Avalanche Advisory for Thursday, April 16, 2015

This advisory expires at 12:00 midnight.

Tuckerman Ravine has Low avalanche danger. Natural and human-triggered avalanches are unlikely. Huntington Ravine is under a General Advisory. You will need to do your own snow stability assessments when traveling in avalanche terrain in Huntington. A danger of falling ice exists, and will persist until it all comes down.

AVALANCHE PROBLEM: Cold temperatures returned to the mountain last night, helping to stabilize our snowpack. Freezing conditions help bond grains of snow together deeper in the snowpack and bridge over deep weak layers that may still exist. This leaves skier induced wet loose, also known as sluff, avalanches as our primary avalanche threat today. Steep slopes that have seen a lot of ski traffic generally have less of this type of problem. Areas that bake in the sun with no ski traffic have the greatest potential for a sizable sluff. The hazard of these heavy, wet piles of snow moving downhill comes from their ability to bulldoze you into bushes, rocks or over cliffs or to push your boards in expected directions.

OTHER HAZARDS: The typical spring hazards are beginning to show themselves.  Numerous areas of large ice have horizontal cracks forming and the Sluice ice, above Lunch Rocks, is already missing some chunks. Be aware of what is above you on a warm day and realize that eating lunch at Lunch Rocks puts you directly in the runout of large pieces of falling ice.  Today’s very warm temperatures will exacerbate this annual hazard. During this period of falling ice every year we do not recommend sitting at Lunch Rocks even though it may have a long tradition for you. The vast majority of icefall injuries over the past 50 years have occurred at Lunch Rocks also dubbed, “Icefall Rocks”.

The snow is slowly moving downhill as a unified mass and is pulling away from cliffs, creating crevasses. These may change quickly so anticipate them growing in size. Undermined snow is creating challenges for exiting the Bowl. While the Little Headwall is still skiable, there is open water both above and below. The best exit from the Bowl may involve walking to Connection Cache and possibly farther.

WEATHER: Once again sunny skies will rule with summit temperatures soaring to 40F, associated with winds increasing to from 40 to 60mph.  Tonight we will start a period of unsettled weather with mixed precipitation on the summits, potentially rain in avalanche terrain. This will continue Friday, and is currently forecast to persist on Saturday.  We’ll certainly get into this weekend weather forecast in tomorrow’s advisory and Weekend Update.  Until then enjoy the sun, wear your sunscreen, and keep spring hazards on the brain.

SNOWPACK: The near freezing conditions over the past couple of days helped to firm up and preserve our snow at Ravine elevations after last Friday’s rain and thaw. In Tuckerman Ravine, plenty of ski traffic has tested and compacted all our slopes and helped to ease our minds about wet slab avalanches. Being a generally cautious person, I wouldn’t leave my beacon, probe and shovel behind for lots of reasons.  Most of these are unlikely, but consider a large icefall or a subsurface meltwater blowout as an unusal, but not impossible, potential trigger. These are just of couple of reasons why we will continue to wearing our avalanche PPE through late spring.  As our snowpack melts, thin spots develop and firm or icy surfaces are exposed so be aware that an ice axe or self-arrest ski pole and crampons may be worthwhile weapons in your quiver.

Please Remember:

  • Safe travel in avalanche terrain requires training and experience. This advisory is just one tool to help you make your own decisions in avalanche terrain. You control your own risk by choosing where, when, and how you travel.
  • Anticipate a changing avalanche danger when actual weather differs from the higher summits forecast.
  • For more information contact the Forest Service Snow Rangers, the Mount Washington Volunteer Ski Patrol, or the AMC at the Pinkham Notch Visitor Center and Hermit Lake.
  • Posted 7:45 a.m. Thursday, April 16, 2015. A new advisory will be issued tomorrow.

Christopher Joosen, Snow Ranger
USDA Forest Service
White Mountain National Forest
(603) 466-2713 TTY (603) 466-2713

2015-04-16 print friendly

Avalanche Advisory for Wednesday, April 15th, 2015

This advisory expires at 12:00 midnight.

Tuckerman Ravine has Low avalanche danger. Natural and human-triggered avalanches are unlikely. Huntington Ravine is under a General Advisory. You will need to do your own snow stability assessments when traveling in avalanche terrain in Huntington. A danger of falling ice exists, and will persist until it all comes down.

AVALANCHE PROBLEM: Avalanche danger today is Low as the past five days have had a stabilizing effect on the snowpack. Warm temperatures during the day and colder temperatures at night trend towards making an isothermal snowpack. The ravine has just about reached this point, creating several days in a row of Low danger. The largest stability hazard we see for today is sluff piles (skier induced wet loose) moving downhill and slowly generating more mass, becoming large enough to carry a skier, rider or climber to an undesired location. If you are traveling above cliffs, managing this will be important.

