Avalanche Advisory for Thursday, February 28, 2013

This advisory expires at 12:00 midnight, February 28, 2013.

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

Huntington Ravine has Considerable avalanche danger.  Natural avalanches are possible and human triggered avalanches are likely in all forecast areas of Huntington Ravine.  Careful snowpack evaluation, cautious route-finding and conservative decision making are essential.

Well, our snowpack is turning around after a lacklaster early winter.  In addition to the obvious economic benefit to the area and the payoff for all the funhogs in the area, snow geeks and avalanche buffs on Mount Washington will be treated to another round of avalanche activity. Almost 13″ of snow fell during this storm and though the snow will end in the valleys today, the mountains will receive another 2-4″ today, 1-3″ tonight, and 1-3″ tomorrow for a grand total somewhere in the neighborhood of 17-19+”.  Wind direction will be shifting from the East to the North or Northwest through the day which will serve to lightly load areas which may have been more scoured than loaded by the high winds that the mountain experienced last night.  In Huntington Ravine these high winds, which gusted to 95 mph and blew steadily in the high 60’s mph, moved snow around in the east facing gullies like Central and Yale and cross loaded areas with a north or south facing aspect as well as lee terrain features.  With winds shifting around towards the north, gullies and terrain features in both Ravines with less snow due to avalanches or wind transport will reload a bit today.  Although winds will be light, blowing 15-30mph, some loading is expecting high in typical start zones.  This will add more instabilities and issues to areas already meeting a Considerable rating.  Anticipate  some slopes in the direct lee of N and NW winds to move towards the upper end of the rating if we pick up multiple new inches today.

There is alot of information critical to determine where and when a natural avalanche is going to occur.  Much of this information may be denied to mountain travelers today due to low visibility conditions with only brief and unreliable “windows” in which to make assessments.  Venturing into either ravine to get close enough to assess which avalanche paths have already slid will be sketchy and coming from the top creates hazards for folks who may be on the floor.  Avalanche slide paths, which are more filled in now due to recent avalanche activity,  will allow avalanches to run further out onto the floor of the Ravines making travel into those areas a roll of the dice.  Assessing the depth and area of slabs, locating and avoiding trigger points, coupled with new precipitation and windloading will challenge the most experienced avalanche practitioner 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 8:45a.m., February 28, 2013. A new advisory will be issued tomorrow.

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

02-28-2013 Print friendly

Avalanche Advisory for Wednesday February 27, 2013

Expires at Midnight Wednesday 2-27-2013

Tuckerman and Huntington Ravines will have CONSIDERABLE avalanche danger today.  Natural avalanches are possible and human triggered avalanches are likely.  Dangerous avalanche conditions will develop making conservative decision making essential.  The only exception to this is the Lower Snowfields and the Little Headwall which will have Moderate avalanche danger where natural avalanches are unlikely and human triggered avalanches are possible.

Another storm is beginning to consume the region as snow has enveloped the higher summits over the past couple of hours.  Snow is expected to increase today, falling heavy at times, from the ESE at 35-50mph (55-80kph) increasing to 60+mph (96kph) later today.  Total accumulations should reach 12-16″ (30-40cm) by the time the system moves out later on Thursday.  Today’s wind velocities will likely be the highest we have seen over the past 6 days.  Currently winds are from the SSE gusting to 47 mph (75kph).  This is generally causing some loading to begin on slopes with a N and NW facing aspect.  This includes the upper start zones of Hillman’s and Left gully in Tuckerman, and the Escape Hatch, South and Odell in Huntington.  Based on winds shifting slightly today through the SE to the ESE, occasionally flirting with the E, these N and NW pointing slopes will reach the Considerable rating first.  Although the 10″ (25cm)of snow from the weekend storm has been sitting above treeline and bonding, increasing resistance to transport from wind, the 60+ mph forecast should begin moving these old crystals mixing them in with today’s storm snow.  This additional snow and perfect loading wind velocities from 40-60mph (64-96kph) will place new unstable slabs in the deposition of many protected lee areas today.

