Avalanche Advisory for Tuesday, Jaunary 31, 2017

This advisory expires at midnight.

Huntington Ravine has MODERATE avalanche danger. Natural avalanches are unlikely and human-triggered avalanches are possible. Heightened avalanche conditions exist on specific terrain features. Evaluate snow and terrain carefully.

Tuckerman Ravine has CONSIDERABLE, MODERATE, and LOW avalanche danger. Sluice and the Lip have Considerable danger. Natural avalanches are possible and human-triggered avalanches are likely. Lobster Claw, Right Gully, Center Bowl, Chute, Left Gully, Hillman’s Highway, and Lower Snowfields have Moderate avalanche danger. Natural avalanches are unlikely and human-triggered avalanches are possible. Heightened avalanche conditions exist on specific terrain features. Little Headwall has Low avalanche danger. Generally safe avalanche conditions exist with natural and human-triggered avalanches being unlikely.

AVALANCHE PROBLEM: Soft Wind Slab developed from four inches of light density snow and west winds just strong enough to transport this snow. With a shift in wind to the NW last night, be on the lookout for new slab that could be responsive to a human trigger. This can be seen in the Tuckerman with a fresh crown line under the ice to looker’s left of the Lip. Isolated pockets like this in the steep terrain such as Lip, Sluice, and Central as well as on rollovers and terrain features will be sensitive to human-triggers today and should be heeded wisely when making travel-decisions.

WEATHER: Sunday delivered around 3” of 5% density snow to the Cutler River Drainage. This fell on steady west winds of 30-45mph. Another inch fell yesterday with winds shifting to the WNW around dark and increasing slightly to the upper 40mph range during the early morning hours. Today, high pressure will allow for clear skies early and winds decreasing to 15-30mph and shifting to the SW. A fast-moving clipper system will bring clouds this afternoon and a possible 2-4” of snow overnight.

SNOWPACK: Steady winds near the century mark last Friday scoured our terrain to a melt-freeze crust. Just over an inch of snow on Saturday blew in and formed pencil to one-finger (P-1F) hard slabs in most areas. As this snow continued to blow in on lessening winds, four-finger to fist (4F-F) slab formed on top of this with a thin wind skim due to a short time-period of increased winds. The upper reaches of northern gullies in both ravines somewhat avoided this snow and have scoured areas that will provide safer travel options for today. Sunday brought 3” of 5% snow with another 0.9” arriving on Monday. Winds around 30mph transported this snow into much of our terrain and created soft slab of fist hardness (F). Between Sunday afternoon and Monday morning, South, Left, Hillman’s and Dodge’s naturally avalanched with soft slab. These appear to have released from the upper reaches of the gullies where the slope angle is the steepest. Winds shifted to the NW last night, hitting 50mph for a brief period before dropping to the current 20mph range. This slight shift and increase in wind may be enough to strengthen the surface slab to one that will sustain a fracture, as evidenced by the slab release in the Tuckerman Headwall. In steep terrain, the soft slab that has formed will be quite deep in places and could entrain a significant amount of snow as forecast zones are now connected. Careful terrain evaluation today will go a long way towards a safe day in the mountains.

The Lion Head Winter Route is open and the most direct route to the summit from the east side of the mountain. Please be on the lookout for machine traffic on the Sherburne.

 

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  8:10 a.m., Tuesday, January 31, 2017. A new advisory will be issued tomorrow.

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

2017-01-31

Avalanche Advisory for Monday, January 30, 2017

This advisory expires at midnight.

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

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

AVALANCHE PROBLEM: Soft Wind Slabs sensitive to human-triggering developed over the past 36 hours and will continue to grow in size today. While winds may be light, snow that arrived yesterday is light enough in density that wind transport will continue. Signs of blowing snow are visible now as well as the formation of small cornices on top of areas like the Boott Spur gullies. Sluff piles are showing under the steepest terrain in both ravines as well as dry-loose debris below Chute, Left Gully and Hillman’s Highway. The red flags are up today, make sure to take note. Developing wind slab will be soft and sensitive, but is growing thick enough in places that it is struggling to stay in place. Heed these cues when moving into terrain and realize that some snowpack evaluation can be done from below. Cautious route-finding and conservative decision-making will be key today.

