Avalanche Advisory for Monday, March 13, 2017

This advisory expires at Midnight.

 

Huntington and Tuckerman Ravine have LOW avalanche danger. Natural and human-triggered avalanches are unlikely. Watch for unstable snow on isolated terrain features. The Little Headwall is not forecast due to a lack of snow.

AVALANCHE PROBLEM: Wind Slab is creating the avalanche hazard today. Today, the danger will remain constant as the forecast weather will not have an impact on the areas of concern or the snowpack as a whole. The largest wind slab in our terrain currently sits just under the rollover of the Tuckerman Headwall with the largest pocket existing in the Lip. This can be identified from afar by its smooth appearance and cleanness when compared to the dirty looking, textured old surface. This old surface is firm and will create the potential for long, sliding falls, something to keep in mind when moving around the mountain.

WEATHER: After a cold and windy weekend, this is a great morning to be in the hills. Steady WNW winds blasted the mountain all weekend. Saturday saw speeds in the 70-90mph range with a slight decrease to the 40-60mph range on Sunday. Overnight, winds shifted to the NW and just now to the W where they should remain for the day, decreasing further to 15-30mph. The last observed snowfall was Friday night at midnight. High pressure this morning cleared the sky and is allowing temperatures to creep near 0F. With the approaching storm and low pressure system, clouds should start to develop in the afternoon as the wind shifts to the S. This may bring a trace of snow, likely occurring after dark.

SNOWPACK: Thanks to the strong wind over the weekend, the majority of the snowpack in avalanche terrain is scoured clean of new snow. This is particularly true in Huntington. Small, isolated pockets of wind slab linger behind terrain features, but these will be easy to avoid by staying on old surface. While many areas of Tuckerman are also scoured, several places saw snow deposited in lee areas. The Chute, Center Bowl and Sluice are displaying pockets of this smooth surface, but these forecast areas are also showing scoured surface that will offer ways to avoid the wind slab. Looking at the Lip, the wind slab (smooth, clean snow) is wall-to-wall at the rollover, making this forecast zone hard to navigate without passing through the avalanche problem. Much of the snow that fell on Friday arrived before winds increased. This allowed for a softer layer to develop that is now sandwiched between the bed surface and the firm wind slab in question today. As the wind slab formed from hurricane force winds that lasted for over 24 hours, the tensile strength of this layer will be very high, bridging the weak layer beneath and creating a slab that will likely be unreactive to human-triggers.

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

Posted 8:15 a.m., Monday, March 13, 2017. A new advisory will be issued tomorrow.
Helon Hoffer, Snow Ranger
USDA Forest Service
White Mountain National Forest
(603) 466-2713 TTY (603) 466-2856

2017-03-13

Thanks for the Support!

Last week, Friends of Tuckerman Ravine held a fundaraiser at Allspeed Cyclery and Snow in Portland. We enjoyed a great turnout and were treated to a discussion with Ben Leoni about his latest Working for the Weekend film, East Coast Avalanche. If you haven’t had the time to check out this film, it’s well worth 7 minutes. The crew does an excellent job of making sure everyone on the scene is safe and then taking the time in the film to talk about what happened. Ben fielded lots of questions at Allspeed and discussed what they learned and the big takeaways from the event. Kudos to Ben and the Ski the East team for a quality production.

A big thanks to everyone that helped make that night possible:

We look forward to events like these in the future. Again, many thanks to all who made this event possible, but a big thank you also to those who came out for the night to talk about snow.

Avalanche Advisory for Sunday, March 12, 2017

This advisory expires at Midnight.

Huntington Ravine has LOW avalanche danger. Natural and human-triggered avalanches are unlikely. Watch for unstable snow on isolated terrain features.

Tuckerman Ravine has MODERATE and LOW avalanche danger. Sluice, Lip, Center Bowl and Chute have Moderate avalanche danger. Natural avalanches are unlikely and human-triggered avalanches are possible. Lobster Claw, Right Gully, Left Gully, Hillman’s Highway, and the Lower Snowfields have Low avalanche danger. Natural and human-triggered avalanches are unlikely. The Little Headwall is not forecast due to lack of snow.

