Avalanche Advisory for Saturday, February 28, 2015

This advisory will expire tonight at 12:00 Midnight.

Tuckerman Ravine has Moderate and Low avalanche danger. 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. Lobster Claw, Right Gully, Left Gully, Hillman’s Highway, the Lower Snowfields, and Little Headwall have Low avalanche danger. Natural and human triggered avalanches are unlikely except in isolated terrain features.

All forecast areas of Huntington Ravine have Low avalanche danger. Natural and human triggered avalanches are unlikely except in isolated terrain features. Recent very cold air in place has stressed some of the ice features and has caused recent ice dam ruptures.

AVALANCHE PROBLEM: The primary avalanche threat today is Persistent Slab. Triggering one of several weak layers in the snowpack requires finding just the right thin spot in the slab. These slabs are generally of the firm (1F-P) variety but, in some areas, they have a weak layer of snow located either between layers or deeper in the snowpack, near a buried crust. Moderate rated areas have the greatest potential for what would be a large, hard slab avalanche. A distant second threat is from Wind Slabs which have formed at various times this week. Though pockety and not reactive in nature, a small slab on steep or challenging terrain could surprise you.

WEATHER: It looks like another cold, crisp bluebird day on tap for today. A high temperature around 0F (-18C) with a NW wind shifting to the W at 25-40 mph (40-65 km/h) on the summit will remind you of the value of hoods, balaklavas and face masks. Gusts to 50 mph (80 km/h) will drive this point home. The next chance for snow appears to be tomorrow (Sunday) night as a frontal system approaches.

SNOWPACK: Howling winds on Monday dumped quite a bit of snow into Tuckerman Ravine but scoured out most of Huntington. Low rated areas of both Ravines predominately received scouring in some places down to a rock hard old surface. Though areas of the aforementioned persistent slab certainly exist in Low rated areas, there are more opportunities to avoid them by staying on the older, harder surface or by otherwise reducing your exposure with cautious travel techniques. The persistent slabs that are the main concern on our radar right now and though tough, they can fail, propagate a crack and generate a destructive avalanche. Chris’s pit beneath the Chute demonstrated this tendency with ECTP 8, 9 and 10. There are at least two faceted layers holding our attention right now. You could find early facets in the soft snow interface between the slabs that most likely developed during wind loading on Saturday and Monday. You are also likely to find deeper and much more advanced facets around a couple of buried crusts. In the bowl beneath Sluice this facet layer was failing 90-95cm down in the moderate range (CT14, 14, and 19). It is likely that these facets will be most advanced on southerly or westerly aspects where temperature gradients have been the greatest. Bigger slopes present the greatest threat with the least number of safer travel options so carefully consider how much you are willing to expose yourself to this threat in order to recreate on firm snow. Remember that this type of avalanche problem is fairly difficult to trigger requiring a thin spot in the slab, a relatively large dynamic load such as surface wind slab avalanche, a new snow (or water) load or a large increase in temperature.

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 8:50a.m. February 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

2015-02-28

Avalanche Advisory for Friday, February 27, 2015

This advisory will expire tonight at 12:00 Midnight.

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

All forecast areas of Huntington Ravine have Low avalanche danger. Natural and human triggered avalanches are unlikely except in isolated terrain features. Recent very cold air in place has stressed some of the ice features and caused some recent ice dam ruptures.

AVALANCHE PROBLEM: Old wind slabs, which have become Persistent Slabs, are the primary avalanche problem to consider today. We have only received about an inch of new snow in the past 3 days, however continued cold weather has kept old wind slabs which formed earlier this week from bonding to bed surfaces. While the likelihood of triggering an avalanche is trending more towards unlikely, the size of a potential avalanche in the moderate rated areas is what is driving our rating. The steepest sections of slopes, wind loaded sidewalls of gullies and thin sections of slab are the most likely potential trigger points. Avoiding the steepest parts of gullies is relatively easy, knowing where thin spots exist is much harder. Assess for potential faceting and weak interfaces between slabs within the snowpack if you choose to travel in this terrain.

WEATHER: Continued cold temperatures today with a high around -10F (-24C) on the summit will likely feel warmer in the Ravines if periods of sunshine pan out. A NW wind in the 25-40 mph (40-65 km/h) range will increase a bit to 35-50 mph (55-80 km/h). This wind will have no effect on stability and will make for a fairly pleasant day in the lee areas of our Ravines despite the cold ambient temperature. Ridgelines will obviously feel colder so be prepared to cover exposed skin. Clear but cold conditions will persistent early this weekend as high pressure takes the stage.

SNOWPACK: Howling winds on Monday dumped quite a bit of snow into Tuckerman Ravine but scoured out most of Huntington. The Sluice through Chute area has large, smooth expanses of snow. We know that historically the Lip and Center Bowl area can fracture in a big way and generate a really large avalanche. There are no bright red flags today, but a combination of snowpack concerns keeps us from dropping these areas to low. The continued cold, a buried crust, and thick wind slabs are the drivers of current ratings and should give you something to think hard about before center-punching a big slope. Lobster Claw and Right Gully share some of these snow structure concerns but are much smaller slopes and allow more options to avoid unstable areas. Field work today should help resolve some of these snow structure questions and help us understand the scope of these potential problems.

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 8:30a.m. February 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

2015-02-27

Avalanche Advisory for Thursday, February 26th, 2015

This Advisory expires at midnight

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

All forecast areas of Huntington Ravine have Low avalanche danger. Natural and human triggered avalanches are unlikely except in isolated terrain features. Be aware of the potential for ice dams with recent very cold air in place.

