Advisory – Past Fifteen Days

Avalanche Advisory for Monday, March 27, 2017

Today, wind slab will be stressed by additional precipitation and will possibly become saturated, creating wet slab and wet loose avalanche problems. The hazard will increase through the day as the amount of precipitation and temperature increases. This avalanche problem is notorious for its unpredictability and today will be no exception. Looking at the amount of water arriving today, it will likely be at most half an inch by midnight. This is not a huge amount of liquid and combined with the ambient air temperature, may not be enough to overwhelm the cohesiveness of the slab. The areas of greatest concern today are rated Considerable due to the larger possible size of an avalanche as well as the steepness of the slope. Moderate rated areas could have similar but smaller avalanches that could be equally dangerous depending on the terrain.

Avalanche Advisory for Sunday, March 26, 2017

Today’s avalanche problem will be driven by heating of the snow by sunshine and warm temperatures. Areas with the most soft wind slabs like Sluice and Lip in Tuckerman Ravine and Central in Huntington have the greatest potential to produce a human-triggered avalanche. As sun warms the snow this morning, the soft snow will become heavy, begin to saturate with water and produce loose wet sluffs and possibly wet slabs large enough to push you around. Today’s warming is not extreme enough to create large wet slabs but skiing will become challenging in the variable “mashed potato” snow and firmer old crust. Areas of old, hard icy snow in Tucks are not widespread but can be found in Left Gully and low in the Chute. This icy surface is generally discontinuous and will create some travel challenges going up or down. Hillman’s Highway has a mix of firmer slabs and softer slabs so expect heavier snow there as well as things heat up.

Avalanche Advisory for Saturday, March 25, 2017

Wind slabs formed from 7” of new snow on west winds in the past 24 hours keeps the likelihood of human-triggered avalanches in the considerable range. Wind velocities were ideal for loading slopes with an east facing aspect. These slabs are likely to be soft enough to be sensitive to a human-trigger and may be large enough to carry you downhill and possibly bury. Though the threat of natural avalanches is by and large past, the likelihood of human-triggered avalanches makes careful evaluation of snowpack, cautious route-finding and conservative decision making essential. Dense summit fog is currently hampering our ability to make observations so consider each avalanche path to be loaded and waiting for a trigger until you confirm otherwise. Forecast areas with a moderate rating are solidly in that range so assess snow and terrain carefully. A disparity in recorded snowfall between the summit and our forecast elevations gives us some uncertainty about the size of potential avalanches today but this shouldn’t change you travel precautions in avalanche terrain.

Avalanche Advisory for Friday, March 24, 2017

We are starting out the day with human triggered avalanches being possible only in the steepest portions of Sluice, Lip and Center Bowl, and possibly Central Gully in Huntington, with human-triggered avalanches being unlikely in all other forecast areas due to the strength or lack of continuity of existing wind slabs. East facing forecast areas, particularly upper start zones, will be in the bullseye for developing these wind slabs this afternoon while other aspects will become crossloaded. New snow on increasing west winds will add a bit of stress to existing wind slabs, but the primary problem will be within the new snow. Increasing temperatures and increasing wind speeds will set the stage for increasingly dense slabs over soft new snow falling later this morning. As the day wears on, small to medium sized natural avalanches will become possible in considerable rated terrain. Moderate rated terrain could generate smaller human triggered avalanches and even some small, loose dry natural avalanches in the steepest areas. Reduced visibility and increasing hazard will make conservative terrain choices a good idea today.

Avalanche Advisory for Thursday, March 23, 2017

Wind slabs remain the primary avalanche problem. Low rated areas are a mix of scoured old surface with areas of heavily wind sculpted and eroded sastrugi snow. You may encounter unstable snow in isolated areas but options to travel on the stable, icy old surface will be plentiful in low rated areas. Stubborn and firm wind slabs may provide easier travel but will also harbor a low probability risk of triggering a stubborn, hard wind slab. Moderate rated areas contain much more smooth wind slab. This typically means that the area was dominated by deposition throughout the wind and snow event. Anticipate firm, continuous thicker slabs in these areas that will also be stubborn and fairly strong but with weaker layers of new snow beneath that bring a higher probability of fracture and failure. As is often the case, these slabs have good bridging power but the possibility of finding and triggering a thin spot in the slab remains. In general, our moderate rated areas are at the lower end of the moderate rating while low rated areas are nudging towards moderate unless you are on the icy, old surface.

Avalanche Advisory for Wednesday, March 22, 2017

This advisory expires at Midnight. Huntington and Tuckerman Ravine have CONSIDERABLE and MODERATE avalanche danger. In Tuckerman, Sluice, Lip, Center Bowl, and Chute have Considerable avalanche danger. Central, Pinnacle, and Odell Gullies in Huntington Ravine have Considerable avalanche danger. Natural avalanches are possible and human-triggered avalanches are likely. Dangerous avalanche conditions exist. Careful snowpack evaluation, […]

Avalanche Advisory for Tuesday, March 21, 2017

This morning, areas of hard wind slab will be encountered on north facing aspects. East and south facing slopes received sun and warmth yesterday that refroze last night and should present more of a long sliding fall hazard than avalanche problem this morning. Snow showers through the day may bring up to 2” of new snow with increasing W and NW wind. Pockets of wind slab will develop, particularly in sheltered areas of westerly wind, creating and increasing avalanche hazard as the day progresses. These pockets will likely be isolated due to the small amount of incoming snow and soft due to lighter wind speeds.

