Avalanche Advisory for Wednesday, February 14, 2018

Huntington and Tuckerman Ravines have LOW avalanche danger. Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.

AVALANCHE PROBLEM: The Ravines hold a predominantly hard refrozen snow surface. Today’s weather could allow some softening on south facing aspects but only for a brief window if at all. Cloud cover will likely keep solar heating and softening of surface snow to a minimum. Therefore, we don’t expect wet loose sluff avalanches to be an issue today. Ice and rock fall could be an issue even with slight warming and should be on your radar as potential overhead hazards. That said, long sliding fall potential on our hard icy snow pack likely remains your greatest hazard. Rocks and other obstacles are exposed below many steep areas, particularly in Huntington Ravine.  Be sure that your crampon and ice axe skills are strong if choosing to climb steep snow slopes today.

 WEATHER: Following a calm, clear night temperatures are currently warmer on the summit than in valley locations with 16F on the summit, 23F at Hermit Lake, and 13F in Gorham. Aloft, southerly flow will continue today bringing clouds but only a trace of precipitation, if any falls at all. Summit level wind will be from the west today in the 50-70 mph range with good visibility at ground level under thickening high clouds. The temperature at the summit will warm to the mid-20s F with limited opportunities for sunshine in Cutler River drainage avalanche terrain.

SNOWPACK: Warming on Saturday and Sunday was followed by a solid refreeze since early Monday morning. Tuckerman and Huntington Ravines hold relatively smooth and hard snow that is difficult to kick a boot into, with only a few exceptions near rocks and vegetation. Sunny, south facing aspects saw minimal softening of the icy surface yesterday due to cool temperatures (20’sF at Hermit Lake). We expect similar conditions today as high clouds and wind will likely limit heating of solar aspects despite warmer air temperatures. The desperate may find a few reasonable turns among many icy ones, but going to the ski area or focusing on a climb may be a more enjoyable option. Take care to avoid a fall on any of our steep slopes. Even the highly skilled would have trouble arresting a sliding fall.

Winter weather, soft snow, and elevated avalanche danger will certainly return. Help ready yourself to come home safely from getting the goods by joining us at IME in North Conway this Saturday at 5:00 PM. This second event in the White Mountain Avalanche Education Foundation’s Continuing Education series will focus on appropriate, strategic use of stability tests and other snowpack observations. It’s free to attend!

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 7:40 a.m., Wednesday, February 14, 2018. 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

2018-2-14

Avalanche Advisory for Tuesday, February 13, 2018

Huntington Ravine and Tuckerman Ravines have LOW avalanche danger. Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.

AVALANCHE PROBLEM: The melt and subsequent refreeze of our surface snow in the past 3 days has dramatically increased stability in our snowpack. You’ll find a mixed bag of surface conditions from breakable crust to dense and supportable refrozen snow. Most if not all of our snow in steep terrain will easily allow a long sliding fall. Rocks, vegetation, and other hazards could be in the path of such a fall. Our terrain does have better snow coverage than late January, but it’s still thin. Be on your game with crampons, ice axe, and alpine travel skills if you’re hoping to climb steep snow today.

 WEATHER: A return to below freezing conditions yesterday was accompanied by strong westerly wind, summit clouds, and no precipitation. It’s currently clear and cold, around -7F on the summit and 8F at Hermit Lake. The summit should see temperatures approach 10F as NW wind decreases to 30 mph. Minimal cloud cover will continue throughout the day and no precipitation is forecast. Tomorrow should bring warming through the day with few clouds. Summit temperatures could approach 32F and we will likely see the mercury rise above freezing in our terrain.

SNOWPACK: Current conditions have changed dramatically since the period of natural avalanche activity late last week. The weekend warming and liquid precipitation have been followed by cold temperatures since early yesterday. Our layers of stability concern of several days ago have been generally penetrated by moisture and subsequently refrozen, lending much greater stability to the snowpack. If you venture into the Ravines today you will find variable refrozen snow conditions that will be breakable under your boots in some areas and supportable in others. It might not be the best day to make turns, but skilled climbers will likely enjoy the good visibility and firm snow conditions. Remember that a sliding fall in steep terrain today could result in serious injury or worse. Use caution to avoid such a fall and be constantly aware of the consequences of the terrain you choose.