OTHER HAZARDS: Hazards other than avalanches are beginning to rear their heads and are worth looking for as much, if not more, than unstable snow.  Numerous areas of large ice have horizontal cracks forming and the Sluice ice, above Lunch Rocks, is already missing some chunks. Be aware of what is above you on a warm day and realize that eating lunch at Lunch Rocks puts you directly in the runout of large pieces of falling ice.  During this period of falling ice every year we do not recommend sitting at Lunch Rocks even though it may have a long tradition for you.

The snow is slowly moving downhill as a unified mass and is pulling away from cliffs, creating crevasses that while may not eat you whole yet, are certainly big enough to swallow a ski. These may change quickly so anticipate them growing in size. Undermined snow is creating challenges for exiting the Bowl. While the Little Headwall is still skiable, there is open water both above and below. The best exit from the Bowl may involve walking to Connection Cache and possibly farther.

WEATHER: Another nice day is upon us, although just a hair cooler than yesterday, with summit temperatures climbing to the mid 20’sF. Sun will once again reign with winds from the NW increasing to 60, gusting to 70mph.  Tonight we will refreeze again falling into the teens locking up the mountain snowpack.  Thursday will see a slight warm up with more sun before trending towards some unsettled weather for Friday and Saturday.

SNOWPACK: The past several days of glorious weather has been pushing us quickly towards a classic spring snowpack.  Initially, some around the clock melting raised some concerns for wet slabs as we transitioned from a cold snowpack towards an isothermal one.  Freezing nights have eased the wet slab potential allowing for a slower transition that snowpacks like.  Lock up will happen again tonight with the coldest night of the week in store. Expect the snowpack to become more stable and firm before daytime heating softens the surface.  Crampons and an ice axe are a good addition to avalanche PPE. Many carry both microspikes for the approach and switch to crampons for steeper terrain.  This is smart thinking as microspikes are not crampons. Skiers and climbers who get an early start, or finishes late, may encounter conditions conducive to long sliding falls. Be wary of a frozen snowpack lock up late in the day which can happen remarkably quick.  Don’t get too greedy for “just one more run” as the late day shadowline rips towards you across the terrain.

Please Remember:

  • Safe travel in avalanche terrain requires training and experience. This advisory is just one tool to help you make your own decisions in avalanche terrain. You control your own risk by choosing where, when, and how you travel.
  • Anticipate a changing avalanche danger when actual weather differs from the higher summits forecast.
  • For more information contact the Forest Service Snow Rangers, the Mount Washington Volunteer Ski Patrol, or the AMC at the Pinkham Notch Visitor Center and Hermit Lake.
  • Posted 7:15 a.m. Wednesday, April 15, 2015. A new advisory will be issued tomorrow.

Christopher Joosen, Snow Ranger
USDA Forest Service
White Mountain National Forest
(603) 466-2713 TTY (603) 466-2713

2015-04-15

Avalanche Advisory for April 14, 2015

This advisory expires at 12:00 midnight.

Tuckerman Ravine has Low avalanche danger. Natural and human-triggered avalanches are unlikely. Huntington Ravine is under a General Advisory. You will need to do your own snow stability assessments when traveling in avalanche terrain in Huntington. A danger of falling ice exists, and will persist until it all comes down.

AVALANCHE PROBLEM: Avalanche danger today is Low as the past four days have had a stabilizing effect on the snowpack. Warm temperatures during the day and colder temperatures at night make an isothermal snowpack. The ravine has just about reached this point, creating several days in a row of Low danger. The largest hazard we see today is slough piles moving downhill and slowly generating more mass, becoming big enough to carry a skier or climber to an undesired location. If you are traveling above cliffs, slough management will be important.

OTHER HAZARDS: Hazards other than avalanches are beginning to rear their heads and are worth looking for as much, if not more, than unstable snow. The Icefall has horizontal cracks forming across it and the Sluice ice is missing chunks. Be aware of what is above you on a warm day and realize that eating lunch at Lunch Rocks puts you directly in the runout of large pieces of falling ice. The snow is slowly moving downhill as a unified mass and is pulling away from cliffs, creating crevasses that while may not eat you whole yet, are certainly big enough to swallow a ski. Undermined snow is creating challenges for exiting the Bowl. While the Little Headwall is still skiable, there is open water both above and below. The best exit from the Bowl may involve walking to Connection Cache and possibly farther.

WEATHER: Bluebird days on Sunday and Monday allowed countless skiers and climbers to enjoy warm spring snow. A cold front is currently moving through the region, having delivered freezing rain, ice pellets, rain, and hurricane force winds to the summit of Mount Washington during the night. As the day progresses and high pressure builds throughout the morning, clouds are forecasted to depart along with decreasing winds and steady temperatures.

