Avalanche Advisory for Sunday, December 21, 2014

This advisory expires tonight at 12:00 midnight.

Tuckerman Ravine has MODERATE and LOW avalanche danger. The Sluice, Lip, Center Bowl, and Chute have Moderate avalanche danger. Natural avalanches are unlikely and human triggered avalanches are possible. Evaluate snow and terrain carefully to identify heightened avalanche conditions and features of concern. All other forecast areas have Low avalanche danger where natural and human triggered avalanches are unlikely. Watch for unstable snow in isolated terrain features.

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

AVALANCHE PROBLEM: The wind slab leftover from Thursday’s loading event is the primary threat today. This includes deeper sluff piles that have the tendency to act as areas of deeper slab and can harbor instabilities while more shallow locations move slowly toward stabilization.

WEATHER: In addition to being National Look on the Bright Side Day, today is the winter solstice, the first day of winter, and the shortest day of the year. With light winds and seasonable winter temperatures, there will be little weather-related movement in our avalanche danger either toward stability or instability. Yesterday was warm and sunny so there was likely some stabilization taking place in the upper layers of the snowpack. However, the sluff piles and slabs that we have concerns about tend to be deeper than the extent to which solar gain and warm temperature would have had a strong stabilizing effect.

SNOWPACK: Despite this year’s winter getting off to a good start, we are still looking at a very early season snowpack. In the ravines this is marked by intense spatial variability, broken and discontinuous snowfields, and large expanses of exposed rocks that should make you think about your travel route and its potential consequences in the event of a slide or fall. In Thursday’s avalanche cycle, multiple avalanches occurred in a wide variety of locations. Some were well outside of the “normal” avalanche paths, e.g. in Huntington to the east of North Gully and a small snow slope high above Diagonal. This should raise your hackles about any small pocket that didn’t release.

Solar gain and warmth yesterday likely had stabilizing effect, especially on slopes with a southerly aspect. However, we are reluctant to lower the ratings in many locations due to the depth of instabilities, particularly in sluff piles, may have prevented the solar energy from truly eliminating the weaknesses. There is a good chance you could be traveling on snow that has good stability, only to very quickly move into deeper slab with worse stability. This is where your ability to read the terrain and evaluate the snow becomes critical.

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 8:00 a.m. December 21, 2014. A new advisory will be issued tomorrow.

Jeff Lane, Snow Ranger
USDA Forest Service
White Mountain National Forest
(603) 466-2713 TTY (603) 466-2856

2014-12-21

Avalanche Advisory for Saturday, December 20, 2014

This advisory expires tonight at 12:00 midnight.

Tuckerman Ravine has MODERATE and LOW avalanche danger. The Sluice, Lip, Center Bowl, Chute and Left Gully have Moderate avalanche danger. Natural avalanches are unlikely and human triggered avalanches are possible. Evaluate the snow and terrain carefully to identify heightened avalanche conditions and features of concern. All other forecast areas have Low avalanche danger where natural and human triggered avalanches are unlikely. Watch for unstable snow in isolated terrain features.

Huntington Ravine has MODERATE and LOW avalanche danger. North, Damnation, Yale, Central and Pinnacle have Moderate avalanche danger. Natural avalanches are unlikely and human triggered avalanches are possible. Evaluate the snow and terrain carefully to identify heightened avalanche conditions and features of concern. Odell, South and the Escape Hatch have Low avalanche danger where natural and human triggered avalanches are unlikely. Watch for unstable snow in isolated terrain features.

AVALANCHE PROBLEM: Wind slab is our primary avalanche concern today. Thursday’s snow and loading winds that created new slabs continue to be our #1 issue.  A number of these slabs naturally avalanched on Thursday and partially reloaded that evening. The reloaded areas and slabs that did not avalanche are now about 30-36 hours old and we have not received new appreciable loading since winds died off late Thursday night. These slabs vary tremendously in depth, weakness, and size. Expect a constant changing condition and stability of the snowpack.

