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

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

Avalanche Advisory for Wednesday February 20th, 2013

This advisory expires at midnight 2-20-2013

Tuckerman Ravine has HIGH, CONSIDERABLE, and MODERATE avalanche danger.  The Sluice, Lip, Center Bowl, and Chute have High avalanche danger.  Natural avalanches are likely and human triggered avalanches are very likely.  Very dangerous avalanche conditions exist. Travel in avalanche terrain is not recommended.  The Lobsterclaw, Right Gully, Left Gully and Hillman’s Highway have Considerable avalanche danger.  Natural avalanches are possible and human triggered avalanches are likely.  Dangerous avalanche conditions exist and conservative decision making is essential. The Lower Snowfields and the Little Headwall have Moderate avalanche danger. Natural avalanches are unlikely and human triggered avalanches are possible.

Huntington Ravine has CONSIDERABLE avalanche danger.  Natural avalanches are possible and human triggered avalanches are likely.  Dangerous avalanche conditions exist and conservative decision making is essential.

The summit has received approximately 4″ (12.5) of new snow, as have we down at Hermit Lake, with an additional 1-3″ expected through today.  Snow began last night around 5pm with winds from the S until about midnight when the shift began towards our current NW.  Southern winds associated with snowfall began with a velocity close to 40mph and fell through the evening into the teens. As winds transitioned to the NW through the early morning velocities increased again and have been gusting into the 60’s mph since dawn.  They are forecasted to continue rising, gusting over 70 later today.

As wind speeds slowed to 15mph around midnight, with new snow falling, a lighter “fist” hardness layer was deposited. In quick hand shears in my travels today I am getting easy shears on this unconsolidated soft layer.  This mid slab layer is the main weakness I am seeing this morning and the most likely issue leading to slab fracture and failure in the Ravines.

With cold air in place we are finding snow in the 5% range deposited in the trees down low.  However, in locations affected by the wind delicate stellars crystals are being destroyed into fragments, increasing the densities as shown at our snowplots and at the summit.  Therefore as winds continue to ramp up I expect slabs of increased hardness to be deposited over the early morning loose layer.  With this said this “increased” hardness is still likely pretty soft in sheltered locations, perhaps ”4 finger”, so anticipate new slabs to be delicate and reactive to human triggers.  As upslope snow continues today the increasing avalanche danger trend will continue.  Expect to see the potential of natural avalanches to be highest on the largest E and SE faces, with Tuckerman’s Lip and Center Bowl leading the charge.  It is likely that the forecasted snow tonight and tomorrow will continue our heightened avalanche dangers for Thursday.

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. 2-20-2013. 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

2013-02-20 Print Version

 

Avalanche Advisory for Tuesday, February 19, 2013

This advisory expires at 12:00 midnight, February 19, 2013

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

All forecast areas of Huntington Ravine have Low avalanche danger.  Natural and human triggered avalanche are unlikely.

The damage done to our snowpack by yesterday’s high winds (129 mph or 210 kph peak wind speed) is the overwhelming impression of Tuckerman from Hermit Lake. Field time yesterday afternoon revealed evidence of four avalanches though the evidence of more would have been erased by the high winds.  Firm, stable, wind sculpted snow is the predominate surface in most of Huntington and Tuckerman Ravines today. Larger areas of windslab exist in the gullies rated Moderate with smaller pockets in Low rated gullies. The windslab creating our concern today will appear smoother and will be less resistant to triggers than the more textured and sculpted areas.  Beware of cracking and hollow sounding slabs in select lee areas. Though further field time today will help us more accurately pin down the hazard in our Moderate rated gullies within that rating, some clues visible from Hermit Lake point to the fact that further loading occurred as the winds died down overnight.  The three foot crown line below the ice in the Lip area has reloaded so that only about a foot, or maybe a bit more, is now visible. Right Gully was loaded more than scoured during the event but with little snow prior to the wind, only enough new slab exists to create a Moderate hazard.  Center Bowl and the Chute were heavily wind packed but some hangfire still exists in the upper portion of the hourglass below the ice in Chute.  The climbers upper left exit of Left Gully slid and didn’t reload but the upper right pocket would be best avoided or approached carefully. Hillman’s Highway was scoured out or wind hammered.  Huntington Ravine gullies suffered significant scouring.  The northern gullies look like they did a month ago…rocks near the top and a thin ribbon of ice and snow below. Central, Pinnacle and Odell Gully were also mostly scoured.