SNOWPACK: Racers during the Inferno on Saturday experienced the result of a frozen saturated snowpack with rock hard surfaces galore. Sunday and Monday brought warm temperatures and the annual migration of spring skiers to Mount Washington. While temperatures during the nights stayed warm, last night’s freeze helped mitigate concerns we had about wet slab avalanches. With temperatures today and tonight remaining slightly colder than the previous days, expect the snowpack to become more stable, even firm in some areas. When traveling in avalanche terrain in this weather with snow conditions as they are, crampons and an ice axe are a good addition to avalanche PPE. Skiers and climbers who get early starts or late finishes may encounter conditions conducive to long sliding falls.

Please Remember:

  • Safe travel in avalanche terrain requires training and experience. This advisory is just one tool to help you make your own decisions in avalanche terrain. You control your own risk by choosing where, when, and how you travel.
  • Anticipate a changing avalanche danger when actual weather differs from the higher summits forecast.
  • For more information contact the Forest Service Snow Rangers, the AMC at the Pinkham Notch Visitor Center, or the caretakers at Hermit Lake Shelters or the Harvard Cabin.
  • Posted 8:30 a.m. Tuesday, April 14, 2015. A new advisory will be issued tomorrow.

Helon Hoffer and Jeff Lane, Snow Rangers
USDA Forest Service
White Mountain National Forest
(603) 466-2713 TTY (603) 466-2713

2015-04-14

Avalanche Advisory for Monday, April 13, 2015

This advisory expires tonight at 12:00 midnight.

All forecast areas of Tuckerman Ravine have Low avalanche danger. Natural and human triggered avalanches are unlikely except in isolated terrain features. Unstable snow may exist on isolated terrain features.

A General Advisory is currently issued for Huntington Ravine. We have stopped issuing daily avalanche forecasts for Huntington for the remainder of the season. You will need to do your own stability assessments when traveling through avalanche terrain. A danger of falling ice will begin to increase, along with other spring hazards, with the seasonal warm-up.  These hazards will persist until melt-out as we transition into early summer.

AVALANCHE PROBLEM: Loose wet avalanches are the primary threat today, with a remote possibility of wet slabs hanging in the shadows. The problems are being driven by yesterday’s warming, the mid-elevation warm band overnight, and today having some of the warmest temperatures we’ve had yet this season. Overall, avalanche activity is unlikely aside from loose wet sluffing in areas that saw few skiers or riders yesterday. The wet slab problem could create a large avalanche, but we feel the likelihood of this taking place is low enough to warrant a Low rating. However, the snowpack is not so stable at this point that I’d leave the beacon, shovel, and probe in the car.

We are also beginning to see weather conducive to the annual spring hazards, such as FALLING ICE, CREVASSE FORMATION, AND UNDERMINED SNOW. These have been kept in check by the cold temps so far this spring, but nevertheless, be alert for them today and in the coming weeks. The streambed from the floor of the ravine to the Little Headwall will have weak snow bridging over some deep water holes.

WEATHER: The previous few days have provided conditions that led toward the stabilization of the snowpack. Friday was a warm, wet and rainy day, followed by refreezing on Saturday. On Sunday, temperatures rose sufficiently to thaw the surface layers of the snow at all aspects and elevations. Last night, temperatures in the ravines stayed warm, without the ambient air temperature going below freezing. Things will only get warmer today – the summits will reach into the 40F range. Winds, starting the day fairly light, will increase in the afternoon along with some cloud cover coming before a precipitation event late today and tonight.

SNOWPACK: The melt-freeze cycle from the weekend did indeed help stabilize the snowpack, but we have unanswered questions as to how far down into the snowpack this effect can be found. Lingering in the back of my mind is the question of whether today’s heating will increase the potential for warm wet slabs fracturing over cold dry weak layers that may be buried deep enough to have not been stabilized by the melt-freeze action. If last night had gone below freezing, this would probably be off my radar. But the lack of a refreeze does have me wondering. Digging into the snowpack to look for how deeply the melt-freeze layer extends may not be a bad idea. Again, the likelihood is remote, but the fact is that Mount Washington is not a man-made environment. There is always some risk of the unexpected.

Note: The streambed leaving the bowl is not a recommended exit route. It has melted out to the point where you cannot ski down the stream until you are below the first aid cache. Both the skiers’ right and left side are also melted beyond the point where we recommend this way out (i.e. you’d be walking over rocks and trees). It is far easier to take off your skis/board, walk down the hiking trail 100 yards to the first aid cache, then begin skiing again from there. Be wary of undermined snow between the cache and the Little Headwall. The john Sherburne Ski Trail is still open to the bottom, but we are beginning to see a handful of bare patches and rocks emerging. Also, there are some large moguls throughout the trail.