AVALANCHE PROBLEM: Wind Slab continues to be the primary threat today. The areas from Tuckerman’s Sluice, through the Center Bowl, over to the Chute harbors the greatest slab problem. Other areas that are assigned a Moderate rating such as Right Gully and the Lobster Claw, as well as all areas rated at Low, have better stability overall and hold more options for avoiding unstable snow. Light snow showers are expected today which should not affect ratings, but could increase some sporadic instabilities in isolated terrain features.  Keep your eyes open for areas of thin new soft wind slab.

WEATHER: The higher summits will be mostly in the clear under cloudy skies today.  There is a slight chance of afternoon snow showers on a shifting and decreasing wind from 60 mph (96 kph) dropping to 20 mph (32 kph) later this afternoon. Temperatures will stay below 0F (-18C) and fall to -20F (-29C) overnight.  Generally, weather conditions won’t change much over the next week with very little potential for precipitation.

SNOWPACK: Yesterday, the summit recorded 0.7” (1.75cm) of snow during light morning showers.  Later today, additional snowfall may bring up to another inch (2.5cm) on falling wind velocities.  As already mentioned, this will not affect the designated danger rating for each forecast area, but may create some pockets of thin, new and isolated wind slab in very strong lee areas.  Watch for this issue, but this should only be a minor problem that will be easily mitigated if recognized.   Over the next couple of days, we will see how slabs may be changing during our field time.  However, with cold temperatures in place you can anticipate very slow changes in stability.  It will be quite likely you will see similar ratings through the weekend.

The most significant problem continues to be an avalanche stepping down into deep slabs that loaded in over the weekend and into Monday.  The bulls-eye is the E and SE aspects from the Sluice through Tuckerman’s Center Bowl.  I would give these areas respect and expect accurate stability tests to be difficult to get unless you are in the thick of it already exposed to avalanche hazard.  Snow pits on representative slopes down low, or on adjacent slopes, may give you “false stables”.

Areas rated Low in Huntington don’t have much for previously existing stability problems. They were scoured clean by strong winds Monday gusting almost to 100mph (162kph). The same can be said for Left Gully and Hillman’s. Right and Lobster Claw have a lot of firm stable snow and some sections of wind loading, so use your safe travel and snowpack assessment skills to help you avoid instabilities in these areas. Any unstable snow in the Lower Snowfields and Little Headwall will be confined to isolated terrain features, so if you go looking for the largest areas of snow here, don’t be surprised to find some avalanche potential.

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. Thursday, February 26, 2015. A new advisory will be issued tomorrow.

Christopher Joosen, USFS Snow Ranger

2015-02-26

Avalanche Advisory for Wednesday, February 25, 2015

This advisory expires tonight at 12:00 midnight.

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

All forecast areas of Huntington Ravine have Low avalanche danger. Natural and human triggered avalanches are unlikely. Be aware of the potential for ice dams today.

AVALANCHE PROBLEM: Similar to yesterday, wind slab is the primary threat today. The focus of attention is in the middle of Tuckerman, in the Sluice, Lip, Center Bowl, and Chute. Other areas of Tuckerman, such as Right Gully and all areas rated at Low, have better stability overall and more options for avoiding unstable snow. There is a chance for new snow today. If we should receive a couple inches, expect avalanche danger to push the limits of their forecasted ratings due to new wind slab creating instabilities and increasing the load on existing instabilities.

WEATHER: In a season marked by many extreme weather events, today seems rather ho-hum. Overcast, fog, and some light snowfalls may obscure visibility. The Observatory is forecasting a trace to 2” (5cm) of snow, and if it continues for a while at the rate at which it’s currently falling, we just might see the full 2”. Winds will be from the W and increasing in speed today, reaching 45-60mph (72-97kph) with higher gusts by the afternoon.

SNOWPACK: Currently it is snowing at Hermit Lake. This makes me think about the potential for new slab to be developing with an increasing W wind. There probably won’t be a lot of snow for the winds to work with, but pay close attention to accumulations and be thinking of increasing avalanche danger if we get 1-2” (2.5-5cm) of new snow. It doesn’t take a lot of new snow to build slabs deep enough to be a problem when the winds are as forecast today.

A good benchmark for the snowpack is Monday, February 16th. Winds this day raged harder than they had in several years. This left a very firm slab in the Center Bowl and Lip. The Sluice had very hard slab as well, but some was avalanched down into the floor. Since the 16th, we’ve had a couple good snowfalls along with winds ranging from the SW to the NW and another avalanche in the Chute. These conditions have created a very variable and layered snowpack in the middle of Tuckerman, which is the primary concern today especially for the potential for a person to trigger something here. I also can’t ignore the possibility of an avalanche stepping down into the hard slab layer from the 16th and producing a large and damaging avalanche.

Areas rated Low in Huntington don’t have much for previously existing stability problems. They were scoured clean by strong winds Monday gusting almost to 100mph (162kph). The same can be said for Left Gully and Hillman’s. Right and Lobster Claw have a lot of firm stable snow and some sections of wind loading, so use your safe travel and snowpack assessment skills to help you avoid instabilities in these areas. Any unstable snow in the Lower Snowfields and Little Headwall will be confined to isolated terrain features, so if you go looking for the largest areas of snow here, don’t be surprised to find some avalanche potential.

