Aspen ===== Current Keywords: CONSIDERABLE, MODERATE, avalanche cycle, avalanche danger, cold front, crust, density, faceted, front, high pressure, human triggered, human triggered avalanches, lee , natural avalanches, settle, settling, slab, slabs, stress, weak layers, wet snow avalanche, wind loading, Mountain Weather and Avalanche Forecast for the Aspen Zone Forecast Issued on 2/28/2008 6:43:23 AM Forecaster: Brian McCall Weather Synopsis Northwest flow continues into Friday with a couple pulses of moisture, one Thursday evening and the second Friday afternoon. Neither is expected to generate more than a few hours of clouds over the northern and central mountains, and maybe a couple of flakes. A ridge of high pressure builds in on Friday and lasts into Saturday. Enjoy the sunshine and mild temperatures while you can. A strong cold front arrives in northwest Colorado by Saturday evening, and then pushes through the remainder of the state overnight. Snow associated with the front and much colder weather return on Sunday. Weather Thursday Night Friday Friday Night Temperature(°F) 23-28 10-15 27-32 Wind Speed(mph) 15-25 10-20 10-20 Wind Direction WNW WNW W Sky Cover Decreasing Mostly Clear Partly Cloudy Snow(in) 0 0 0 Snowpack Discussion Once again, time and some mild temperatures since our last storm on Monday are helping to settle and bond the upper layers in our snowpack. Natural avalanche activity is decreasing but you will still need to think about human triggered avalanches. On some slopes these avalanches have the potential to propagate long distances and become large avalanches. A careful check of the upper snowpack layers is definitely required before committing to steeper slopes at this time. As we move into late winter, we need to start thinking about the effects of sun and mild temperatures on our snowpack. Cloud cover this morning will cut down on the heating in the snowpack for today but the sun should return on Friday. Although we have not seen a wet snow avalanche cycle yet, rapidly warming temperatures can stress the connection of the newer snow to the older snow layers. Rapid settling with the warm weather can also create some stress at this boundary, so always raise your caution when you see a rapid warm-up, mild temperatures, and strong radiation. Our biggest concern for avalanche activity this week has been the bond between recent storm snow and a variety of weak layers that made up the old snow surface. Recent avalanches have failed on layers of small faceted snow grains, some crust and facet combinations on sunnier aspects, and layers of lower density old snow that was on the surface before last weekend's storm. Some of these layers will remain a persistent problem for some time and others will settle out quickly with the help of the warm weather this week. Your snowpack observations should include a careful look at this upper snowpack slab and weak layer problem before you venture into steeper terrain. At higher elevations, winds out of the Northwest yesterday afternoon were strong enough to transport some snow onto easterly aspects above treeline. These NW winds are forecasted to continue today as well with speeds just strong enough to continue to move snow into the lee start zones. Keep an eye out for some shallow new winds slabs at the snow surface. These slabs will be adding an additional load to these upper snowpack weak layers we are concerned with today. In areas of the Aspen zone where the snowpack in a bit shallower and weaker, these avalanches may step down to some lower snowpack weak layers as well. Areas around the upper Castle Creek valley and Independence Pass are the most worrisome for these deeper, old snowpack weak layers. A little extra caution is required if you are traveling in these zones. These deep weak layers will be hard to trigger but if they do fail, watch out! Avalanche Danger Avalanche danger for today around the Aspen zone is CONSIDERABLE on slopes above treeline facing NE, E, and SE. On these aspects, the combination of recent wind loading and some upper snowpack weak layers will keep natural avalanches possible and human triggered ones probable. On all other aspects and elevations, the avalanche danger is MODERATE. Remember though, at a MODERATE rating human triggered avalanches are still possible. In the right location some of these triggered avalanches have plenty of potential to be large and dangerous events. Be careful out there. The CAIC Aspen office needs your avalanche, snowpack, or weather observations. Drop us and