AVALANCHE PROBLEM: Firm Wind Slab developed from Friday’s snow and strong WNW winds on Saturday. Today, continued wind loading on decreasing winds will deposit remaining snow available for transport onto these areas, but should not be enough to increase the hazard for the day. Slopes in lee areas of WNW winds have the largest pockets of wind slab. These are identifiable by a smooth appearance and cleaner looking snow when compared next to the gray, refrozen old surface. In Tuckerman, wind slab connects Sluice through the Chute, creating the potential for a larger avalanche when compared to pockets in Low rated areas. Strong winds are creating small particles of snow that are finding a way to stick in many places to the textured old surface. Because of this, many areas which are smooth and would appear to have new wind slab are actually old surface that is just hidden under a skim of broken snow grains. This should highlight the importance of continued snowpack evaluation while moving around in terrain today.

WEATHER: After 5.8” of snow on Friday, strong winds and cold temperatures dominated Saturday. WNW winds blew in the 70-100mph range all day yesterday with temperatures bottoming out at -35F. Today, high pressure is approaching from the west and may allow for some clearing during the day. This will compete with moisture in the air creating some summit fog as well as the continued winds blowing loose snow. Up to an inch of snow may arrive this afternoon before skies clear overnight.

SNOWPACK: Prior to a week ago, our snowpack went through several melt/freeze cycles creating a firm base layer with an icy surface. Over the past week, cold temperatures prevented significant snow loss and several inches of snow has created scattered areas of wind slab. Before the wind really picked up Friday evening, this new snow was creating soft slab. As winds increased and began scouring in places, this 5.8” of snow created a mix of exposed old surface and areas of firm wind slab. This morning, one-finger hard slabs were encountered at the base of the Ravines with likely firmer slabs at higher elevations. In areas like the Lip of Tuckerman, these firm slabs sit on top of the softer slab that formed on Friday, creating a weak layer. With this layering in mind, add the fact that yesterday’s slab will be firm and strong. The edge of these slabs can be thin and are often the place where a person can impact the soft layer below, something to keep in mind when moving around on changing snow surfaces.

 

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 8:20 a.m., Sunday, March 12, 2017. A new advisory will be issued tomorrow.
Helon Hoffer, Snow Ranger
USDA Forest Service
White Mountain National Forest
(603) 466-2713 TTY (603) 466-2856

2017-03-12

 

Avalanche Advisory for Saturday, March 11, 2017

This advisory expires at Midnight.

Huntington Ravine has MODERATE avalanche danger. All forecast areas have Moderate avalanche danger. Natural avalanches are unlikely and human-triggered avalanches are possible.

 Tuckerman Ravine has CONSIDERABLE and MODERATE avalanche danger. Lip, Center Bowl and Chute have Considerable avalanche danger. Natural avalanches are possible and human-triggered avalanches are likely. All other forecast areas have Moderate avalanche danger. Natural avalanches are unlikely and human-triggered avalanches are possible. The Little Headwall is not forecast due to lack of snow.

 AVALANCHE PROBLEM: Widespread, boot top thickness, soft wind slabs which existed yesterday in Lip, Center Bowl and Chute, as well as scattered through other forecast areas, will add to the potential size of avalanches today. New wind slabs which formed overnight, and which will continue to form through the day, will create dangerous avalanche conditions in the floor of Tuckerman Ravine as well as higher in avalanche paths. Other forecast areas with a Moderate danger rating will have heightened avalanche conditions and will require careful snow and terrain evaluation. Wind, blowing snow and cold temperatures will reduce visibility and make group communication challenging so conservative decision making is advised in all forecast areas.