Avalanche Advisory for Monday, March 20, 2017

Our primary avalanche problem today will be caused by the breakdown of strength in existing wind slabs due to heating of the snow. These firm slabs have been strong enough to bridge over soft weak layers beneath and resist failure but today’s heating will be the first real test since their formation. Today’s ratings are based on slope aspect as well as the size and continuity of the slabs. Lobster Claw and Right Gully along with North Gully in Huntington have much less snow in them or have already seen heating during yesterday’s mid-day warmth. As a result, those slopes are less likely to avalanche due to a human-trigger than nearby slopes with a moderate rating. When you begin to sink in to your boot tops or when it becomes easy to make a snowball on a steep slope, it will be time to reevaluate whether you should be travelling in that terrain.

Avalanche Advisory for Sunday, March 19, 2017

Wind slab remains our avalanche problem today. Primarily formed Wednesday night and Thursday, this firm slab exists over much of our terrain, is largest in Sluice, Lip, and Center Bowl, and can be found in pockets of varying size on most aspects. Bonds between this layer and the underlying snow surface have gained strength over the past several days. While resistant to a human trigger, the resulting avalanche could be large. This possibility, albeit unlikely, certainly remains and demands respect in your travel decisions.

Avalanche Advisory for Saturday, March 18, 2017

It’s still winter up here! The recent Nor’easter, followed by a significant wind event, has maintained a dynamic snowpack in the ravines. A strong and supportable rain crust formed several weeks ago is present in the snowpack in essentially all of our terrain. Moderate winds from nearly every direction during and after the Nor’easter created a layering of varied density wind slabs, much of which were subsequently wiped out by stronger West to Northwest winds Wednesday night and Thursday. Areas lee of these winds, particularly Center Bowl, Lip, and Sluice, hold a firm, pencil to one finger hardness wind slab of varied thickness from an inch to several feet. Other areas hold pockets of a similarly deposited snow. These slabs will be stubborn to trigger and offer fairly good conditions for travel, still demanding cautious travel practices. The old rain crust is the primary surface where this recently deposited snow does not exist. This crust is quite stable but is smooth and icy and would easily allow a long sliding fall.

Avalanche Advisory for Friday, March 17, 2017

Densely packed, wind transported snow has built wind slab over a softer layer of loose snow over the past 48 hours. Due to the potential size of these slabs and the challenges posed by avoiding them, they are the primary avalanche problem in moderate rated areas today. While these slabs may propagate a crack, the strength of the firm slab above makes these slabs very stubborn. This type of wind slab is most concentrated in areas in the lee of a northwest wind such as just beneath the ice in Center Bowl, below the rollover in the Lip and high in Chute. Central Gully appears to have an area of this firm slab, as well. In addition to the primary firm, wind slab problem, softer pockets of wind slab exist here and there in both Ravines but are much smaller and discontinuous so shouldn’t pose too much of a challenge to avoid. Hillman’s and Left Gully are on the low end of the moderate rating due to more areas being scoured. Evaluate snow and terrain carefully today.

Avalanche Advisory for Thursday, March 16, 2017

This advisory expires at Midnight. Huntington Ravine and Tuckerman Ravine have CONSIDERABLE avalanche danger. Natural avalanches are possible and human-triggered avalanches are likely. Dangerous avalanche conditions exist. The only exception to this rating is Little Headwall which has Low avalanche danger. A combination of small wind slabs, ice bulges and open water exist there. AVALANCHE […]

Avalanche Advisory for Wednesday, March 15, 2017

This advisory expires at Midnight.   Huntington Ravine has CONSIDERABLE and MODERATE avalanche danger. Central, Pinnacle, Odell, South and Escape Hatch have Considerable avalanche danger. Natural avalanches are possible and human-triggered avalanches are likely. Danger avalanche conditions exist. Careful snowpack evaluation, cautious route-finding, and conservative decision-making are essential. North, Damnation, and Yale Gully have Moderate […]

Avalanche Advisory for Tuesday, March 14, 2017

The incoming Nor’easter will create Wind Slab in avalanche terrain. Wind direction will dictate where this problem forms and to what degree loading happens with increasing hazard through the day. Light south winds this morning will load north-facing slopes during the morning. As the wind shifts to the east and increases in speed, north-facing as well as south-facing slopes will see cross-loading. While our forecast areas do not include slopes with a western aspect, west-facing slopes outside of our forecast area will see significant wind loading as the wind shifts to the east. As the wind direction continues its move toward the north, south-facing slopes will see the most loading with cross-loading finally bringing snow to east-facing slopes. As this shift to the N and NW takes place, areas in Tuckerman and Huntington Ravine may exceed the Considerable rating after this advisory expires at midnight.

Avalanche Advisory for Monday, March 13, 2017

Wind Slab is creating the avalanche hazard today. Today, the danger will remain constant as the forecast weather will not have an impact on the areas of concern or the snowpack as a whole. The largest wind slab in our terrain currently sits just under the rollover of the Tuckerman Headwall with the largest pocket existing in the Lip. This can be identified from afar by its smooth appearance and cleanness when compared to the dirty looking, textured old surface. This old surface is firm and will create the potential for long, sliding falls, something to keep in mind when moving around the mountain.