e-mail at [57]caic@qwest.net with any observations you have from today. Front Range =========== Current Keywords: MODERATE, avalanche danger, cold front, front, high pressure, settle, settling, shears, slab, Mountain Weather and Avalanche Forecast for the Front Range Zone Forecast Issued on 2/28/2008 6:34:46 AM Forecaster: John Snook Weather Synopsis Northwest flow continues into Friday with a couple pulses of moisture, one Thursday evening and the second Friday afternoon. Neither is expected to generate more than a few hours of clouds over the northern and central mountains, and maybe a couple of flakes. A ridge of high pressure builds in on Friday and lasts into Saturday. Enjoy the sunshine and mild temperatures while you can. A strong cold front arrives in northwest Colorado by Saturday evening, and then pushes through the remainder of the state overnight. Snow associated with the front and much colder weather return on Sunday. Weather Thursday Night Friday Friday Night Temperature(°F) 25-30 10-15 30-35 Wind Speed(mph) 15-25 G50 15-25 G50 15-25 Wind Direction WNW WNW W Sky Cover Decreasing Partly Cloudy Partly Cloudy Snow(in) 0 0 0 Snowpack Discussion As we move toward the first week in March (and a return to winter) you have probably noticed more daylight hours and a little warmer feel to the day time temperatures. The snowpack does too. On the less sun exposed northern aspects the snowpack is still in a winter regime, while the E-S-W aspects are settling and gaining some strength. The upper snow pack layers especially so once the sun pops out. We are in the transition phase from winter to spring. This can be a tricky time for judging instabilities in the snowpack. Recent obs said N aspects remained winter like with several clean shears reported in the top 20-40 cm of the snow. Deeper slab problems seem to be easing on the troublesome southerly aspects, but we are still seeing some deeper slab problems on the northerly aspects. March still has a reputation for being deadly, so think about how you transition into spring. As always we recommend moving into the steeper terrain carefully. Our snowpack base is still a winter one, though the upper layers settle and bond faster than they do mid-January. Avalanche danger should ease off quicker at this time of year, but the up coming storm cycle for early March could create some big problems. Try not to let the longer days and all that vitamin D from the sunshine tweak good judgment. A couple skier triggered slides came in from the Loveland Pass area on Monday. These involved the newer snow, maybe a foot deep and ran only a couple hundred feet. One fractured on a subtle convex roll near a rock outcrop, the other in the middle of a small open bowl, both just above treeline. These were not big slides, but showed the classic pockets of instability. CDOT had good results in the Seven Sisters, northerly aspects on Loveland Pass, and on the Stanley Path, southerly aspects, of Berthoud Pass Tuesday morning. Not far away, over in Summit County & Vail area a number of wet loose slides ran mid-afternoon. There was one report of an 8 foot diameter pin-wheel of snow (some people call them cinnamon rolls) that trundled down slope. So we are still seeing fresh slide activity, always a good (bad?) sign of lingering instability. Actually, the best (worst?) sign of instability. Avalanche Danger The avalanche danger for the Front Range zone is overall MODERATE. Grand Mesa ========== Current Keywords: LOW, avalanche danger, cold front, front, high pressure, settlement, wet slides, Mountain Weather and Avalanche Forecast for the Grand Mesa Zone Forecast Issued on 2/28/2008 6:35:44 AM Forecaster: John Snook Weather Synopsis Northwest flow continues into Friday with a couple pulses of moisture, one Thursday evening and the second Friday afternoon. Neither is expected to generate more than a few hours of clouds over the northern and central mountains, and maybe a couple of flakes. A ridge of high pressure builds in on Friday and lasts into Saturday. Enjoy the sunshine and mild temperatures while you can. A strong cold front arrives in northwest Colorado by Saturday evening, and then pushes through the remainder of the state overnight. Snow associated with the front and much colder weather return on Sunday. Weather Thursday Night Friday Friday Night Temperature(°F) 32-37 20-25 35-40 Wind Speed(mph) 5-15 0-10 5-15 Wind Direction NNW NNW SW Sky Cover Decreasing Mostly Clear Partly Cloudy Snow(in) 0 0 0 Snowpack Discussion Warm temperatures continue to aid in the