Please Remember:

  • Safe travel in avalanche terrain requires training and experience. This advisory is just one tool to help you make your own decisions in avalanche terrain. You control your own risk by choosing where, when, and how you travel.
  • Anticipate a changing avalanche danger when actual weather differs from the higher summits forecast.
  • For more information contact the Forest Service Snow Rangers, the AMC at the Pinkham Notch Visitor Center, or the caretakers at Hermit Lake Shelters or the Harvard Cabin.
  • Posted 8:15 a.m. Monday, April 13, 2015. A new advisory will be issued tomorrow.

Jeff Lane, Snow Ranger
USDA Forest Service
White Mountain National Forest
(603) 466-2713 TTY (603) 466-2713

2015-04-13

Avalanche Advisory for Sunday April 12th, 2015

This advisory expires at Midnight.

All forecast areas of Tuckerman Ravine have Low avalanche danger. Natural and human triggered avalanches are unlikely except in isolated terrain features. Unstable snow may exist on isolated terrain features.

A General Advisory is currently issued for Huntington Ravine. We have stopped issuing daily avalanche forecasts for Huntington for the remainder of the season. You will need to do your own stability assessments when travelling through avalanche terrain. A danger of falling ice will begin to increase, along with other spring hazards, with the seasonal warm up.  These hazards will persist until melt-out as we transition into early summer.

AVALANCHE PROBLEM: Rain and warm temperatures induced intense melting and free water percolation deep into the upper snowpack on Friday.  This was followed by high winds and a cold front Friday night and Saturday, beginning the refreezing process from the surface down.  The resulting lock up has dramatically reduced the avalanche problem and hazard.  As temperatures increase today and winds fall, anticipate the potential for skier induced Wet Loose sluffing to occur.  This is particularly true in locations that have not seen any traffic or sluffing already and appear to be the most desirable steep S or SE facing slopes.  The greatest associated hazard with wet sluffing today will be the potential of entrainment and being dragged over things that you weren’t planning on like rocks or cliff bands.  If temperatures warm up significantly and penetrate deep, melting bonds in the upper snowpack, a sizable wet sluff has the remote potential to trigger a wet slab.  This is generally unlikely, but worth considering depending how the afternoon temperatures develop.

WEATHER: Temperatures have been holding rock steady in the mid teens F since yesterday.  The mercury will rise today, likely to break the freezing mark even on the higher summits.  Winds will fall from their current of 65mph (kph) to as low as 35mph (kph) from the NW under mostly sunny skies.  For those prepared it should be a fairly pleasant day to be in the mountains.

SNOWPACK: Surface snow took a beating on Friday due rain settlement channels and chunky wet sluff debris. Making turns across some of these runnels or wet debris will be challenging until things warm up significantly.  Expect today to be one of those classic mornings where waiting for a slight warm up and then getting onto S facing slopes to be way more enjoyable than running onto slopes facing toward the NE first thing this morning.  As mention above, think about skier induced sluffing in the near surface snow as connecting bonds melt into the afternoon.  This can be managed by using good sluff tactics allowing moving snow to go by giving it a wide berth.  If you are someone below a skier entering untouched snow consider this potential.  This probability will not be a widespread issue, but something to consider as the day warms up.  A more distant issue could be a wet sluff impacting a slope below inducing a wet slab to fail. This would likely need to be a sizable sluff coming over a cliff band to provide enough impact so this is fairly remote, but not impossible very late in the day.

OTHER HAZARDS:  The greatest hazard this morning and again very late in the day will be long sliding falls on the icy, refrozen snow. Ice axe and crampons are highly recommended for travel on angled terrain anywhere beyond mellow hiking trails. Microspikes or other traction devices along with ski poles are helpful to hike up from Pinkham to the base of the Ravines.  However they are NOT crampons and do not replace them, an ax and the skill to self-arrest in steeper terrain. We are seeing an increasing number of accidents in recent years because of people misunderstanding the limits of Microspikes.  Serious accidents and fatalities have resulted from this misperception.

The Lion Head Winter route remains the recommended east side route to the summit. It requires mountaineering skills and experience.  Skiing from the Ravine down the Sherburne ski trail to the parking lot is still possible.

Please Remember:

  • Safe travel in avalanche terrain requires training and experience. This advisory is just one tool to help you make your own decisions in avalanche terrain. You control your own risk by choosing where, when, and how you travel.
  • Anticipate a changing avalanche danger when actual weather differs from the higher summits forecast.
  • For more information contact the Forest Service Snow Rangers, the AMC at the Pinkham Notch Visitor Center, or the caretakers at Hermit Lake Shelters or the Harvard Cabin.
  • Posted 8:10.m. Sunday, April 12, 2015. A new advisory will be issued tomorrow.