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 8:15a.m. February 25, 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

2015-02-25

Avalanche Advisory for Tuesday, February 24, 2015

This advisory expires tonight at 12:00 midnight.

Tuckerman Ravine has Moderate and Low avalanche danger. Lobster Claw, Right Gully, the Sluice, Lip, Center Bowl, and Chute have Moderate avalanche danger. Natural avalanches are unlikely and human triggered avalanches are possible. Left Gully, Hillman’s Highway, the Lower Snowfields, 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 Low avalanche danger. Natural and human triggered avalanches are unlikely. Be aware of the potential for ice dams today.

AVALANCHE PROBLEM: Avalanche problems in our forecast zones today are largely confined to Tuckerman with very few potential problems in Huntington. Wind slab is the primary threat. Recent wind-loading has triggered natural avalanches on some slopes, which is considered “bulls-eye” information pointing toward instability. The Sluice, Lip, Center Bowl, and Chute in Tuckerman are the areas with the greatest potential for avalanches. We are beginning to see and hear of avalanches and/or unstable snow conditions outside of our forecast areas, so pay attention whenever you are near potential avalanche terrain.

WEATHER: In the last 7 days, the summit has recorded 16.5” of new snow (42cm). More than this has been recorded at our manual snow plot at Hermit Lake. Yesterday, strong NW winds blew at an average speed of 71mph (114kph) with a peak gust of 98mph (155kph). Today, wind speeds will be much more manageable, decreasing through the morning but increasing again in the afternoon. Temperatures will remain very cold; in the ravines you can expect temperatures hovering around 0F (-18C).

SNOWPACK: A quick visual scan of Tuckerman this morning gave me goosebumps. It’s amazing how quickly the Sluice, Lip, and Center Bowl have grown to a size that should make anyone stop and stare for a moment or two. There is currently a lot of snow loaded into these slopes and it has not been shedding it off regularly in avalanches as it often does. The net effect is a deeply layered snowpack capable of producing a very large avalanche. The snow on these slopes is also well-connected from one path to another, which allows a single fracture to propagate across multiple avalanche paths. You might be wondering about the stability of the snow here. Well, so am I. We tend toward conservative decision making, especially when consequences are high, so you won’t find me center-punching a bootpack up the Lip or headwall today. Although I don’t have hands-on information to give, I have a lot of confidence in the potential for a person traveling through here to trigger an avalanche.

Right and Lobster Claw have a much different snowpack. Expect areas of new windslab with some reasonable options for climbing and avoiding much of the troublesome snow (but not all). The Chute has reloaded in the zone between the choke and the upper rollover. Left Gully and Hillman’s were scoured pretty heavily. The Lower Snowfield has a lot of “isolated terrain features” that can have unstable snow. In the Little Headwall, there is a lot of windblown snow. I recommend going cautiously through here if you are one of the first today. I observed fresh crown lines this morning on the Lion Head Trail (summer traverse) and in the Gulf of Slides south snowfields.

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 8:15a.m. February 24, 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

2015-02-24

Avalanche Advisory for Monday, February 23, 2015

This advisory expires tonight at 12:00 midnight.

All forecast areas of Tuckerman Ravine have Considerable avalanche danger. Natural avalanches are possible and human triggered avalanches are likely. The only exception to this is the Little Headwall, which has Low avalanche danger. Natural and human triggered avalanches are unlikely.

Huntington Ravine has Considerable and Moderate avalanche danger. North, Damnation, Yale, Central, and Pinnacle gullies have Considerable avalanche danger. Natural avalanches are possible and human triggered avalanches are likely. Odell, South, and Escape Hatch have Moderate avalanche danger. Natural avalanches are unlikely and human triggered avalanches are possible.

AVALANCHE PROBLEM: Our avalanche concerns today are focused on recently developed wind slabs as strong winds mix and redistribute a small amount of new snow with previously existing snow sitting above treeline. This will create new slab instabilities throughout most of our forecast areas; however, the most significant loading and hazard is centered in the vicinity of the Sluice, Lip, and Center Bowl. In addition to new wind slabs, there is an increasingly complex snowpack around the ravines (particularly Tuckerman) that may allow for avalanches to step down into older layers, creating larger more damaging slides.

WEATHER: The big story for weather today is the falling temperatures and increasing wind speeds. This will make travel in alpine areas very inhospitable. Read the full summits weather forecast, plan and pack accordingly, and make conservative decisions today. As for avalanche related weather, we have received about 1” of snow early this morning. Winds have already risen to their forecasted speeds of 60-80mph with higher gusts. In our field observations yesterday, we found ample snow on the summit cone on E and NE aspects that will be blown around on these winds, making visibility poor and contributing to stability problems.

SNOWPACK: The number one thing you’ll want to be thinking about is the new snow loading taking place today, creating potential for naturally triggered avalanches and increasing the likelihood of human triggered slides. Prior to this, there was a wide range of conditions in Tuckerman. Right Gully had been cleaned out of the 20” of snow that fell over the last week, leaving firm but skiable conditions for several people to enjoy yesterday. The SW winds are to blame, but they also loaded and cross-loaded other slopes such as the Center Bowl, Chute, and Left Gully. In these areas you can expect to find a mix of hard and soft layers sitting on top of the very hard slab formed on 2/16. The potential exists for this hard slab layer to be triggered if the load is great enough (e.g. an avalanche runs over it). If this happens, you will want to be nowhere near the runout of the Center Bowl in floor of Tuckerman.

