Avalanche Advisory for Tuesday, May 5, 2015

This advisory expires tonight at 12:00 midnight.

Tuckerman Ravine has Low avalanche danger. Natural and human-triggered avalanches are unlikely. Watch for small avalanches on isolated terrain features. 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: The snow stability is generally very good at this time. Avalanches are a lesser concern than other hazards that you will need to pay attention to if traveling in Tuckerman Ravine. Looking at the water flowing down the waterfall adjacent to the Lip, I can’t help but wonder about the potential for a wet slab avalanche. Currently it appears as though the water is draining well and the chances of a wet avalanche remain unlikely. However, unusual events do happen. On April 19, 2013, a chunk of ice plugged the drainage channel and unexpectedly triggered a wet slab. The pre-existing conditions then were not all that different from what we have today, but historically, these events have been rare. I am keeping the rating today at Low danger, but remember that you are the one responsible for the decisions for where you travel, and our standing recommendation is to treat avalanche terrain with respect, even when danger is low.

OTHER PROBLEMS/HAZARDS: The Great Mt. Washington Melt-out has begun in earnest. The prolonged melting is bringing the usual springtime hazards to the forefront. These include:

FALLING ICE – There is still an incredible amount of ice in the Sluice and Center Bowl area. You do not want to be below these locations when the ice breaks off. Don’t underestimate the speed and random trajectory of chunks of falling ice. Reduce your time spent in Lunch Rocks, the Sluice, Lip, and Center Bowl and you will reduce your risk of injury or death due to this hazard.

CREVASSES AND UNDERMINED SNOW – The focus of the deepest slots is in the Lip and Sluice area with others located directly beneath rock buttresses above longer slopes. These glide cracks are getting larger by the day as the huge mass of snow melts and creeps downhill. Choosing a boot pack to ascend that avoids these hazards is a great way to reduce the risk of a fall into one of these holes. Aside from the prominent stream under the Lip area, most gullies in Tuckerman also have running water under the snow. Through the years we have seen the most incidents of people punching through into these smaller streams in Hillman’s, the Sluice, and Right Gully.

 WEATHER: Today will be another warm day on the mountain. Last night temperatures did not fall below freezing for most of the mountain, additionally, there was a warm front that passed through late last night bringing 0.19″ of rain to the summit. Fog appears to be burning off already, which will allow sunshine to hasten the melting process today. This is all creating a lot of melt water and saturated snow.

For all practical purposes, the Little Headwall has fully collapsed and is unskiable. The best descent alternative is to hike back down to Hermit Lake, where you can choose to rejoin the John Sherburne ski trail. The Sherburne trail is disintegrating rapidly and is currently closed at the #7 crossover, 2 miles up the Tuckerman Ravine Trail from the parking lot. At the rope, please avoid the muddy descent and cross to the hiking trail and walk down. Do not ski on the hiking 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 Mount Washington Volunteer Ski Patrol, or the AMC at the Pinkham Notch Visitor Center and Hermit Lake.
  • Posted 8:45 a.m., Tuesday, May 5, 2015. A new advisory will be issued tomorrow.

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

2015-05-05

Avalanche Advisory for May 4, 2015

This advisory expires tonight at 12:00 midnight.

Tuckerman Ravine has Low avalanche danger. Natural and human-triggered avalanches are unlikely. Watch for small avalanches on isolated terrain features. 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: Relatively slow moving but dense and heavy Wet Loose avalanches will flow from steep terrain today. These slides can be dangerous if they push you into a terrain trap, crevasse or over a cliff. A lot of loose surface snow was cleaned off of our forecast areas yesterday but warm temperatures last night and baking temperatures today will loosen the surface snow and set the stage for more sluffing.

OTHER PROBLEMS/HAZARDS: It is next to impossible to predict but really easy to mitigate the risk of icefall in Tuckerman Ravine. Reduce your time spent beneath frozen waterfalls in Lunch Rocks, Center Bowl and elsewhere and you will reduce your risk of injury or death due to this hazard. Don’t underestimate the speed and random trajectory of chunks of falling ice. Beware of crevasses and undermined snow. The focus of the deepest slots is in the Lip and Sluice area with others located directly beneath rock buttresses above longer slopes. These glide cracks are getting larger by the day as the huge mass of snow melts and creeps downhill. The main waterfall beside the Lip is also growing rapidly which is a sure sign that the channel beneath the slope growing and melting the snow above. Choosing a boot pack to ascend that avoids these hazards is a great way to reduce the risk of a fall into one of these holes.