WEATHER: Steady snow showers persisted yesterday and continued through the night. Hermit Lake recorded 8cm (3.2”) of 5% snow. This fell on west winds that stayed between 30-45mph. This fell on top of the 11+” that arrived on strong west winds (averaging 70mph) between Thursday and Saturday. High pressure today will allow for clearing but also keep temperatures around 0F. Winds will drop slightly to 20-35mph, shifting from the west to NW early afternoon. Clouds may develop late with cold temperatures tonight and winds increasing up to 50mph.

SNOWPACK: Looking at the snowpack, the base layer currently is the melt-freeze crust that formed last Wednesday. During time in the field yesterday morning, we found widespread soft wind slab that starts at pencil or one finger (P-1F) hardness on top of the crust and transitions to fist (F) hardness at the surface. This was true in several locations between Lobster Claw and Sluice as well as around the lower portions of Chute, the difference being the overall thickness of the slab, with the slab on the right side of the Tuckerman being 30-40cm thick while the left side was much thicker at 85cm+. Compression tests resulted in shearing of interfaces within the slab, but not on the interface of the wind slab and the melt-freeze crust. Extended Column Tests did not propagate. Much of the snow as well as the maximum wind speed yesterday came after our time in the field. The new snow is of light enough density that even the 20-35mph winds today will be enough to provide transport. More soft wind slab will form on top of the layer that already exists. This may begin to form a cohesive slab that could propagate and fracture when stressed by a human-trigger. Snowfields are growing large in size, particularly in the southern gullies in both Ravines, and are connecting forecast areas. Soft slab avalanches today could contain a large amount of snow.

The Lion Head Winter Route is open and the most direct route to the summit from the east. Please be careful of bridge construction debris near crossover 7 on the Sherburne Trail when skiing or riding.

Please Remember:

  • Safe travel in avalanche terrain requires training and experience. This advisory is just one tool to help you make your own decisions in avalanche terrain. You control your own risk by choosing where, when, and how you travel.
  • Anticipate a changing avalanche danger when actual weather differs from the higher summits forecast.
  • For more information contact the Forest Service Snow Rangers, the AMC at the Pinkham Notch Visitor Center, or the caretakers at Hermit Lake Shelters :or the Harvard Cabin.
  • Posted  8:30 a.m., Monday, January 30, 2017. A new advisory will be issued tomorrow.

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

2017-01-30

Avalanche Advisory for Sunday, January 29, 2017

This advisory expires at Midnight.

Huntington and Tuckerman Ravine have MODERATE avalanche danger today. Natural avalanches are unlikely and human-triggered avalanches are possible. Evaluate snow and terrain carefully to identify features of concern. The only exception to this rating is the Lower Snowfields and Little Headwall which have LOW avalanche danger. Natural and human-triggered avalanches are unlikely there. Open water and water ice remain exposed in the Little Headwall and the creek above.

AVALANCHE PROBLEM: Winds that created the wind slab avalanche problem over the past couple of days finally died down yesterday afternoon. These wind slabs along with newer, softer wind slabs should remain on your radar as you move into steep terrain today. The high velocity of the winds over the past several days has most likely created a wide mix a stiffness to these slabs, with the majority of them most likely being fairly stubborn in most areas. The northern gullys in both Ravines, while still having a moderate danger rating, are probably more scoured than loaded but new wind slabs will develop today. East facing areas served as a deposition zone for the snow which fell over the past few days and most likely went through a natural avalanche cycle during that time. Softer and smaller wind slabs are also in the mix due to the inch of snow that fell last night plus another inch or two falling today. These slabs will be much more sensitive to human-triggering and could result in a fairly significant avalanche if we receive the upper end of the forecast snow fall.

WEATHER: Just an inch of snow fell on the summit overnight however another 11” was recorded there since Thursday. In addition to the steady localized, upslope snowfall over the past several days, the main weather factor driving our avalanche problem is the continuously high winds that blew since Thursday night. The wind blew in the 70-100 mph range during that period from the west with a few hours from the WNW.  The past 12 hours has finally brought a steady decline in wind speed. Expect moderate winds today in the 30-45 mph range with lingering fog and snow showers bringing another inch or two of accumulation. Temperatures will be around 5F on the summit.

SNOWPACK: The icy crust created on Tuesday and Wednesday by sleet transitioning to rain is now well buried in wind sheltered terrain. Limited field observations due to elevated avalanche danger and low visibility tempers our ability to rate any forecast area low, but it is likely that North, Damnation and Yale and to a lesser degree, Lobster Claw and Right Gully were predominately scoured down to that old surface with pockets of wind slab in places. Hard, stubborn wind slabs will be possible to trigger in certain locations even though they may appear very firm. Ease into the terrain today and reduce you exposure to wind slabs. Dry-loose avalanches could become an easily manageable issue in steep terrain if the upper end of the forecast pans out.

