Advisory – Past Fifteen Days
A series of storms over the past week brought nearly 30 inches of snowfall to the summit of Mt. Washington. This new snow continues to rapidly alter coverage. Developed avalanche paths are still the exception rather than the rule, but skiers and climbers will likely be drawn to these developed snowfields. Early season conditions still exist in the alpine and are even more pronounced at lower elevations. Areas with a more developed snowpack, like the south side of Tuckerman Ravine, have shown the ability to avalanche already with natural activity observed earlier this month as well as in October. The adage, “If there’s enough snow to ride, there’s enough snow to slide” is certainly true and should motivate you to make careful snowpack assessments this weekend.
After a fitful but early start, winter is taking a solid hold on higher elevation terrain. Snow is beginning to fill in the windswept alpine zone and the mercury is dipping well below the zero mark. Snowfields are growing in size while boulder strewn gullies, cliffs and trees are beginning to be covered by wind-blown snow. All this adds up to conditions which can produce enough snow to build wind slab avalanches along with the bed surfaces needed for the avalanches to slide on.
An early visit from old man winter deposited close to 29″ of snow through the last week of October on the summit of Mount Washington. While a return to warmer temperatures brought freezing rain and then rain and above freezing temperatures, snow on the ground will likely be around for a while. All this snow […]
Our recent weather pattern likely has us all thinking winter. Options to slide on snow or climb ice don’t yet abound, but we all need to be ready to make the most of our cold playground when they do! The Eastern Snow and Avalanche Workshop (ESAW) returns to the Laura Hill Eastman Performing Arts Center, […]
This is the final bulletin issued by the Mount Washington Avalanche Center for the 2017-18 season. It will remain in effect until complete melt out. Travel in the backcountry requires careful snow evaluation and mountain sense. Hazards due to snow and ice will persist until both are all gone. Summer snowstorms on Mount Washington are uncommon, but not unheard of. If venturing into the mountains, be sure to use all available resources to help plan your trip and make safe travel decisions.
Due to open glide cracks and undermined snow, the Tuckerman Ravine Trail is now closed in the Ravine between Lunch Rocks and its junction with the Alpine Garden Trail. This closure includes the Lip area, which presents numerous hazards to the recreating public and potential rescuers alike.
We are no longer issuing daily avalanche advisories for Tuckerman Ravine this season. We will continue to provide snowpack and weather information as conditions change. We are no longer monitoring conditions in Huntington Ravine, but similar hazards will persist there until snow and ice is gone. Temperatures at night will dip below freezing with daytimes […]
Cool weather will give way to an approaching warm front, though temperatures should remain somewhat cold through the weekend. The summit is forecast to remain below freezing today. Intermittent and partial cloud cover is forecast to continue through tomorrow. Saturday will also bring a chance of rain showers as temperatures warm by a few degrees. Wind today will gust to 90 mph but diminish by afternoon. Warming temperatures on Sunday may allow loose wet sluffing to again become a concern, but until then, the potential for icy refrozen snow makes long sliding falls a primary hazard. Cloud cover and a chance of showers makes Saturday not ideal for skiing. Sunday looks like a sunny day with soft snow. Glide cracks continue to grow and will soon result in closure of the Lip area.
High pressure will build into the region from Canada on Monday, keeping clear conditions until late in the week. Temperatures during the days will reach into the 40sF and nighttime lows will drop into the 30sF. Low pressure will move into the area late in the week bringing unsettled weather. Our springtime isothermal snowpack has generally reduced avalanche concerns to sluff management in steep terrain.
Rain and possibly thunderstorms on Friday will set up a clearing pattern for Saturday. Temperatures close to the freezing mark to start Saturday combined with wind speeds over 100mph on the summit may make a late start the right choice as winds may drop to a more reasonable speed later in the afternoon. Rain on Sunday will be followed by what looks like a good corn cycle next week with sunny skies, warm days and colder nights. An isothermal snowpack has reduced the concerns for large avalanches, though history has shown that intense periods of heavy rain can make the waterfall hole in the Lip do strange things no matter what the snowpack is. Sluff management should be a priority for skiers, in particular the first several of the day on each slope.