Yesterday I observed what I think may have been a long stauchwall on the summit cone, in the same slope as last year’s March 29th close call. I was able to safely get to a small section of crown and found very poor structure in the top 30cm of snow. I have a low degree of confidence that this was anything more than just a small 20’ long avalanche on a rollover, but it may have been a large soft slab avalanche if the whole snowfield slid the way I think it might have. I’m thankful that no one was up there skiing yesterday, because the stability would earn a poor to fair rating on that slope. Remember, just because a slope isn’t forecasted or doesn’t regularly slide does not mean it cannot avalanche.

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. February 23, 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

2015-02-23

Avalanche Advisory for Sunday, February 22, 2015

This advisory expires tonight at 12:00 midnight.

All forecast areas of Tuckerman and Huntington Ravine 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. Lower Snowfields has 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.

AVALANCHE PROBLEM: Wind slab is the primary avalanche problem today. This wind slab is likely to be sensitive to human-triggering due to relatively low summit wind speeds, by Mount Washington standards, last night. Wind at the start of the storm was from the SW and shifted around to its current WNW which built these wind slabs in all aspects of our forecast terrain. Expect these wind slabs to be on the softer side and capable of fracturing large enough to produce an avalanche which could hurt or kill you.

WEATHER: Snow began falling on the mountain last night around 4pm. At that time, winds from the southwest were blowing around 50mph on the summit. By 11pm winds were from the west at roughly the same velocity with snow falling at an increasing rate for a couple of hours. By 2am, the snow fall stopped but wind loading continued from the west with a bit higher wind speeds recorded. Wind speeds are diminishing as forecast for today with good visibility for a spell at 7:30am, though an undercast exists which is moving in and out of both Ravines making visibility uncertain. Summit winds should relax to the 20-35 mph  range, if they haven’t already, with temperatures in the low teens (-10C range). There is the potential for a trace to 2” of snow this morning. Later tonight, an arctic airmass will blow in, sending the mercury freefalling to -20F (-28C) with winds increasing to the 60-80 mph (95-130 km/h) range with gusts to 90 mph (145 km/h). The temperature on Monday will continue to fall to around -35F(-38C) with even higher winds making a backcountry adventure particularly dangerous.

SNOWPACK: A smooth blanket of snow covers Pinkham Notch and the Tucks trail and might lead you to believe that deep loose and unconsolidated powder waits for you in the Ravines. Don’t be disappointed when you arrive at the mouths of the Ravines to find steep wind drifts. The drifts tell the tale of wind affected snow, around 6” of which was recorded at Hermit Lake (12.5-14cm with wind effect on the boards). Snow here at Hermit Lake is also slightly denser than lower elevations, most likely due to settled cold air allowing larger crystals to grow. Good visibility this morning revealed smooth snow, wide spread large pillows of snow particularly in upper Hillman’s, through Chute, Center Bowl, the Lip and Sluice. Some sastrugi indicates a  stronger wind effect above the ice in Center Bowl with a cornice and wind drifts across the top of Left Gully. The only new crown line we are seeing so far is above the choke in Chute where it looks as if sluffing triggered a thin slab. Visibility was non-existent this morning in Huntington Ravine. Bed surfaces are growing in the Lower Snowfields along with the sluff and debris pile out of Duchess so be careful with your terrain and snowpack assessments if venturing into this area.

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. February 22, 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

2015-02-22 print friendly

Avalanche Advisory for Saturday, February 21, 2015

This advisory expires tonight at 12:00 midnight.

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

All forecast areas of Huntington Ravine currently have Low avalanche danger. Natural and human-triggered avalanches are unlikely. Watch for unstable snow in isolated terrain features.

AVALANCHE PROBLEM: The existing wind slab is the primary problem for today, followed by the growth of new wind slab as snow begins to fall this afternoon and evening. Numerous naturally-triggered avalanches occurred recently on a variety of slopes, which should be an indicator of potential instability today. The area of greatest concern is in the Sluice through Center Bowl of Tuckerman, though all forecast areas of Tuckerman should be treated with caution today. Even those rated Low may hold smaller isolated pockets of unstable snow, the Little Headwall is one example of this. New snow this afternoon and evening will cause avalanche danger to rise, possibly exceeding some of today’s ratings before midnight.

WEATHER: Today is a good day to get out early and move quickly. Weather will be deteriorating as clouds lower, snow falls, and winds increase in velocity. Current winds of 40mph (65kph) gusting to 50mph (80kph) are already enough to cause low drifting snow to cascade down the headwall of Tucks. Much of today’s avalanche danger is brought on by ~18” (46cm) of light density snow (as measured at Hermit Lake) that fell this week, followed by winds yesterday afternoon and evening gusting in the 80-90mph (130-145kph) range.

SNOWPACK: We’ve had a good avalanche cycle in the last 24 hours, with large slides in many areas. I’m not sure which is my favorite avalanche this morning, the summer Lion Head Trail where it traverses at treeline or the one in the upper Chute. Both tell a good story about what’s happened with our snowpack just recently. Although winds have subsided a good deal since most of the loading took place, cold temperatures are going to keep a lot of the snap in the slabs that did not avalanche. The Lip and Center Bowl look like they may have already slid once, but if they did, reloading is hiding much of the evidence. The easy weak layer to look for is going to be weak, soft snow deposited before noontime yesterday. It will be much softer than the slab that is likely sitting on top of it. However, don’t only look for this structure. Very often, it’s subtle changes in wind speeds or directions that can create weak interfaces within a slab layer. These vary widely from one place to another, so be sure collect a lot of information today that’s relevant to your intended route.