Today’s weather forecast is creating a good window for those looking to get out and climb and hike during this busy vacation week. Forecasting for crowds has proven to be challenging but it is safe to say that more than the usual caution is warranted due to the increased likelihood of people generating rock and ice fall or even finding the sweet spot that triggers the slab above you. Afternoon fog and cloud cover is forecasted to descend through the afternoon as winds increase so consider your pace and account for deteriorating visibility. Temperatures will rise to the mid 20’s on the summit but we have already hit 32F (0C) at Hermit Lake at 7:30 am with calm winds. Enjoy the balmy conditions while they last.  Enough snow is forecasted tonight and tomorrow to change our avalanche animal dramatically so check in tomorrow morning for the latest forecast before committing to a route.

Remember that Lions Head trail is a steep mountaineering route with several areas of 3rd class rated terrain.  Climbing rock and steep snow and ice slopes in crampons may require ropes to protect you or members of your party.  Anticipate possible delays due to crowds and be patient with others as they negotiate this terrain which has been the scene of numerous injuries in the past.

 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 19, 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

2013-02-19 Print friendly

Avalanche Advisory Monday 2-18-2013

This advisory expires at 12:00 midnight, February 18, 2013

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

All forecast areas of Huntington Ravine have Low avalanche danger. Natural and human triggered avalanches are unlikely except on isolated terrain features.

Hopefully if you’re reading this advisory today, it’s from the warmth and comfort of an indoor facility. Current conditions on the mountain are exceptionally brutal. Due to clouds and blowing snow, visibility is near zero.  Temperatures are just above zero F at Hermit Lake. Some trees are swaying back and forth like hippies at a Grateful Dead show, while other trees look more like headbangers at a Metallica concert. Don’t be fooled by the diminishing winds and clearing skies forecasted for today; the wind will only decrease 80-100mph (130-160kph) and you should expect airborne snow to be acting as a sandblaster until well after dark today.

Yesterday, the summit recorded 3.6″ (9cm) of snow with increasing wind speeds reaching a crescendo this morning. They’re currently 115mph (185kph) with gusts pushing close to 130mph (210kph). What is this doing for snow stability? The easier ravine to forecast is Huntington. Sustained winds overnight have likely scoured out and wind-hammered the gullies into stable hard slab and old exposed crust. There may be small and isolated pockets of unstable snow in the most well-protected locations, so as always, be vigilant to changing conditions. We have yet to get a view of the ravines, so there is some uncertainty to the rating, but I am fairly confident that it would be difficult to find stability problems in Huntington.

Tuckerman is a little different story. It’s less prone to scouring than Huntington due to its being more protected from strong winds. There is currently wind transport of snow taking place in all locations of Tuckerman. The snow moving around is likely from yesterday morning’s snowfall as well as older snow being picked up from the other side of the mountain. The Considerable forecast for many areas is due to the potential for slabs building in lee areas, creating the possibility of naturally triggered avalanches in these areas. Any slab being formed today will be hard and dense, which are typically quite strong. However, if these hard slabs do fracture and fail, the destruction left in their wake can be impressive. Overall I suspect that many of the areas are being hammered by the wind so strongly that they will be strong enough to not avalanche, but until we can confirm this, the safe bet is to go with the reliable data rather than the assumption. In this case, I know for certain that snow will continue to be transported into Tuckerman at a good rate today. The areas posted at Considerable are the strongest contenders for unstable snow. In areas posted at Moderate, remember that “unlikely,” which is used in the definition for naturally triggered avalanches in Moderate hazard, is different from “not possible,” which is not part of any danger rating definition but is commonly how we see people act in avalanche terrain. The lesser rating reflects the overall hazard compared with other forecast areas, but Moderate avalanche hazard is still dangerous, particularly when active loading is taking place.