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., Tuesday, February 13, 2018. A new advisory will be issued tomorrow.

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

2018-2-13

Avalanche Advisory for Monday, February 12, 2018

Huntington and Tuckerman Ravine will have LOW avalanche danger today. Generally safe avalanche conditions exist for all forecast areas.

AVALANCHE PROBLEM: The warm and moist conditions of the weekend are gone and the layers of instability are gaining strength. The crust forming on our snow surface, and your ease of travel on it, will vary through the terrain. You will probably find both supportable and breakable crust surface conditions. These variable conditions, which will include hard, refrozen snow, could allow a long sliding fall and will likely be a greater concern to you than avalanches. Crampons, ice axe, and your ability to use them effectively will be necessary tools above tree line. Microspikes are no substitution but will be a useful tool on hard packed trails at lower elevations.

WEATHER: The Summit of Mount Washington reached a high of 36F yesterday in the late evening with a trace of snow and a total water equivalent of 0.11”, largely coming in the form of freezing rain in the afternoon. As high pressure built in from the west overnight, temperatures began to plummet, with temperatures at 7am reading 9F at the Summit and the high teens at Hermit Lake. Wind speeds reached 80mph from the west at midnight, and will increase slightly to the century mark and shift to the NW today. Snow flurries may appear this morning, giving way to clearing skies as the day progresses.

SNOWPACK: Our upper snowpack is currently refreezing following the recent above freezing temperatures and wet precipitation. Around Hermit Lake, the crust forming is currently one inch thick and breakable. Prior to the warm conditions which began midday Saturday, our surface snow was a mix of soft and hard wind slab with scattered areas of exposed January melt-freeze crust. Stability concerns of these layers are becoming minimal with the refreeze. These varied surface conditions will reflect today in the form of a crust that will likely be breakable in previously soft areas and supportable in previously hard areas. Expect a mixed bag of travel techniques to be necessary. Long sliding falls should be on your mind today; consider breaking your rope for third and fourth class terrain. Realize that areas with a crust breakable under your boots might easily support the weight of a sliding human body.

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 7:20 a.m., Monday, February 12, 2018. A new advisory will be issued tomorrow.

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

2018-02-12

Avalanche Advisory for Sunday, February 11, 2018

Huntington Ravine has CONSIDERABLE and MODERATE avalanche danger. Central and Pinnacle gullies have Considerable avalanche danger. Dangerous avalanche conditions. Careful snowpack evaluation, cautious route finding, and conservative decision making are essential. All other forecast areas have Moderate avalanche danger. Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully to identify features of concern.

 Tuckerman Ravine has CONSIDERABLE and MODERATE avalanche danger. Sluice, Lip, Center Bowl, and Chute have Considerable avalanche danger. Dangerous avalanche conditions. Careful snowpack evaluation, cautious route finding, and conservative decision making are essential. All other forecast areas have Moderate avalanche danger. Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully to identify features of concern.  The Little Headwall is the exception with Low avalanche danger. Watch for unstable snow on isolated terrain features.

AVALANCHE PROBLEM: Existing wind slabs formed late last week will be stressed by added moisture and warmth from our current weather and are becoming wet slabs. By either name, these relatively soft slabs that a human could likely trigger should lose stability through the day. Areas of greatest concern due to size of soft slabs on the surface are the Headwall area in Tuckerman and Central and Pinnacle Gullies in Huntington. Realize that moderate rated areas likely hold this same slab that while smaller could still produce an avalanche capable of burying you. Wet loose sluffs that you could initiate in steep, soft snow that is less cohesive are also a significant concern. The risk of travelling on or below avalanche terrain might not be worth the reward on a damp day like today.