WEATHER: Yesterday’s low winds and moderately cool temperatures will continue this weekend becoming even more comfortable over the next 48hours.  Clear skies today may see a bit of clouds according to forecasts, but the low wind speeds falling to 10mph (16kph) and temperatures between 25-27F (-4 to -3C) degrees will make it quite pleasant to be sporting in the mountains. On Sunday it won’t be quite as nice with a slight chance of snow showers, a bit cooler, and winds up to 35mph, but clearly still a reasonable winter day.  This weekend’s weather should not add new avalanche concerns to our present conditions.
SNOWPACK: Frank and I got into Tuckerman yesterday and battled with a shifting cloud deck that pulled the veil back and forth over the terrain.  This gave us some visibility and then took back away.  We were able to see natural avalanche activity results out of the Lip, several locales in the Center Bowl, the Chute and Left Gully.  Some of these areas have reloaded by sluffing from steep terrain above and wind transported snow.  Other areas that were exposed to high NW winds, gusting regularly to 85mph (136kph) and peaking at 98mph (157kph) on Thursday, have been eroded sending crystals down into the trees. You will find an intense amount of variability as you move across the terrain. Expect to find a vast variety of snow stability so it will be important to choose assessment techniques that you can do quickly so you can perform them often.  Do not be happy with just one stability test, the variability in slabs dictates doing assessments frequently. In Tuckerman, we decided there was certainly enough concern to rate some areas at Moderate. With that said, an experienced user with avalanche knowledge should be able to pick out a route that links stable areas and islands of water ice and rock due to clear visual clues and clear sky conditions.  This is true if you are flexible with your route choices as some areas in the Ravine have less concerns to mitigate than others.  Pockets of slab near the Lip, under the Headwall ice, and above the fracture in the Chute are a few example of places to avoid.  In Huntington, this can be more difficult because your route choices become more limited in narrow gullies.  Again, the visibility today should allow you to spend some time picking out clues that will help your route decisions.  Certainly be prepared with rock and ice gear and lace up areas if you find yourself in unstable snow that you didn’t avoid through your pre-planning.  If you look closely you will see avalanche debris in many places and we believe most of the Huntington gullies sluffed or slab avalanched during this last cycle. As mentioned yesterday, be cautious of the bluebird day mentality. Beautiful days often find us enjoying our experience so much we avoid looking for hazards.  This leads us to fall into heuristic traps and drawing us in deeper into risk than we would if we were focused.

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 8:19 a.m. December 20, 2014. A new advisory will be issued tomorrow.

Christopher Joosen, Snow Ranger
USDA Forest Service
White Mountain National Forest
(603) 466-2713 TTY (603) 466-2856

2014-12-20

Avalanche Advisory for Friday, December 19, 2014

This advisory expires tonight at 12:00 midnight.

Tuckerman Ravine has CONSIDERABLE and MODERATE avalanche danger. The Sluice, Lip, Center Bowl, Chute and Left Gully have Considerable avalanche danger. Natural avalanches are possible and human triggered avalanches are likely. Careful snowpack evaluation, cautious route-finding and conservative decision making are essential. All other forecast areas have Moderate avalanche danger. Natural avalanches are unlikely and human triggered avalanches are possible.

Huntington Ravine has CONSIDERABLE and MODERATE avalanche danger. Central, Pinnacle, and Odell Gullies have Considerable avalanche danger. Natural avalanches are possible and human triggered avalanches are likely. Careful snowpack evaluation, cautious route-finding and conservative decision making are essential. All other forecast areas have Moderate avalanche danger. Natural avalanches are unlikely and human triggered avalanches are possible.

AVALANCHE PROBLEM: Wind slab is our primary avalanche concern again today. New snow and increasing wind speeds yesterday created hard wind slab in many areas. Where these wind slabs exist, they are likely to be hard, fairly thick and capable of propagating a crack on a slope above you. In other areas more sheltered from the strongest NW winds, softer Storm Slabs mixed with the wind slabs may also present a problem. Travel very carefully to avoid these unstable slabs as well as the paths and terrain traps beneath them.