Huntington Ravine starts today with a heavily scoured snow surface. I don’t expect avalanche danger to rise much during daylight hours, but after dark it may go above the Low threshold.  Within the Low rating, there may be small terrain features with unstable pockets of wind slab. Below the ice bulge in Central is one such example.

Looking for something to do tonight? Come by International Mountain Equipment at 6:30 for a free avalanche continuing education session. Snow Ranger Frank Carus will be presenting tips and techniques for effective terrain management in Tuckerman and Huntington 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 AMC at the Pinkham Notch Visitor Center, or the caretakers at Hermit Lake Shelters or the Harvard Cabin.
  • Posted 8:30 a.m. February 21, 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

2015-02-21

Avalanche Advisory for Friday, March 20, 2015

This advisory expires tonight at 12:00 Midnight.

All forecast areas of Tuckerman and Huntington Ravine 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. The only exception to this rating is the Lower Snowfields and the Little Headwall. The Lower Snowfields has Moderate avalanche danger. Natural avalanches are unlikely and human-triggered avalanches are possible. The Little Headwall has Low avalanche danger. Natural avalanches and human-triggered avalanches are unlikely. 

AVALANCHE PROBLEM:  The dry, light snow that fell Wednesday night and Thursday will be transported by increasing NW winds and build wind slabs over a weak layer of this low density snow. Expect these wind slabs to be largest in lee areas of this NW wind such as Sluice, Lip, and Center Bowl with the greatest potential for a natural avalanche in these areas. Adjacent areas are less prone to avalanche naturally but still certainly possible. In Huntington, many areas in the lee of the NW wind will harbor dangerous wind slabs until the wind reaches higher into the 90 mph (145 km/h) range late in the day. At that point snow in Huntington will begin to be scoured out but not before becoming dangerously sensitive to human-triggering.

WEATHER: The increase in wind speed and shift to the NW was delayed yesterday keeping today’s forecast similar. Winds are forecast to reach the 50-70 mph (80-115 km/h) before ramping up further to the 70-90 mph (115-145 km/h) range. Wind speeds are currently already blowing out of the NW at 59 mph (95 km/h) which is the highest velocity since yesterday’s new snow accumulation. Increasing NW wind plus around 7” of snow on the summit yesterday are the bright “red flags” signaling our avalanche danger. Expect summit fog and blowing snow to hamper visibility though cloud cover should begin to clear late in the day as high pressure takes over. Temperatures will be well below zero so anticipate arctic conditions with a temperature around -15F (-26C). Peak gusts on the summit are expected to hit 110 mph (175 km/h) before diminishing through the night.

SNOWPACK: As discussed yesterday, a small but intense storm system dumped widely variable amounts of snow on the area Wednesday night. While 14” fell at Hermit Lake, only 4.6” fell on the summit with some amount in between falling in our start zones and above in our fetch zone. Snow shower activity yesterday deposited another 2.5” to 3” on the summit. All this snow was very light density which makes the snow easily transported by the wind and also very weak. This weak and uncohesive snow was enjoyed by a few skiers yesterday who It is likely that the slow ramp up of wind yesterday allowed for the weak layer of new snow to adjust somewhat to the new load being piled on by the wind. This is the primary reason why I feel that a High rating is not warranted today. That said, you will find slabs growing to a sizable dimension today with the potential for natural and human-triggered avalanche activity more than likely peaking mid-day. Sluice unleashed a wind slab earlier in the week but Lip and Center Bowl did not so consider deeper wind slabs to contribute to an avalanche coming from these areas. In Huntington, the timing for potential avalanche activity also would correspond to the typical climbers travel plans with scouring not occurring until later in the afternoon. At that point, you could look forward to potential lower avalanche hazard while climbing in sub-zero temperatures and winds pushing towards the century mark. It seems like tomorrow might be a better option.

The Continuing Education series continues Saturday night at 6:30 p.m. at IME in North Conway where the presentation and discussion will be on the subject of Terrain Management so come on down and join me in getting my avalanche geek on.

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 7:20 a.m. February 20, 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

2015-02-20 print friendly

Avalanche Advisory for Thursday, February 19, 2015

This advisory expires tonight at 12:00 midnight.

All forecast areas of Tuckerman and Huntington Ravine have HIGH avalanche danger. Natural avalanches are likely and human-triggered avalanches are very likely. Very dangerous avalanche conditions today. Travel in avalanche terrain including the floor of the Ravines is not recommended. The only exceptions to these ratings are the Lower Snowfields and the Little Headwall. The Lower Snowfields has Considerable avalanche danger. Natural avalanches are possible and human-triggered avalanches are likely. The Little Headwall has Moderate avalanche danger. Natural avalanches are unlikely and human-triggered avalanches are possible.

AVALANCHE PROBLEM: Dry loose avalanches are your first concern right now in both ravines. Wind slab avalanches will begin to threaten travelers in our terrain and grow in size and likelihood through the day and into the night as winds increase and shift to the northwest through the west.  These wind slabs could bury a person and will grow more destructive through the day as wind speeds increase and transport snow into slopes and gullies with an easterly aspect. Older, deeper wind slabs in the Center Bowl and Lip area could play a role in generating a large avalanche if the new slab weight or moving debris exceeds the load carrying capacity of the underlying slab.