 WEATHER and SNOWPACK: Sunshine and warm temperatures will turn slopes to mush and saturate the snowpack with water today. Temperatures will hit 50F (10C) on the summit with breezy and increasing winds and gathering clouds in the afternoon as a cold front approaches. Soft conditions are setting the stage for further erosion of the snowpack as sluff channels develop from flowing wet, loose snow and moguls develop on heavily trafficked slopes. Today’s soft snow will once again create ideal conditions for various lower leg musculoskeletal injuries. Don’t forget to develop a preplan for handling an emergency and step up to help others if necessary. It is remarkable how fast a warm, bluebird day can turn on you when you are lying in the snow unable to walk the 3.5 miles to the road.

The Little Headwall has open holes over the waterfall and undermined snow in the drainage above and below. It was virtually unrideable on Sunday and is easily assessed on the hiking trail from Hermit Lake. A better descent alternative is to hike back down to Hermit Lake and rejoin the John Sherburne ski trail there. The trail is disintegrating rapidly and is currently closed at the #7 crossover, 2 miles up the Tuckerman Ravine Trail from the parking lot. At the rope, please avoid the muddy descent and cross to the hiking trail and walk down. Do not ski on the hiking 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 Mount Washington Volunteer Ski Patrol, or the AMC at the Pinkham Notch Visitor Center and Hermit Lake.
  • Posted 7:30 a.m., Monday, May 4, 2015. A new advisory will be issued tomorrow.

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

2015-05-04 print friendly

Avalanche Advisory for Sunday, May 3, 2015

This advisory expires tonight at 12:00 midnight.

Tuckerman Ravine has Low avalanche danger. Natural and human-triggered avalanches are unlikely. Watch for small avalanches on isolated terrain features. 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: We have built strength due to settling, consolidation, and skier compaction from 2000 people on Saturday.  Some steep untracked slopes could still produce dense and heavy skier induced Wet Loose sluff avalanches today, but these should be minimal. A number of these occurred yesterday until slopes were fully tracked. These slides can be dangerous if they push you into a terrain trap or over cliffs so use sluff management techniques and have a preplan. Think about this if going to other less used Ravines and Gulfs. There is a remote possibility of a Wet Slab avalanche in the coming days with intense heating, around the clock melting and percolating of freewater deep into the snowpack hunting for an impermeable layer to lubricate.  This may be exacerbated by afternoon thunderstorm potential through tomorrow.  We will trend away from this Wet Slab potential in several days. Stay tuned.

OTHER PROBLEMS/HAZARDS: ICEFALL IS OUR PRIMARY HAZARD TODAY. It is next to impossible to predict, but really easy to mitigate the risk of icefall in Tuckerman Ravine.  Avoid hanging out under the most probable fall lines from the Center Headwall and the Sluice and the risk of injury or fatality diminishes greatly.  LUNCH ROCKS IS A DANGEROUS PLACE TO SIT AND IS NOT RECOMMENDED. Of all places, although traditional, this place gets hit with a lot of ice and has the distinction of producing the most icefall injuries in the Ravine. A set of rocks further away would be better for setting up as your base for the day.  Hot sun today will continue weakening large automobile sized chunks.  I would not want to be beneath the Sluice or Center Bowl ice when either loses the battle with gravity.

Be aware of crevasses hidden beneath wet and weak snow bridges. The focus of the deepest slots is in the Lip area with others located directly beneath rock buttresses.  These will grow today, and all week, with warm temperatures and round-the-clock melting. Choosing a boot pack to ascend that avoids these hazards is a great way to eliminate the risk of a fall into one of these slots. Just because other people are skiing somewhere it doesn’t mean it is a safe, hazard free area.  As an example, the most heavily used Lip has more hazards than other gently used locations areas like the Lobster Claw, Right Gully, Left Gully and Hillman’s Highway.

