Aspen ===== Current Keywords: CONSIDERABLE, Human triggered, MODERATE, avalanche danger, cold front, density, facets, front, human triggered, low pressure, natural avalanches, path, probe, settle, surface hoar, trough, weak layer, weak layers, Mountain Weather and Avalanche Forecast for the Aspen Zone Forecast Issued on 1/15/2008 7:02:48 AM Forecaster: Brian McCall Weather Synopsis The next cold front is boiling over Wyoming, and will spill south Tuesday afternoon. A low pressure trough is driving the front and the associated cold, maritime polar air mass down on northerly flow. We will see light snow ahead of the front, starting mid afternoon in northwest Colorado, reaching the Ike before dusk, and the San Juans around midnight. The front follows, and temperatures will drop abruptly and winds swing to the north. The cold air and little available moisture will limit accumulations, but what falls will be low density, though. Cold northerly flow will stick around through Thursday. There is just enough moisture in the air mass that we can expect some light scattered snow, especially in the northern mountains. Later in the week upper level flow turns northwesterly, and blows in some weak disturbances to produce more light snow. Weather Tuesday Night Wednesday Wednesday Night Temperature(°F) 15-20 -8 to -3 -5 to 0 Wind Speed(mph) 15-25 15-25 10-20 Wind Direction N N NW Sky Cover Partly Cloudy Mostly Cloudy Partly Cloudy Snow(in) 0-2 2-5 0-2 Snowpack Discussion Thanks to everyone who attended last night's fundraiser at Restaurant Six89. The evening was a great success and I'd like to thanks all those involved who helped make this such a fun event! Mild temperatures and light winds are allowing the snowpack to settle and adjust to the weight of the last storm's snow. The last slide that we know of occurred on Sunday, when skiers in the West Willow drainage near Snowmass triggered a large avalanche on a SE aspect just above treeline. The slide was triggered mid path and thankfully, no one was caught. Although the likelihood of natural avalanches has diminished throughout the zone, human triggered slides remain possible to probable. Consider the recent weather events before heading into big terrain. Large accumulations of snow during the last couple weeks as well as some strong winds have added a big load to some older weak layers in the snowpack. These avalanches will be harder to trigger today but the consequences of doing so could be a ride in a large destructive slide. Recent avalanche activity has predominately occurred on slopes facing NE, E, and SE at all elevations. The downside of the of clear skies and cool temperatures during the last two days has been the formation of surface hoar and surface facets on top of the snowpack in many areas. These cold nights with clear skies are perfect for forming that next weak layer in our snowpack. These two types of snow grains are notorious weak layers that may persist for long periods of time in the snowpack. If you are out traveling today, pay attention to the snow surface and on which aspects and elevations you find them. Look for weak layers in the snowpack at the old snow surface/ new snow interface, about 2-3 ft below the snow surface, and also at the base of the snowpack. Slabs have the potential to initiate in the upper snowpack before stepping down to weak facets at the ground. These persistent grains will not go away anytime soon so dig around and try to get a feel for their depth and distribution. The snowpack is complex and highly variable out there. Your probe pole is not just for rescue. It can be another great tool for getting the feel for snowpack depths, layering, and variability. Try using it as another observation tool on your next tour. Look for more tender conditions in areas of the zone where the snowpack remains thinner, namely the Castle Creek, Ashcroft and Independence Pass areas. Remember, you can avoid most avalanche problems by opting for lower angled terrain. It has been a rare month for snowfall and weather in our area. Be on the look out for out of the ordinary conditions. Continue to use a conservative approach and investigate the snowpack with scrutiny. Avalanche Danger The avalanche danger is CONSIDERABLE on northeast, east, southeast and south aspects near and above treeline. Natural avalanches are possible and human triggered ones probable. Triggered avalanches may be large and destructive like the one reported in West Willow on Sunday. The avalanche danger on all other aspects near and above treeline as well as all slopes below treeline is an overall MODERATE. Human triggered avalanches are still possible