Avalanche Advisory for Wednesday March 12, 2014

This advisory expires  at midnight.

Tuckerman and Huntington Ravine have CONSIDERABLE avalanche danger.  Natural avalanches are possible and human triggered avalanches are likely. Dangerous avalanche conditions exist; careful snowpack evaluation, cautious route finding, and conservative decision making are essential.  Expect an increasing avalanche danger today and overnight.

AVALANCHE PROBLEM:  A WINTER STORM WARNING is in effect.  Problem #1 will be shared between Storm Slabs and Wind Slabs today.  Wind slabs that developed over that past 36 hours will be the leading problem this morning followed by new Storm Slabs and new Wind Slabs this afternoon.  Heavy snowfall will increase load and instability later today bumping the potential for natural and human triggered avalanches.  New snow slab failure could step down into the Persistent Slab weaknesses that have been difficult to trigger as of late.  This secondary persistent problem is mostly a concern for the ultimate size of an avalanche.  This is due to new snow avalanches that may be more load  and stress than these lower facet weaknesses can take, causing failures to step down to deeper slabs.

WEATHER: Today’s winter storm should bring 18-24+ inches ( 45-60+cm) of snow beginning this morning, picking up this afternoon, and into tomorrow.  This will start off with  a WSW wind quickly moving counter clockwise through the SW, S, and eventually from the SE increasing in speed from 20-30mph this morning to 40+mph later.  Snow will increase in intensity and become a full rager overnight. Temperatures will fall from a high of 20F today to -10F tonight, with an increasing and shifting wind.  Winds will continue to wrap through the E into the N during darkness and blow over 70mph.  Thursday will be cold with the wind shift continuing to the NW.

SNOWPACK: To keep this discussion on point I will avoid much of our deeper issues as they will become moot compared to today’s storm problems, and the loading from the last couple of days.  Anticipate the greatest instabilities, as well as natural and human triggered avalanche potential, to occur on faces with a northerly facing component today.  As winds today rotate through the S expect slopes such as the Chute,  Left Gully, Hillmans, and the Boott Spur gullies in Tuckerman;  as well as Odell, South, and the Escape Hatch gullies in Huntington, to see the heaviest loading.  New snow will start with a lighter wind allowing it to load into the terrain deposition as a light density layer. This will likely act as the weak layer for future avalanches as densities become heavier with increasing wind velocities.  As today’s storm continues overnight, and winds wrap all the way around the compass rose, expect heavy loading.  This will initiate as cross loading, due to an E wind, then major loading on slopes facing S, and then SE and E tomorrow.

We will be bumping the ceiling of the Considerable ratings later today and will move towards HIGH during the overnight and EXTREME avalanche danger sometime Thursday morning if the storm plays out as forecasted. It is absolutely not a good day to be be running late in your mountain adventures.  Get home early and hit the hot tub.

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 800am 3-12-2014. A new advisory will be issued tomorrow.

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

2014-03-12 Print

Avalanche Advisory for Tuesday, March 11, 2014

This advisory expires tonight at 12:00 midnight.

Tuckerman Ravine will have CONSIDERABLE and MODERATE avalanche danger today. The Sluice, Lip, Center Bowl, and Chute will have Considerable danger. Dangerous avalanche conditions exist; careful snowpack evaluation, cautious route finding, and conservative decision making are essential. Natural avalanches are possible and human triggered avalanches are likely in these locations. All other forecast areas have Moderate avalanche danger. Natural avalanches are unlikely and human triggered avalanches are possible.

Huntington Ravine also has CONSIDERABLE and MODERATE avalanche danger. Central Gully has Considerable danger. Natural avalanches are possible and human triggered avalanches are likely. All other forecast areas have Moderate avalanche danger. Natural avalanches are unlikely and human triggered avalanches are possible.

AVALANCHE PROBLEM: Developing new wind slab is the avalanche problem causing a rise in danger ratings today. Expect steep slopes with east-facing components to build touchy soft slabs today. In the strongest lee areas, the danger will rise to the point where natural avalanche activity may occur. In adjacent areas, the same problem will exist but the danger will rise to a lesser extent.