Winds have created some good drifts on the Tuckerman Trail. My hope is that they also filled in the Little Headwall. We may find out more later today. The Sherburne will have some icy scoured locations and a few deep drifts to play around 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 8:35a.m., February 18, 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

2013-02-18 Print Friendly

Avalanche Advisory for Sunday, February 17, 2013

This advisory expires at 12:00 midnight, February 17, 2013

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

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

Avalanche danger in all forecast areas will be increasing from yesterday’s ratings through today!

Today’s impending wind event was apparent this morning as I got in the car in Brownfield, Maine. A steady wind and distant dull roar brought memories of near misses by hurricanes as a young lad growing up in the South. The big low pressure system, now southeast of Cape Cod, will remain too far away in the Gulf of Maine to bring the snow that the area desperately needs. However, pressure differentials will be deep enough to generate significant winds with 1-3” (3-8cm)of new snow today and a trace to 2” (5cm)tonight. The new snow, which is in the 4-5% range so far, will be transported by wind which will increase through the day. Currently, winds are blowing from the N at 35-50 mph (55-85 kph) but will shift to the NW and increase in velocity through the day to the 100 mph (160 kph) range this afternoon. This will load the upper avalanche start zones near the top of Damnation, Yale, Central and crossload other areas in the same gullies as well as Pinnacle, Odell, and South. North and Escape will also receive crossloaded pockets of snow but natural avalanches are unlikely there due to the scarcity of continuous snowfields and abundance of anchors. Lookout for the light density snow piling up into sizable slabs at the base of steep ice and rock features. In Tuckerman Ravine, the wind and new snow will also conspire to build new slabs in Right Gully, Sluice, Lip and crossload other areas particularly across the bowl in the Center Headwall Left Gully and even Hillmans Highway. Lobster Claw and Hillmans are rated at Moderate due to the smaller size of snowfields there but careful travel there is still warranted. The lower half of Hillmans is mostly ice chunder with a veneer of snow due to the huge ice dam slush burst during our last thaw.

If the forecasted snow totals pan out, the possibility of natural avalanches is definitely there in both ravines. If snowfall is lighter than expected, we still have two issues to consider. One is the cold slabs remaining from Monday and Tuesday.  These slabs are fairly stubborn, both in their longevity and their resistance to triggers. Hard wind slabs are tempting due to easier travel and consistently carvable skiing but the softer layer which exists below can spell doom when some unlucky soul finds the sweet spot that fractures and fails the slab.  Several skiers, including Joe and I, found thick slabs over one hardness step lighter snow in Central, Left and South over the course of the last two days. These slabs would take a large trigger, a new heavy load or a particularly well aimed trigger in a thin spot between rocks, for instance.  A natural avalanche of today’s storm snow could also step down into this layer creating a larger than expected problem.

Difficult off trail travel will make bailing off of usually packed out trails on the ridgetops a significant challenge.  The high windspeeds and low visibility will add to the challenge today. Speedy ascents will be the best option today to get off the mountain before the white witch unleashes her dragon. Remember that 60-75 mph (95-120 kph) NW summit winds make walking increasingly difficult and accidents more and more likely. Windspeeds will increase beyond that to upwards of 120mph (190 kph)tonight so wise climbers will adjust turn around times accordingly. Coupled with a plunging mercury to -15F (-26C) will make for unforgiving brutal conditions.

 

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 17, 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

2013-02-17 Print friendly

Avalanche Advisory for Saturday 2-16-2013

This advisory expires at 12:00 midnight, February 16, 2013

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. The Lobster Claw, Right Gully, Left Gully, Hillman’s Highway, the Lower Snowfields, and the Little Headwall have Low avalanche danger. Natural and human triggered avalanches are unlikely.

Huntington Ravine has MODERATE and LOW avalanche danger. Central and Odell gullies have 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.