settlement and strengthening of the snowpack. Temperatures will be a few degrees cooler today which will temporarily slow the threat of wet slides. The avalanche danger has decreased to LOW over all and should stay that way through Saturday. LOW does not mean avalanches will not run, but the hazard is declining. Avoid terrain traps and enjoy No fresh avalanches have been reported since Monday the 25th. That slide was on a NE aspect at around 9,650 feet. Avalanche Danger The avalanche danger for the Grand Mesa zone is overall LOW. Please send observations from this or any other zone to [57]caic@qwest.net San Juan North ============== Current Keywords: CONSIDERABLE, MODERATE, avalanche danger, cold front, creep, crown, crowns, explosive, front, high pressure, natural, natural avalanches, naturally, path, point release, settle, slab, Mountain Weather and Avalanche Forecast for the Northern San Juan Mountain Zone Forecast Issued on 2/28/2008 6:37:19 AM Forecaster: Mark Rikkers Weather Synopsis Northwest flow continues into Friday with a couple pulses of moisture, one Thursday evening and the second Friday afternoon. Neither is expected to generate more than a few hours of clouds over the northern and central mountains, and maybe a couple of flakes. A ridge of high pressure builds in on Friday and lasts into Saturday. Enjoy the sunshine and mild temperatures while you can. A strong cold front arrives in northwest Colorado by Saturday evening, and then pushes through the remainder of the state overnight. Snow associated with the front and much colder weather return on Sunday. Weather Thursday Thursday Night Friday Temperature(°F) 30-35 18-23 32-37 Wind Speed(mph) 10-20 0-10 5-15 Wind Direction NNW N W Sky Cover Decreasing Clear Mostly Clear Snow(in) 0 0 0 Snowpack Discussion It has been really nice to have the sun out recently - spring is in the air, at least for the time being. However, very warm temperatures and an increasingly high sun angle are tugging at the snowpack and causing it to act up quite a bit. A series of remote weather stations throughout our zone are positioned from treeline to just over 13,000'. Data show that temperatures ranged from 18-36F in the last 24 hours, with two of the lower stations recording between 4 and 6 hours at or above 32F yesterday in the late afternoon. This intense solar radiation is helping the snowpack settle out and gain strength in some areas, particularly on low angle terrain and shady slopes that don't get direct sun. However, in steeper terrain, particularly on aspects that catch a lot of sun and have exposed rocky outcroppings, the sun is causing the snow to deform rapidly, accelerating its naturally slow and creeping movement downslope. Dark rocks are absorbing the sun's rays and storing the heat like a bank - as this happens, the snow around the rocks heats up and loses its strength. The result: plenty of natural avalanches are pulling out in the backcountry. Royer Gulch, a large south facing path above Telluride, ran full track yesterday with a crown line 4-5' deep - scary. On virtually all the southerly terrain in the Telluride area there is evidence of natural loose and some slab avalanche activity. Telluride snow safety teams have been reporting consistent results from explosive mitigation, including 1-2' deep slab releases from areas including Sunrise and E-Shock over the past two days. In the Ophir valley, an observer reported a fresh slab release on a southerly aspect of Silver Mt. Near Eureka, just outside of Silverton, several natural avalanches were reported from steep, craggy, solar aspects above treeline. One particularly large slide came out from above the popular ice climb Stairway to Heaven from generally southwest terrain above treeline. The entire bowl above the climb fractured and ran across the river and up and over road on the other side of the canyon, taking out old timber and the tops of trees within 100m of the Outward Bound Hotel. The other half of the slide (the "descent route" just to the north) also took out old timber and lay down trees going back uphill and upstream for nearly 300 meters. Also in this area, several point releases ran and cut out slab avalanches with crowns up to 1 meter deep. Our snowpack is in a transition phase it would be wise to adapt! We aren't yet in true spring conditions, but it would be a good idea to start and end your tours earlier, avoiding sunny aspects as the temperatures begin to climb throughout the day. Colder weather is on its way on Sunday - that will slow the avalanche