WEATHER: A dark cloud looms ominously over Mt. Washington this morning, which is sometimes referred to as “Mt. Doom” by local old timers. Today certainly feels like Mt. Doom is an appropriate name. It’s also hard to focus on today when there is a large winter storm approaching for tomorrow, but we’ll save that discussion for later. Today you’ll be in thick clouds with blowing snow and the possibility for additional upslope snow to be falling. The visibility may be terrible, but at least temperatures will be on the mild side, maybe even going above freezing on the lower portions of the mountain. Westerly winds are the key factor for today, 50-70mph speeds will be redistributing yesterday’s snowfall. And if you were wondering, we received just shy of 2″ of new snow in the last 24 hours. About 1/2″ of this came early yesterday as large stellar dendrites and with light winds. The rest came after dark as winds shifted from the WNW toward the WSW during the latest snowfall period.

SNOWPACK: Looking at how the snow fell yesterday and what the winds were doing will give you a good idea of where today’s avalanche problem lies. Imagine a thin layer of light density crystals floating down from the sky while winds were blowing from the WNW at 30mph. This speed is light enough to allow this layer to land on any aspect, waiting to become a future weak layer. As the second round of snow began, winds ramped up eventually reaching gusts near 70mph from the SW. This pattern likely created sensitive soft slabs sitting on top of a thin weak layer. As we see winds increase again today, additional wind loading on top of these layers will cause danger to rise further.

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 Visitor Center, or the caretakers at Hermit Lake Shelters and Harvard Cabin.
  • Posted 8:10a.m. 03-11-2014. A new advisory will be issued tomorrow.

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

2014-03-11 Print friendly

Avalanche Advisory for Monday, March 10, 2014

This advisory expires 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. All other forecast areas have Low avalanche danger. Natural and human triggered avalanches are unlikely. Watch for unstable snow on isolated terrain features.

Huntington Ravine has Moderate and Low avalanche danger. Central Gully, Pinnacle, and Odell have Moderate 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, except in isolated terrain features.

AVALANCHE PROBLEMS: Difficult to trigger wind slabs will be the primary avalanche hazard early today with new storm and wind slabs developing later. Timing of new snow falling during snow shower activity will determine the degree of danger presented by these new slabs. If snow fall rates increase earlier than forecast, avalanche hazard will also increase. The persistent wind slabs in the Sluice through Chute areas remain a threat due to the potential size of a hard slab avalanche that could be triggered by a large load or on a thin spot in these locations. Continue to treat these areas with respect.  I would not want to descend steep avalanche paths in the late afternoon or evening as new slabs are likely to be touchy. There is the outside potential for these slabs to step down if the weakening ice crust is overloaded. An afternoon descent via winter Lions Head would be my choice over other options.

WEATHER: About a 1/2″ of snow fell in the early hours today with a trace to 2″ forecast through the day. 2-4″ more are forecast for tonight. West winds in the 25-40 mph range will diminish to 15-30 mph through the day while summits will remain obscured by clouds. Reduced visibility due to ground level clouds and light snowfall will be the rule today. Temperatures will be in the mid-teens F on the summit to mid-20’s at Pinkham Notch.

SNOWPACK: Existing surface conditions are predominately pencil hard wind slab with marginally softer slabs in some well protected lee areas such as Sluice through Chute in Tuckerman and other pockets throughout the ravines . Exposed ice crust exists as well, particularly in the fall line of gullies which have seen strong scouring action due to avalanche activity or wind erosion. Climbers left side of Left, Hillmans and South are examples of this. Expect new snow to form thin but touchy slabs today especially where it lands on the ice crust. It is hard to imagine that the small amount of snow will build to a depth capable of producing anything other than a small (D1) avalanche but even small avalanches can create problems when moving in steep terrain. Small natural sluff avalanches in a few very isolated areas would be within the realm of possibility but their small size doesn’t warrant a considerable or even moderate rating in our minds. Remember that a low rating doesn’t mean no avalanches.

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 Visitor Center, or the caretakers at Hermit Lake Shelters and Harvard Cabin.
  • Posted 8:15 a.m. 03-10-2014. A new advisory will be issued tomorrow.

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

2014-03-10 Print friendly

Avalanche Advisory for Sunday, March 9, 2014

This advisory expires 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.

Huntington Ravine has Moderate and Low avalanche danger. Central Gully has Moderate 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, except in isolated terrain features.