here. Your backcountry weather, avalanche, and snowpack observations are a valuable asset to our forecasts. Please drop us an e-mail at caic@qwest.net with anything your seeing in the backcountry today. Front Range =========== Current Keywords: CONSIDERABLE, MODERATE, avalanche danger, cold front, cross loaded, density, drifts, explosive, facets, front, human triggered, lee , low pressure, natural avalanches, slabs, start zones, stress, trough, weak layers, Mountain Weather and Avalanche Forecast for the Front Range Zone Forecast Issued on 1/15/2008 6:48:24 AM Forecaster: Spencer Logan Weather Synopsis The next cold front is boiling over Wyoming, and will spill south Tuesday afternoon. A low pressure trough is driving the front and the associated cold, maritime polar air mass down on northerly flow. We will see light snow ahead of the front, starting mid afternoon in northwest Colorado, reaching the Ike before dusk, and the San Juans around midnight. The front follows, and temperatures will drop abruptly and winds swing to the north. The cold air and little available moisture will limit accumulations, but what falls will be low density, though. Cold northerly flow will stick around through Thursday. There is just enough moisture in the air mass that we can expect some light scattered snow, especially in the northern mountains. Later in the week upper level flow turns northwesterly, and blows in some weak disturbances to produce more light snow. Weather Tuesday Tuesday Night Wednesday Temperature(°F) 12-17 -13 to -8 -5 to 0 Wind Speed(mph) 20-30 15-25 15-25 Wind Direction W NW NW Sky Cover Increasing Mostly Cloudy Mostly Clear Snow(in) 0-2 pm 1-4 0-2 Snowpack Discussion Reminders of the conditionally unstable nature of our snowpack continue to roll in. Observers reported a couple fresh slides in the Berthoud Pass area on Monday. A remotely skier triggered slide ran on an easterly face in the 110s. It cracked about 3 feet deep and 150 feet wide, running to the ground in places. A much larger explosive triggered slide ran in the nearby Jones Pass area on a southeast aspect above treeline. This impressive slide was also roughly 3 feet deep and ran to the ground. It fractured 600 feet across before running 1200 feet down the mountain. Winds have redistributed lots snow out there. Even though new snow accumulations have been modest, lee start zones are quite loaded, stressing weak layers in the snowpack. One forecaster noted that drifts look "pregnant and ready to pop". We know that is where it looks fun to ride, but it is also the most likely place to trigger and avalanche. You don't want to be the straw that broke the avalanche dragon's back! Most of the recent avalanche activity has occurred on easterly aspects both above and below treeline. Wind affected snow and more reactive slabs can be found on these lee aspects. Watch for cross loaded terrain features as well. Old slabs have the potential to run on weak facets at the ground. These persistent grains will not go away anytime soon so dig around and try to get a feel for their depth and distribution. The snowpack is complex out there. Remember, you can avoid most avalanche problems by opting for lower angled terrain. Avalanche Danger The avalanche danger is CONSIDERABLE on north, northeast, east, southeast, south, and southwest aspects at all elevations. There are pockets of CONSIDERABLE danger on cross loaded terrain features on west and northwest aspects near and above treeline. Human triggered avalanches are probable, and natural avalanches possible. Below treeline the danger is MODERATE on west and northwest aspects. Grand Mesa ========== Current Keywords: LOW, MODERATE, avalanche danger, cold front, cross loading, density, drifts, front, low pressure, settling, slabs, sluffs, trough, wind-loaded, windslabs, Mountain Weather and Avalanche Forecast for the Grand Mesa Zone Forecast Issued on 1/15/2008 2:40:57 PM Forecaster: Spencer Logan Weather Synopsis The next cold front is boiling over Wyoming, and will spill south Tuesday afternoon. A low pressure trough is driving the front and the associated cold, maritime polar air mass down on northerly flow. We will see light snow ahead of the front, starting mid afternoon in northwest Colorado, reaching the Ike before dusk, and the San Juans around midnight. The front follows, and temperatures will drop abruptly and winds swing to the north. The cold air and little available moisture will limit accumulations, but what falls will be low density, though. Cold northerly flow will stick around through Thursday. There is just enough moisture in the air mass that we can expect some light scattered