WEATHER: Visibility today, though improving, will be hit or miss as remnants of this last low pressure system clear out. Temperatures will rise to around 20F (-7C) with light to moderate wind from the north in the 25-35 mph (40-55 kph) range. Gusts, potentially to 45 mph (75 kph), will keep things cool but should allow for a decent summit day. Don’t forget that we are approaching the shortest day of the year with around 9 hours of daylight with which to get things done. Sunset is at 4:07 pm.
SNOWPACK: Yesterday snowfall rates continued to impress us adding 6+” (15+cm) by noon, totaling 16.6″ (42cm) for the storm event.  Wind speed increased from the NW during the early morning hours on Thursday and ramped up over several hours moving snow from the alpine zone, mixed with new snowfall, into aspects with an eastern component.  Undoubtedly some crossloading occurred on slopes perpendicular to the prevailing NW direction.  We believe new slab density increased as wind speeds climbed through daylight peaking around 6pm creating an unstable snowpack with dense over lighter slabs.  High volumes of snow were transported into most forecast areas creating a peak instability more than likely close to the twilight hours. Velocities dropped all night to a current of 18mph.  As winds fell back down below about 50mph around 10pm, the vast majority of loading shut down.  This information has us less focused on natural avalanche activity, but based on the cold temperatures and short duration for natural settlement humans have a possible to likely chance of triggering slab avalanches. Expect slab densities and instability to change depending on whether or not slopes were exposed to high NW winds. You may start ascending on heavily wind scouring locations down low and then move into much lighter and unstable slabs as you approach protected terrain features.

Both Ravines are still encapsulated in clouds so we are unable to verify where avalanche activity occurred or what forecast areas received more snow than others. However, historically the locations posted at Considerable today receive the most volume, harbor higher slab instabilities, and require more caution from weather events similar to the last 48 hours.  We expect clouds to begin clearing soon allowing us to get into the terrain for new data collection that will get posted in the Weekend Update late in the afternoon.  In the mean time expect cold slabs to be unstable and hold the ability to propagate a fracture.  With bluebird days approaching with light winds watch yourself and the heuristic traps we can fall into when we are basking in what appears to be an “unbelievably awesome” day. Anticipate lingering instability in the high mountains this weekend.

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 7:50 a.m. December 19, 2014. A new advisory will be issued tomorrow.

Frank Carus/Christopher Joosen, Snow Rangers
USDA Forest Service
White Mountain National Forest
(603) 466-2713 TTY (603) 466-2856

2014-12-19

 

Avalanche Advisory for Thursday, December 18, 2014

This advisory expires tonight at 12:00 midnight.

Tuckerman Ravine has HIGH and CONSIDERABLE avalanche danger. The Sluice, Lip, Center Bowl, Chute and Left Gully have High avalanche danger.  Very dangerous avalanche conditions exist.  Natural avalanches are likely and human triggered avalanches are very likely. All other forecast areas have Considerable avalanche danger. Dangerous avalanche conditions exist.  Natural avalanches are possible and human triggered avalanches are likely.

Huntington Ravine has HIGH and CONSIDERABLE avalanche danger. Central, Pinnacle, and Odell Gullies have High avalanche danger.  Very dangerous avalanche conditions exist.  Natural avalanches are likely and human triggered avalanches are very likely. All other forecast areas have Considerable avalanche danger. Dangerous avalanche conditions exist.  Natural avalanches are possible and human triggered avalanches are likely

AVALANCHE PROBLEM: Wind Slab today will create widespread avalanche hazard in both ravines. A strong northwest wind will continue to grow in velocity and with it, Wind Slab will grow in size. Areas rated High are likely to avalanche naturally at some point today due to the weak layer, comprised of yesterday’s new snow. Very dangerous avalanche conditions will exist today and travel in avalanche terrain or onto the floor of either Ravine is not recommended. This includes the area around Lunch Rocks, the Tuckerman Ravine trail and the Fan in Huntington Ravine. Our avalanche paths survived the recent warmup and are large enough to generate avalanches which could easily bury and kill a person. Some forecast area avalanche tracks are certainly less developed but are still capable of producing a dangerous avalanche.