AVALANCHE PROBLEMS: With the lack of recent snow, our avalanche problem discussion has moved toward persistent slabs. In reality, the true problem is the interaction between the weak layer beneath the slab and the slab itself. The snowpack generally has a good amount of strength, which decreases the probability of triggering a slide. However, an avalanche triggered in a Moderate rated area could be large and carry significant consequences. The locations where we have the greatest concern for this problem are on east-facing, strong lee slopes such as the Lip, Center Bowl, and Central Gully. In some isolated terrain features, you may also encounter pockets of wind slab from earlier this week. These will likely be smaller in size and have good stability, but treat them as you would any isolated pocket of wind slab…with an appropriate level of caution.

WEATHER: So far, March has been a lackluster month for snowfall. The Observatory has recorded a mere 3.6” in the first 9 days of the month. Thankfully, we might start to get some refreshment this week with snowfall on Monday and possibly a large storm on Wednesday. For today, you can expect fair weather for being out on the mountain (fair as in slightly worse than good, not the fair that implies sunny skies and pleasantly warm breezes.) Winds will pick up late today and clouds will be dropping over the mountain as well, so if you’re out late, be prepared for poor visibility.

SNOWPACK: On the whole our snowpack has good stability. This is true not only for locations that have exposed crust such as Left Gully, but also for the areas with stiff pencil-hard slabs at the primary surface (e.g. Hillman’s). Additionally, I would go so far as to say the areas rated Moderate today have good stability, but this statement comes with a strong caveat. That is, while it may have good overall strength, if you were to trigger a slide it would be deep and large and full of blocks of hard slab. This is not the type of avalanche you want to be involved with. So far this season our snowfall has been lower than average, which means that many rocks and ice bulges in the ravines are not deeply buried. In the vicinity of these hidden features you will often find weak points in the snowpack. Triggering these hard slabs would most likely be done either at a weak point or by a large impact (e.g. dropping an ice cliff, taking a tumbling fall, etc.).

We’ve been watching the freezing rain crust pretty closely over the past couple weeks. It is changing over time and its characteristics are becoming more variable. The key point to remember is that there is a weak layer just beneath the crust, and this would be the most likely failure layer for avalanche activity 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 Visitor Center, or the caretakers at Hermit Lake Shelters and Harvard Cabin.
  • Posted 8:10a.m. 03-08-2014. A new advisory will be issued tomorrow.

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

2014-03-09 Print friendly

Avalanche Advisory for Saturday, March 8, 2014

This advisory expires at 12:00 midnight.

Tuckerman Ravine has Moderate and Low avalanche danger today. The Sluice, Lip, Center Bowl, and Chute have Moderate avalanche danger. Natural avalanches are unlikely, human triggered avalanches are possible. All other forecast areas have Low danger. Natural and human triggered avalanches are unlikely except in isolated terrain features.

Huntington Ravine has Moderate and Low avalanche danger today. Central Gully has Moderate avalanche danger. Natural avalanches are unlikely, human triggered avalanches are possible. All other forecast areas have Low danger. Natural and human triggered avalanches are unlikely except in isolated terrain features.

AVALANCHE PROBLEM: From my vantage point as a Snow Ranger, the biggest avalanche problems I expect to see today are the herd mentality and poor safe travel techniques. From a strictly snow stability perspective, the biggest problem is persistent slab with newer wind slab a close second (see below). But, as one who is responsible for assisting accident victims, this time of the year seems to bring out people whose perception of the risks they are taking is vastly different than reality. Don’t be one of these people! Often, to increase your  margin of safety only requires small adjustments that don’t cost you much in time, effort, or enjoyment. When better safety costs so little, there is really no good excuse to not travel in this way. If you have questions about this, seek out one of the Snow Rangers or volunteer ski patrollers working on the mountain today.

WEATHER: It’s been a bit of a dry spell here this past week. On Wednesday we received about 2.7″ (6.5cm) of new snow, which did blow into some areas of the ravines and trigger at least one small avalanche in the Center Bowl. Today we will see increasing cloudiness and some light snow showers in the afternoon. Temperatures will also be falling during the day. Expect travel conditions up high to worsen as the day progresses, so it’s a good day to get an early start and move efficiently.