snow, especially in the northern mountains. Later in the week upper level flow turns northwesterly, and blows in some weak disturbances to produce more light snow. Weather Tuesday Night Wednesday Wednesday Night Temperature(°F) -5 to 0 0-5 -10 to -5 Wind Speed(mph) 5-15 5-15 5-15 Wind Direction NNW NNE NE Sky Cover Mostly Clear Partly Cloudy Partly Cloudy Snow(in) 2-4 0-2 0-1 Snowpack Discussion Thus far, no one has reported any unstable slabs from the last storm, though this does not mean they do not exist. New snow and light winds will add a new load to east, southeast, and south aspects. Expect to find some soft windslabs and drifts, as well as a bit of cross loading on northeast through east through southwest aspects. Slabs will be most reactive on steep slopes near rock bands, especially in the Crag Crest area. Older instabilities are settling out, so the main avalanche concerns will be sluffs and recent wind affected snow. Avalanche Danger The avalanche danger for the Grand Mesa zone is MODERATE on north, northeast, east, southeast, and south aspects at all elevations. Human triggered avalanches are possible, especially on wind-loaded slopes 35 degrees and steeper. The danger is LOW on other aspects. 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, crowns, density, front, human triggered avalanches, low pressure, natural, naturally, powder , settle, settling, slab, starting zones, trough, Mountain Weather and Avalanche Forecast for the Northern San Juan Mountain Zone Forecast Issued on 1/15/2008 7:41:16 AM Forecaster: Spencer Logan Weather Synopsis The next cold front is boiling over Wyoming, and will spill south Tuesday afternoon. A low pressure trough is driving the front and the associated cold, maritime polar air mass down on northerly flow. We will see light snow ahead of the front, starting mid afternoon in northwest Colorado, reaching the Ike before dusk, and the San Juans around midnight. The front follows, and temperatures will drop abruptly and winds swing to the north. The cold air and little available moisture will limit accumulations, but what falls will be low density, though. Cold northerly flow will stick around through Thursday. There is just enough moisture in the air mass that we can expect some light scattered snow, especially in the northern mountains. Later in the week upper level flow turns northwesterly, and blows in some weak disturbances to produce more light snow. Weather Tuesday Night Wednesday Wednesday Night Temperature(°F) 20-25 -1-4 5-10 Wind Speed(mph) 10-20 5-15 5-15 Wind Direction N NNE NNW Sky Cover Increasing Mostly Cloudy Partly Cloudy Snow(in) 0-1 1-3 0-1 Snowpack Discussion A welcome break in the weather has allowed the snowpack to settle and adjust to the weight of recent storm snow a bit. Observers from different parts of our zone are reporting that the snowpack is settling out relatively quickly, which is a good indication that the snowpack is gaining stregth. However, reports of natural and triggered avalanche activity, particularly above treeline, continue to come in. Recent strong winds set off a brief but impressive natural cycle in the alpine zone around the Cement Creek area. An observer in the area noted several large slides, mostly on easterly slopes, with crowns up to 4 feet deep that stepped down to the ground. An observer in the Ophir area noted three recent slides, also above treeline, that were likely triggered by the same wind event, though fracture lines were not as deep. Wind is a major factor in avalanche activity and it is not uncommon to see slides run naturally days after snowfall has stopped because of wind, even in starting zones that have already pulled out. Remember that wind, especially near and above treeline, can transport significant amounts of snow and redistribute it into different areas. Along the way, the wind causes the snow grains to break apart and take on a smaller, simpler form that allows them to pack in tightly together. The result is often a new, cohesive slab with good propagation potential sitting on top of whatever surface snow was there previously. It is wise to keep track of wind direction and wind speeds regularly, not just snowfall amounts. You can check local weather stations with hourly averages on the internet; the links are on the CAIC's home page. Our snowpack, as is often the case, is complex and difficult to generalize about. At this point, while the snowpack is generally settling out, particularly below treeline, the wind has played a major role in keeping conditions near and above treeline tender on all aspects. This last storm cycle was significant and any steep slopes