Christopher Joosen, Snow Ranger
USDA Forest Service
White Mountain National Forest
(603) 466-2713 TTY (603) 466-2713

2015-4-12

Avalanche Advisory for Tuesday, March 31, 2015

This advisory expires tonight at 12:00 midnight.

All forecast areas of Tuckerman and Huntington Ravines have Considerable avalanche danger. Dangerous avalanche conditions exist. Natural avalanches are possible and human triggered avalanches are likely. Cautious route finding and conservative decision making are essential. The only exception to this is the Little Headwall in Tuckerman, which has Moderate avalanche danger. Natural avalanches are unlikely and human triggered avalanches are possible in this location.

AVALANCHE PROBLEM: New and developing wind slabs are the primary avalanche problem today. This hazard is already present but will be increasing through the morning. With the current and forecasted wind speeds and direction, all forecast areas will be on the receiving end of wind transported snow, creating dangerous wind slabs that may avalanche multiple times during this cycle. Hiking beyond the first aid cache at the entrance to Tuckerman will put you at risk of avalanches hitting you from up above.

WEATHER: Current visibility at Hermit Lake is limited to about 50 meters. This is from snow, blowing snow, and fog. Expect this to be the dominant weather pattern through the day. Since yesterday morning, we have received about 3” of 10-12% density snow. This snow event started with rimed particles and graupel, then became mostly non-rimed crystal types but with rimed dendrites and graupel still in the mix.

Today’s weather forecast includes up to another 2” of new snow. Most of this is expected to fall this morning. Although winds are expected to diminish this afternoon, you should be prepared for snow to continue loading into the ravines all day.

SNOWPACK: The most important snowpack information you will need to know about today is the rate of wind loading into the avalanche starting zones. Since you won’t easily get to these upper elevation locations where the slabs are developing, and you can’t see it visually, you’ll need to use other available information and your imagination to form a picture of what’s going on up high. This morning, slabs are likely developing quickly and potentially deeply.

In order to recognize the hazard, you don’t need to know much about potential weak layers or bed surfaces, but here’s my take on the problem. The ravines had a pre-existing instability problem that was demonstrated with multiple avalanches on Sunday. These slabs have had a couple days to settle down, but I don’t believe that’s sufficient to fully stabilize them. A very weak layer of snow over a crust was the problem on Sunday. This was not the case everywhere—some locations were wind scoured and stable. But the riming and graupel period at the start of the most recent snow with winds from a SW direction and lighter than they currently are makes me think that an easily triggerable weak layer may have formed over most aspects. Winds shifted to the W and slowly to the NW with increasing speeds, laying a denser slab on top of this weak layer. If areas have already avalanched, ongoing loading and reloading of the slopes will keep the hazard elevated.

Please Remember:

  • Safe travel in avalanche terrain requires training and experience. This advisory is just one tool to help you make your own decisions in avalanche terrain. You control your own risk by choosing where, when, and how you travel.
  • Anticipate a changing avalanche danger when actual weather differs from the higher summits forecast.
  • For more information contact the Forest Service Snow Rangers, the AMC at the Pinkham Notch Visitor Center, or the caretakers at Hermit Lake Shelters or the Harvard Cabin.
  • Posted 8:20 a.m. Tuesday, March 31, 2015. A new advisory will be issued tomorrow.

Jeff Lane, Snow Ranger
USDA Forest Service
White Mountain National Forest
(603) 466-2713 TTY (603) 466-2713

2015-03-31

Avalanche Advisory for Monday, March 30, 2015

This advisory expires tonight at 12:00 midnight.

Tuckerman Ravine has Considerable and Moderate avalanche danger. Sluice, Lip, Center Bowl, Chute and Lower Snowfields have Considerable avalanche danger. Natural avalanches are possible and human triggered avalanches are likely. Lobster Claw, Right Gully, Left Gully and Hillman’s Highway have Moderate avalanche danger. Natural avalanches are unlikely and human triggered avalanches are possible. The Little Headwall has Low avalanche danger. Natural and human triggered avalanches are unlikely.

Huntington Ravine has Moderate and Low avalanche danger. Central, Pinnacle, Odell, South and Escape Hatch have Moderate avalanche danger. Evaluate snow, weather and terrain carefully. North, Damnation and Yale have Low avalanche danger. Natural and human triggered avalanches are unlikely. Watch for unstable snow in isolated terrain features.

AVALANCHE PROBLEM: Wind Slabs developing today, in some areas on an already poor snow structure, are the primary problem. With the exception of the Lip, which was raked down to the bed surface yesterday, Considerable rated areas contain the largest expanses of older wind slab going into today’s weather event. This wind slab was reactive to human triggers yesterday and is most likely still reactive. South facing gullies in both Ravines, though still containing pockets of the older wind slab, benefitted from a period of settlement yesterday due to warming and, in Tuckerman, was also cut up by ski traffic.