The Lion Head Winter Route is open and the most direct route to the summit from the east. Please be careful of bridge construction debris near crossover 7 on the Sherburne Trail when skiing or riding.

Please Remember:

  • Safe travel in avalanche terrain requires training and experience. This advisory is just one tool to help you make your own decisions in avalanche terrain. You control your own risk by choosing where, when, and how you travel.
  • Anticipate a changing avalanche danger when actual weather differs from the higher summits forecast.
  • For more information contact the Forest Service Snow Rangers, the AMC at the Pinkham Notch Visitor Center, or the caretakers at Hermit Lake Shelters :or the Harvard Cabin.
  • Posted  7:30 a.m., Sunday, January 29, 2017. A new advisory will be issued tomorrow.

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

2017-01-29

Avalanche Advisory for Saturday, January 28, 2017

This advisory expires at Midnight.

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

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

AVALANCHE PROBLEM: Natural wind slab avalanches are possible in both Ravines today. High winds and continuous snowfall for the past 2 days has built fairly thick wind slabs. History has shown that these wind slabs will exist in middle start zones such as beneath the ice in the Center Bowl, around the fork of Hillmans and on the approaches and middle pitches of climbs in Huntington. Strong westerly winds tend to scour northern gullies in Huntington Ravine. Natural avalanches are less likely in Lobster Claw and Right Gully but smaller and still dangerous human-triggered avalanches could occur there.

WEATHER: It is truly a different world up here compared to the surrounding valleys due to intense upslope snowfall from lingering moisture. Snow has been continuous for over 48 hours with high winds and drifting snow and making accurate measurements challenging. The sheltered snow study plot near Hermit Lake was wind effected again this morning with only 6 cm recorded, and 8.9cm recorded from midnight to 6am on the summit. Looking around, it is pretty obvious that lots of snow has fallen, probably more than has been recorded, with grinning skiers reporting great runs on local ski trails. Expect heavy drifting and scouring above tree line today. Low visibility and cold temperatures in the single digits F will make patient observation and decision making in avalanche terrain challenging. West winds 65-85 mph will relax through the day diminishing to 50-70 mph by nightfall.

SNOWPACK: Strong winds and snow fall yesterday limited field time due to the risk of natural avalanches. Suffice it to say that signs of wind loading were obvious and occurred all day. Snow squalls were observed last night as well. Hourly observations from the summit show wind speeds in the 70-90 mph range for the past 36 hours or so. Expect weaker layers to exist near the refrozen, rimed crust from Tuesday/Wednesday’s sleet and rain event as well as within the new snow from wind speed and snow particle changes included rimed snow crystals. The strong recent winds have most likely made stubborn wind slabs with more sensitive wind slabs in strongly sheltered areas. Safe travel in avalanche terrain while successfully navigating avalanche paths will be challenging today, at best.

The Lion Head Winter Route is open and the most direct route to the summit from the east. Please be careful of bridge construction debris near crossover 7 on the Sherburne Trail when skiing or riding. The recent dense “snow” has resulted in good coverage on the Sherburne which will be a good and relatively wind sheltered place to enjoy the new snow falling 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  8:00a.m., Saturday, January 28, 2017. A new advisory will be issued tomorrow.

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

2017-01-28

 

Website changes

You may have noticed the new map adjacent to our avalanche advisory on our homepage this week. MWAC superstar volunteer, Jeff Fongemie, created this map plugin and and brought to fruition a goal of ours to make it easier to visualize areas of hazard in our forecast areas. Additionally, many folks either don’t know the names and locations of our forecast areas or have some of the alternative run names for the areas in mind when looking at our written advisory. The details of the forecast can be hard to remember after an hour hike into the terrain but hopefully a visual display of the hazard ratings may help you identify places to go as well as avoid. Though it may seem obvious, it is important to remember that the graphic is more a tool to help you understand the avalanche problem than an actual map to navigate through the hazard. For that reason, we drew the polygon shapes of the avalanche paths in the generally area of the feature and generally larger than it’s largest historical path. The location of each polygon is however a good reflection of the compass orientation and aspect, to some degree, of the slope so identifying avalanche problems due to prevailing wind loading or scouring, and solar gain should be more apparent.