that did not slide naturally during the storm remain especially suspect. Observers are digging some deep pits and finding mixed results - stability here, instability there. This is a time to remain cautious - any slides that do occur have the potential to run fairly big. It looks like we're in for some good weather this week, and there is plenty of powder out there calling. As you start to venture further out into the backcountry, to places you've been thinking about for a while now, remember that in the past week observers have seen and reported natural and triggered avalanches in places they have never seen run! This means we cannot take any area for granted. Cautiously evaluate your choice of terrain and decision making while traveling in the backcountry today. The extensive natural and artificially triggered avalanches over the past week should make it perfectly clear that we have a tender snowpack. Avalanche Danger The avalanche danger for the Northern San Juan zone is CONSIDERABLE on all aspects and elevations near and above treeline. Natural avalanches are possible and human-triggered avalanches are probable on all steep slopes. Below treeline, the danger is MODERATE on all aspects, and human triggered avalanches remain possible, particularly on steep, convex slopes. San Juan South ============== Current Keywords: LOW, MODERATE, avalanche danger, cold front, cross loaded, crust, density, faceting, front, human triggered avalanches, low pressure, powder , settle, trough, weak layers, wind loading, windloaded, windslabs, Mountain Weather and Avalanche Forecast for the Southern San Juan Mountain Zone Forecast Issued on 1/15/2008 6:45:04 AM Forecaster: Spencer Logan Weather Synopsis The next cold front is boiling over Wyoming, and will spill south Tuesday afternoon. A low pressure trough is driving the front and the associated cold, maritime polar air mass down on northerly flow. We will see light snow ahead of the front, starting mid afternoon in northwest Colorado, reaching the Ike before dusk, and the San Juans around midnight. The front follows, and temperatures will drop abruptly and winds swing to the north. The cold air and little available moisture will limit accumulations, but what falls will be low density, though. Cold northerly flow will stick around through Thursday. There is just enough moisture in the air mass that we can expect some light scattered snow, especially in the northern mountains. Later in the week upper level flow turns northwesterly, and blows in some weak disturbances to produce more light snow. Weather Tuesday Night Wednesday Wednesday Night Temperature(°F) 25-30 -5-0 8-13 Wind Speed(mph) 10-20 5-15 5-15 Wind Direction SW NNW NNW Sky Cover Partly Cloudy Partly Cloudy Partly Cloudy Snow(in) 0 0-2 0-1 Snowpack Discussion The break in the weather has allowed the snowpack to settle and adjust to the weight of recent storm snow. Monday on the border between the Northern and Southern San Juan zones, observers triggered an avalanche on a windloaded southerly aspect just off the ridge. Otherwise, observers have seen very little avalanche activity or signs of instability for a couple days, though reports avalanches that slid during the storm continue to trickle in. Observers reported great skiing and stable snow in both the La Platas and the Wolf Creek Pass area over the weekend. If you are in the Southern San Juan along the 550 corridor today, we encourage you to read the Northern San Juan forecast as well, since zone boundaries are not distinct. The snowpack in that region may be touchier than in the Wolf Creek Pass area. You may find recently deposited windslabs and cross loaded terrain features on exposed slopes facing north through east through south. Check the stability on those slopes before committing to them. Gradually work onto steeper and more exposed slopes as you get a feel for the snowpack and weak layers. Reevaluate the new snow often, as instabilities may be localized. The snow surface is changing. A thin sun crust has started to form on sunny southerly aspects with warming temperatures. The clearing skies have started the near surface faceting process, and the recycled powder will just get better over the next few days. Enjoy, but do so in a way that will not add you to our statistics. Avalanche Danger The avalanche danger is MODERATE on all aspects and elevations except southwest, west and northwest aspects below treeline, where the danger is LOW. Human triggered avalanches are possible on steep slopes with recent wind loading. Sangre de Christo ================= Current Keywords: CONSIDERABLE, Human triggered, MODERATE, avalanche danger, cold