WEATHER: Wintry weather continues as a cold front pushes through today bringing some moisture and wind to the region. The main weather factor affecting stability will be the wind. Currently, west winds in the 50 mph range are pushing some snow into east aspects. The wind is expected to pick to the 50-70 mph range later today. These wind speeds are the highest since roughly 6” of snow fell late last week which means that there is enough snow laying around higher terrain to provide the building blocks for new hard wind slabs. Light snow and snow showers through the afternoon hours may contribute 1-3” more snow to the slab building process.

SNOWPACK: Avalanche danger is starting out one rating lower in each forecast area that isn’t already rated Low. The above ratings are based on wind transported snow, plus 1-3” of new snow falling today, which will cause danger to rise.

A crown profile in the 50cm x 20m natural avalanche in the Lower Snowfields revealed that the failure layer of the slab was within soft (4F) snow and rimed snow particles. The overlying harder slab (1F) was softer than we often see due to the light winds that built it being only around 40 mph. This crown thickness and structure is very similar to that in the much larger Lip avalanche and is the same as you might find in other slopes and gullies, only in varying thicknesses and distribution.  In summary, signs of recent avalanche activity in the previous 24-48 hours are one red flag to consider today. Another is active wind loading, as evidenced by snow moving along the ground at the ridgetop and above treeline, A third is a small amount of new snow and a weather forecast that includes wind speeds capable of moving that snow and building wind slabs. It’s pretty hard to miss these signs today, so if you choose to enter avalanche terrain, do so very carefully and limit time spent in avalanche runouts or, better yet, avoid them entirely.

Please Remember:

  • Safe travel in avalanche terrain requires training and experience. This advisory is just one tool to help you make your own decisions in avalanche terrain. You control your own risk by choosing where, when, and how you travel.
  • Anticipate a changing avalanche danger when actual weather differs from the higher summits forecast.
  • For more information contact the Forest Service Snow Rangers, the AMC at the Pinkham Notch Visitor Center, or the caretakers at Hermit Lake Shelters or the Harvard Cabin.
  • Posted 8:16 a.m. Monday, March 30, 2015. A new advisory will be issued tomorrow.

Frank Carus, Snow Ranger
USDA Forest Service
White Mountain National Forest
(603) 466-2713 TTY (603) 466-2713

2015-03-30

Avalanche Advisory for Sunday, March 29, 2015

This advisory expires tonight at 12:00 midnight.

Tuckerman Ravine has Considerable, Moderate, and Low avalanche danger. Dangerous avalanche conditions exist. The Lip, Center Bowl, and Chute have Considerable avalanche danger. Natural avalanches are possible and human triggered avalanches are likely. The Sluice and Lower Snowfields have Moderate avalanche danger. Natural avalanches are unlikely and human triggered avalanches are possible. Lobster Claw, Right Gully, Left Gully, and Hillman’s Highway, and the Little Headwall have Low avalanche danger. Natural and human triggered avalanches are unlikely. Watch for unstable snow in isolated terrain features.

Huntington Ravine has Low avalanche danger. Natural and human triggered avalanches are unlikely. Watch for unstable snow in isolated terrain features.

AVALANCHE PROBLEM: Wind slabs are the primary avalanche threat today. The main driver behind the Considerable rating for some areas is the low drifting snow currently cascading down steep slopes. This slow loading has caused good-sized avalanches in the past, even on bluebird days like today. It is taking place in the Sluice as well, though as a slightly lesser rate. The Lower Snowfields contains snow with varying levels of stability. I expect the worst to be tight under the rock buttresses. Left Gully and Hillman’s have pockets of new snow loaded into isolated terrain features. Although posted at Low, they may contain unstable snow capable of producing an avalanche. It ain’t spring yet, folks, regardless of what the calendar says.

WEATHER: Blue skies will dominate today, but it will feel more like a nice day in February than the end of March. Expect temperatures below normal. Even south-facing slopes may not get enough heat to moisten the uppermost snow. Westerly winds around 30-40mph will have two noticeable effects. One is to generate additional wind loading, particularly low drifting snow in the center of Tuckerman. The other is to suck the heat away from the snow in south facing slopes, making it harder for the sun to soften the surface. Over the last four days, Mt. Washington has received about 7” of new light density snow, which is at the center of our avalanche concerns.

SNOWPACK: I wrestled with the ratings for Tuckerman today and decided on the higher rating of Considerable for locations where there currently is snow drifting down over the headwall. Today would not be the first time I’ve seen a seemingly small amount of loading trigger an avalanche. I’ll caution you all that as long as this is going on, you will want to be extra cautious. This means that even going into the floor of Tuckerman to access a Low rated area will put you at risk. If it shuts off completely, we’ll be left with a human trigger problem rather than a natural trigger problem. Although this isn’t ideal for recreation, it’s more manageable.