 WEATHER: Over the past 24 hours, temperatures have plummeted, consistent westerly winds have increased to gusts in the 80 mph range, and we’ve received a shot of new snow. Winds have challenged data recording, but several inches of new snow fell yesterday at Hermit Lake with the summit recording 5.8”.  Weather should be remarkably consistent throughout the day today, with summit conditions near -20 F, 60 mph winds with gusts to 80.  In the morning hours, models are showing a 20% chance of snow with little accumulation expected.  It goes without saying that today’s weather demands respect; plan and make travel decisions accordingly.

SNOWPACK:   Our deeper snowpack was exposed to a prolonged period of warm weather and rain which has created a strong snowpack but with an icy surface mixed with new wind slabs. It’s as if someone flipped the hazard switch back to the traditional winter problems involving avalanches, cold challenges and long sliding falls from the recent spring problems of icefall, crevasses and undermined snow over running water. Remember that we still have a relatively thick snowpack on east and north facing terrain which creates larger and more connected slopes that can produce larger avalanches. Southern facing terrain in both Ravines has much less snow coverage. Right Gully is mostly rocks and bushes at the top and has boulders showing in the runout. Lobster Claw remains snow to the top but is very tight. Northern gullies in Huntington are a mix of ice, rock and snow. Field time yesterday revealed much softer snow in the Lip area than 100 mph wind gusts would lead you to expect. That layer could be the weak layer in an avalanche propagating today or it could add volume to an avalanche starting in newly formed wind slab. Either way, the floor of Tuckerman Ravine is in the crosshairs. Overall, surface conditions on local ski trails have vastly improved over the past few days, particularly on the Sherburne and Tuckerman Ravine trails between Pinkham Notch and Hermit Lake.

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 Harvard Cabin.
  • Posted  8:10 a.m., Saturday, March 11, 2017. A new advisory will be issued tomorrow.

Frank Carus/Ryan Matz, Snow Rangers
USDA Forest Service
White Mountain National Forest
(603) 466-2713 TTY (603) 466-2856

2017-03-11

March 11, Elevated avalanche danger and continued wind loading

5″ of snow in the past 24 hours combined with strong west winds make large, human-triggered avalanches possible in Tuckerman Ravine. As a result, expect Considerable avalanche danger in the Lip, Center Bowl and Chute. Wide spread but smaller wind-slabs in Huntington so expect Moderate danger there, possibly pushing towards Considerable in a few strong lee locations. Full advisory will be issued soon.

Avalanche Advisory for Friday, March 10, 2017

This advisory expires at Midnight.

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 on isolated terrain features.

Tuckerman Ravine has MODERATE and LOW avalanche danger. Lip, Center Bowl and Chute have Moderate avalanche danger. Natural avalanches are unlikely and human-triggered avalanches are possible. All other forecast areas have Low avalanche danger. Natural and human-triggered avalanches are unlikely. The Little Headwall is not forecast due to lack of snow.

 AVALANCHE PROBLEM: Wind slabs that developed yesterday will be the primary avalanche problem for the first half of the day with danger ratings at the lower end of those written above. Snow squall activity along with steadier upslope precipitation this afternoon will drive these ratings up and make human-triggered avalanches possible in all forecast areas. Avalanche paths, like Lip and Center Bowl as well as Central and Pinnacle Gully, that are in the lee of west winds, will reach maximum instability towards evening as winds reach prime loading velocities. The size of potential avalanches will depend on the amount of snow produced by the combined upslope snow showers along with a Norlun trough. Expect potential wind slabs this morning to be on the smaller side in moderate rated areas but grow to medium sized avalanches capable of burying a person by nightfall if we receive the upper end of the 3-5” forecast by the MWObs. Wind speed and direction are prime to create touchy wind slabs which could propagate easily. Evaluate snow, weather and terrain carefully today.

 WEATHER: The timing of increasing west wind and amount of total snowfall are challenging forecast model consensus due to dry air aloft as well as the fickle nature of the Norlun trough. Bands of dry air may reduce much of the potential snowfall to only an inch or two. Should the trough stream moister air to the Whites than some models indicate, we could receive 5” of new snow. Light winds this morning will continue until mid-day and then begin ramping up. Visibility will begin to diminish in the afternoon, unfortunately just as accumulating snow improves skiing.