WEATHER: Forecasted NW wind with speeds today in the 50 mph range, gusting to 85 mph, will be ideal for loading our slopes and gullies with snow. Snow will taper to snow showers this afternoon and will continue to add to the snow available for wind loading. Visibility will be strongly diminished through most of the day due to this classic weather pattern that frequently comes with the passage of a Low pressure system. Freezing fog will further hamper visibility through the day. Some clearing tomorrow will allow for snowpack assessment, but anticipate elevated avalanche danger tomorrow as well.

SNOWPACK: Yesterday was a good example of how important it is to stay on your toes and make decisions based on new information from Mother Nature.  We had an uneasy feeling about the weather forecasts, hence the discussions about an increasing avalanche danger if weather differs from forecasts.  Sure enough, by 1045 am Wednesday morning between 6-7” (15-18cm) had fallen from a SE direction, more than the entire 24 hour forecast.  As snow continued, adding up to 9.5” (24cm) of 9.9% density by midnight, the avalanche forecast remained accurate because the forecasted wind increase occur remaining in the teens mph.  This is all changing as current weather screams avalanches!  Since midnight snow has continued and is expected to give us another 2-4”, giving the alpine zones about a foot (30cm) for the ramping NW winds to transport.  Overnight NNW wind speeds in the 40’s began to move snow into the ravine, but over the past several hours gusts are into the 60’s from the NW.  Velocities are expected to increase to 80-85 mph today which will move large volumes of snow into eastern aspects.  This is a fairly straight forward, watch out situation.  We expect natural avalanche activity in our forecast areas to be between possible and likely.  Building winds should develop slabs of increasing density over the low density layer from yesterday afternoon.  Slabs will develop with cold snow that fell between temperatures of 25 and 28F Wednesday morning to the current of 12F.  Certainly a day to give the terrain a wide berth. We’ll stay out of the terrain today, but look forward to assessing conditions tomorrow if the hazard decreases for a good Weekend update Friday afternoon on www.mountwashingtonavalanchecenter.org

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 7:45 a.m. December 18, 2014. A new advisory will be issued tomorrow.

Frank Carus/Christopher Joosen, Snow Rangers
USDA Forest Service
White Mountain National Forest
(603) 466-2713 TTY (603) 466-2856

2014-12-18

Avalanche Advisory for Wednesday, December 17, 2014

This advisory expires tonight at 12:00 midnight.

All forecast areas of Tuckerman and Huntington Ravine currently have Low avalanche danger. Natural and human triggered avalanches are unlikely. Watch for unstable snow in isolated terrain features which may be capable of producing small avalanches.

AVALANCHE PROBLEM: Today’s avalanche problem #1 will be small Wet Slabs. This will depend greatly on the timing of the temperature drop and if  we receive rain before the forecasted mixed precipitation and snow set it later today.  Problem #2 are the lingering pockets of Wind Slab that have been hanging on in completely shaded gullies that don’t see direct solar effect.  I wouldn’t quite call them persistent, but they are getting a little long in the tooth compared to the secondary wind slab problem with new snow expected today.  The timing and accumulation of new snow is critical and the most important issue to watch today. A rating of Low danger is the most appropriate assignment to both Ravines, but it includes the possibility for unstable snow in isolated terrain features or in extreme terrain. Today will also be dynamic with changes occurring to the snowpack……read on for more insight.

WEATHER: Yesterday witnessed a pretty interesting inversion around the beltline of Mount Washington. As winds shifted to the SW around 3pm the temperature peaked on the summit to just shy of 36F.  The Ravines pushed even higher due to ample sun, but below Hermit Lake in the undercasted clouds it remained below freezing.  As already mentioned today will be dynamic.  A total expected water equivalent (QPF) of 0.4-0.5″ is forecasted by very late tonight.  A wintry mix should transition to snow after lunch time with the mercury drop and continue into Thursday delivering 3-6″ (7.5-15cm) by dawn. Anticipate the potential for some rain early this morning.