In Lobster, Right Gully, Left Gully, and Hillman’s, the majority of the surface snow is old and stable. However, there are locations where you may find unstable snow, such as the skiers’ left side of Left Gully or hard on the skiers’ left side of Hillman’s. Other examples may exist, too. You’ll need to be alert for these pockets, assess their stability, and determine whether or not you want to pass through them. You may also need to make a decision whether or not you want to be below someone who is making a similar decision!

Please Remember:

  • Safe travel in avalanche terrain requires training and experience. This advisory is just one tool to help you make your own decisions in avalanche terrain. You control your own risk by choosing where, when, and how you travel.
  • Anticipate a changing avalanche danger when actual weather differs from the higher summits forecast.
  • For more information contact the Forest Service Snow Rangers, the AMC at the Pinkham Notch Visitor Center, or the caretakers at Hermit Lake Shelters or the Harvard Cabin.
  • Posted 8:23 a.m. Sunday, March 29, 2015. A new advisory will be issued tomorrow.

Jeff Lane, Snow Ranger
USDA Forest Service
White Mountain National Forest
(603) 466-2713 TTY (603) 466-2713

2015-03-29

Avalanche Advisory for Saturday, March 28, 2015

This advisory expires tonight at 12:00 midnight.

Tuckerman Ravine has Considerable, Moderate and Low avalanche danger. The Chute has Considerable avalanche danger. Natural avalanches are possible and human-triggered avalanches are likely. The Sluice, Lip, Center Bowl, Left Gully, Hillman’s Highway and Lower Snowfields have Moderate avalanche danger. Natural avalanches are unlikely and human triggered avalanches are possible. Lobster Claw, Right Gully, and Little Headwall have Low avalanche danger. Natural and human triggered avalanches are unlikely. Watch for unstable snow in isolated terrain features.

All forecast areas of Huntington Ravine have Moderate avalanche danger. Natural are unlikely and human triggered avalanches are possible.

AVALANCHE PROBLEM: Wind Slab and Storm Slab are the primary concerns today with Dry Loose avalanches also on the list. 3.5” (8cm) of new snow in the past 2 days has created a variety of soft slabs in our terrain. Due to the low wind speeds, the new snow is piling up beneath steeper terrain and forming slabs just cohesive enough to create potentially dangerous slabs. Small avalanches could turn larger by entraining the surprising amount of low density snow laying around.

WEATHER: The Low pressure trough continues to feed clouds and moisture into the area. 1-3” (2.5 – 7.5cm) of new snow is expected today on very lights winds shifting to the North. Expect flat light at best and possibly denser fog to create some challenges for navigating and keeping eyes on the skier. It is likely that the overcast skies above the summit fog will limit incoming solar heating on southern aspects today, unlike yesterday.  The height and intensity of the spring sun is a factor this time of year and could conceivably have a positive effect on stability on these aspects again today. Quite a bit of warming occurred yesterday, in spite of the dense fog.

SNOWPACK: Currently, very low density snow is sluffing off steep terrain and contributed to these slabs. In Tuckerman, Chute holds the greatest amount of soft slab, with boot-top and deeper snow in and above the choke. The narrows of Left, as well as near and above the fork of Hillman’s, were also a concern yesterday. Cracking and increasingly deep snow lead experienced parties to turn around in both locations. 1” (2.5cm) of new snow on even lighter winds last night plus 1-3” more today will contribute to this problem. It is impressive how this paltry amount of snow piles up beneath steep terrain like cliff bands, ice bulges and sidewalls of gullies. Huntington is a mixed bag of Moderate. Greenhouse warming yesterday contributed to stability on south facing aspects so expect more stability concerns from Central to Escape Hatch with more stability from Yale to North.

Field time in Tuckerman confirmed that we still have a dynamic snowpack. Despite cold air temperatures, greenhousing conditions over the past several days have begun to drive heat into the upper 30-40 cm of snow, though the temperatures beneath are far from isothermal. Stability tests yesterday confirmed the new snow was well bonded to the hard surfaces but was slabbing up due to either surface heat gain, light wind effect or sluffing. The older bed surface was just barely negotiable without crampons (2-3cm boot penetration) yesterday but has refrozen more solidly this morning. Expect a slippery, dust on crust surface especially on southerly aspects unless heating occurs. Deeper in the snowpack pooled graupel and a thick, decomposing melt/freeze crust failed cleanly but are well bridged and not much of a concern for the time being.