front, density, front, low pressure, slab, slabs, trough, wind loaded, windloaded, Mountain Weather and Avalanche Forecast for the Sangre De Cristo Zone Forecast Issued on 1/15/2008 6:46:00 AM Forecaster: Spencer Logan Weather Synopsis The next cold front is boiling over Wyoming, and will spill south Tuesday afternoon. A low pressure trough is driving the front and the associated cold, maritime polar air mass down on northerly flow. We will see light snow ahead of the front, starting mid afternoon in northwest Colorado, reaching the Ike before dusk, and the San Juans around midnight. The front follows, and temperatures will drop abruptly and winds swing to the north. The cold air and little available moisture will limit accumulations, but what falls will be low density, though. Cold northerly flow will stick around through Thursday. There is just enough moisture in the air mass that we can expect some light scattered snow, especially in the northern mountains. Later in the week upper level flow turns northwesterly, and blows in some weak disturbances to produce more light snow. Weather Tuesday Night Wednesday Wednesday Night Temperature(°F) 20-25 -8 to -3 0-5 Wind Speed(mph) 15-25 15-25 15-25 Wind Direction WSW NW NNW Sky Cover Partly Cloudy Partly Cloudy Partly Cloudy Snow(in) 0-1 0-3 0-2 Snowpack Discussion There was an avalanche accident in the Sangres on Thursday near Little Bear Peak, west of Blanca Peak. A pair of hikers were caught in a hard slab avalanche mid-day Thursday as they crossed a steep and rugged southwest slope well above treeline. The slide broke near the ridge in complicated terrain. It was about 4 feet deep, 400 feet wide, and ran 800 to 1000 vertical feet over some cliffs. The debris was up to 10 feet deep. One hiker was buried to his waist, and was able to free himself. He searched but could not find his sister who he had been traveling with. The hiker made his way out of the mountains overnight, and was finally able to place a 911 call Friday morning. Search and Rescue crews began the long process of searching the debris, though the body of the second hiker has not yet been located. Ample "hang fire" or additional snow that has not yet slid, still exists above the search area, creating a hazardous situation for rescuers. I should have the preliminary report, with maps and photos, up this morning. The recent storm cycle generated very little snow for the Sangre de Cristo Mountains, though you will find older pockets of plump, windloaded terrain. Cold weather and strong winds from around the New Year likely created a classic strong over weak Colorado snowpack, especially on north through east to south aspects. Steep, wind-loaded slopes present the greatest avalanche danger today. North aspects have been almost completely stripped by winds while south aspects hold deep hard slabs above narrow terrain traps. Other aspects have been cross loaded. The northern Sangre's currently have more snow than the southern portion. Use caution and always choose your terrain carefully. Avalanche Danger The avalanche danger in the Sangre de Cristo Zone is CONSIDERABLE above trelline and MODERATE below treeline. Human triggered slides are possible to probable today. Carefully evaluate steep wind loaded slopes. Please send observations from this or any other zone to [57]caic@qwest.net Sawatch ======= Current Keywords: CONSIDERABLE, MODERATE, avalanche danger, avalanche paths, cold front, cross loaded, crossloaded, density, facets, front, human triggered, human triggered avalanches, lee , low pressure, powder , settle, slab, slabs, trough, wind loaded, Mountain Weather and Avalanche Forecast for the Sawatch Range Zone Forecast Issued on 1/15/2008 6:21:58 AM Forecaster: Brad Sawtell Weather Synopsis The next cold front is boiling over Wyoming, and will spill south Tuesday afternoon. A low pressure trough is driving the front and the associated cold, maritime polar air mass down on northerly flow. We will see light snow ahead of the front, starting mid afternoon in northwest Colorado, reaching the Ike before dusk, and the San Juans around midnight. The front follows, and temperatures will drop abruptly and winds swing to the north. The cold air and little available moisture will limit accumulations, but what falls will be low density, though. Cold northerly flow will stick around through Thursday. There is just enough moisture in the air mass that we can expect some light scattered snow, especially in the northern mountains. Later in the week upper level flow turns northwesterly, and blows in some weak disturbances to produce more light snow. Weather Tuesday Tuesday Night Wednesday