SNOWPACK: Yesterday the solar gain continued to drive heating down into the snow pack.  We found the differences of a slight aspect change to be a remarkable player in how deep you could find wet snow.  As you would expect, the S facing slopes were far more gloppy, wet, and harder to deal with when traveling than N facing areas.  Even with fairly warm temperatures close to 40F, areas completely shaded remained cold and could actually harbor some propagation potential.  This threat is minimal, but worthy to remember. As the temperature drops the current snowpack is moving towards strength as free water refreezes from the surface down.  The issue of wet grain depth based on aspect will be a player in the speed of a complete lock up.

The main thing to pay attention to today is exactly what form precipitation takes and when transitions occur.  Forecasts are somewhat conflicting with one showing a frozen mix moving to rain before a late snow change and another showing mixed precipitation moving to snow. Be prepared for a variety of changing forms today.  If we get rain for a period I would be most concerned about the isolated cold pockets of snow that still exist, such as in North gully or perhaps Pinnacle.  The vast majority of areas that have been cooking and settling should accept a bit of liquid with little effect.  The second thing to watch is the timing and accumulation of new snow.  If weather forecasts are realized with snow accumulations becoming more consistent this afternoon expect some new loading late in the day by an increasing NW wind. However, some light new snow is currently falling with the summit temperature of 25F and Hermit Lake at 32F.  If snow continues from this point forward and does not change forms, which is contradictory to the forecast, I expect some thin new slabs to develop hedging us to a Moderate rating this afternoon. I mention this because it is a possibility that we may see a changing avalanche danger with weather differing from the expected forecast.  Tomorrow anticipate danger ratings and the avalanche forecast to increase.

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 7:50 a.m. December 17, 2014. A new advisory will be issued tomorrow.

Christopher Joosen, Snow Ranger
USDA Forest Service
White Mountain National Forest
(603) 466-2713 TTY (603) 466-2856

2014-12-17

Avalanche Advisory for Tuesday, December 16, 2014

This advisory expires tonight at 12:00 midnight.

All forecast areas of Tuckerman and Huntington Ravine have Low avalanche danger. Natural and human triggered avalanches are unlikely. Watch for unstable snow in isolated terrain features which may be capable of producing small avalanches.

AVALANCHE PROBLEM: Today’s avalanche problems will be any lingering pockets of wind slab or small wet slabs, depending on how quickly and how far temperatures drop during the day today. Low danger means conditions are generally safe, but it includes the possibility for unstable snow in isolated terrain features or in extreme terrain. In the current early season snowpack, pretty much all the snowfields except for a few can be considered “isolated terrain features” or “extreme terrain.” Wind slabs that developed this past Sunday have had time to stabilize, but I won’t rule out the potential for some instabilities to still be found out there, particularly in areas such as the Lip, Center Bowl, or Central Gully.

WEATHER: Yesterday the Mt. Washington Observatory recorded a max temperature of 41 degrees F (5C) and stayed above freezing for most of day and overnight. Temperatures at Pinkham Notch were down below freezing during this same period. Today we are expecting temperatures to drop slightly at the upper elevations. Increasing clouds will foreshadow a weather system moving in later tonight and sticking around until early Thursday. Keep your eyes on the summits weather forecasts if you are planning a trip for Wednesday or Thursday.

SNOWPACK: A prominent player in the snowpack discussion today is the elevation of the warm/cold line and, more importantly, just how warm the snowpack in the ravines in the last 24 hours. In this case, I would expect that warmth entering the snowpack has worked toward stabilization of previously existing wind slabs. If these became very warm and saturated wet, then the trend might have worked in the opposite direction as there would be a wet slab sitting on top of an ice crust or in some locations plain water ice, hence the discussion about the potential for pockets of unstable slab in isolated terrain features. I don’t want to get too bogged down in the nuances of warmth on snow, because I’m hopeful that falling temperatures will continue to strengthen the snowpack to where we will sit solidly in Low danger before long. Until lock-up happens, you should expect to find generally good stability with the potential for some small unstable slabs.

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 7:50 a.m. December 16, 2014. A new advisory will be issued tomorrow.