WEATHER and SNOWPACK: Today an increasing cloud trend will occur with the potential for afternoon showers and thunderstorms.  Temperatures will shoot up into the upper forties on the summit and is already there at mid-elevation on the mountain.  These factors will continue to produce heavy, slushy riding conditions. I would not want to be caught above treeline during a lightning event, especially with a saturated snowpack.

The Little Headwall has open holes of water undermined snow, and has become more hazardous over the past 24 hours. Collapsing around open holes occurred overnight evidenced by some cracks visible this morning. Based on this continued decay we can no longer recommend a ski descent and believe the walk out is a vastly safer option. The John Sherburne ski trail is disintegrating rapidly and the majority is currently closed.  At the rope, please avoid a slippery and muddy descent down the ski trail and cross to the hiking trail to walk down. Do not ski on the hiking 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 Mount Washington Volunteer Ski Patrol, or the AMC at the Pinkham Notch Visitor Center and Hermit Lake.
  • Posted 8:15 a.m., Sunday, May 3, 2015. A new advisory will be issued tomorrow.

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

2015-05-03 print friendly

Avalanche Advisory for Saturday, May 2, 2015

This advisory expires tonight at 12:00 midnight.

Tuckerman Ravine has Low avalanche danger. Natural and human-triggered avalanches are unlikely. Watch for small avalanches on isolated terrain features. 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: Relatively slow moving but dense and heavy Wet Loose avalanches will flow from steep untracked terrain today. These slides can be dangerous if they push you into a terrain trap or over cliffs. There is a remote possibility of a Wet Slab avalanche from Sluice or Center Bowl/Lip area as heat penetrates further into recent new snow or if the waterfalls begin to run between and lubricate deeper layers. Due to the risk of both types of avalanches plus the potential for falling ice, Lunch Rocks and the floor of the Ravine, close to the base of the Headwall, are not safe places to hang out. Reduce your exposure to these threats by gathering well away from the fall line of these areas. Wet debris has virtually no pore space for air to flow through. People have died under just a few inches of this type of debris so consider this when evaluating these seemingly benign threats.

 OTHER PROBLEMS/HAZARDS: Be aware of crevasses hidden underneath the recent snow. The focus of the deepest slots is in the Lip area with others located directly beneath rock buttresses above longer slopes. These glide cracks are getting larger as the huge mass of snow moves downhill. Choosing a boot pack to ascend that avoids these hazards is a great way to eliminate the risk of a fall into one of these slots. It is next to impossible to predict but really easy to mitigate the risk of icefall in Tuckerman Ravine. I’ve watched with curiosity over the past several weeks as the 30 foot high pillar of ice on the roadcut on Rt. 16 as it delaminated from the cliff then slowly leaned to one side. The big pile of ice on the ground yesterday morning was evidence that gravity finally won, as it always does. I would not want to be beneath Sluice or Center Bowl ice when either lose the battle with gravity.

WEATHER and SNOWPACK: Light winds and a high temperature in the mid 40’s F on the summit with some afternoon clouds and possible rain showers are on tap for today. These weather conditions will further saturate the upper snowpack and create heavy, slushy riding conditions. Slopes such as Hillman’s Highway, Left and Right Gully, have seen the most ski traffic and will be more raked off, providing easier conditions for making turns. The past two weeks brought a foot of snow which accumulated much more deeply in the strong lee areas such as Sluice through Chute. The upper right side of Left Gully also has a large area of wind-loaded mush as well. Plenty of loose, untracked snow exists so expect lots of sluffing today. People with water skiing or wake boarding skills will be most comfortable with the turns and speed required to manage this slushy snow.

The Little Headwall has open holes of water and undermined snow, but it continues to be a skiable option for descending from the Bowl. Use extreme caution if choosing this route. Another alternative is to hike down to Hermit Lake or to leave the Little Headwall at its top and thread your way through the trees towards the Lower Snowfields.  The John Sherburne ski trail is disintegrating rapidly.  It’s currently closed at the #5 crossover, 1 mile up the Tuckerman Ravine Trail from the parking lot. At the rope, please avoid the muddy descent and cross to the hiking trail and walk down. Do not ski on the hiking 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 Mount Washington Volunteer Ski Patrol, or the AMC at the Pinkham Notch Visitor Center and Hermit Lake.
  • Posted 7:00 a.m., Saturday, May 2, 2015. A new advisory will be issued tomorrow.