This past weekend was a perfect reminder of how fickle spring weather can be. Saturday’s crowds were delighted by sunshine and abundant spring snow while those who ventured up to the Ravines on Sunday found rain and sleet at mid elevations and 11.1” of new snow on the summit. With light and variable winds, this snow likely blanketed higher terrain. Lingering instability in the atmosphere Monday will keep temperatures around the freezing mark for another 1-3” of snow and sleet on the summit. Building high pressure on Tuesday will create a clearing trend into Wednesday along with increasing wind speeds and temperatures. New snow from Sunday will experience rapid warming over the forecast period. Those venturing into avalanche terrain should be aware of the potential for wet avalanches. While wet-loose sluffs may be slow moving, this sort of “push avalanche” can easily take a skier over a cliff or into a glide crack. New snow will also cover developing holes in the snowpack, making safe navigation that much more difficult.
Over two inches of rain and temperatures into the 40’s and 50’s over the past two days in the Ravines has consolidated the snow but has done little damage to the ski gullies in Tuckerman Ravine. A few lines such as the skier’s right fork of Hillman’s have shrunk into the barely skiable category but the Lip and most of the other main lines are still full with snow. Glide cracks are just beginning to emerge. Huntington’s ice climbs were damaged but still passable, though continued warm weather will make these increasingly sketchy due to undermining of the remaining ice and loose rocky topouts. The weather forecast is continuing to favor those with flexible work schedules and punish the 9-5ers. Rain will return Friday night and in the words of today’s MWObs forecaster “plague” the area through the weekend with rain shower activity. Warm temperatures remain in place through early Sunday which means flowing water and weak snow bridges will remain a problem especially in main watercourses. Periods of freezing temperatures may return briefly late Saturday night and more certainly Sunday afternoon and elevate the potential for slide-for-life conditions. Though icy, the Winter Lion Head Route remains the preferred option for summit hikers due to the fall hazard at the traverse near treeline on the summer trail. The lower section of the Sherburne Ski Trail is closed around the switchbacks of the Tuckerman Ravine trail, about ½ mile or 400+ vertical feet from the parking lot. In order to reduce erosion on the ski trail, please walk over to the Tucks trail and hike the rest of the way to Pinkham Notch.
Avalanches, falling rocks and ice, undermined snow, large glide cracks and icy refrozen surfaces will remain a threat in and below steep terrain as long as snow remains in the mountains. Spring weather brings about rapid changes to the snowpack and changes objective hazards accordingly. Remember to ski, climb or hike the snowpack and weather conditions that exist and not a date on the calendar!
Wet Slab is becoming our primary avalanche problem and will increase in likelihood with continued warming through the day. Wet slab avalanches are characterized by uncertainty, with the timing of peak instability for slab avalanches quite difficult to pin down. Our warming wind slabs that are becoming wet slabs also lend uncertainty to potential size of avalanches today, with large avalanches remaining a possibility. As surface slabs warm they may ultimately lose cohesion and be more likely to produce loose wet avalanches, or sluffs. Both of these avalanche problems will be most prevalent on sun exposed slopes. Areas receiving Low avalanche danger ratings today are rated so for limited potential size of avalanches.
In addition to avalanche concerns, spring hazards are emerging in the ravines. Icefall will be a key hazard resulting from today’s warm temperatures and solar heating. Areas under southerly facing ice, like Lunch Rocks, are particularly unwise places hang out. Melt water flowing under ice and potentially building up pressure will make ice dams a concern for climbers. Undermined snow will result from flowing melt water, with open holes and weak snow bridges over streams a potential concern in a number of locations including the Little Headwall.
Wind slabs that formed over the weekend will still be our primary concern today. Warming yesterday may have allowed some additional bonding of these wind slabs to the icy bed surface. While they appear similar, these slabs are variable depths across the terrain. They proved firm and stubborn to human trigger yesterday however that doesn’t mean they are stable. We would expect an avalanche today to be medium to large in size, particularly in Moderate rated terrain. Again today’s problem makes it a relatively low probability, high consequence day. With the rising temperatures today spring hazards should being part of your travel decision making. The forecast temperature and solar gain for today will help move us toward a traditional spring snowpack. However, we have not reached this point yet so please continue to bring your avalanche gear and a mid-winter mindset.