SNOWPACK: A combination of extreme temperature swings and liquid precipitation over the past several weeks has created a solid, relatively uniform snowpack in our forecast areas. Over the top of this, the past several days have brought as much as 8 inches of new snow along with very high winds. 100 + mph gusts were recorded on the summit of Mt. Washington yesterday.  As a result, Tuckerman and Huntington Ravines display a mixed bag of recently formed wind slabs and scoured old snow surface.  Avoiding these wind slabs will reduce exposure to our avalanche problem, but increase risk of sliding falls on the hard old snow. This wind transported snow has likely bridged many of the large glide cracks that had opened in the past several weeks, be aware that these bridges could be thin and unsupportable.  Overall, though, surface conditions have vastly improved over the past week, particularly on the Sherburne and Tuckerman Ravine trails between Pinkham Notch and Hermit Lake.

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 Harvard Cabin.
  • Posted  8:10 a.m., Friday, March 10, 2017. A new advisory will be issued tomorrow.

Frank Carus/Ryan Matz, Snow Rangers
USDA Forest Service
White Mountain National Forest
(603) 466-2713 TTY (603) 466-2856

2017-03-10

Avalanche Advisory for Thursday, March 9, 2017

This advisory expires at Midnight.

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 on isolated terrain features.

 Tuckerman Ravine has MODERATE and LOW avalanche danger. Sluice, Lip, Center Bowl and Chute have Moderate avalanche danger. Natural avalanches are unlikely and human-triggered avalanches are possible. All other forecast areas have Low avalanche danger. Natural and human-triggered avalanches are unlikely. The Little Headwall is not forecast due to lack of snow.

 AVALANCHE PROBLEM: Wind slabs developing in terrain features downwind of strong westerlies are creating heightened avalanche conditions. Evaluate snow and weather conditions carefully if you are travelling in avalanche terrain today. Snow shower activity like we have seeing this morning at Pinkham Notch and Hermit Lake have a tendency to pile up more snow than you might expect at upper elevations. Current and projected wind speeds will move 1-3” of new snow, plus the 4.5” that have fallen in the past 48 hours, into our start zones resulting in the potential for medium sized human-triggered avalanches in moderate rated areas. Pockets of wind slab in Low rated areas could also cause problems so consider travelling on the old, refrozen snow surface exposed by wind-scouring action. Wind slabs may become increasingly sensitive today due to an increase in density of snow near the surface.

 WEATHER: Current temperature on the summit is 8F and falling with 30F at Pinkham Notch. Strong west winds are blowing light and moderate snow showers on gusty winds currently blowing at 66 mph. Wind will continue from a westerly direction and increase slightly through the day. Expect 70-80mph WNW winds with gusts to 100mph through the day with a shift to NW later this afternoon. Continued upslope snow showers are expected to bring 1-3” of new snow today to add to the 4.5” of snow that has fallen in the past 48 hours.

SNOWPACK: Despite the lack of snow at lower elevations around the region, it is still game-on in the snowy Presidential Range. This is especially true of the north and east facing terrain in and around the Cutler River drainage where 220” of snow since December 1st has filled our forecast areas and developed avalanche paths to nearly maximum extent. Large and close to historic sized avalanche activity in Hillman’s Highway, the Lip and Center Bowl and the looker’s left in Gulf of Slides is testament to the intensity of the season’s avalanche cycles. Unfortunately for snow lovers, winter temperatures have been a roller coaster with mid-winter warmth and enough rain to wreck powder but to create a solid, deeper snowpack. Going forward, expect a mixed bag of avalanche activity along with spring hazards like falling ice, thinly covered crevasses and open drainages.

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 Harvard Cabin.
  • Posted  8:15 a.m., Thursday, March 9, 2017. 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

2017-03-09

 

Avalanche Advisory for Wednesday, March 8, 2017

This advisory expires at Midnight.