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

2015-05-02 print friendly

Avalanche Advisory for Friday, May 1st, 2015

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. Lobster Claw, Right Gully, Left Gully, Hillman’s Highway, the Lower Snowfields, and the Little Headwall have Low avalanche danger. Natural and human-triggered avalanches are unlikely in these locations. Huntington Ravine is under a General Advisory. You will need to do your own snow stability assessments when traveling in avalanche terrain in Huntington.

AVALANCHE PROBLEM: We have been continuing a slow moving trend towards more snow stability with temperatures above freezing during the day and below at night. Our field time today will focus on deep digging to conclude how the expected warm up over the next few days will effect wet slab and deep wet slab potential. Deeper areas of the newest snow from earlier in the week are rated Moderate due to concerns that further heating today, coupled with a slight chance of precipitation, continues the remote potential for Wet Slab avalanches.

OTHER PROBLEMS/HAZARDS: Be aware of the potential for crevasses to be hidden underneath the recent snow and the potential for falling ice. These issues will grow in intensity over the next several days due to the expected warming trend.  Although crevasses have been limited, they will grow in number and size quickly in the coming days.  These slots have already grabbed some people this week.

WEATHER: Fourteen days in a row of new snow has kept visibility low and intermittent as well as some avalanche conditions lingering on Mount Washington.  As unsettled weather tries to push out today, a clearing trend is expected which will feel like hot weather compared to the winterish April that concluded yesterday.  The prolonged period of low pressure systems that have plagued the higher terrain should give way to clear skies over the next 24 hours.  A chance of mixed precipitation once again exists today with a mix of clouds and sun. Temperatures will be in the mid thirties with a N wind, falling into the 10 mph range from a current of 25mph.

SNOWPACK:  New snow from early in the week has gone through some nice consolidation and sintering due diurnal swings above and below freezing. Today’s warm up will do more of the same, but will start a long period of around the clock melting with no nightly freeze up likely.  This has us thinking about meltwater percolating deeper than it has yet, bringing heat, more melting, and weakening into the week old snow that is quite deep in places.  This may increase the chance of wet slab avalanche problems in several isolated areas.  Our field time today will focus on this question and hopefully answer some of the nagging concerns regarding, “what will happen when it really gets hot out?”  The greatest concerns linger from the Sluice through the Left Center Headwall, with the bullseye being in the steepest open terrain from the Lip to the Center Bowl.  Continue to consider this hazard and your risk exposure in your field decisions and travel choices.  We are hoping for clear sky conditions to get a number of pictures up later today and don’t forget to look for the Weekend Update this afternoon.  We will provide an update based on what our field time tells us today.

The Little Headwall has open holes of water and undermined snow, but it continues to be a skiable option for descending from the Bowl. Expect this to change rapidly and may not be a good option by mid-weekend! Use extreme caution if choosing this route. Another alternative is to hike down to Hermit Lake, although expect an icy trail making microspikes and ski poles handy.  The John Sherburne ski trail will disintegrate rapidly so expect to hike more as the days get warm and be pleasantly surprised if you get to ski.  It’s currently closed at the #5 crossover, 1 mile up the Tuckerman Ravine Trail from the parking lot. At the rope, please avoid the muddy descent and cross to the hiking trail and walk down. Do not ski on the hiking 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 Mount Washington Volunteer Ski Patrol, or the AMC at the Pinkham Notch Visitor Center and Hermit Lake.
  • Posted 8:15 a.m., Friday, May 1, 2015. A new advisory will be issued tomorrow.

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

2015-05-01

Avalanche Advisory for Thursday April 30, 2015

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. Lobster Claw, Right Gully, Left Gully, Hillman’s Highway, the Lower Snowfields, and the Little Headwall have Low avalanche danger. Natural and human-triggered avalanches are unlikely in these locations. Huntington Ravine is under a General Advisory. You will need to do your own snow stability assessments when traveling in avalanche terrain in Huntington.