Temperature(°F) 20-25 -10 to -5 0-5 Wind Speed(mph) 15-25 15-25 10-20 Wind Direction WNW N NW Sky Cover Increasing Mostly Cloudy Mostly Cloudy Snow(in) 0-1 2-4 0-2 Snowpack Discussion A preliminary report of the fatal avalanche that occurred in the East Vail area Saturday morning is now posted in our Accidents section on our web site. Also, a preliminary report on the close call near Cottonwood Pass from over a week ago will be up soon. News from the Sawatch Range has really slowed since the weekend. Warmer temperatures have allowed the snowpack to settle a bit though problem layers are there until spring. Wind and snow over the past week have added several layers of both hard and soft slab on north through east to south aspects. Recent avalanche activity has predominately occurred on northeast, east, and southeast aspects at all elevations. Wind affected snow and more reactive slabs can be found on these lee aspects in near and above treeline areas as well as in exposed areas below treeline. Be mindful for cross loaded terrain features as well. Many hard slabs from our last ferocious wind event are now covered by softer snow A layer of facets still lurks deep in the snowpack, but the distribution is patchy and the strength inconsistent. Some impressive slides have run in the neighboring Vail Summit zone to the north on these basal layer facets. These persistent grains will not go away anytime soon so dig around and try to get a feel for their depth and distribution. The snowpack is complex out there. A report from the Mt. Princeton area warned of a very inconsistent snowpack. Dense hard slab and wind effected snow was located next to full depth sugar. Remember, you can avoid most avalanche problems by opting for lower angled terrain. One the biggest concern is powder fever. Traveling safely in the backcountry will require solid skills in snowpack assessment, terrain evaluation, route finding, as well as smart travel practices. There is great snow out there, but there is also a complicated, variable snowpack. Do not push your luck with the avalanche dragon. Consider the consequences of your decisions and actions. Stick with lower angle terrain and be aware of both large avalanche paths and smaller terrain features as human triggered slides remain possible to probable today. Continue to exercise safe travel procedures as they will save you when your prdictions are wrong. 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. Human triggered avalanches are probable on steep, loaded slopes. On other aspects and below treeline the danger is MODERATE. [57]Please let us know if you see any avalanche activity or experienced signs of instability. Steamboat ========= Current Keywords: MODERATE, avalanche danger, cold front, cross loaded, density, facets, front, lee , low pressure, powder , settlement, slabs, trough, weak layers, windloaded, Mountain Weather and Avalanche Forecast for the Steamboat and Parks Range Zone Forecast Issued on 1/15/2008 6:47:49 AM Forecaster: Spencer Logan Weather Synopsis The next cold front is boiling over Wyoming, and will spill south Tuesday afternoon. A low pressure trough is driving the front and the associated cold, maritime polar air mass down on northerly flow. We will see light snow ahead of the front, starting mid afternoon in northwest Colorado, reaching the Ike before dusk, and the San Juans around midnight. The front follows, and temperatures will drop abruptly and winds swing to the north. The cold air and little available moisture will limit accumulations, but what falls will be low density, though. Cold northerly flow will stick around through Thursday. There is just enough moisture in the air mass that we can expect some light scattered snow, especially in the northern mountains. Later in the week upper level flow turns northwesterly, and blows in some weak disturbances to produce more light snow. Weather Tuesday Night Wednesday Wednesday Night Temperature(°F) 18-23 -10 to 5 -5 to 0 Wind Speed(mph) 15-25 10-20 10-20 Wind Direction SW NW NNW Sky Cover Increasing Mostly Cloudy Partly Cloudy Snow(in) 1-3 3-5 0-2 Snowpack Discussion Observers have raved about the conditions in the Steamboat Zone over the past several days, where roughly 3 feet of fluff fell in the last storm. Temps have remained cold enough for powder to stay fresh, but warming enough to allow for some settlement in the new snow layers. The main avalanche concern today is the strength of the interface between the old snow surface and all that new snow that fell over the weekend. We still have concerns with the lowest portion of the snowpack as well. Though it will take a large load