Huntington Ravine and Tuckerman Ravine have LOW avalanche danger. Natural and human-triggered avalanches are unlikely in all forecast areas. Watch for unstable snow on isolated terrain features. The Little Headwall is no longer forecast this season as it is now an open river.

AVALANCHE PROBLEM: Rain and warm temperatures created a wet slab problem this morning. Wet slabs will be found today in areas that contained wind slab over the past few days, largely in the Lip and Center Bowl with scattered pockets elsewhere. This avalanche problem is hard to predict and can be caused by quickly adding weight to the slab or by meltwater lubricating a sliding surface within the snowpack. With rainfall diminishing and temperatures dropping, the likelihood of wet avalanches will diminish due to the snowpack refreezing. Later in the day, a fast moving system may bring periods of heavy snow and up to 3” total. Increasing wind from the west has the potential to turn this snow into wind slab. If we receive the upper end of the forecast snow total, the avalanche hazard rating may exceed the current Low rating and require careful snow and terrain evaluation for safe travel.

WEATHER: Temperatures in the 30s and 40sF yesterday and into the night allowed 0.25” of water to fall as rain. A sudden downturn in temperature at 7am has the summit at 25F and Hermit Lake at 35F. Rain and mixed precipitation should be light and continue for the morning with less than 0.1” of liquid before clouds dissipate. Later in the day, an upper level trough may bring a brief period of instability to the region along with the possibility for snow. With winds increasing to 50-70mph and a possible period of heavy snow with 1-3”, watch for blizzard conditions if traveling later in the day.

SNOWPACK: Prior to this past Friday, our snowpack consisted of refrozen snow that was shaping up to offer good spring ski conditions. Cold temperatures over the weekend and a total of 7” of snow since March 3 created firm wind slab in lee areas of NW winds. Rain last night soaked these wind slabs creating wet slabs. With the heaviest rain and warmest temperatures pre-dawn today, the period of highest instability has likely passed. Temperatures are plummeting and the snowpack as a whole should freeze as the day progresses. Up to 3” of snow on strong W winds later in the day will likely create pockets of wind slab in lee areas of the steepest terrain and sheltered areas of terrain features. Travel in terrain today will require keeping an eye on the weather and constant revaluation of what the current conditions are doing to the snowpack.

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 Harvard Cabin.
  • Posted  8:15 a.m., Wednesday, March 8, 2017. A new advisory will be issued tomorrow.

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

2017-03-08

Avalanche Advisory for Tuesday, March 7, 2017

This advisory expires at Midnight.

Huntington Ravine and Tuckerman Ravine have LOW avalanche danger. Natural and human-triggered avalanches are unlikely in all forecast areas. Watch for unstable snow on isolated terrain features. The Little Headwall is no longer forecast this season as it is now an open river.

AVALANCHE PROBLEM: The avalanche problem today will change as the day progresses, from wind slab this morning to wet slab tonight. Two inches (2”) of snow overnight combined with up to another inch this morning on 30 mph SW winds will deposit isolated pockets of wind slab near the start zones of our forecast areas. These will be larger in gullies with N or E aspects like Central, Odell, South, Left and Hillman’s Highway, but as these displayed the largest amounts of scouring during this past weekend, the contrast between this newly deposited snow and the old hard surface will make safe travel possible.  As precipitation changes to rain this evening, these newly formed wind slabs as well as the wind slab that formed over the weekend will turn to wet slab. As the rain adds weight to the slabs, stability will decrease, with the greatest period of instability occurring after this advisory expires at midnight.

WEATHER: After a bluebird day yesterday with light winds from the NW, snow showers began last night at the same time winds shifted to the SW. It is likely light precipitation will be intermittent through the day. As temperatures warm, snow will switch to mixed precipitation and eventually to rain around dark with 0.25” of rain forecasted. Winds will stay from the SW and start to increase around the same time rain arrives. Rain should stay light and steady overnight.