AVALANCHE PROBLEM: We are continuing to trend slowly towards stability as all the new snow in upper elevations settles down. Warm ambient temperatures yesterday wet the snow and a period of freezing temperatures last night contributed to stabilization. Deeper areas of the new snow are rated Moderate due it’s depth and concerns that further heating today, coupled with some rain showers, will make these areas more prone to human-triggered Wet Slab or Wet Loose avalanches.

OTHER PROBLEMS/HAZARDS: Be aware of the potential for crevasses to be hidden underneath the recent snow. These slots have been growing in the Lip and are beginning to grow in other locations extending from the Sluice over to the Chute. Also anticipate the potential for falling ice today.  These issues will grow in intensity over the next several days due to the expected warming trend.

WEATHER: Yesterday was the 13th day in a row for new snow on the Mount Washington summit.  Recently, scant precipatation amounts have had little effect on the avalanche problem, but has maintained some lingering stability concerns over the past week.  This, in addition to cold temperatures, has kept conditions changing very slowly. Frankly it feels more like the end of March than April.  The prolonged period of low pressure systems that have plagued the higher terrain should give way to sunny skies over the next 24 hours. However, we will go through a round of snow, sleet, freezing rain and rain in avalanche terrain today before conditions improve on Friday. Summits will be in the clouds with a chance of mixed precipitation associated with a NE wind from 5 to 20 mph (8-32 kph). Temperatures will increase from the current of 24F into the mid-thirties.

SNOWPACK: Areas posted at Low danger today did not receive very much loading from recent snowfalls. The surfaces in these locations are as close as you’ll get to typical springtime corn snow. In the Sluice through Chute, conditions vary by aspect, but they all have a similar bed surface of old melt-freeze crust above mostly isothermal snow. New snow from this week has gone through a number of changes as the temperature hovered just above, and dipped below, the freezing point. Today’s warming trend will continue the melting/rounding process of the snow grains which will make for sloppy snow in the upper snowpack. It is the deeper areas of snow, such as the bowl like feature below the ice in Sluice, under the ice in Center Bowl and in the Chute where we have the most concerns for avalanche activity today. If you recall, the early days of our continuing period of unsettled weather, which brought 14” of snow in the last week, was cold with light winds. These weather conditions allowed the snow to fall somewhat undisturbed and though this snow bonded well to the warm crust beneath, it was a fairly weak layer in itself. While the upper snowpack went through a lot of changes since that time, suffice it to say that none of these changes was a dramatic, penetrating cycle of heating and refreezing. This melting and refreezing cycle would normally take most avalanche concerns off our radar this time of year. It is important to understand that while we have fair to good stability in Moderate rated areas, the potential for a wet slab avalanche remains enough of a concern that you should continue considering this hazard in your travel choices and trip planning. I’ll be carrying my beacon until I see a hard refrozen snowpack without the potential for these wet slabs. The upcoming warm weather will ensure that I’ll be carrying it at least through the weekend if not till the end of the season.

The Little Headwall has open holes of water and undermined snow, but it continues to be a skiable option for descending from the Bowl. Use extreme caution if choosing this route. Another alternative is to hike down to Hermit Lake, although expect an icy trail making microspikes and ski poles handy. The Sherburne ski trail is now closed at the #5 crossover, 1 mile up the Tuckerman Ravine Trail from the parking lot. At the rope, please avoid the muddy descent and cross to the hiking trail and walk down. Do not ski on the hiking 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 Mount Washington Volunteer Ski Patrol, or the AMC at the Pinkham Notch Visitor Center and Hermit Lake.
  • Posted 8:15 a.m., Thursday, April 30, 2015. A new advisory will be issued tomorrow.

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

2015-04-30

Avalanche Advisory for Wednesday, April 29, 2015

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. Lobster Claw, Right Gully, Left Gully, Hillman’s Highway, the Lower Snowfields, and the Little Headwall have Low avalanche danger. Natural and human-triggered avalanches are unlikely in these locations. Huntington Ravine is under a General Advisory. You will need to do your own snow stability assessments when traveling in avalanche terrain in Huntington.