activity down. Until then - be safe out there! Avalanche Danger Near and above treeline, the avalanche danger in the Northern San Juan is CONSIDERABLE on east-south-west aspects and MODERATE on northerly slopes. Below treeline the danger is MODERATE on all aspects. Remember that the snowpack will generally become more reactive throughout the day as temperatures warm. [57]Please let us know if you see any avalanche activity or signs of instability. San Juan South ============== Current Keywords: LOW, avalanche danger, cold front, front, high pressure, wet slide, Mountain Weather and Avalanche Forecast for the Southern San Juan Mountain Zone Forecast Issued on 2/28/2008 6:36:01 AM Forecaster: John Snook Weather Synopsis Northwest flow continues into Friday with a couple pulses of moisture, one Thursday evening and the second Friday afternoon. Neither is expected to generate more than a few hours of clouds over the northern and central mountains, and maybe a couple of flakes. A ridge of high pressure builds in on Friday and lasts into Saturday. Enjoy the sunshine and mild temperatures while you can. A strong cold front arrives in northwest Colorado by Saturday evening, and then pushes through the remainder of the state overnight. Snow associated with the front and much colder weather return on Sunday. Weather Thursday Night Friday Friday Night Temperature(°F) 35-40 22-27 35-40 Wind Speed(mph) 10-20 0-10 5-15 Wind Direction NNW NNW SW Sky Cover Decreasing Clear Mostly Clear Snow(in) 0 0 0 Snowpack Discussion At this time of the year, in our most southern zone, the snowpack gains strength quickly once a storm cycle has ended. Areas to be more concerned with are above treeline where it is a little colder, and where winds have moved snow around leaving some areas with a little less snow, and a potentially less stable snowpack, and some areas with tens of feet packed in hard will be stronger. Be cautious around convex rolls, and rock out-crops. The last avalanches reported from the Wolf Creek Pass area were on Monday the 25th, and from the southern Highway 550 corridor the last slides were reported on Saturday the 23rd. On Tuesday several small wet loose slides were reported, and we expect this trend to continue on the next couple of days as temperatures remain warm. We will lower the danger across the South San Juan this afternoon. Some wet slide activity may occur each afternoon for the next several days. Avalanche Danger The avalanche danger in the Southern San Juan is LOW. Be aware of an increasing chance for small wet slide activity as temperatures rise. [57]Please let us know if you see any avalanche activity or signs of instability. Sangre de Christo ================= Current Keywords: avalanche danger, cold front, front, high pressure, wind slabs, Mountain Weather and Avalanche Forecast for the Sangre De Cristo Zone Forecast Issued on 2/28/2008 6:36:16 AM Forecaster: John Snook Weather Synopsis Northwest flow continues into Friday with a couple pulses of moisture, one Thursday evening and the second Friday afternoon. Neither is expected to generate more than a few hours of clouds over the northern and central mountains, and maybe a couple of flakes. A ridge of high pressure builds in on Friday and lasts into Saturday. Enjoy the sunshine and mild temperatures while you can. A strong cold front arrives in northwest Colorado by Saturday evening, and then pushes through the remainder of the state overnight. Snow associated with the front and much colder weather return on Sunday. Weather Thursday Night Friday Friday Night Temperature(°F) 35-40 20-25 35-40 Wind Speed(mph) 10-20 G30 10-20 10-20 Wind Direction W W SW Sky Cover Decreasing Clear Mostly Clear Snow(in) 0 0 0 Snowpack Discussion As we move toward Spring and warmer temperatures, the southern aspects will start to show afternoon wet, loose activity. Meanwhile, the northern aspects will retain a winter-like snowpack with wind slabs and a hard mid-pack. But lingering deep slab instabilities likely remain on these northerly aspects as well. You should watch for these aspect dependent changes as you travel in the backcountry. Avalanche Danger We have insufficient information to make an avalanche danger rating for the Sangres at this time. Watch for wet, loose activity on southern aspects. Please send observations from this or any other zone to [57]caic@qwest.net Sawatch ======= Current Keywords: MODERATE, avalanche danger, cold front, front, high pressure, human triggered avalanches, lee , path, slab, wet slide, Mountain Weather and