Jeff Lane, Snow Ranger
USDA Forest Service
White Mountain National Forest
(603) 466-2713 TTY (603) 466-2856

2014-12-16

Avalanche Advisory for Monday, December 15, 2014

This advisory expires tonight at 12:00 midnight.

Tuckerman Ravine has MODERATE and LOW avalanche danger. The Lip, Center Bowl, and Chute have Moderate avalanche danger. Natural avalanches are unlikely and human-triggered avalanches are possible. Lobster Claw, Right Gully, the Sluice, Left Gully, and Hillman’s Highway have Low avalanche danger. Natural and human-triggered avalanches are unlikely. Watch for unstable snow in isolated terrain features. Lower Snowfields and the Little Headwall are not posted due to lack of snow cover.

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

AVALANCHE PROBLEM: Wind slab is the avalanche problem you are most likely to see today. For the most part, the terrain in the ravines is very discontinuous at this point early in the season. There are some larger snowfields with more continuous snow cover, but in most forecast areas you will be moving from one distinct patch of snow to another. This requires ongoing assessment of snow stability and solid route-finding skills to keep you away from unstable snow. Many areas posted at Low danger do have wind slabs that may be unstable. The primary differentiating factors between the Moderate rated locations and the Low rated areas are the size and distribution of the slab, not necessarily the likelihood of you triggering the snow.

WEATHER: If you are a fan of mild weather, today is your day. Temperatures will be rising above freezing all the way up to the summit while winds diminish to a gentle 5-20mph from the NW (Beaufort 3-4 for the nautical-minded). Warmth will persist through the night, until temperatures begin to fall back on Tuesday in advance of a weak weather system mid-week.

SNOWPACK: As already mentioned, one defining characteristic of the current snowpack is that it is very broken up. There are few large connected snowfields, which means that any avalanche that is triggered will be relatively small but can be quite dangerous. Areas posted at Low have more options for avoiding instabilities than those rated Moderate. In these conditions it can be quite tempting to take the “easier” route through the snow rather than the “safer” route that avoids instabilities, but I’d recommend choosing the less hazardous route unless you can confidently say that the snow has good stability.

Yesterday I spent some time in Tuckerman looking at the snow structure. What I found would be very disturbing if the ravine was more filled in than it currently is, and is certainly disturbing when found in exposed areas like the Lip or Center Bowl. There is slab at the surface that was formed during Sunday’s winds. This sits on top of a layer of light unconsolidated snow (read: weak snow). Beneath this is a sleet crust and other crusts. Stability tests at our location provided very easy results – CT0, CT0, ECTP4 – at the interface between the uppermost slab and the weak snow. As the columns popped off the pit wall, the weak snow layer was left intact on top of the crust. You should expect the depth of these layers to be quite variable as you move from one location to another.

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. December 15, 2014. A new advisory will be issued tomorrow.

Jeff Lane, Snow Ranger
USDA Forest Service
White Mountain National Forest
(603) 466-2713 TTY (603) 466-2856

2014-12-15

Avalanche Advisory for Sunday, December 14, 2014

This advisory expires tonight at 12:00 midnight.

Tuckerman Ravine has MODERATE and LOW avalanche danger. The Sluice, Lip, Center Bowl, the Chute, and Left Gully have Moderate avalanche danger. Natural avalanches are unlikely and human-triggered avalanches are possible. Lobster Claw, Right Gully and Hillman’s Highway have Low avalanche danger. Natural and human-triggered avalanches are unlikely. Lower Snowfields and the Little Headwall are not posted due to lack of snow cover. Watch for unstable snow in isolated terrain features.

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

AVALANCHE PROBLEM: Wind slab is the primary avalanche problem for today due to recent snow being redistributed around the mountain by strong N and NNW winds yesterday. These slabs formed on a variety of potential bed surfaces, including water ice and ice crusts from the recent thaw as well as lighter density storm snow. Expect to find these slabs in lee areas and gullies which generally face south and east. They may be on the smaller side due to our early season snowpack, but they could pack a punch especially if the sweep you down rocky terrain. Slabs formed from sluffing and spindrifting snow (a.k.a. Loose-Dry avalanches) run a close second on the list of avalanche concerns. Expect these firm slabs beneath steep terrain features and approaches to steep pitches of ice.