Many forecasted areas will develop instabilities much slower than the aforementioned locations above.  Slopes pointing directly into the expected winds today like the Lip and Yale gullies shouldn’t see rapid loading from new snow through most of today.  They also don’t have alpine zones with waiting snow to load into them from the SE.  As winds move to the ESE and perhaps the E, slopes pointing S and N will see additional cross loading with some old alpine zone snow mixing in.  To sum up all the nuances today here are some bull’s-eye points to remember:

**Slopes with a northerly component will see the most loading today and should be the first aspects to reach the Considerable rating due to a shifting, increasing, wind from the SSE, SE, and ESE with heavy snow.

**As winds arrive at their expected ESE/E direction crossloading of S and N facing slopes should be at their maximum.  Effecting locales like the Lobsterclaw, Right, North, and Damnation gullies in addition to those already discussed that face N.

**Instabilities on forecasted slopes facing E and SE such as portions of the Sluice, Lip, Center Bowl, Yale and Central gully will likely linger just a bit behind S aspects, but do have larger bed surfaces to consider.  I would anticipate all forecasted areas posted at Considerable to have natural avalanche potential by later this afternoon. 

**As the storm intensifies overnight with more heavy snow the avalanche danger will increase pushing to a “High” rating likely sometime after midnight.  You should be prepared for elevated avalanche danger ratings tomorrow. 

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 February 27, 2013.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

2013-02-27 Print Version

Avalanche Advisory for Tuesday 2-26-2013

This advisory expires at 12:00 midnight, February 26, 2013.

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

Huntington Ravine has Moderate and Low avalanche danger. Central Gully has 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.

This has been an unusual stretch of weather for Mt. Washington. Average wind speeds on the summit have been around 20-25mph (30-40kph) each of the last 4 days. Today is no different; light winds and relatively warm temperatures will continue to allow for comfortable alpine recreation. With over 60″ on the summit so far and another storm arriving tomorrow, February has been a good month for snow, though the overall lack of snow leading into the month means a couple things. One is that many avalanche paths are only now developing to their “regular” size. Another is that many of the climbs in Huntington have very thin conditions near the top outs.  Also, getting out of the bowl is either an adventurous bushwhack to get to a thinly covered Little Headwall, or a hike down the trail.

We’re posting Moderate avalanche danger in many areas today. This means that you might trigger an avalanche in these locations. Some areas are at the lower end of the rating, while others are more in the middle of the rating range. The concerns stem from the most recent snow we received on Saturday and Sunday. NNW winds picked up on Sunday night and relocated this new snow around the mountain. The area I’d be most concerned with in Tuckerman is the Sluice, Lip, and Center Bowl; in Huntington this honor goes to Central Gully. These locations have the largest snowfields, are easily wind-loaded, and are some of the most frequent producers of avalanche activity. Old fracture lines in these areas have been reloaded, indicating the existence of windslab on top of old bed surfaces. We expected to see greater instabilities yesterday in Lobster Claw and Right Gully. In our trip to the top of Right we found a lot of hard old snow through much of the gully without a lot of loading, but there were stability concerns in the steep top section. Lobster Claw will have a similar issue as Right, so I’d say these qualify as being on the lower end of Moderate.

Left Gully also is dominated by older wind-affected snow through much of the route. However, the top climbers left side does fit the description of a pocket, or an “isolated terrain feature,” so you should approach this snow carefully and assess it as you go. Most of the gully has very good stability, hence the Low rating. Other areas in Huntington might have similar pockets in these isolated terrain features, so you should be watchful for signs of unstable snow as you travel. The top left side of South Gully is one example. The tops of Yale and Damnation did fill in with snow, but remember that before last weekend the tops of these were exposed rock and turf.

 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 26, 2013. A new advisory will be issued tomorrow.

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

2013-02-26 Printable

Avalanche Advisory for Monday, February 25, 2013

This advisory expires at 12:00 midnight, February 25, 2013.