Avalanche Forecast for the Sawatch Range Zone Forecast Issued on 2/28/2008 6:32:14 AM Forecaster: Brad Sawtell Weather Synopsis Northwest flow continues into Friday with a couple pulses of moisture, one Thursday evening and the second Friday afternoon. Neither is expected to generate more than a few hours of clouds over the northern and central mountains, and maybe a couple of flakes. A ridge of high pressure builds in on Friday and lasts into Saturday. Enjoy the sunshine and mild temperatures while you can. A strong cold front arrives in northwest Colorado by Saturday evening, and then pushes through the remainder of the state overnight. Snow associated with the front and much colder weather return on Sunday. Weather Thursday Thursday Night Friday Temperature(°F) 25-30 12-17 28-33 Wind Speed(mph) 15-25 G40 10-20 10-20 Wind Direction WNW W W Sky Cover Decreasing Mostly Clear Partly Cloudy Snow(in) 0 0 0 Snowpack Discussion Over night temperatures indicate a slight cooling trend but the winds have been on the increase, coming from the west and north west. Above tree line fetches still have plenty of snow available to be transported to lee aspects facing north through east and south. Anticipate finding freshly loaded areas to be tender. Although avalanche activity has slowed, a slide was reported on Clover Mountain, which is north east of Monarch Pass. This slide started above treeline and ran on a SSE aspect. The observer noted it was as big as he had seen this path run in quite some time. It probably ran late on the 26th. Another slide was reported from the S face of Mt. Princeton as well as another near Taylor Park. All of the reported activity occurred on a south aspect, above tree line and had deep fracture lines and most likely occured due to rapid warming on Tuesday afternoon. With the approaching cooler air for today, the threat of wet slide activity will end. Moderate to strong winds will add a little more wind deposited snow onto lee aspects, primarily NE-S aspects. Avalanche activity involving the new slab would be shallow and likely would not run far. March looks to arrive like a hungry lion, if you are out exploring the next few days, take a look at what surfaces the new snow will fall on. The next cycle could be a good snow producer, so we do expect avalanche dangers to increase as we move into the new month. Continue to choose your terrain and slope angles wisely. Being on or below slopes steeper than 35 degrees still hold risks. Moderate danger does not mean no danger. Human triggered avalanches will remain possible for a few more days but expect the danger to rise quickly going into next week. Avalanche Danger The avalanche danger for the Sawatch zone is MODERATE over all. Human triggered avalanches are possible. Be especially cautious on freshly loaded steep slopes facing NE-SE-S that are at and above tree line. [57]Please let us know if you see any avalanche activity or signs of instability. Steamboat ========= Current Keywords: CONSIDERABLE, Human triggered, MODERATE, avalanche danger, cold front, front, high pressure, human triggered, settle, ski cut, Mountain Weather and Avalanche Forecast for the Steamboat and Parks Range Zone Forecast Issued on 2/28/2008 6:34:25 AM Forecaster: John Snook Weather Synopsis Northwest flow continues into Friday with a couple pulses of moisture, one Thursday evening and the second Friday afternoon. Neither is expected to generate more than a few hours of clouds over the northern and central mountains, and maybe a couple of flakes. A ridge of high pressure builds in on Friday and lasts into Saturday. Enjoy the sunshine and mild temperatures while you can. A strong cold front arrives in northwest Colorado by Saturday evening, and then pushes through the remainder of the state overnight. Snow associated with the front and much colder weather return on Sunday. Weather Thursday Night Friday Friday Night Temperature(°F) 25-30 10-15 30-35 Wind Speed(mph) 15-25 15-25 10-20 Wind Direction W W W Sky Cover Decreasing Partly Cloudy Partly Cloudy Snow(in) 0 0 0 Snowpack Discussion Temperatures near and below treeline warmed into the low 40s on Wednesday. Four human triggered slides were reported on a southeast aspect of Soda Mountain. Crowns were at 10,400' with depths varying from 10 to 20", and slope angles were 40-45 degrees. Near Buffalo Pass on a north aspect at 9600', a smaller slide (18" x 50' x 100') was released with a ski cut, but it put a good amount of debris on the upside of trees. Temperatures are a few degrees cooler this