Above all, continue to read our advisory, the weather, the snowpack history and then reassess as you enter the terrain. Snow and weather changes and with it, so does the hazard so think critically and realize that there is much more to the story than the ultra-basic message contained in a one-word rating.

Check out the map. We hope it helps.

Thanks also to Jon Hall who put it a lot of work and is doing some interesting stuff with 3D mapping of avalanche terrain.

 

Avalanche Advisory for Friday, January 27. 2017

This advisory expires at Midnight.

Tuckerman Ravine has HIGH and CONSIDERABLE avalanche danger. The Lip, Center Bowl and Chute have High avalanche danger. Natural avalanches are likely and human-triggered avalanches are very likely. All other forecast areas have Considerable avalanche danger. Natural avalanches are possible and human-triggered avalanches are likely.

 Huntington Ravine has CONSIDERABLE avalanche danger. Natural avalanches are possible and human-triggered avalanches are likely in all forecast areas of Huntington Ravine. Dangerous avalanche conditions exist.

 Travel in avalanche terrain is not recommended today.

AVALANCHE PROBLEM: Natural wind slab avalanches will be likely to occur in both Ravines today. The floor of Tuckerman Ravine or the Fan and avalanche paths in Huntington will be a risky spot to spend any time today. Snow yesterday evening and overnight along with new snow today will be easily transported by the wind into avalanche start zones and will build wind slabs on east facing aspects while cross-loading others. Northern gullies in Huntington have been more scoured to this point but diminishing wind speeds and continued snowfall will build more wind slabs later today. The likelihood of natural wind slab avalanche in Central, Pinnacle and Odell almost deserve a High danger rating.

WEATHER: 4” of new snow fell on the summit since yesterday afternoon on winds increasing from the 80’s to 100 mph. Light snow is continuing this morning with 1-3” more expected through the day on winds diminishing to the 60-80 mph range. The upslope snow showers will pick up in intensity this afternoon with another 2-4” forecast to fall overnight. Expect seasonable temperatures near 10F on the summit, mid-twenties F at Pinkham Notch.

SNOWPACK: Field time and reported observations yesterday confirmed the existence of a widespread, rime covered crust throughout our terrain. In some areas this crust was on top of (50cm) of loose, granular sleet from the 40% density precipitation that fell Tuesday and overnight Wednesday. This thin crust of ice supported the weight of a skier but was breakable underfoot and was covered in rime which likely makes for decent bonding of the new snow. As is typical with the wind slab problem we frequently deal with here, the failure layer will be in the new snow, probably just above the existing crust. It’s hard to say whether avalanches today and tomorrow will break through this crust and entrain even more mass and resulting destructive power. With low visibility, very high winds creating clear and present signs of a growing wind slab problem, I’d rather not be in the terrain long enough to find out.

The Lion Head Winter Route is open and the most direct route to the summit from the east. Please be careful of bridge construction debris near crossover 7 on the Sherburne Trail when skiing or riding. The recent dense “snow” has resulted in good coverage on the Sherburne which will be a good and relatively wind sheltered place to enjoy the new snow falling 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  8:40a.m., Friday, January 27, 2017. A new advisory will be issued tomorrow.

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

2017-01-27

 

Avalanche Advisory for Thursday, January 26, 2016

This advisory expires at Midnight.

Tuckerman and Huntington Ravine have 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. In Tuckerman Ravine, the Little Headwall is not rated due to thin snow cover.

AVALANCHE PROBLEM: The main concern today will be loose-dry avalanches in steep terrain today. These avalanches could be very heavy due to the high water content of recent precipitation and could cause some significant problems over a bad runout, cliff or terrain trap. Primary locations would be beneath steep terrain where sleet mixed with snow may have pooled deeply as well as areas with a north facing lee component like Escape Hatch, South and Hillman’s Highway. An icy glaze capping the snow and 24 hours of conditions favorable for settlement have reduced our propagation concerns that could lead to the fracture of a wind slab but limited visibility and field observations does create some uncertainty. Travel carefully despite the rating today.

WEATHER: No new snow has been recorded in the past 30 hours though some blowing snow was observed for an 8 hour period yesterday evening. Given the density of the existing snow and ice glaze on the ground, it is likely that not a lot was transported into our avalanche start zones. Lingering moisture resulting in a low cloud cap are currently reducing visibility. This situation is unlikely to improve as a passing cold front will bring more clouds with snow showers this afternoon. Current temperature at Hermit Lake is a balmy 34F but will drop to the mid-20’sF later today with mid-teens on the summit. West winds currently in the 35-50 mph range will increase to 50-70 mph with higher gusts. A trace to an inch of snow may fall during daylight hours with another 1-3” tonight.