Tuckerman Ravine will have CONSIDERABLE and MODERATE avalanche danger today. Careful snowpack evaluation, cautious route finding, and conservative decision making are essential. Lobster Claw, Right Gully, Sluice, the Lip, Center Headwall have Considerable avalanche danger. Natural avalanches are possible and human triggered avalanches are likely. Chute, Left Gully, Hillmans Highway, Lower Snowfields and Little Headwall in Tuckerman have Moderate avalanche danger. Natural avalanches are unlikely and human triggered avalanches are possible.

Huntington Ravine has MODERATE avalanche danger today. Natural avalanches are unlikely and human triggered avalanches are possible in all forecast areas. Evaluate snow and terrain carefully to identify features of concern.

It is important to note that low visibility will challenge your ability to perform snow stability evaluations on the mountain today as it has challenged ours. What we know about current avalanche concerns is developed from weather observations. The key information is that we received 6 inches additional new snow on light winds from midnight to midnight yesterday with another ½” from midnight to 6am today.  Remember that 3” of snow fell prior giving us almost 10” of snow to deal with. Winds also increased for a period last night. So, several conditions lead us to formulate the ratings that we have today.

  • New snow has accumulated most everywhere in our forecast area which has created a widespread thick soft slab of varying thickness laying over softer, weaker snow deposited earlier in the storm.
  • Wind gusts increased during the overnight and morning hours today to a point where wind slabs of increasingly dense snow have formed in the higher start zones of our gullies as well as in other high, wind sheltered terrain features. These wind gusts came from the North and transported snow from drifts that were formed earlier yesterday when the wind was from a more southerly direction.  The snow was light enough to be carried by these moderate winds.
  • A slippery interface exists on south facing aspects in the form of a sun crust which formed on Friday. This sun crust will make for poor bonding of the new snow and will form the bed surface for any avalanches triggered in Lobster Claw, Right Gully, the Sluice and the Lip. South facing gullies in Huntington have a similar crust but new snow there did not accumulate in the upper start zones to as great a depth as in Tuckerman. Where this poor bonding surface exists in smooth areas of older snow, sensitive slabs may exist on fairly low angle slopes.  I would be heads up in areas such as the approach to Right Gully and the slope beneath Harvard Bulge below Yale and Damnation buttress.
  • Though the forecast is for a cloudy summit today, filtered sunlight through thin cloud cover can create a greenhouse effect which may warm the slab just enough to reduce its strength and lead to failure.  The same process would make it more likely for slabs to be triggered by a skier or climber. The sun is currently barely obscured and it is bright outside at Hermit Lake and has been for half an hour which leads me to this concern.

Though the overall trend now is moving towards stability due to diminishing winds and no current snowfall, a lot of factors are at play today which can change this. Don’t let the calm winds and warm temperatures lure you into complacency.

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 2-25-2013. A new advisory will be issued tomorrow.

Frank Carus, Snow Ranger
USDA Forest Service
White Mountain National Forest
(603) 466-2713 TTY (603) 466-2817

2013-02-25 Print friendly

Avalanche Advisory for Sunday, 2-24-2013

This advisory expires at 12:00 midnight, February 24, 2013.

Tuckerman and Huntington Ravines will have CONSIDERABLE avalanche danger today. 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. The only exceptions to this rating are the Lower Snowfields and  Little Headwall in Tuckerman, which will have Moderate avalanche danger. Natural avalanches are unlikely and human triggered avalanches are possible.

The use of the future tense in the paragraph above is intentional. With a winter weather advisory in effect today and additional snow forecasted to fall through tonight, avalanche danger will be on the rise and eventually reach the posted rating. Due to a few variables in the weather forecast, there is some uncertainty in what exactly will take place with snow and avalanches.  Pay attention out there today. The rise up to Considerable avalanche danger could take place rather quickly, leaving you less time to adjust your plans in response to changing conditions.