morning, so the upper snowpack layers will be a little stronger for a while. With the recent reports of slide activity, all so far human triggered, in steeper terrain, 35 degrees plus, and all on N aspects, we will keep the CONSIDERABLE on the NW-N-NE aspects. This can be described under the MODERATE category but there have been 5 plus slides in the Fish Creek and Buffalo Pass area in the last two days. Here is where terrain selection is good, avoid terrain traps, use good protocols, and you should have good turns. On Tuesday afternoon observers looking at the Monday slide in Fish Creek Canyon noted a couple slides triggered from around 100 feet away on N aspects around 9,200 ft. These included the newer snow only. There was also one skier triggered slide and one person went for a short ride and was partially buried. No injuries, just a bit spooked. A 48 hour warm-up will have helped settle the upper snowpack layers. The due north aspects that are sheltered from any solar gain may be the exception, so the colder aspects would be the area of greatest concern. Avalanche Danger The avalanche danger for the Steamboat Zone is CONSIDERABLE on NW-N-NE aspects, all elevations and MODERATE elsewhere. Human triggered avalanches are probable to possible. If you have any observations or data to share, please send them to [57]caic@qwest.net. Vail ==== Current Keywords: MODERATE, avalanche danger, cold front, front, high pressure, human triggered avalanches, natural, settled, wind slabs, Mountain Weather and Avalanche Forecast for the Vail and Summit County Zone Forecast Issued on 2/28/2008 6:34:40 AM Forecaster: Brad Sawtell Weather Synopsis Northwest flow continues into Friday with a couple pulses of moisture, one Thursday evening and the second Friday afternoon. Neither is expected to generate more than a few hours of clouds over the northern and central mountains, and maybe a couple of flakes. A ridge of high pressure builds in on Friday and lasts into Saturday. Enjoy the sunshine and mild temperatures while you can. A strong cold front arrives in northwest Colorado by Saturday evening, and then pushes through the remainder of the state overnight. Snow associated with the front and much colder weather return on Sunday. Weather Thursday Night Friday Friday Night Temperature(°F) 23-28 10-15 27-32 Wind Speed(mph) 15-25 G35 15-25 G35 15-25 Wind Direction WNW WNW W Sky Cover Decreasing Mostly Clear Partly Cloudy Snow(in) 0 0 0 Snowpack Discussion Weather stations around the zone report a cooling trend with temps ranging between the teens and low 20's. Winds on the other hand have remained from the west and north west but gusts have ramped up to the 30's and 40's. There is still plenty of snow available in the fetches available for transport, so expect to find fresh wind slabs on east through south aspects. Avalanche activity has slowed but they are still being reported. The natural activity still tends to be larger in size but also activity is occurring on slopes that do not slide very frequently. Artificially (human) triggered slides have been occurring on slopes that are repeat offenders. They have been triggered by riding through likely tigger points; convex roll overs and near exposed rock bands. With no reports of avalanche activity from the far western portion of the zone, the warmer temperatures seem to have settled the snow pack more. Just to be clear, unintentionally triggering an avalanche is not cool. It means you made a poor decision. Moderate danger does not mean no danger. It means human triggered avalanches are possible. Continue to practice smart travel procedures as they will save you when your predictions are wrong. Tip for the day: climb what you intend to ride. By ascending similar aspects to what you intend to ride, will allow you to gather more information about the snow pack stability and therefore you will feel more confident if you choose to follow through with your plan. In order to follow through with this tip, more initial effort is required but it will also instill more confidence in your decision making. If you do trigger an avalanche, please let us know. The information really helps us a lot! Choose your terrain wisely and have fun. There is a lot of really fun riding out there. Avalanche Danger The avalanche danger for the Vail-Summit zone is rated MODERATE overall. Human triggered avalanches remain possible. Be especially cautious on freshly loaded steep slopes facing NE-SE-S at and above tree line. Thanks to all those that have sent us recent obs. Most appreciated.