SNOWPACK: The inch and half of snow water equivalent that fell Monday night and Tuesday fell in an upside down configuration that would have created much greater avalanche problems had it not fallen on 80 mph easterly winds. Much of the early, lighter snow appears to have been either scoured out, wind packed into denser slabs, or had any energy, reactivity or propagation potential crushed out of it by subsequent wet snow, sleet, and a cap of freezing rain. Reports from a skier up Right and down Lobster Claw indicate a breakable crust over granular snow and sleet that has pooled deeply in places. The crust was supportable and edgeable on skis and allowed a survivable trip down Lobster Claw. Right Gully was predominately scoured.

The Lion Head Winter Route is open and the most direct route to the summit from the east. Please be careful of bridge construction debris near crossover 7 on the Sherburne Trail when skiing or riding.

Continued internet access problems again today resulted in a hasty trip back to Pinkham Notch to post this advisory. Apologies for the delay!

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  8:20a.m., Thursday, January 26, 2017. A new advisory will be issued tomorrow.

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

2017-01-26

 

Avalanche Advisory for Wednesday, January 25, 2017

This advisory expires at midnght.

Huntington and Tuckerman Ravine have MODERATE avalanche danger. Natural avalanches are unlikely and human-triggered avalanches are possible. Heightened avalanche conditions exist on specific terrain features. Evaluate snow and terrain carefully. Little Headwall and Lower Snowfields are not forecast due to thin snow cover.

AVALANCHE PROBLEM: Wind Slab formed Monday night into Tuesday on strong east winds. This wind slab will be found high in Pinnacle, Odell, South and Escape Hatch as well as Left Gully and Hillman’s Highway. Ice pellets likely rolled downhill, pooling around terrain features while freezing drizzle then fell widespread over the terrain. This added weight to the already formed wind slab, but also created a new surface for the next round of possible snow. If the higher end of snow forecast for today arrives (2”), expect new wind slab to form, creating the possibility for natural avalanches and exceeding our current rating.

WEATHER: While true rain never fell yesterday, the Summit recorded just about every other type of precipitation. All in all, over the past 36 hours, 1.5” of water fell, starting as snow, then pellets, then freezing rain, back to ice pellets and then finally back to light snow for a brief period overnight. Temperatures maxed out at 27F yesterday and winds calmed through the day and into the night. Current winds are NW at 30mph and the temperature is in the mid-25F. Lingering moisture in the air may bring snow showers today (a trace to 2”).The temperature will drop into the teens and winds will shift to the west, increasing to 60mph+ by the end of the day.

SNOWPACK: The snowpack is made of alternating layers of dry and wet snow at the moment. For today’s avalanche problem, the layers that formed starting Monday morning are of most concern. The warm period over the weekend was followed by a brief cold snap Monday morning. This created a thin crust, but one seemingly strong enough to create a bed surface. Roughly 5” of snow fell on this yesterday with a SWE of 1.5”. The storm started with strong east winds Monday into Tuesday, cross-loading north facing gullies and likely creating wind slab in the start zones. Visuals yesterday afternoon indicated east and south facing slopes avoided much of the loading. Ice pellets that fell yesterday have been scattered in all locations due to shifting winds. If snowfall accumulates today, expect winds to transport this and create new winds slab in lee areas of the steep terrain.

The Lion Head Winter Route is open and the most direct route to the summit from the east side of the mountain. Please be on the lookout for machine traffic on the Sherburne.

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  8:20a.m., Wednesday, January 25, 2017. A new advisory will be issued tomorrow.

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

2017-01-25

 

Avalanche Advisory for Tuesday, January 24, 2017

This advisory expires at midnight.

Huntington and Tuckerman Ravine have CONSIDERABLE avalanche danger. Natural avalanches are possible and human –triggered avalanches are likely. Careful snowpack evaluation, cautious route-finding, and conservative decision-making are essential. Dangerous avalanche conditions exist.

AVALANCHE PROBLEM: The current avalanche problem is the developing Wind Slab. New snow, wind, and a good bed surface are key ingredients for this problem and all exist this morning. Strong east winds are cross-loading many slopes, particularly the start zones of Pinnacle through Escape Hatch in Huntington and Left Gully and Hillman’s Highway in Tuckerman. Be aware that in our terrain, lower angled slopes often have several start zones above. Depending on what the weather does today, we may see these wind slabs become saturated with rain, turning into Wet Slab. With such a degree of uncertainty in the weather forecast today, it is imperative to keep an eye on the ground and to the sky, continually evaluating the snowpack.