SNOWPACK: As mentioned above, persistent slabs are the biggest avalanche problem you’ll face today. This is related to the weakened freezing rain crust and another layer of weak snow deeper down. On the whole, the snow above the potential weak layers has a lot of strength. However, it is entirely possible that a slope with numerous sets of boot or ski tracks on it may avalanche. You just can’t know where exactly the weak points are until you find one. 

The most recent snow from earlier this week did load into wind slabs in many areas, but these have had some time to stabilize and have seen some light traffic already. Where you do find relatively soft slab at the top of the snowpack, it is most likely these newer wind slabs. In our field work, we have found these to be on the smaller side and not especially sensitive to human triggering, though the do retain some potential for avalanching. This is true both in areas rated Moderate and in areas rated Low. The difference is is the size and distribution of the wind slab.

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 Visitor Center, or the caretakers at Hermit Lake Shelters and Harvard Cabin.
  • Posted 8:10a.m. 03-08-2014. A new advisory will be issued tomorrow.

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

2014-03-08 Printable

Avalanche Advisory for Friday, March 7, 2014

Expires at Midnight

Tuckerman Ravine has Moderate avalanche danger.  Natural avalanches are unlikely and human triggered avalanches are possible. Evaluate snow and terrain carefully.  The Little Headwall has Low danger.

Huntington Ravine has Moderate and Low avalanche danger. Yale, Central and South Gully have Moderate 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, except in isolated terrain features.

AVALANCHE PROBLEMS: Persistent slabs and wind slabs are jockeying for position as our primary avalanche problem today. The variability in our upper snow pack presents a range of hazards in our terrain. Careful route finding and continuous snowpack evaluation can make it possible to travel safely in gullies with a southerly aspect. The uncertain stability of deeper persistent layers in the upper 1 meter of the snow warrants careful travel techniques and the proper gear. Afternoon and evening wind forecasts hold the potential to quickly load start zones so keep an eye out for this loading. Warming today will weaken areas of surface wind slab on the steepest south facing terrain.

WEATHER: 2.7” (5.2cm) of snow which fell on Tuesday night and Wednesday is still laying around due to light winds since then.  Southerly aspects dampened in the strong solar radiation yesterday though cold ambient temperatures slowed heat gain and stabilization deeper in the snowpack. Clear skies and warmer ambient temperatures near 20 F today will continue some heating of the snowpack though winds this afternoon will offset this heating to some extent as they ramp up. Some loading and sluffing was observed this morning in Central and Yale. Winds are forecast to reach 50 mph later today, gusting higher this evening.

SNOWPACK: Light winds over the past several days laid a tempting blanket of fresh snow in lee areas. These surface slabs were reactive yesterday and easily broke out at switchbacks and steep rollovers and failed on isolation in stability tests, especially where they thinned out at the edges of pillows. Right Gully has benefitted from skier compaction in the last couple of days but lingering, larger pockets on the hikers left side deserve respect.  The new wind slab was inverted and likely to be much deeper moving through Sluice to Center Bowl and Chute were sastrugi in the upper steep sections indicate minor scouring with deposition below the ice in the bullseye mid-section of those start zones. That said, folks enjoyed fine ski runs in the new snow and soften ice crust on the lower angled terrain, out of the runout, between Lobster Claw and Right Gully. Stability tests in Sluice area showed the existence of a weak layer of needle forms lingering since late last month which produced clean shears in the moderate range (CT11-14). Due to the depth of this weakness, this layer has my hackles up as much as any other since it is close enough to the surface to trigger but deep enough and not obvious enough to go unnoticed when digging hand pits or probing with an axe or pole. Other interfaces exist in older finger hard wind slabs before you reach the pencil hard wind slabs deeper down which are mostly bombproof. A couple of these shallower layers in the snow failed high in the hard range but produced clean shears so remain capable of avalanching. With a nice weather forecast for today and possible for the weekend, I am expecting a lot of climber and skier traffic so look out for others above you and be respectful of those below you. Cold temperatures at night and in shaded areas are continuing to put the stabilization process on hold with very cold snow temperatures. 4” (10cm) down from the surface yesterday, on a south facing slope in the early afternoon, snow temperatures were still only -12C, though the surface 2” of snow was moist.  Reducing your exposure to avalanche paths when traveling un-roped or skiing, protecting yourself when roped and using solid micro-route finding skills remains key.