WEATHER: A variable thickness blanket of ultra low density snow covers the area with 35.5cm (14″) recorded this morning at Hermit Lake but only 4.6″ (12cm) collected on the summit in low winds. Pinkham recorded 11″ (28cm). These variable totals are not surprising given the nature of this small, but relatively intense system. Light wind is currently blowing out of the SSW in the 20 mph range on the summit but is going to ramp up in speed and, by 2-3pm, is expected to hit 40 mph or so while shifting W to NW. Wind speeds will continue to climb to the 40-55 mph range with gusts to 65 mph by sunset.

SNOWPACK: The kind of champagne powder that blankets Pinkham Notch and Hermit Lake would be ideal for magazine photo shoots for skiing in Utah. Beth’s sample of 14″ from the Hermit Lake snow plot was 3.5%! Sadly, much of this light snow is sitting on a very firm wind hammered surface in steep terrain and would most likely be raked off easily. The new layer of light snow will also form a soft, fist (F) hardness weak layer on which firmer wind slabs will build later in the day. Plumes of snow are already visible coming off of Boott Spur and over Dodge’s Drop. Expect today’s wind slabs to be touchy. By tomorrow, winds approaching 100 mph will change everything.

The variation in snowfall totals lends some uncertainty as to the timing our ratings today. Also, the size and destructive power of the wind slabs will depend alot on the amount of snow available to be transported into the Ravines. With all the recent snow smoothing out and filling in the rocks and broccoli forests at and above treeline, coupled with the ridiculously low densities, make us believe that there will be plenty of snow to generate dangerous avalanches in both Ravines 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 8:30 a.m. February 19, 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

2015-02-19 print friendly

Avalanche Advisory for Wednesday, February 18, 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. All other forecast areas 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 Low avalanche danger. Natural and human triggered avalanches are unlikely. Watch for unstable snow in isolated terrain features.

AVALANCHE PROBLEM: Wind slabs are the problem you’re most likely to see today. In Tuckerman, the Moderate-rated areas have firm, strong wind slab that will be resistant to human impacts, though the possibility exists that you’ll find a weak spot in the slab. Although the likelihood is somewhere between possible and unlikely, the resulting avalanche could be a very large and destructive. Other areas, including many rated Low danger, may hold smaller pockets of firm slab that do not have quite as much strength and an unlucky climber could still trigger it even in Low danger. With a small amount of new snow, there is also the chance that fresher, much softer wind slabs will form late in the day.

WEATHER: There is not a lot to say about today’s weather. If every day were like today, life on Mt. Washington would be pretty boring. Expect light winds, fair skies turning to overcast, and seasonable temperatures. Thankfully, this afternoon we are expecting some light snow to begin. This will intensify overnight and hopefully leave us with modestly significant accumulations by Thursday.

SNOWPACK: A trip into Tuckerman yesterday confirmed what we believed to be the situation around the ravine, and even gave us enough information to drop a couple forecast areas from Moderate to Low danger. The very strong winds early in the week laid a beat down on the snowpack. Avalanche activity was widespread in Tuckerman, likely Sunday night through Monday morning. Lobster Claw, Right Gully, the Sluice, and the Chute all avalanched during this time. What is left behind is a very strong and thick slab from Sluice through Chute. Although it has a lot of strength and the chances of a gently traveling person impacting it enough to cause it to release are on the lower end, the consequences of the potential avalanche are great enough to warrant a Moderate danger rating. Believe me, you don’t want to trigger the Lip and Center Bowl today.

The areas rated Low have been subjected to avalanches and wind-hammering effects. Some of the resulting surfaces are great for cramponing, while others are icy bed surfaces from prior avalanche activity, and others are thin breakable crusts. You will still want to be aware of the potential for smaller pockets of unstable snow. Low danger does not mean you should leave the beacon, shovel, and probe in the car. Come with an understanding of the hazard and you can be rewarded with good climbing conditions. The ski conditions are not ideal; generally when you want crampons for climbing the snow is firm enough that descending on skis or boards can be a harrowing proposition for even the hardiest New England skier.

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 7:30 a.m. February 18, 2015. A new advisory will be issued tomorrow.

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

2015-02-18

Avalanche Advisory for Tuesday, February 17, 2015

This advisory expires tonight at 12:00 midnight.

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

All forecast areas of Huntington Ravine have Low avalanche danger. Natural and human triggered avalanches are unlikely. However, unstable snow may exist in isolated terrain features.

AVALANCHE PROBLEM: Wind slab leftover from recent strong winds is the avalanche problem you’ll need to watch out for today. This can be found in isolated locations within forecast areas rated Low (e.g. the very top of Yale Gully) or in more widespread distribution in the Moderate-rated areas in Tuckerman. Slabs will have a lot of strength, which could lead you into a feeling of good stability, but if you should find a weak spot or tickle the weak layer in just the right way, you could produce a sizeable and destructive avalanche.

WEATHER: Compared to the last couple days, today will be a very pleasant day on the mountain. Light winds and temperatures above 0F are to be expected. There will be increasing cloudiness during the day as well, with a chance for some very light snowfall.