AVALANCHE PROBLEM: Today we are transitioning from wind slab avalanche problems to wet slab or wet loose avalanche problems. Overall the snowpack has been doing a good job working toward stabilization, but some areas still pose a threat due to the prolonged warming of near-surface layers. Expect avalanche danger to increase slowly but steadily through the day as temperatures creep upward. Though we are in the more stable end of the Moderate range, wet avalanche problems can be quite unpredictable and difficult to assess through snow pit stability tests.

OTHER HAZARDS: Be aware of the potential for crevasses to be hidden underneath the recent snow. These had been growing in the Lip more than other areas, but we typically see these in various locations from the Sluice through the Chute. Icefall is also a possibility today despite there being plenty of cloud cover.

WEATHER: Much of the snow that has fallen near the end of April has not fallen at ravine elevations. It has fallen above 5000’ and up to the summit. Today we expect mostly cloudy conditions with temperatures staying above freezing for most of the day. You may even get spit on by snow or rain (in fact, it’s snowing lightly as I write). Diurnal fluctuations have not been strong (i.e. nighttime lows are staying fairly warm) which means that the snowpack is mostly moist down to the older melt-freeze crust from mid-April.

SNOWPACK: Areas posted at Low danger today did not receive very much loading from recent snowfalls. The surfaces in these locations are as close as you’ll get to typical springtime corn snow. In the Sluice through Chute, conditions vary by aspect, but they all have a similar baseline of the old melt-freeze crust from over a week ago. Above this layer, you’ll find a mostly “rightside-up” snowpack in the Chute, so expect loose wet avalanches to be the primary threat here. Over closer to the Sluice, we found a 4-5” thick shin-bruising breakable melt-freeze crust at the surface over softer snow that was either moist or dry depending on the thickness. Stability was generally good yesterday, but this was primarily due to the bridging effect of the crust on top. As this layer loses strength today, the potential exists for wet slab avalanches. This will be greater in locations harboring cold dry weak layers underneath, such as in the Lip or tucked in deeper pockets under the ice in the Center Bowl. The likelihood of triggering a slide has been moving from possible to unlikely. However, we’re not quite there yet. Additionally, the size of a potential slab or loose avalanche that you can expect today could be large. These factors lead us to continue with a Moderate rating, and should be considered in your own decision making today as well.

The Sherburne is now closed at the #5 crossover, which is about 1 mile up the Tuckerman Ravine Trail from Pinkham Notch. At the rope, please cross to the hiking trail and walk down. Do not ski on the hiking trail.

The Little Headwall has some open holes of water and undermined snow, but it continues to be a skiable option for descending from the bowl. Use extreme caution if choosing this route. Another alternative is to hike down all the way to Hermit Lake, but when icy this has proven challenging to many and presents it’s own unique hazard.

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 8:25a.m., Wednesday, April 29, 2015. A new advisory will be issued tomorrow.

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

2015-04-29

 

Avalanche Advisory for Tuesday, April 28, 2015

This advisory expires tonight at 12:00 midnight.

Tuckerman Ravine has Moderate avalanche danger. Natural avalanches are unlikely and human-triggered avalanches are possible. The only exceptions are Hillman’s Highway, the Lower Snowfields, and Little Headwall which have Low avalanche danger. Natural and human-triggered avalanches are unlikely in these locations. Huntington Ravine is under a General Advisory. You will need to do your own snow stability assessments when traveling in avalanche terrain in Huntington.

AVALANCHE PROBLEM: As winter refuses to release Mt. Washington from its grip, wind slab avalanches are the primary threat again today. Yesterday’s snowfall brought yet another round of snow into Tuckerman, which was likely transported on northerly winds into aspects that have a southerly-facing component. Expect the greatest avalanche danger to be found on the looker’s right side of Tucks as well as in the Lip and Center Bowl. In these areas you may find very stable snow near the bottom or middle, but unstable snow near the middle or top. Be careful of what you are traveling underneath.