to create a failure in the basal facets, if initiated, slides will be big. Observers have noted few signs of instability on lower angled terrain. With clearing weather, backcountry travelers may venture up into higher, more exposed terrain. Windloaded lee and cross loaded slopes are the most likely place to trigger an avalanche today. Winds have predominately blown out of the northwest, moving snow to east, southeast and south aspects. Windslabs can be quite soft and feel like powder, but can become destructive slides once all that snow starts moving down the mountain. Gradually work onto steeper and more exposed slopes as you get a feel for the snowpack and weak layers. Reevaluate the new snow often, as instabilities may be localized. Avalanche Danger The avalanche danger in the Steamboat Zone is MODERATE on all aspects and elevations. Continue to watch for steep slopes with windloaded snow. 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, density, faceting, front, lee , low pressure, natural, natural avalanches, slab, slabs, start zones, stress, trough, weak layers, wind drifts, Mountain Weather and Avalanche Forecast for the Vail and Summit County Zone Forecast Issued on 1/15/2008 6:16:30 AM Forecaster: Brad Sawtell Weather Synopsis The next cold front is boiling over Wyoming, and will spill south Tuesday afternoon. A low pressure trough is driving the front and the associated cold, maritime polar air mass down on northerly flow. We will see light snow ahead of the front, starting mid afternoon in northwest Colorado, reaching the Ike before dusk, and the San Juans around midnight. The front follows, and temperatures will drop abruptly and winds swing to the north. The cold air and little available moisture will limit accumulations, but what falls will be low density, though. Cold northerly flow will stick around through Thursday. There is just enough moisture in the air mass that we can expect some light scattered snow, especially in the northern mountains. Later in the week upper level flow turns northwesterly, and blows in some weak disturbances to produce more light snow. Weather Tuesday Tuesday Night Wednesday Temperature(°F) 15-20 -15 to -10 -8 to -3 Wind Speed(mph) 20-30 15-25 15-25 Wind Direction W NNW NW Sky Cover Increasing Mostly Cloudy Mostly Cloudy Snow(in) 0-2 pm 2-5 0-2 Snowpack Discussion A preliminary report of the fatal avalanche that occurred in the East Vail area Saturday morning is now posted in our Accidents section on our web site. Reports of avalanche activity has slowed since the weekend. However, I would like to point out a few themes with the ones that were reported. Both natural and artificially triggered slides have occured on E-S-SW aspects. Most of them were quite large; many being size 4's (with a 5 being the largest), as well as fracture lines have been deep (5-10 feet!). Most occured at or above tree line and some of the human triggered slides were triggered remotely from a far distance. When you can trigger an avalanche from far away, think hard slab. The hard slab problem is here to stay for the season. Being caught in a hard slab avalanche is a real bummer and the consequences can be severe. Winds have redistributed lots snow out there. Even though new snow accumulations have been modest, lee start zones are quite loaded, stressing weak layers in the snowpack. Wind loaded areas look "pregnant and ready to pop". Westerly aspects above treeline are begining to be quite thin again, making us look for deeper snow. As a result, we tend to migrate towards these loaded areas, but it is also the most likely place to trigger an avalanche. You do not want to be the one to wake up a tigger! Pay close attention to loaded areas as the layers beneath the slabs have turned into a sugar factory. Sugar snow is very weak. Expect the incoming cold temperatures to put the faceting process back into overdrive, making the weak layers weaker. Additionally, pay close attention to how the snow feels beneath you while you are in lower angle terrain. If layers below you feel sloid, do not think that it is. Dig below the hard slab and you will find plenty of weak snow. Continue to exercise safe travel procedures as they will save you when your prdictions are wrong. Avalanche Danger The avalanche danger in the Vail Summit Zone is CONSDIERABLE on north, northeast east, southeast, and south aspects at all elevations. Human triggered avalanches are probable, and natural avalanches possible. New snow and strong winds have created fresh wind drifts and slabs, and some avalanches are running to the ground. On west and northwest aspects all elevations the danger is MODERATE.