SNOWPACK: I’ll start with the easier discussion…Huntington Ravine has been pounded by very strong winds over the last two days. The surfaces there will be very firm and textured. As for avalanche concerns, there may be lingering pockets of instability. One that caught my eye this morning was the hangfire above a crown line at the very top of Yale Gully. You would be challenged to exit that route without climbing up over the crown and into the hangfire. In Tuckerman, Hillman’s and Left Gully have similar conditions as most of Huntington. As another example of how punishing these winds were, Dodge’s Drop (with a windward aspect) has eroded sufficiently that it is no longer continuously skiable snow. Be wary of any hard surface that sits on top of softer, weaker snow.

Elsewhere in Tuckerman, leeward aspects had windblown snow throughout much of the past two days. Yesterday morning, a thick slab released from the Sluice, but the Lip and Center Bowl showed no sign of recent avalanche activity. This tells me that these areas, and probably parts of Lobster Claw, Right Gully, and the Chute, stand a good chance at having unstable snow. It’s hard to ignore the bulls-eye data of recent avalanche activity on adjacent slopes as a sign of instability. Again, you should anticipate hard strong slabs but be on the lookout for any potential weaknesses, such as a thin spot toward an edge or locations near buried rocks or bushes.

I’d like to express my deepest sympathy for the family and friends of the hiker who perished while attempting to traverse the Presidential Range on Sunday. It’s important for us to remember that with adventure comes inherent risks, and we can never fully remove or mitigate the risk. This is true for seemingly benign trips as much as it is true for those where the risks are more obvious and apparent. I would like to encourage everyone who travels into the mountains to use this incident as a catalyst for self-reflection, rather than assigning fault, finding errors, or questioning judgment. We all have pushed our limits at one time or another. This is a case where one person’s choice for adventure had a very tight margin of safety, and due to circumstances that no one will ever fully know, she paid the ultimate price. For that, I am truly saddened.

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 8:25 a.m. February 17, 2015. A new advisory will be issued tomorrow.

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

2015-02-17

Avalanche Advisory for Monday, February 16, 2015

This advisory expires tonight at 12:00 midnight.

Tuckerman Ravine has Moderate and Low avalanche danger today. Lobster Claw, Right Gully, Sluice, Lip, Center Bowl, and Chute have Moderate avalanche danger. Natural avalanches are unlikely but human-triggered avalanches are possible. Heightened avalanche conditions on specific terrain features exist. Left Gully, Hillmans Highway, Lower Snowfields and the Little Headwall have Low avalanche danger. Natural and human-triggered avalanches are unlikely.

All forecast areas of Huntington Ravines have Low avalanche danger. Natural avalanches and human-triggered avalanches are unlikely. Watch for unstable snow on isolated terrain features.

AVALANCHE PROBLEM: Extreme northerly winds continue to work on the snowpack. Higher and more exposed areas are being scouring while certain leeward and lower elevation spots are catching snow and building hard, stubborn and potentially large wind slabs. If you managed to crawl against the wind into these Moderate rated areas you could trigger a dangerous hard slab avalanche given the right terrain feature, slab thickness or more accurately thin-ness.

WEATHER: Probably the more prevalent danger than today’s avalanche problem is the high wind and cold temperatures. The last four hourly observations on the summit show NNW winds blowing steadily from 105-119 mph with gusts as high as 131 mph. Temperatures will warm slightly to -15F and wind will diminish some to the 70-90 mph range later this afternoon but expect extremely challenging conditions above tree line until then. Even below tree line, the danger of frostbite is real this morning. Falling trees and branches present a real risk and drifting on trails will slow progress. Gusts at Hermit Lake are testing the cabin’s construction and remind me of tornadoes and hurricanes that I have experienced. Jeff and I had to cut our way through two live downed trees on the Tuckerman Ravine trail to get to Hermit Lake. It is not nice day out.

SNOWPACK: Severe weather or low visibility have kept us from getting into the field over the last 4 days to dig for weak layers and assign numbers to our instabilities using the standard battery of snow stability tests. Weather history, some visual assessments and institutional knowledge all point to the obvious issues in the upper snowpack as being the most concerning feature. In addition to wind slabs loading in today, thicker wind slabs which developed Thursday and Friday and a thinner slab problem from the weekend are out there scattered around the terrain.  Older hard surfaces are also exposed in places making for challenging and potentially hazardous climbing on steeper terrain such as the Fan in Huntington or the lower slopes of Tuckerman Ravine without the use of crampons. Hopefully the snowpack discussion today is just an academic exercise in snow science without any application to your recreational goals in higher terrain today.

Current rescue operations are going on in the northern Presidential range so please yield to these rescue efforts. Expect drifting snow, limbs, branches and possibly downed trees as well as very firm snow on all trails including the John Sherburne ski trail 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 8:45 a.m. February 16, 2015. A new advisory will be issued tomorrow.

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

2015-02-16 print friendly

 

Avalanche Advisory for Sunday, February 15, 2015

This advisory expires tonight at 12:00 midnight.

Tuckerman Ravine has HIGH and CONSIDERABLE avalanche danger. The Sluice, Lip, and Center Bowl have High avalanche danger today. Very dangerous avalanche conditions exist. Natural avalanches are likely and human-triggered avalanches are very likely. Travel in avalanche terrain is not recommended.

All other forecast areas of Tuckerman and Huntington Ravines have Considerable avalanche danger. Natural avalanches are possible and human-triggered avalanches are likely. The Little Headwall has Moderate avalanche danger. Natural avalanches are unlikely and human-triggered avalanches are possible.