WEATHER: Yesterday around 2.5″ (6 cm) of new snow were recorded on the summit though only a trace (.5 cm) was collected at Hermit Lake. Regardless of the total amount of new snow, strong wind transport occurred for a 4 to 5 hour period mid-day yesterday when winds were steady in the 50-60 mph (80-95 kph) range with gusts to 70 mph.

Relatively warm temperatures today will continue to improve snow stability. Today’s weather forecast marks a break from our unsettled weather due to the Low pressure which has been parked off the coast for the past week. Though temperatures will warm into the 30’s F at mid-elevations today, expect lingering clouds, flat light and some fog to hamper visibility at times. Wind from the NW will diminish to the 20-35 mph range, though gusts to 55 mph will remind you why you carry goggles and spare gloves here. The temperature on the summit at 8 am was a balmy 19F and will approach the freezing mark through the day. Enjoy the warmth while it lasts since the coldest month of the year is right around the corner.

SNOWPACK: Somewhere in the neighborhood of 2′ (60cm) of snow exists in wind sheltered areas of higher terrain. With the exception of the new snow (3-7″, depending on location) that has fallen in the past 48 hours, most of this snow is encapsulated by a stiff crust of refrozen snow. Beneath this crust another ice lens existed. Relatively warm temperatures have helped to further stabilize these deeper layers leaving us with wind slab and sluff slab as our main concern.

The summer Lion Head trail to the summit remains open and is the safer option than other choices on the east side of the mountain. A variety of hiking conditions exist, with traction devices, including crampons and ice axes, recommended, if not required for travel near and above treeline.

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. December 14, 2014. A new advisory will be issued tomorrow.

Frank Carus, Snow Ranger
USDA Forest Service
White Mountain National Forest
(603) 466-2713 TTY (603) 466-2856

2014-12-14 print friendly

Avalanche Advisory for Saturday, December 13, 2014

This advisory expires tonight at 12:00 midnight.

Tuckerman and Huntington Ravines have Considerable avalanche danger. Dangerous avalanche conditions exist. Natural avalanches are possible and human triggered avalanches are likely.  Careful snowpack evaluation, cautious route-finding and conservative decision-making are essential.

This is the initial Avalanche Advisory for the 2014-2015 season using the North American Public Avalanche Danger Scale (a.k.a. the “5-scale system.”) Bear in mind that the existing conditions and snow coverage are in a state of transition. We recognize that Considerable is a strong rating for the paths that are just beginning to fill in with snow, but in others where the bed surfaces are much more developed we feel this rating most accurately describes the potential hazard today. Naturally triggered avalanches are a possibility. You will need to be able to carefully assess the terrain as well as the snowpack in order to minimize your exposure to the hazard.

AVALANCHE PROBLEM: Wind slabs are the primary avalanche problem for today due to recent snow being redistributed around the mountain. Slabs will form on a variety of early season surfaces, including water ice and ice crusts from the recent thaw.

WEATHER: The weather on Mt. Washington has been substantially different than down in the valley over the last few days. Tuesday night we received a heavy dose of wet snow, which was followed up by some rain and mixed precipitation. Following this the temperature lowered and we began to receive snow. Approximately 5″ (12.5cm) were measured at the summit since Thursday morning. Today’s forecast calls for an additional 1-3″, bringing to total amount sitting above treeline and available for transport to somewhere around 6-8″ with an average density of about 9%. Wind today will be from the NW and gusting into the mid-60mph range (95-100kph), which should be sufficient for loading to take place.

SNOWPACK: The warm spell that followed the heavy snow is setting the stage for avalanche activity. It left behind an ice crust that can act as a slippery bed surface for new wind slab to build on. When the winds shifted from the E to the NW on Thursday, they started out rather light. Expect a layer of light density snow between the crust and the denser slabs at the surface. Newly developing slabs with these conditions may feel soft and and buttery smooth underfoot, but even the small ones can be dangerous if they take you off your feet and into the rocky terrain below.