SNOWPACK: The thaw around the start of the month created a very stable snowpack. Five inches (5”) of snow fell on top of this snowpack at the end of last week and into the weekend. In Huntington, strong NW winds carried this all down into the trees. In Tuckerman, this 5” formed firm (pencil hard) wind slab in isolated areas, the largest being in the Lip. Cold temperatures over Saturday and Sunday allowed facet growth at the interface of the old surface and this wind slab. Field tests indicated reactiveness, but with wide variability and uneven distribution of the snow combined with the firmness of the slab, initiating a crack that is capable of propagation is unlikely. The two inches of snow that fell overnight is heavy with some areas at lower elevations already seeing mixed precipitation, meaning lighter winds today will struggle to transport this snow. Old surface is identifiable in many areas due to the high contrast of dirty old surface to new snow and indicates that winds are not forming widespread slabs. When rain arrives tonight, the wind slab from the weekend as well new snow from last night will turn wet, decreasing the stability of the snow.

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 Harvard Cabin.
  • Posted  8:20 a.m., Tuesday, March 7, 2017. A new advisory will be issued tomorrow.

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

2017-03-07

Avalanche Advisory for Monday, March 6, 2017

This advisory expires at Midnight.

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

Tuckerman Ravine has MODERATE and LOW avalanche danger. The Lip 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. The Little Headwall is not forecast due to lack of snow.

AVALANCHE PROBLEM: Sunshine and warming temperatures will decrease the stability of existing wind slabs. These slabs are limited in distribution through our forecast areas with the largest of them in the Lip in Tuckerman, and to a lesser extent, low in Central Gully beneath the ice bulge in Huntington. These wind slabs were stubborn yesterday but are medium to large sized and potentially dangerous in the Lip and Center Bowl area. Smaller pockets of wind slab will weaken sooner and could pose a problem in steep terrain in other low rated forecast areas. Be wary of any of these wind slabs on east and south facing aspects today and do some stability tests or hand shears before committing to the slope. Old refrozen gray surfaces will present more stable travel options, though carry a greater risk of long sliding falls, especially on shady aspects. The snowpack is starting out quite cold so the timing of warming and associated softening of the snow is uncertain.

WEATHER: Calm winds are allowing an inversion this morning. Temperatures at 6:45a.m. are -2.5F at Pinkham Notch, 18F at 4,000’ on the Auto Road and 9F at the summit. Current winds of 25mph from the north are forecast to shift to the west and stay in the 20-35mph range but could be even lower. Low wind speeds and temperatures near freezing with sun, at least in the morning, may work to soften surface snow. High thin clouds, which may appear this afternoon as a warm front approaches, can increase this effect due to reflection of long wave radiation.

SNOWPACK: Strong northwest winds continued to transport snow through the morning hours yesterday. During that time, Ryan and I visited the crown face low in the Lip and our tracks and stability pit filled quickly with snow. The new wind slab was a meter thick in our location and the slab in many areas across the Lip forecast area is likely to be up to that thickness over the hard icy refrozen snowpack. Though we won’t see enough warming today to have significant wet slab concerns, the heat could certainly weaken the wind slabs, especially at the edges where they are thinner. Remember that wind slabs are easier to trigger in thinner spots, especially less than a meter thick. Yesterday’s crown profile indicated that the failure layer was 50cm down with another interface about 90 cm down both failing in the lower moderate (CT11 and 15) on a minor snow density change. Low quality shears (Q2) and a rugged pencil hard surface made the slab stubborn but anticipate growing sensitivity to human-triggers as the day wears on and warms the slab.

The Mount Washington Backcountry Ski Festival will be happening this coming weekend, March 10-11. A portion of the proceeds will benefit go to Friends of Tuckerman Ravine to help support our mission. Thanks again to Friends of Tuckerman Ravine, Allspeed, Black Diamond Equipment, Black Point Surf Shop, Julbo, Liberty Skis, Mammut, Ski the East, and Tuckerman Brewing for their generosity and support at last Thursday’s event in Portland!

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 Harvard Cabin.
  • Posted  7:35 a.m., Monday, March 6, 2017. 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

2017-03-06