New snow began yesterday afternoon at a light rate. It continued into the night, with totals this morning coming at 1.6″ (4cm) at Hermit Lake and 3″ (7.5cm) at the summit. Early snow densities are light, between 3 and 5% at the summit and 7% at Hermit Lake. Additional snowfall of 2-5″ (10-25cm) is forecasted for today, plus another 2-3″ (10-13cm) expected overnight. Up until about midnight last night, summit winds were blowing from the SSW at 25-30mph (40-50kph). After midnight velocities dropped substantially, down to about 15mph (24kph) on average. During today, winds will stay on the lighter side but will quickly shift in a counter-clockwise direction in the afternoon, moving from the SSW quickly through the E and N, around until they are coming from the NW.

So, you don’t need to be a snow scientist to see that I just threw out a lot of information, some measured and some forecasted. Now you might be asking “So What?” Here’s how we’re thinking this will play out:

  • Some loading took place overnight on N and NE aspects. On other aspects a light blanket of low density snow was laid down on top of generally stable surfaces. This blanket is also sitting in low density drifts above treeline waiting for winds to redistribute it as soon as the speed reaches the magic number.
  • Snow densities are light enough that low wind speeds should be able to create very tender, easily triggerable soft slabs. If winds are at the upper end of their forecasted range, we might see loading rates increase significantly. If they stay light, then the multiplier effect will be diminished but thinner soft slabs will still be able to form.
  • While winds are from a southerly direction, north-facing slopes will be developing these soft slabs more quickly than other aspects. Remember, these are the same slopes that were pre-loaded last night with 25-30mph wind speeds.
  • When winds shift to the NW, slab development will be concentrated on SE aspects, but in reality NW winds affect just about all of our forecast areas.
  • Some sluffing might take place on steep slopes, perhaps piling up on lower angle terrain features. These piles can act as cohesive slabs, which means they could still avalanche despite already having sluffed down slope.

We are fairly confident in the development of soft slabs on N and NE aspects from last night’s snow and wind. There’s more uncertainty in the ability of the winds to pick up and transport snow into SE aspects. The variables at play are exactly how much snow falls, what its density is, and exactly how strong the wind speeds are. The safe bet would be to expect loading to take place, and make travel choices accordingly. Stability problems in areas such as Lobster Claw and Right Gully in Tuckerman and North, Damnation, and Yale in Huntington will lag behind those that were loaded last night    (e.g. South, Odell, Pinnacle and Hillman’s, Left, and Chute).

If the subtleties of the forecast seem like a lot, that’s a good sign, because it’s not an easy one today. If you think it’s simple and straightforward, that’s a good indicator that you should sign up for another avalanche class and stay out of avalanche terrain in the meantime. Skiing the Sherburne or GOS ski trails is a good option for avoiding avalanche terrain.

Please Remember:

  • Safe travel in avalanche terrain requires training and experience. This advisory is just one tool to help you make your own decisions in avalanche terrain. You control your own risk by choosing where, when, and how you travel.
  • Anticipate a changing avalanche danger when actual weather differs from the higher summits forecast.
  • For more information contact the Forest Service Snow Rangers, the AMC at the Pinkham Notch Visitor Center, or the caretakers at Hermit Lake Shelters or the Harvard Cabin.
  • Posted 8:30 2-24-2013. 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

2013-02-24 Printable

Fall on Lion Head Winter Route

On the descent from a summit hike, a hiker fell approximately 50′ down a steep section of the Lion Head route. He injured his lower leg in the fall. One member of the man’s party quickly hiked to Hermit Lake to notify USFS Snow Rangers. At the same time, a distress signal was sent using a SPOT  satellite device. Snow Rangers responded, found the man ambulatory, and transported him to Pinkham Notch via snow tractor.

Climbers stranded on Damnation Buttress

Three climbers became stranded on steep rocky terrain after they climbed off route. USFS Snow Rangers and Mountain Rescue Service volunteers , along with assistance from the Mt. Washington Observatory and AMC and HMC caretakers, located and rescued the climbers without injury. More details will be posted soon.

Avalanche Advisory for Saturday 2-23-2013

This advisory expires at 12:00 midnight, February 23, 2013.