Please Remember: Safe travel in avalanche terrain requires training and experience. This advisory is just one tool to help you make your own decisions in avalanche terrain. You control your own risk by choosing where, when, and how you travel.Anticipate a changing avalanche danger when actual weather differs from the higher summits forecast. For more information contact the Forest Service Snow Rangers, the AMC at the Pinkham Notch Visitor Center, or the caretakers at Hermit Lake Shelters or the Harvard Cabin.Posted 8:40 3-07-2014. A new advisory will be issued tomorrow.

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

2014-03-07 Print friendly

Avalanche Advisory for Thursday March 6, 2014

Expires at Midnight

Tuckerman Ravine has Moderate avalanche danger.  Natural avalanches are unlikely and human triggered avalanches are possible. Evaluate snow and terrain carefully.  The Little Headwall has Low danger.

Huntington Ravine has Moderate and Low avalanche danger. Yale, Central Gully, and South gullies have Moderate 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, except in isolated terrain features.

AVALANCHE PROBLEMS: New Wind Slabs loaded in the deposition zones from W winds yesterday is the primary avalanche problem today.  This loaded over wind slab instabilities that were created during the past several days.  The most widespread wind slab problems can be found in the Sluice through the Chute of Tuckerman. They are interspersed with the secondary problem, Persistent Slabs.  These are in the form of older pencil hard wind slabs in varying stages of faceting above and below the crust.  This faceting is creating a wide range of variability across our forecast areas.

WEATHER: The summit picked up 2.7” (1.75cm) in the last 48 hours, 2.1” (5.2cm) of which fell on Wednesday.  Clear conditions prevail this morning, dawning cold with a pink alpine hue across the east facing terrain.  Temperatures will rebound from subzero temperatures to the singles F, while winds fall from a current of 23mph (37kph) from the NNE, to 5-20 (8-32kph) from the NW later today. Expect cold air in place overnight before starting a slow warm up into Saturday.

SNOWPACK: Yesterday 2.1” of new snow, with a density of 6.6%, was delivered on modest winds from the W and WNW between 10 and 35mph (16-56 kph).  This has laid a surprisingly consistent new soft slab across Tuckerman making her as picturesque as she’s been all winter. As you would expect, I believe the main issue and avalanche problem is in the steepest strong lee of the Ravine from the Sluice over to the Chute.  In Huntington the upper half of Yale has new soft slabs from cliff wall to cliff wall forcing a climber through instabilities, unless he/her get up on rock faces.  South Gully has new enough slabs to bump it to Moderate, but barley so.  Areas posted at Low do have isolated pockets of instability that could be triggered, but are easily avoided, so pay attention to your travel route.  In both Ravines expect these new slabs to be thin, very soft, and touchy.  The new low density snow above treeline will likely sit in place due to benign winds over the next day.

You are likely getting a little tired of the crust discussion, but unfortunately it makes it no less of an issue.  The weakening crust has early facets growing both under and over it, which has been a driver for our persistent slab problem.   Some of yesterday’s discussion is still valid so….“As you travel this crust should be a reference point to look for in your snowpack evaluations.  Mainly, how deep in the snowpack is this crust?  In places where newer wind slabs are layered over the crust I would focus attention to how the upper slabs closer to the surface are bonded between hardness transitions first. Then, focus on the facet development just above this breakable layer.  This priority will be dependent on depth of the crust and the degree of facet development.”  A failure in the new wind slab from last night could step down near this crust layer.

Please Remember:Safe travel in avalanche terrain requires training and experience. This advisory is just one tool to help you make your own decisions in avalanche terrain. You control your own risk by choosing where, when, and how you travel.Anticipate a changing avalanche danger when actual weather differs from the higher summits forecast. For more information contact the Forest Service Snow Rangers, the AMC at the Pinkham Notch Visitor Center, or the caretakers at Hermit Lake Shelters or the Harvard Cabin.Posted 8:40 3-06-2014. A new advisory will be issued tomorrow.

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

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Avalanche Advisory for Wednesday March 05, 2014

This advisory expires at 12:00 midnight

Tuckerman Ravine has Moderate and Low avalanche danger. The Sluice, Lip, Center Bowl, Chute, Left Gully, and Hillman’s Highway have Moderate avalanche danger. Natural avalanches are unlikely and human triggered avalanches are possible. Evaluate snow and terrain carefully. All other forecast areas have Low avalanche danger. Natural and human triggered avalanches are unlikely in these areas.