WEATHER: Throughout yesterday, snow showers brought about 3” of snow to the summit. Down at Hermit Lake we received only a trace. Given the temperature trends, I strongly suspect the snow that fell above the ravines is cold enough to have been moved by overnight winds. These winds came from a NNE direction and increased in speed from 40mph at 6pm to gusts in the 70mph range around midnight. Winds today will diminish slightly, forecasted to be from the N at 45-60mph. Ravine temperatures may hover around the freezing mark again today while uppermost elevations should remain below freezing.

SNOWPACK: This stretch of weather has been interesting from an avalanche forecasting perspective. Snow totals and winds do not tell the complete story of what’s taking place. The relatively warm temperatures are one prominent factor keeping things interesting. With the ravine temps hovering around freezing, the ability of the new snow to move toward better stability is much greater than is typical in mid-winter; this is happening in the absence of the usual springtime melt-freeze cycles. I expect that this process is underway, especially within the 3” of snow that came in the week prior to yesterday, we do not have enough evidence yet of stable snow to forecast Low avalanche danger. This means that your ability to carefully assess the snowpack will be critical to your decision of whether or not to travel on a certain slope today. You should also be paying attention to the amount of solar energy penetrating the snowpack. This can help stabilize some thinner slabs, but if it doesn’t reach deeply enough in thicker slabs, it might only serve to weaken the uppermost snow, which makes human triggered avalanches more likely.

If you want to avoid much of the new loading hazard, stay away from the right and center of Tuckerman. Hillman’s Highway and the Lower Snowfields have much less risk and have been providing enjoyable skiing for many people in the last few days. Remember though that Low avalanche danger does not mean “No Danger.” Stay alert for isolated slabs and be wary of traveling in the avalanche path below others.

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 8:15 a.m., Tuesday, April 28, 2015. A new advisory will be issued tomorrow.

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

2015-04-28

Avalanche Advisory for Monday, April 27, 2015

This advisory expires tonight at 12:00 midnight.

Tuckerman Ravine has Moderate and Low avalanche danger. Lobster Claw, Right Gully, Sluice, Lip, Center Bowl, Chute, and Left Gully have Moderate avalanche danger. Natural avalanches are unlikely and human triggered avalanches are possible. Hillman’s Highway, Lower Snowfields, and Little Headwall have Low avalanche danger. Natural and human triggered avalanches are unlikely except in isolated terrain features. Huntington Ravine is under a General Advisory. You will need to do your own snow stability assessments when traveling in avalanche terrain in Huntington.

AVALANCHE PROBLEM: Avalanche danger will be increasing today as wind slabs form during daylight hours. The danger will increase most quickly on slopes such as Right Gully and Sluice. Prior to new snow, areas such as the Lip and Center Bowl hold the greatest hazard and will receive cross-loading of new wind slab today. Should temperatures in the ravine stay on the warm side and precipitation falls as rain, there is the chance for either wet loose avalanches or wet slabs. The location for both of these wet avalanche problems would be across all forecast areas in locations that have collected snow from the previous week.

WEATHER: Another round of light precipitation is expected to fall today. Liquid equivalents in the 0.10” (2.5mm) range will bring another 1-3” (2.5-7.5cm) of snowfall to the summit. We expect this to fall as snow at the elevation of Tuckerman and higher, but temperatures will be very close to the point where it may fall as rain. This precipitation will coincide with an increasing wind from the N and NE, rising to 50-65mph (80-105kph) with higher gusts.

April has been a very snowy month on the summit, though unfortunately not all of this snow has fallen on lower elevations. This is very normal at this time of year, and it means that the weather you are experiencing at Pinkham Notch or at Hermit Lake may not be representative of what’s taking place above treeline. Today will be another example of this, and it’s the higher elevation weather that will play a role in the avalanche conditions more than what’s down below.

SNOWPACK: Today’s concerns are driven by two sets of factors. First are the pre-existing conditions. Were it not for incoming snow and increasing wind, there would probably be more areas rated at Low danger. The recent snowfalls have had some time for some stabilization, and in some locations the snow did not completely blanket the terrain in new slab. Areas such as the Sluice, Lip, and Center Bowl did show smooth blankets of new slab, while Hillman’s, Right Gully, and Lobster Claw have many locations with exposed old surfaces. If you’re venturing out into the right or left side of the ravine, be wary of areas of deeper snow. This is an indicator that wind loading has taken place and the snowpack might be unstable.