Whether you’re here for just today or for the long holiday weekend, today looks to be the best day to get out and play on Mt. Washington. Temperatures will be seasonable, winds will be on the light side, and there is a chance that clouds on and above the summit will be breaking up. We got a dusting of new snow early this morning, but it’s not enough to increase the avalanche hazard. The stability problems we are currently monitoring are left over from two days of light snowfall on Monday and Tuesday totaling about 5″, which fell with strong SW winds Monday then strong NW winds on Tuesday. Through the course of the past week, we’ve been able to lower the danger ratings in a number of locations. Today, Pinnacle is the only additional area moving from Moderate to Low. The other areas that remain posted at Moderate will continue to trend in a similar direction, but we don’t have the confidence needed to drop them a full rating.

What you’ll find in many areas, particularly those posted at Moderate, is fairly deep wind transported snow. Layers of softer, weaker snow, and pools of graupel in some places, are lying underneath slabs that are more firm than what is below. We’ve seen clean shears at a lot of the interfaces between the various layers, but overall the snowpack is lacking “snap.” The technical way to say this is that there is limited potential for fracture propagation, but I like to think of it in terms of made-up words like snappiness. While the overall snowpack has limited snapiness, in some locations this property exists sufficiently for a person to trigger an avalanche. Examples include weak points in snow near buried rocks or ice bulges, shallower snow on top of water ice or rain crust, and more open steep slopes such as under the Lip in Tuckerman. Avalanche runout paths are not at all forgiving right now, most are filled with rocks, ice chunks, trees, etc., so the consequences of being involved in even a small slide could be dire.

It’s a holiday weekend, which typically means a lot of people on the mountain. While you and your group may be making good choices, don’t expect everyone out there to be knowledgeable about avalanches. Where you see tracks does not necessarily equate to prudent decisions! Pay attention to who may be above and below you, and whenever possible avoid traveling in the runouts of avalanche paths. The full fury of winter on Mt. Washington will be on display tomorrow and Monday. You’d be wise to get an early start Sunday and move quickly, because conditions will worsen through the day.

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 8:10a.m., February 16, 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

2013-02-16 Print Friendly

Avalanche Advisory for Friday, 2-15-2013

This advisory expires at 12:00 midnight, Friday 2-15-2013

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

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

Though less than ideal weather conditions exist today for skiing, generally good stability could yield nice skiing and riding  in Tuckerman Ravine today for those willing to lower their standards a bit.  Our snowpack is still shallow for this time of year so lots of ice is showing in the headwall and Sluice and lots of bushes will limit you to short radius turns in Lobster Claw, Right and lower in Left Gully. Safe travel techniques when skiing will be challenging due to limited visibility, due to fog and a trace to 2″ (5cm) of new snow coming and may necessitate short pitches of skiing in order to maintain “eyes on” your partner. Climbers will find lots of ice trending to the “fatter” side in Huntington Ravine gullies.

Pockets of pooled, heavily rimed snow crystals are the areas of concern in both ravines today. Though not widespread, you will find areas of windslab on top of the weak rimed interface that are reactive to a moderate to hard trigger.  If you stumble into a larger, deeper area of this slab, you could trigger a consequential avalanche.  Yesterday, Chris and I observed several reactive layers, varying in depth from 6″-12″ (15-30cm), created by changes in snow density. These weak interfaces are probably deeper, perhaps significantly, in places.  Stay tuned in to the qualities of the upper layer(s) of snow and be alert to changing cohesion and reactivity of the slab.  Cracks shooting out more than a foot or so are a warning sign to remind you to manage the hazard by either tweaking your route to avoid the slab or finding and placing pro.

Boot penetration averages around 25 cm with deeper postholing in the faceted areas around rocks and bushes. Additionally, old rain crust is showing in spots and harder windboard exists in others. There was strong solar gain in the upper 4″ (10cm) of the snow on steep south facing terrain that moistened the snow and helped the stability process but created a bit of sun crust today.  Be sure to check our Weekend Update later today or this evening for more information about the busy upcoming holiday weekend.

Please Remember:

  • Safe travel in avalanche terrain requires training and experience. This advisory is just one tool to help you make your own decisions in avalanche terrain. You control your own risk by choosing where, when, and how you travel.
  • Anticipate a changing avalanche danger when actual weather differs from the higher summits forecast.
  • For more information contact the Forest Service Snow Rangers, the AMC at the Pinkham Notch Visitor Center, or the caretakers at Hermit Lake Shelters or the Harvard Cabin.
  • Posted 8:35a.m. Friday 2-15-2013. A new advisory will be issued tomorrow.