Tuckerman Ravine has MODERATE and LOW avalanche danger. The Sluice, Lip, and Center Bowl have Moderate avalanche danger. Natural avalanches are unlikely and human triggered avalanches are possible. All other forecast areas in Tuckerman 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 Gully has Moderate avalanche danger. Natural avalanches are unlikely and human triggered avalanches are possible. All other forecast areas in Huntington have Low avalanche danger. Natural and human triggered avalanches are unlikely.

We’ve been watching the developments of this incoming winter storm with eager anticipation, but the latest news is that accumulating snow is not expected until after dark today. For today, the majority of the snow stability issues you’ll content with are the results of approximately 10” of snow that fell on the mountain mid-week.

In Huntington, much of this snow got blown out of the gullies, leaving behind well-scoured surfaces, many with raised remnants of footprints. Aside from the usual isolated unstable pockets in strongly protected lee areas, the biggest concern is the snowfield between the top of the Fan and the Central Gully ice bulge. This lies in the lower end of the Moderate rating, but it does extend from wall to wall in the gully so it would be difficult to get around it. The other big issue in Huntington is found at the top outs of many of the climbs, particularly Central, Yale, Damnation, and North. There simply isn’t much snow at the tops of these climbs, so be prepared for poor protection, rock scrambling, and if you’re lucky, frozen turf to swing into.

Tuckerman Ravine yesterday felt like being in a giant solar collector. Full sunshine, light winds, and mild temperatures made for very comfortable conditions, yet for some reason very few people ventured above the floor of the ravine. Again, the biggest concerns in Tuckerman are from slabs developed on Wednesday and Thursday. Today, the bulls-eye for instability will be centered on the areas around the Lip and under the ice in the Center Bowl. Warmth and solar energy helped to stabilize slopes facing into the sun, such as Right Gully, but in the Lip and Center Bowl the aspect is just off enough that the sun provided only a glancing blow. Hangfire above existing crown lines and reloaded bed surfaces will harbor instabilities at weak layers and interfaces beneath the snow surface. In many locations posted at Low, you should be aware of the potential for unstable slabs in isolated terrain features. Examples include on the steep climber’s left side walls of Right Gully and Lobster Claw (similar aspect and slope angle to the Lip), above the narrows of the Chute, and at the top climber’s right side of Hillman’s Highway. If you find one of these pockets, the avalanche may be small, but consequences will be large.

Light snowfall is currently underway on the mountain. Pay attention to accumulations! While we are not expecting much during daylight hours or early evening, if our expectations are off, we will see avalanche hazard on the rise before this advisory expires. The first places I’d expect to see rise are locations rated Low, particularly those with N and E aspect such as Left Gully or Odell Gully. Also expect elevated danger ratings tomorrow due to the storm.

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 2-23-2013. 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

2013-02-23 Printable

Avalanche Advisory for Friday, February 22, 2013

This advisory expires at 12:00 midnight, February 22, 2013.

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

After 3 days of snow and blowing snow that totaled just shy of 10” (25cm) on the summit, we finally have beautiful clear conditions.  During the High danger rating on Wednesday we had an avalanche cycle in the Center Bowl and Lip that left a number of fracture lines in its wake.  The big question we are dealing with right now is will south faces warm enough today with sun and very low wind to become unstable due to rapid warming?

Over the past 24 hours we have seen 3” (7.5cm) of snow with winds predominately out of the N.  Speeds increased from 28mph (45kph) yesterday morning to almost 70mph (113kph) by 7pm (1900hrs). This increasing velocity from the N loaded new snow into Tuckerman’s south and southeast aspects, namely The Lobster Claw, Right Gully, and the greater Sluice area.  These newest slabs will be affected by a cooking sun today as clear conditions are expected with a dropping wind from the NE and E perhaps reaching down into the 5-10mph (8-16kph) range.  Therefore slopes facing south will see rapid warming which will initially start stabilizing slabs by decreasing their ability to propagate. But then the big question, will heat penetrate deep enough into thin slabs to head us towards instability.  I would expect some of these slopes in Tuckerman to move towards the upper end of the Moderate rating this afternoon bumping the ceiling of the definition.  Although natural avalanche activity will still be unlikely the steepest most sheltered lee will being inching closer to “possible”.  In Huntington the lack of snow makes this solar heating much  less of a problem.  Damnation and Yale, the biggest south facing slopes in Huntington have mostly scoured slopes, but keep an eye on snow near the top exits.  Cornices developed during the last Nor’easter are unlikely to be a problem today due to their long term developing strength but they shouldn’t be ignored.  The greater issue nearby, and our number one concern in Huntington, is the bottom snowfield leading to the ice bulge in Central Gully.  This area harbors some cold newly deposited slab instabilities.