WEATHER: Yesterday started with clear skies and calm NW winds. Through the day, winds shifted to the E and picked up in intensity while clouds slowly built. Snow began around midnight with steady E 60mph winds. Temperatures bottomed out at 12F and are rising with a current temperature of 20 on the Summit. Expect temperatures to continue rising, possibly reaching the 30sF during the day. Current E 80mph winds should decrease gradually through the day. Precipitation will fall all day; as to what form it will take up is in the air. Most scenarios are showing snow for the morning, transitioning to sleet and freezing rain midday with possible rain, and then returning to snow at the end of the day. Tonight, temperatures will move into the 20sF, winds will shift to the NW and increase, and snow/sleet will continue.

SNOWPACK: Warmer temperatures from January 20 through the morning of January 23 allowed the top ~30cm of our snowpack to develop a melt freeze layer. Snow below remained cold and dry. Conditions yesterday allowed a thin crust to form, but not one supportive to body weight. Three inches of snow fell overnight. Strong east winds are transporting this snow and cross-loading slopes with a northern and southern aspects. With rising temperatures, precipitation will become denser. Wet snow and maybe freezing rain falling on top of this slab will further the idea of an upside-down snowpack, possibly creating wet slabs. Whiteout conditions through the day will make tough visibility, a key component of traveling safe on a day like today. Winds shifting to the NW tonight may further load slopes, especially those with an easterly or southern aspect. Dangerous avalanche conditions exist today. Constant evaluation of what the weather is actually doing combined with keeping your hands in the snow will help make good decisions on a day like today.

The Lion Head Winter Route is open and the most direct route to the summit from the east side of the mountain. Please be on the lookout for machine traffic on the Sherburne.

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., Tuesday, January 24, 2017. A new advisory will be issued tomorrow.

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

2017-01-24

Avalanche Advisory for Monday, January 23, 2016

This advisory expires at midnight.

Huntington and Tuckerman Ravine have LOW avalanche danger. Natural and human-triggered avalanches are unlikely. In Tuckerman Ravine, Little Headwall and Lower Snowfields are not forecast due to thin snow cover.

AVALANCHE PROBLEM: Water in the snowpack appears to be refrozen at most elevations and aspects on the mountain. As a result of this refreeze, the probability of Loose-Wet and Wet Slab avalanches will continue to decrease. One factor that is hard to pin down is the cloud cover forecast. On sunny aspects, the refreeze may slow or even reverse; be vigilant about snowpack evaluation as you venture onto steeper sunny slopes later today. No evidence of wet slab avalanches exist from yesterday which points to a generally settled and well-bonded snowpack, but wet-loose debris points to the continued need for terrain and sluff management. As the breakable crust thickens, expect travel conditions to be challenging due to postholing .

WEATHER: Yesterday’s warm front lingered around the area for most of the day. High pressure finally moved in this morning just before dawn, shifting winds to the NE and allowing temperatures to drop from the mid to high 20sF into the teens. This high pressure and an inversion will keep summit skies clear for part of the morning before a coastal low pressure system arrives. Clouds may develop this morning with summits possibly becoming clouded by the afternoon. Temperatures should remain in the teens through the day with winds shifting to the east and increasing to 40mph by the end of the day. We may see snowflakes in the air today, but the meat of the approaching storm will begin overnight. We likely will have a few inches on the ground by sunrise tomorrow.

SNOWPACK: After about 80 hours with temperatures staying above 20F on the summit and at times rising above freezing, we are seeing a return of colder air. This extended period of near freezing temperatures combined with periods of calm winds and clear skies allowed our snowpack to warm and about the top 30cm of snow to become wet. As this wet snow freezes, expect the current surface crust layer to become thicker and more supportive. Be particularly aware of sluff and terrain management on sunny aspects if skies stay clear as the day progresses. As the freezing process takes place, this will become a shin scraping crust and eventually a supportive surface, though this may not happen until after dark if temperatures stay in in the high teens and low 20sF as forecast.

The Lion Head Winter Route is open and the most direct route to the summit from the east side of the mountain. Please be on the lookout for machine traffic on the Sherburne.

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., Monday, January 23, 2017. A new advisory will be issued tomorrow.

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

2017-01-23