Huntington Ravine has Moderate and Low avalanche danger. Central Gully has Moderate 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 in these areas.

AVALANCHE PROBLEMS: Wind Slabs are the primary avalanche problem today. The most widespread wind slab problems can be found in the Sluice through the Chute of Tuckerman. They are interspersed with the secondary problem, Persistent Slabs.  These are in the form of older pencil hard wind slabs in varying stages of early faceting which has created variability in areas such as Left Gully, Hillman’s, and Central Gully in Huntington.

WEATHER: The summit picked up 0.7” (1.75cm) in the last 24 hours and is currently seeing light snowfall.  Snow showers are expected to deliver up to an additional 2” (5cm) today.  If recent history is a guide to forecasted snow amounts, it’s unlikely we will see this much fall. Building winds will stay fairly modest moving from the current of about 20-25 (36kph) to 40 mph (64kph) later today.  High pressure sliding in will bring arctic air to the mountains again dropping the mercury to -15F (-26C) for the high peaks.  A warming trend into the weekend should offer more seasonable temperatures before moving back into sub-zero F conditions next week.

SNOWPACK: Recently snowpack discussions have revolved around the freezing rain (ZR) crust from 2 weeks ago.  Specifically, are there multiple new wind slabs sitting on top of this layer? Or have they been scoured back down close to the crust?  This issue is the primary driver of our spatial variability.  Additionally, this crust has been slowing changing, being cannibalized through the temperature/pressure gradient created recently from the arctic air.  This process, in addition to vapor transfer from areas further away from the crust, has created facets below and above the crust.  This in turn has weakened the ZR layer, contributing to the persistent slab problem.  As you travel this crust should be a reference point to look for in your snowpack evaluations.  Mainly, how deep in the snowpack is this crust?  In places where newer wind slabs are layered over the crust I would focus attention to how the upper slabs, closer to the surface, are bonded between hardness transitions first. Then focus on the facet development just above this breakable layer.  This priority will be dependent on depth of the crust and the degree of facet development.  As W and NW winds move new, light amounts of snow into the Ravines keep your eyes peeled for new soft slab in pockets.  Realize areas posted at “Low” may have isolated pockets of instability to watch out for this afternoon.  Pinnacle, Odell, and South gully in Huntington are prime locales to consider this situation.

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 8:35a.m. March 5, 2014. A new advisory will be issued tomorrow.

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

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Avalanche Advisory for Tuesday, March 4, 2014

This advisory expires at 12:00 midnight.

Tuckerman Ravine has Moderate and Low avalanche danger. The Sluice, Lip, Center Bowl, Chute, Left Gully, and Hillman’s Highway have Moderate avalanche danger. Natural avalanches are unlikely and human triggered avalanches are possible. Evaluate snow and terrain carefully. All other forecast areas have Low avalanche danger. Natural and human triggered avalanches are unlikely in these areas.

Huntington Ravine has Moderate and Low avalanche danger. Central Gully has Moderate 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 in these areas.

AVALANCHE PROBLEMS: Once again, wind slab is the primary avalanche problem. The most widespread wind slab problems can be found in the Sluice through the Chute of Tuckerman. Elsewhere, such as Left Gully and Hillman’s, you’ll find more hard wind slabs interspersed with areas of relatively softer slab and areas with wind affected snow. Huntington has been more affected by winds, almost to the point that it would be better described as scouring. There are areas of hard slab here as well, which leads into the secondary avalanche problem of persistent slabs. See below for more detail on this problem.

WEATHER: Despite the news headlines about the blast of arctic air that was supposed to invade last night, it really doesn’t feel much colder than it has all winter long. Where I sit writing at Hermit Lake it is a balmy +5F (-15C), but the lack of strong winds and bright sunshine makes it feel a little nicer than that. During the daylight hours, you should expect increasing clouds and the possibility of light snow shower activity late today. There are no significant storms threatening us for the next several days at least.