Back over in Tuckerman cold slab instabilities will also be found on slopes faced away from the south.  Between the Chute and Lip which face generally east should hang on to their cold slab properties.  A number of crown lines exist in this area from avalanche activity over the past 48 hours.  Some of these have been partially reloaded and some steep slopes above fracture lines (hangfire) are still to be respected.  As you move high to the Left Headwall and Chute you will find some locations that did not avalanche which makes it likely that some deeper slabs will found in these locations. Overall, it’s a “heads up” kind of day. With this weather and recent snow we expect to see people out moving around on the mountain, so pay attention and be prepared to change your plans if the actions of others warrant doing so.

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 8:39 2-21-2013. 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

2013-02-22 Printable

Avalanche Advisory for Thursday February 21, 2013

Expires at Midnight Thursday 2-21-2013

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

Huntington Ravine has MODERATE avalanche danger.  Natural avalanches are unlikely and human triggered avalanches are possible.

Over the past 36 hours the summit has picked up 8.1” (20.5”) of upslope snow with an additional 1-3” (2.5-7.5cm) expected today.  While this 8”of snow fell winds have been active moving from the S to the N with velocities in the teens up to yesterday’s max of 102 mph (165kph).  Temperatures have also been quite cold, falling to -8F (-22C) keeping the dominate crystal as stellars and plates which have been easily broken up and transported into lee areas.  In hindsight yesterday’s rating were on the money as witnessed by new fracture lines such as in the Center bowl right under the headwall ice.  This has undoubtedly helped fill in the Ravine floor a bit as it’s in desperate need of some good avalanche cycles to cover the wide spread vegetation that still exists. Some brief clearing on the southern end of both ravines gave us short glimpse of how this entire snow event has been playing out.  Unfortunately, areas of most concern today on the northern side of Tuckerman and Huntington are still shrouded in a cloak of blowing snow and fog.

Since the high winds last night the mountain has seen a couple of inches of snow with more forecasted for today.  These 2 inches came in on a decreasing wind from the WNW and NW to the current average in the 40’s mph (60’s kph).  As the day continues winds should wrap to come from the N and increase back up to 60-80 mph (97-129kph) with higher gusts.  This should start another loading event picking up snow lying in alpine zones that will be vulnerable to a compass rose wind shift and higher speeds.  New snow from the sky will also mix in with the redistributed snow, loading in slopes with a south facing component.  Although North gully and the Lobster claw are south facing, they have smaller bed surfaces than their neighboring sister paths.  Therefore, they are less of a concern than Damnation, Yale, and Central gully in Huntington and Right Gully, Sluice, and the Lip in Tuckerman.  These locations may be on the upper end of their Moderate and Considerable ratings depending exactly how wind speeds and new accumulations play out today.

Avalanche classes would have a worthwhile experience in the field today because there is so much good evidence that we have instabilities susceptible to natural and human triggers.  Large drifts on approach trails; Fist and 4 finger soft slabs over lower density snow; stability tests likely producing a mix of “yellow” and “red” light results; and visible wind transport of snow are several bulls-eye clues that a cautious conservative approach would be important in many locations.  The south faces that will likely get the new slab deposition today will be dealing with a potential new factor tomorrow-solar gain.  Clear skies, warmer temperature and low winds are expected so anticipate some continued stability problems tomorrow albeit a different fire breathing dragon.

The Sherburne ski trail should be a great alternative to venturing into avalanche terrain.  Expect some variable conditions due to some high winds but overall good skiing can be expected.

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 8:39 2-21-2013. 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

2013-02-21 Print Version