The second set of factors is related to the new snow coming today. We’re expecting some loading to take place on aspects facing south through east. How quickly this develops will depend on how much snow we receive and the wind’s ability to transport it from upper elevations down into the avalanche start zones. You’ll need to monitor this carefully, especially later in the afternoon.

OTHER HAZARDS: Be aware of the potential of falling ice, crevasses, and undermined snow. The best you can do to mitigate the risk from these objective hazards is to avoid them, especially during times when they are more probable. Recent cold has kept these in check to some extent. Emerging crevasses in the ravine and holes in the Little Headwall may be hard to recognize today due to being hidden by new snow. The greatest hazard today is the threat of avalanches and debris running on to the floor of the ravine.

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 8:15 a.m., Monday, April 27, 2015. A new advisory will be issued tomorrow.

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

2015-04-27

Avalanche Advisory for Sunday, April 26, 2015

This advisory expires tonight at 12:00 midnight.

Tuckerman Ravine has Moderate avalanche danger. Natural avalanches are unlikely and human-triggered avalanches are possible. The only exceptions are the Lower Snowfields and Little Headwall which have Low avalanche danger. Huntington Ravine is under a General Advisory. You will need to do your own snow stability assessments when traveling in avalanche terrain in Huntington.

AVALANCHE PROBLEM: Wind slabs exist throughout much of the ravine, providing snow stability conditions from the upper end of the Moderate range right down through the lower end of the range. Your terrain choices will certainly play a role in how much exposure you have to the avalanche hazard. Remember, by the time you have reached the floor of Tuckerman, you have already entered avalanche terrain and are at risk of an avalanche hitting you and your group from above. The areas of greatest concern are in the Sluice, Lip, Center Bowl, and Chute, as well as in the flat terrain beneath these areas.

WEATHER: Today will be much like yesterday as far as weather is concerned. We currently have some visibility, but with the forecast as it is, I think the prudent thing would be to expect thick fog to obscure sight lines at elevations above Hermit Lake. If visibility gets better, we should consider ourselves fortunate. There is a chance for a light snowfall to bring a trace to 2” to the summits, though I doubt if we get this it will affect snow stability to a great degree. Temperatures in the ravine will rise to somewhere near the freezing mark, but the fog and humidity makes things feel much less comfortable than a typical 30-35F day.

SNOWPACK: The story of the snowpack begins with a buried melt-freeze crust layer that is still holding heat and moistening the snow immediately above it. However, you don’t have to look far above the crust to find cold dry snow with a layer of weak rimed crystals mixed in. Slab that built from the recent snow on top of this weak layer is denser and dry. If you are on foot, you’ll feel the discomforting “upside-down” snowpack, which should raise the hairs on the back of your neck. If you’re on skis, you might not notice this underfoot, but a couple pole-probes should alert you to the presence of weak snow under strong snow. The majority of the new wind-loaded slab has built in the mid-elevations of the ravine, such as directly above and below the ice in the Center Bowl. Hillman’s has old surface showing in places all the way to the top, but the narrow section just above the fork appears to be holding deeper slab. Where we poked around under Right and Lobster Claw, the slabs were between knee-deep and thigh deep, but there are pockets of old surface showing here and there as well. This leads us to believe that there is a wide variety of stability falling within the Moderate range throughout all areas.

OTHER HAZARDS: Be aware of the potential of falling ice, crevasses, and undermined snow. The best you can do to mitigate the risk from these objective hazards is to avoid them, especially during times when they are more probable. Recent cold has kept these in check to some extent. Emerging crevasses in the ravine and holes in the Little Headwall may be hard to recognize today due to being hidden by new snow. The greatest hazard today is the threat of avalanches and debris running on to the floor of the ravine.

The Sherburne Ski Trail is open about 2/3 of the way down. You’ll see the rope across the trail directing you back to the Tuckerman Ravine Trail, where you will need to hike 3/4 mile down to the parking lot.

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 8:30 a.m., Saturday, April 26, 2015. A new advisory will be issued tomorrow.

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

2015-04-26