As mentioned earlier, the snowpack is in a transitional state. We are primarily concerned about the locations where bed surfaces have been developing faster. As is typical, these areas include the Lip, Center Bowl, Chute, and Left Gully in Tuckerman. In Huntington, you’ll find that Central has the largest snow surface but potential bed surfaces exist in multiple gullies. The exit snowfields in Damnation, Yale, Central, and Odell strike me as places where unstable slabs might be found. Also don’t overlook the smaller snowfields down lower in the ravine, such as on the approaches to climbs like Yale, Central, and Pinnacle.

There are some forecast areas that are not likely to be truly at Considerable danger. After the clouds clear from the mountain and we can make more accurate assessments, we may bring these areas down to “Not Posted” due to a lack of snow. Until then, we want you to recognize that hazards may exist even in smaller terrain features. Lobster Claw, Right Gully, the Lower Snowfields, and Little Headwall in Tuckerman fit this description, while in Huntington, the Escape Hatch is the leading contender for not reaching Considerable danger today.

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 8:40 a.m. December 13, 2014. A new advisory will be issued tomorrow.

Jeff Lane, Snow Ranger
USDA Forest Service
White Mountain National Forest
(603) 466-2713 TTY (603) 466-2856

2014-12-13

General Advisory for Tuckerman and Huntington Ravines

Posted 9:00a.m. Thursday, December 11, 2014. Expires at 12:00 midnight Saturday, December 13, 2014 unless updated based on a change of conditions.

This is an early season GENERAL AVALANCHE ADVISORY.  A new General Advisory will be issued if conditions warrant or within 72 hours of this release. General Advisories are issued when isolated areas of unstable snow may exist within the forecast areas. Forecasts using the 5-scale danger rating system will begin when snowfields and bed surfaces become more developed. Please remember that avalanche activity may occur before the issuance of a 5-scale danger rating forecast. As always, make your own snow stability assessments when traveling in avalanche terrain.

A large area of Low pressure sitting on the Maine coast will continue to send moisture laden air into our area. New precipitation will be wet snow or freezing rain for Thursday before transitioning to all snow Friday and into Saturday. Snow water equivalent is forecast to be in the range of a tenth to .15″ today (Thursday) which should fall as wet snow with some freezing drizzle and freezing fog mixed in.  Over the past two days, about 12″ (30cm) of snow and mixed precipitation has fallen; 10.5″ (26cm) of snow topped by wet snow and rain on Tuesday and Tuesday night, and  1.5″ (3.75cm) mixed frozen forms, rimed pellets, ice and snow (38% density) on Wednesday and Wednesday night. This mixed bag of precipitation is continuing to enlarge and connect our snow slopes and create the bed surface for new snow and wind loaded snow coming Thursday and Friday. Be prepared to assess slopes and gullies for new slabs of wet snow which may be unstable and respond to a human trigger. Some new wind loading may occur later Thursday and into Friday as winds shift to the NW and increase in velocity. Hopefully a reasonable level of visibility will allow for some visual assessment and photos today but I will at least dig in the snow to check out the snow structure and look for signs of deeper weak layers that pre-existed the larger snowfall on Tuesday-Wednesday and resulted in a human triggered, hard slab avalanche in Diagonal Gully on Monday. Currently, our best way to post photos is on the Mount Washington Avalanche Center Facebook page so seek us out, like us and look there for photos there.

Remember that the current limited snow cover can not only produce avalanches but the existing rocky terrain can beat you up in the event of a fall or being carried by an avalanche. Now is the time to carry avalanche rescue gear, be searchable by wearing your transceiver (which is turned on, right?!) and to be prepared for full winter conditions with the proper equipment, clothing and mindset.

The Sherburne Ski Trail has been getting a good bit of ski traffic though there are still some open waterbars to avoid. If you’re heading there or to the Gulf of Slides Ski Trail, remember that it is still very early in the season. Expect abrupt waterbars, hidden rocks, and plenty of exposed vegetation.

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.

Frank Carus, Snow Ranger
USDA Forest Service
White Mountain National Forest
(603) 466-2713 TTY (603) 466-2856

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