SNOWPACK: Remember back in February when we got that freezing rain crust? Well, that crust has begun to break down. As this happens, the crust loses both tensile and compressive strength. When it comes to weak layers, in my opinion the loss of compressive strength is the more worrisome component. The faceting that is beginning to happen around this crust makes for a weak layer that is prone to collapse, and since weak layer collapse is the first event in the process of an avalanche releasing, this is an important feature of the snowpack that we’ll be keeping an eye on (and you should be looking at, as well.)  This won’t be a big deal in places where there is no snow above the crust, i.e. the crust is the surface layer or very close to the surface. Where it comes into play are locations where wind slabs sit above the crust. This may be “triggerable” in places where hard slabs are thinner or in places where the slabs are relatively softer. The older, harder slabs are the ones I would describe as “persistent,” while the more recent softer slabs fall into the wind slab problem definition. Also, as mentioned in yesterday’s advisory, above the crust there is an interface between two layers that has shown some signs of instability as well. Keep an eye out for this as you do your assessments in the field 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 Visitor Center, or the caretakers at Hermit Lake Shelters and Harvard Cabin.
  • Posted 8:10a.m. 03-04-2014. A new advisory will be issued tomorrow.

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

2014-03-04 Print friendly

And since you read down this far, here are some photos from Huntington this morning…

2014-03-04 Hillman's 2014-03-04 Escape Hatch 2014-03-04 Yale and Damnation 2014-03-04 Central Gully 2014-03-04 Odell Gully

Avalanche Advisory for Monday, March 3, 2014

This advisory expires tonight at 12:00 midnight.

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

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

AVALANCHE PROBLEM: Wind slab is the primary avalanche problem today. The largest and most concerning of these recently formed slabs can be found in Tuckerman’s Sluice, Lip, Center Bowl, and Chute, as well as in Central Gully in Huntington. Other areas of Huntington have less continuous problem areas, but certainly there are locations within each of the gullies that you’ll need to treat with respect. In Tuckerman, the different forecast areas today are doing their best to stretch the range of Moderate. Areas such as Hillman’s and Left Gully are on the lower end, having been more wind effected, while locations in the general headwall area are pushing the upper limits of Moderate. In addition to the upper wind slab layers, we are also beginning to think about persistent slabs being an avalanche problem. This problem is related to the old freezing rain crust that is breaking down over time. Faceted snow near this layer can act as a weak layer for snow above it, and the weakened crust offers less protection to any underlying slabs than it previously had.

WEATHER: We’re in a period of cold dry weather for the next several days. Sadly, no big storms are on the horizon. Today’s weather will be standard winter weather on Mt. Washington. Winds will blow around 45-60mph with temperatures on the summits well below zero F. Yesterday we received 0.7” (1.8cm) of new snow and winds blew from the WNW around 40-50mph (65-80kph) much of the day.

 SNOWPACK:  To be honest, I found the snowpack yesterday to be a little on the boring side. There wasn’t enough stability to make me feel confident enough to want to ride some of the nice looking lines that are filling in, but the instability in my location wasn’t so great that my nerves were tingling. The small amount of new snow was blanketing most every surface in a soft unconsolidated layer, but it was only a couple inches deep at most. Below the new snow is a mostly “right-side-up” snowpack of 1F+ over P, sitting on top of a deteriorating and faceting crust. The interface between the 1F and P slabs is where I’d put my money on a person initiating an avalanche. From there I’d double down that it would rip out down to and including the crust. Some of the more wind-exposed locations have crust on the surface (good stability here) or more recent slabs that are heavily wind effected (fair-good stability in these).

It is great to see some of the classic ski lines finally coming into shape. The upper Chute, the Center Bowl, and the Sluice have all recently gone from “where’s the snow” to “that looks good…” The challenging thing is knowing when these lines will be stable enough that the risk involved falls into the manageable category. With the weather I see on the horizon, these routes will not easily move to a clear Low danger. So until then, they will sit there tempting skiers and riders. My advice to you, as always, is to do your own assessments and make your own decisions. Don’t fall into the trap of believing that tracks on a slope imply safety. Don’t talk yourself into why you know better and why it won’t happen to you. The slopes will eventually stabilize, you might just need to wait a little while longer if you want to keep the risk down.

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 Visitor Center, or the caretakers at Hermit Lake Shelters and Harvard Cabin.
  • Posted 8:35a.m. 03-03-2014. A new advisory will be issued tomorrow.

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

2014-03-03 Print Friendly