AVALANCHE PROBLEM: The avalanche problem you’ll be dealing with today is wind slab, though I encourage you to give your attention to the weather forecast for today as a significant problem you’ll need to be ready for if you’re out on the mountain. See below for details on the weather. The development of wind slabs will be most intensely focused on wind-sheltered SE-facing slopes such as the Lip and Sluice in Tuckerman. Slopes adjacent to these will also be on the receiving end of wind-transported snow and have a significant avalanche hazard. Travel into avalanche terrain, particularly the floor of Tuckerman, is not recommended due to the potential for naturally-triggered avalanches to extend into flat terrain. You don’t need to be on steep slopes to be at risk of avalanches today!

WEATHER: Mt. Washington will truly be putting on a show today and tomorrow. Its well-earned reputation for harsh winter weather will be on display, and I’d recommend taking a seat away from the action for this show. We only received a few inches of 10% snow from yesterday’s storm. Honestly, it was quite a disappointment. If we’re lucky we might get 1-2” (2.5-5cm) more during the morning hours, but any lingering snow showers will have wrapped up by afternoon. Temperatures will be falling today, reaching -35F (-37C) on the summit overnight.  During this time, wind speeds will be rising quickly up to the 100mph (161kph) mark with gusts possibly reaching 125mph (201kph). These conditions are not to be taken lightly. I encourage you to be judicious in your choice of adventure today. Even if your plan is to stay well below treeline today, bring plenty of warm clothes and extra food and water.

SNOWPACK: We’re not likely to be out in the ravines digging into the snowpack today, and you don’t need to be to understand the avalanche problem. Even though the storm was a letdown, there are still a few inches of new snow around the mountain, a little more possible today, and ample amounts of snow sitting around both above and below treeline. All this will be available to very strong NW winds for redistribution into the ravines. I expect to see the greatest loading rates and largest slab development in the strongly protected slopes in Tuckerman. Also, smaller terrain features may protect slopes enough to allow for slab development as well, regardless of whether it’s in the direct lee of prevailing NW winds. You should expect increasing avalanche danger today, with some areas rising up beyond the Considerable rating. Wind speeds that we are expecting can push slabs down lower into the ravines than you might think, so don’t be surprised to find unstable snow in areas such as the Lower Snowfields, Little Headwall, or the Fan in Huntington.

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. February 15, 2015. A new advisory will be issued tomorrow.

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

2015-02-15

Avalanche Advisory for Saturday, February 14, 2015

This advisory expires tonight at 12:00 midnight.

Tuckerman Ravine has Considerable and Moderate avalanche danger. Sluice, Lip and Center Bowl have Considerable avalanche danger. Natural avalanches are possible and human-triggered avalanches are likely. All other forecast areas except the Little Headwall have Moderate avalanche danger.  Natural avalanches are unlikely and human-triggered avalanches are possible. Evaluate snow and terrain carefully.  Little Headwall has Low avalanche danger where natural and human-triggered avalanches are unlikely.

All forecast areas of Huntington Ravine have Moderate avalanche danger. Natural avalanches are unlikely and human –triggered avalanches are possible. Evaluate snow and terrain carefully to identify features of concern.

AVALANCHE PROBLEM: Wind slabs which developed yesterday should be your primary avalanche concern today. The wide distribution and variable resistance to human-triggering of these slabs, along with the variable integrity of weak layers beneath, will make ongoing assessment of your chosen route a critical task. High wind speeds yesterday morning moved around 11” (28cm) of low density snow from storms earlier in the week. These winds scoured many areas while building firm, and less firm, more sensitive wind slabs in others. Pre-existing weak layers of soft snow and poor bonding to icy older surfaces contribute to the potential for areas of this firm wind slab to fracture some distance from your feet and even above you. The potential exists for small areas of new unstable wind slab to develop later this afternoon and certainly tonight as heavier rates of  snowfall develop while the approaching winter storm settles into the region.

WEATHER: The low pressure system that is approaching as already begun to influence our visibility on the mountain. An aerosol of very light snowfall and flat light are current harbingers of more significant snow developing later this afternoon and overnight as the latest major Winter Storm affects the area. While the new snow is not expected to generate much in the way of avalanche problems during daylight hours, it certainly will overnight and tomorrow.

SNOWPACK: Strong winds yesterday appear to have generated a fair amount of avalanche activity in our terrain. Even now with much lighter winds, signs of continued loading are evident. As I alluded to in the avalanche problem section, lots of spatial variability is the defining feature of our upper snowpack. You would find icy old surface, softer slabs from low wind speeds, as well as hard stubborn wind slabs during an ascent of any of our forecast areas. Careful travel and assessment with a strong suspicion of someone dropping in from above, particularly later in the day, would be the advice I’d give to anyone venturing into avalanche terrain today. A 5-minute window of reasonable light this morning allowed us to see surface features in Tuckerman Ravine. Surface textures, debris, and almost buried crown lines indicate that the lower Lip (at the choke), Chute and Left Gully avalanched yesterday and have since reloaded with smoother and likely sensitive slab. The bowl beneath the ice of Sluice looks ripe with newly loaded snow while the upper part, as well as most of the higher slopes at the rim in the rest of Tuckerman, is mostly scoured or covered in heavily wind sculpted snow (sastrugi). Solar effect on south facing slopes on Tuesday and particularly Wednesday resulted in a melt freeze crust on those slopes which resulted in breakable, read horrendous, ski conditions on those aspects.

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 8:35 a.m. February 14, 2015. A new advisory will be issued tomorrow.

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

2015-02-14 print friendly