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

2013-02-15 Print friendly

Avalanche Advisory for Thursday, February 14, 2013

This advisory expires at Midnight, Thursday 2-14-2013

Tuckerman Ravine has LOW and MODERATE avalanche danger.  Hillman’s Highway, Lower Snowfields, the Little Headwall and Lobster Claw have Low avalanche danger. Natural and human triggered avalanches are unlikely. Right Gully, Sluice, Lip, Center Headwall, Chute and Left Gully have Moderate avalanche danger. Natural avalanches are unlikely and human triggered avalanches are possible.  Evaluate snow and terrain carefully to identify features of concern.

Huntington Ravine has LOW and MODERATE avalanche danger. Escape Hatch has Low avalanche danger. Natural and human triggered avalanches are unlikely.  All other forecasted gullies have Moderate avalanche danger.  Natural avalanches are unlikely and human triggered avalanches are possible.

Time and physical processes have brought slow stabilization to the windloaded areas of both ravines.  A wide variety of surface conditions exist so climbers and skiers planning  a trip into the ravines should be prepared for anything from hard wind slab, bullet hard rain crust as well as areas of soft snow thrown in to make things more interesting.  Most areas rated at Moderate are at the low end of the rating so arm yourself with key weather data and exercise sound travel skills today.

Over the past three of days the summit received 5.5” (13 cm) of new snow on winds coming from the SW to the NW with the majority of the snow (5.1″) falling on Monday and Tuesday. Winds abated through the day yesterday, with speeds dropping steadily from the 50’s mph 24 hours ago to around 25 mph by lunchtime yesterday and further into the teen’s mph (15-30 kph)where they have remained for the last 12 hours.  The low windspeeds have laid a veneer of new snow which is obscuring many of the visual clues that indicate the texture and, by extension, the travel qualities of the snow pack.  Opportunities to visually assess the snow will increase as the clouds lift through the day but expect a mix of riding and skiing qualities top to bottom in any gully from boot top height, but wind affected, snow to icy crust more suited to World Cup downhill record setting courses.  Be on the lookout for gray old surface just peeking through the new snow.  While the Chute, sections of the Center Headwall and the Lip appear attractive at first glance, remember that these areas suffered scouring as well as cross loading during the nor’Easter so the existing snow is extremely variable in thickness making more trigger points available as well as making a slide for life situation possible in places.

Huntington Ravine has a similar mix of surfaces and climbers will find it necessary to be flexible in their micro-route finding as they pick their way up a gully.  Escape Hatch is currently Low hazard with not much snow to avalanche, while South and Odell Gully are not far behind with a low side of Moderate rating.  Pinnacle through North gully have a greater area of bed surface and have large enough areas of new windslab that climbers should use caution when climbing these gullies as a human triggered avalanche is possible in select steep features and lee aspects.

Chris bulleted some key points yesterday which I have updated and carried over below:  

Main points to remember in the field today:  1. 3.3” of snow fell on Monday with high SW winds creating some instabilities on aspects with a NE facing component. 2.  Since Monday afternoon winds shifted to the W and WNW peaking midday Tuesday with an additional 1.8”of snow.   These Tuesday conditions developed new slabs mostly on E facing slopes.  3.  New loading will came close to shutting down yesterday morning as winds dropped to 15-20mph focusing our main concern on slabs created on Monday and Tuesday.  Some of these should be solidly in the Moderate rating. 4. 1/2″ of new snow in the last 24 hours has obscured many visual clues but not improved riding conditions. 5. Expect variable conditions so be ready for constant changing surfaces under foot depending on where you travel.  From sweating over a long slide on icy terrain one second, to triggering an avalanche the next, plan on encountering different hazards in both Ravines.

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 8:55a.m. Thursday 2-14-2013. A new advisory will be issued tomorrow.

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

2013-02-14 Print friendly