 WEATHER: It’s become warm and wet, but we shouldn’t see enough warm precipitation to drastically alter snow coverage. Yesterday and last night saw predominantly above freezing temperatures in our terrain with a few inches of moist new snow and mixed precipitation totaling 0.25-0.5 inches of liquid water (SWE). Today will be slightly warmer, remaining above freezing at Hermit Lake and possibly exceeding 32F on the summit as well. Mixed precipitation today should total less than 0.25 inches of liquid water (SWE). Tomorrow will be colder with no forecast precipitation, forming a crust of our currently moist snow surface.

SNOWPACK: A series of storms with wind over the past week allowed significant new wind slabs to develop and produce natural avalanches. Our snow surface which is becoming increasingly moist varies from soft to hard slab, with the melt/freeze crust formed mid-January exposed in small wind-scoured areas. The primary stability concern today is the weakening of our softer surface snow by moisture and warm temperatures. Considerable rated areas which have generally more cohesive slabs could produce large avalanches, and you could easily initiate a significant loose wet sluff in steeper snow that is less cohesive. We don’t expect human triggered avalanches to be likely in areas with firmer surface slabs, though our upper snowpack will generally lose strength until a refreeze occurs late tonight or 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 Harvard Cabin.
• Posted 8:15 a.m., Sunday, February 11, 2018. A new advisory will be issued tomorrow.

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

2018-2-11

Avalanche Advisory for Saturday, February 10, 2018

Huntington Ravine has CONSIDERABLE avalanche danger. All forecast areas have Considerable avalanche danger. Careful snowpack and weather evaluation and cautious route-finding are essential.

Tuckerman Ravine has HIGH and CONSIDERABLE avalanche danger. Chute and Center Bowl have High avalanche danger. Travel in the floor of the Ravine is not recommended. All other forecast areas have Considerable avalanche danger. Careful snowpack and weather evaluation and cautious route-finding are essential. Little Headwall has Low avalanche danger.

AVALANCHE PROBLEM: The new and reactive wind slabs developing today will contribute to existing avalanche problems by adding stress to the older wind slab. Prime conditions for wind slab development on Wednesday and Thursday spawned a large natural avalanche that ran to the mouth of Tuckerman Ravine in the early afternoon Thursday, with another crown observed left of the Harvard Bulge in the snowfield to the right of the Fan in Huntington. Many other areas did not avalanche during that cycle and still contain the weak layer and slab above. Today, new snow, wind slabs and natural releases of dry loose snow will strain the snowpack and the weak layer beneath. High rated areas hold the greatest potential for a large avalanche due to the thicker wind slabs in place before today’s snowfall. Considerable rated areas hold similar concerns, though avalanches in these areas are likely to be a bit smaller or less likely to fail naturally due terrain configuration or a lower angle. No matter the rating, you’ll need to bring your A game to this tournament if you want to make it to the next round.

WEATHER: Harvard Cabin recorded 2” (5.5cm) of new snow at 6:30am with around 4” recorded on the summit. Snow will continue today and bring another 2-4” new snow to higher terrain. Wind from the WSW is currently in the 50-60 mph range on the summit with higher gusts. These wind speeds will move enough snow to create reactive and soft wind slabs. New snow and fog will reduce visibility on and off through the day. Today’s weather pattern is remarkably similar to Wednesday when lots of natural dry loose avalanches and one skier triggered wind slab occurred.  Summit temperatures will rise to 25F from the low 24 hours ago of -9F. Hermit Lake was 24F at 6:30am.

SNOWPACK: Warming temperatures will be another red flag on display today. The deeper instabilities, mentioned above, that create our greatest risk for a large avalanche will be subjected to warm temperatures for the first time since their development. Weak, poorly bonded snow that fell Wednesday on pre-existing firm slabs led to the large avalanche in Tuckerman Ravine. This was evident by the lack of ice crust visible at the bed surface, though a few areas of slab stepped down to that layer. Lots of wind slab was observed in our terrain yesterday with large smooth pillows in the Fan in Huntington and very large smooth wind slabs in the Chute. The upper portions of Right Gully, Sluice and Hillman’s Highway have grown in expanse and Lobster Claw is continuous and wider now with an ugly terrain trap at its bottom. To make a long story short, winter is showing up again today and brought a dynamic snowpack with it. Today is a good day to keep it well on the conservative side of the line.