Please Remember:

  • Safe travel in avalanche terrain requires training and experience. This advisory is just one tool to help you make your own decisions in avalanche terrain. You control your own risk by choosing where, when, and how you travel.
  • Anticipate a changing avalanche danger when actual weather differs from the higher summits forecast.
  • For more information contact the Forest Service Snow Rangers, the AMC at the Pinkham Notch Visitor Center, or the caretakers at Hermit Lake Shelters or the Harvard Cabin.
  • Posted 8:23 a.m. Saturday, March 28, 2015. A new advisory will be issued tomorrow.

Frank Carus, Snow Ranger
USDA Forest Service
White Mountain National Forest
(603) 466-2713 TTY (603) 466-2713

2015-03-28

Avalanche Advisory for Friday, March 27, 2015

This advisory expires tonight at 12:00 midnight.

Tuckerman and Huntington Ravine have CONSIDERABLE avalanche danger. Careful snowpack and weather evaluation, cautious route-finding and conservative decision making are essential.

 AVALANCHE PROBLEM: We are starting out this morning with a Moderate avalanche danger. 3.1” (7.8cm) of new snow on the summit, with probably just a little less in the Alpine Garden and forecast area, and another trace to 2” (TR-5cm) forecast today, creates the threat of Storm Slab avalanches. A small crown line was visible this morning in Center Bowl which indicates that this new storm snow is cohesive enough to avalanche. That said, a highly skilled user could negotiate this hazard with careful terrain management choices with a careful eye on wind, new snow and the snowpack. Wind Slab may become your greatest concern should you choose to venture into avalanche terrain today. Based on forecast wind speeds, these wind slabs are likely to be smaller than we ordinarily see but will probably form high in our start zones. Either type of avalanche could entrain enough snow to carry you and bury you should you be caught. Remember that while the new snow is “right-side up”, it is resting on a firm bed surface which probably only softened a little bit from yesterday’s brief warming and is refreezing as I write this. This firm surface could make escaping an avalanche with your ski edges or self-arrest tool difficult. If wind does not ramp up today, the Moderate avalanche danger formed by existing Storm Slabs, plus a trace to 2” (TR-5cm) more snow, sluff piles beneath steep terrain and some small wind slabs are what you will have to manage.

WEATHER: 3.1” (7.8 cm) of snow and snow pellets (graupel) were recorded on the summit yesterday afternoon and evening on light winds around 30 mph (50km/h). About 2.4” (6cm) of new snow, starting out as mixed wet particles and freezing rain, fell at Hermit Lake. In all likelihood, 2- 3” of 10% snow is available for transport by the wind into our forecast area from the Alpine Garden area above the Ravines. Both Ravines are moving in and out of the clouds.  Challenging visibility will be the story all day. Temperatures have already dropped to the mid-teens Fahrenheit. NW winds will shift to the West, blowing 15-30 mph (25-50km/h) with gusts to 45 mph (70km/h).

SNOWPACK: Currently the snowpack at Hermit Lake is “punchy” in a few areas. This tells me the crust beneath the new snow is beginning to refreeze following yesterday’s warmup to 44F (7C) at this elevation. Limited visibility this morning only gave us a brief glimpse of Tuckerman Ravine but we did gather some information. The steepest terrain like the narrows of Sluice by the water ice, and the Lip, and probably many other similar areas, appear to have gone through a loose or point release avalanche cycle with debris just beneath the start zones and older, textured surfaces currently visible. The small slab release beneath the ice in Center Bowl showed a crown line approximately 8-10m wide by 10-12 cm thick. It is hard to say whether it released spontaneously or was triggered by a sluff off of the ice bulge above. In any case, the slab character is not typical of other areas we’ve seen this morning. The snow at Hermit Lake is only barely cohesive, and remarkably dry…it takes some effort to make a marginally solid snowball.

Tomorrow will defy expectations for spring conditions again. Expect similar conditions as today so remember to bring your good judgment, avalanche rescue gear and well-honed decision making skills if you are headed this way for the weekend. And remember that a back-up plan to skiing or climbing in steep avalanche terrain should be a desirable alternative that is acceptable to the group.

Please Remember:

  • Safe travel in avalanche terrain requires training and experience. This advisory is just one tool to help you make your own decisions in avalanche terrain. You control your own risk by choosing where, when, and how you travel.
  • Anticipate a changing avalanche danger when actual weather differs from the higher summits forecast.
  • For more information contact the Forest Service Snow Rangers, the AMC at the Pinkham Notch Visitor Center, or the caretakers at Hermit Lake Shelters or the Harvard Cabin.
  • Posted 8:49 a.m. Friday, March 27, 2015. A new advisory will be issued tomorrow.

Frank Carus, Snow Ranger
USDA Forest Service
White Mountain National Forest
(603) 466-2713 TTY (603) 466-2713

2015-03-27 print version