of very stiff surface slabs from the Mt. Antero area as well as in the Cumberland Pass and Cottonwood Pass areas. The report from Cottonwood pass also noted "On Cottonwood Pass snowmobilers are getting away with really stupid stuff on very steep slopes above tree line on slopes facing east and south." The report continued: "The (snow) pack has compacted alot on the top and the surface layer is very solid, but we know what the lower layers are like in that area." Terrain choice is the key these days. If you do not want to trigger a big avalanche, avoid big terrain features. You may be able to recreate on some slopes but if you find the sweet spot or a trigger point, know that the whole season's snowpack remains balanced on top of weak basal facets from early in the season. This is a tricky time because while we are not seeing many slides, the ones that are running are being described using many adjectives. Our snowpack remains complex, with multiple slabs mixed with weak layers. While the recent deep slabs activity certainly gets our attention, our main avalanche concern lies in the upper snowpack where unstable slabs exist near the snow surface. Avalanche activity has become less frequent though weak interfaces persist, keeping human triggered slides possible on steep slopes on a variety of aspects. Continually poke at the upper layers to gather snowpack information before venturing onto steeper terrain. Avalanche Danger The avalanche danger for the Sawatch Zone is MODERATE on all aspects near and above treeline and LOW on all aspects below treeline. Human triggered avalanches are possible on steep, windloaded slopes, and have the potential to break deeply. [57]Please let us know if you see any avalanche activity or experienced signs of instability. Steamboat ========= Current Keywords: LOW, MODERATE, avalanche danger, consolidate, convective, crossloaded, facets, low-pressure, precipitation , slabs, trough, Mountain Weather and Avalanche Forecast for the Steamboat and Parks Range Zone Forecast Issued on 2/21/2008 7:28:55 AM Forecaster: Ethan Greene Weather Synopsis A low-pressure circulation is moving through the Four Corners region this morning. This system will track along the Colorado/New Mexico boarder today pushing clouds and precipitation into the southern and central mountains. Snow totals this morning are in the 5-9 inch range on the west side of the San Juan zones, and 2-4 inches in other parts of the southern and central mountain zones. Expect mostly cloudy to overcast skies today with light winds that shift from southerly to easterly. The winds are not very strong with this system, but there is enough instability to produce nice convective showers. Snowfall will be greatest in the southern mountains and decrease as you move north trough the state. Snow showers will linger into the evening, but decrease after midnight. The next system moves in on Friday, bringing unsettled weather to most mountain areas through Saturday. A third and strong system is forecast to move into Colorado Sunday night. Weather Thursday Thursday Night Friday Temperature(°F) 25-30 10-15 25-30 Wind Speed(mph) 5-10 5-15 5-15 Wind Direction WNW WSW SW Sky Cover Mostly Cloudy Mostly Cloudy Mostly Cloudy Snow(in) 0-2 0-2 0-2 Snowpack Discussion Backcountry travelers in the Steamboat Zone triggered a few 8" to 10" deep soft slabs on south and southeast aspects near Buffalo Pass on Tuesday. These small pockets ran in steep terrain near 10,600'. A skier north of the Steamboat Lake Ranger station triggered a small slide on a northeast aspect below treeline on Tuesday as well. Mild weather and warm daytime temperatures have helped to consolidate the snowpack, but facets continue to form in the near surface layers at night. Recent slides have been modest in size and limited to surface layers. Sluffing in the surface snow, especially on steep shady slopes, and slabs formed by winds earlier in the week continue to be our biggest avalanche problems. Observers note that southerly aspects are particularly "plump", but you will find crossloaded pockets on a variety of aspects. Check the bond within upper layers before committing to steeper terrain. Avalanche Danger The avalanche danger for the Steamboat Zone is MODERATE on northeast, east, southeast and south aspects near and above treeline. The danger is LOW on all aspects below treeline and on southwest, west, northwest and north aspects at all elevations. If you have any observations or data to share, please send them to [57]caic@qwest.net. Vail ==== Current Keywords: LOW, MODERATE, convective, crusts, facets, human triggered, low-pressure, precipitation , probe, settle, settled, slab, slabs, trough, windloaded, Mountain Weather and Avalanche Forecast for the Vail and Summit County Zone Forecast Issued on 2/21/2008 6:46:44 AM Forecaster: Brad Sawtell Weather Synopsis A low-pressure circulation is moving through the Four Corners region this morning. This system will track along the Colorado/New Mexico boarder today pushing clouds and precipitation into the southern and central mountains. Snow totals this morning are in the 5-9 inch range on the west side of the San Juan zones, and 2-4 inches in other parts of the southern and central mountain zones. Expect mostly cloudy to overcast skies today with light winds that shift from southerly to easterly. The winds are not very strong with this system, but there is enough instability to produce nice convective showers. Snowfall will be greatest in the southern mountains and decrease as you move north trough the state. Snow showers will linger into the evening, but decrease after midnight. The next system moves in on Friday, bringing unsettled weather to most mountain areas through Saturday. A third and strong system is forecast to move into Colorado Sunday night. Weather Thursday Thursday Night Friday Temperature(°F) 20-25 10-15 17-22 Wind Speed(mph) 0-10 0-10 5-15 Wind Direction Variable N W Sky Cover Overcast Mostly Cloudy Mostly Cloudy Snow(in) 1-3 1-3 0-2 Snowpack Discussion Winds overnight have been light and variable from the south west, west and north west. Temperatures were the only consistent reading low teens. The warmer day time temperatures have helped the snowpack settle and strengthen quite a bit over the last week, however, they have also settled, forming very stiff slabs. We have entered the time of the season where you need to ask yourself what is under the stiff slab? On the surface you will find that most aspects have formed surface facets. Below tree line on southly aspects have formed stout crusts and you may see signs of wet loose activity. Yesterday, I toured in to the site where the snowmobile triggered slide occurred, near Independence Pass. Touring in, I observed signs of several avalanches that had occurred on north, east and south east aspects; probably occurring last weekend. It appears that the riders were doing some cliff hucking as there were three noticeable dents in the snow surface, just above the fracture line. I measured the fracture line to be between 3 and 8 feet deep, 300 yards long, running between 360 and 400 vertical feet. It occurred on an east aspect above tree line and slid on the old snow-new snow interface, stepping down to the ground in some places. The slope angle measured a consistent 40 degrees and ended abruptly in a terrain trap. I classified the avalanche as a HS-AM-R4D2-I/O/G. In addition to surface instabilities deep slab instabilities are still lurking. Thinking of the human triggered slides lately, one theme really sticks out; they all have been large, deep avalanches. These slides remind us that deep slabs remain a very real problem; particularly near and above treeline. It may take just the right trigger to release such a slide, but the resulting avalanche could be VERY large. Rember that the whole season's snowpack remains balanced on top of weak basal facets from early in the season. This is a tricky time because while we are not seeing many slides, the ones that are running are being described using many adjectives. Use caution in exposed, above treeline terrain and slowly work your way onto steeper slopes. Poke around to get a feel for where and how thick layers of concern are. By saying "poke" I really do mean poke...use your probe pole. Avalanche Danger The danger is MODERATE on all aspects near and above treeline and LOW on all aspects below treeline. Keep an eye on on steep, windloaded east, southeast, and south aspects near and above treeline. Human triggered avalanches are possible on steep, windloaded slopes, and have the potential to break deeply. [57]Please let us know if you see any avalanche activity or experienced signs of instability.