The Sherburne Ski Trail is a great alternative to skiing in avalanche terrain 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 Harvard Cabin.
• Posted 8:10 a.m., Saturday, February 10, 2018. 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

2018-2-10

Avalanche Advisory for Friday, February 9, 2018

This advisory expires at Midnight.

Huntington Ravine will have CONSIDERABLE, MODERATE, and LOW avalanche danger. Central Gully has Considerable avalanche danger. Travel in avalanche terrain is not recommended. Yale, Pinnacle, Odell, South, and Escape Hatch have Moderate avalanche danger. Evaluate snow and terrain carefully. North and Damnation have Low avalanche danger. Watch for unstable snow on isolated terrain features.

Tuckerman Ravine will have CONSIDERABLE, MODERATE, and LOW avalanche danger. Sluice, Center Bowl and Chute have Considerable avalanche danger. Travel in avalanche terrain is not recommended.  The Lip, Left Gully, Hillman’s Highway, and Lower Snowfields have Moderate avalanche danger. Evaluate snow and terrain carefully. Lobster Claw, Right Gully, and the Little Headwall have Low avalanche danger. Watch for unstable snow on isolated terrain features.

AVALANCHE PROBLEM: Today’s avalanche problem is wind slab. This developed Wednesday night into Thursday and has naturally released in a few steep, wind loaded areas. Continued cold weather today will not improve stability. Areas of the greatest concern are larger wind loading slopes in the lee of W and WNW wind, such as Central Gully, the Sluice and Chute, places that received significant loading but have not avalanched. Avalanche activity yesterday below the ice in the Lip to the Center Bowl and the area beneath Harvard Bulge and Yale failed on the interface between old wind slab or ice crust and the new snow. This natural activity should serve as a red flag for areas that still contain areas of wind slab and no signs of avalanche activity. Evaluate snow carefully before you commit to a slope.

WEATHER: A total of 10” of snow arrived over the past 48 hours. This snow began to fall on relatively light southerly winds and ended as the wind shifted to the NW and increased to 80mph. Currently, it is -8.5F on the summit with a W wind of 38 mph. Today, the temperature should remain below zero for the day and begin to rise as darkness sets in. Wind will shift to the SW and increase to 60mph before decreasing late in the day. Clouds will linger with periods of clearing, possibly delivering up to an inch of snow in the afternoon.

SNOWPACK: Wind slab that formed Wednesday night into Thursday is the dominant snow surface in avalanche terrain. The bottom of this layer is soft (fist hardness) snow and then increases in hardness to finger to pencil hard at the surface. Northwest winds of 70 mph Thursday morning left mostly firm old snow in the northern gullies of both ravines that will provide good climbing. Areas in the lee of W and WNW winds, such as Central Gully, and Sluice through Chute saw more significant loading, leaving a smooth or pillowed surface in places that did not avalanche. Routes like Yale and Hillman’s, while not receiving the most loading, contain areas of wind slab that will need to be carefully negotiated. Natural activity occurred yesterday, notably in the Fan of Huntington below Harvard Bulge and across the Lip and Center Bowl of Tuckerman. These failures occurred at the interface of the wind slab and old snow. The large avalanche in Tuckerman did step down into old snow, leaving the melt/freeze crust from mid-January exposed in places lower in the Bowl and in the Lip.

 

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 8:30 a.m., Friday, February 9, 2018. 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

2018-02-09

Avalanche Advisory for Wednesday, January 31, 2018

Huntington Ravine has LOW avalanche danger. All forecast areas have Low avalanche danger. Watch for unstable snow on isolated terrain features.

Tuckerman Ravine has LOW avalanche danger. All forecast areas have Low avalanche danger. Watch for unstable snow on isolated terrain features. The Little Headwall is not rated due to a lack of snow.  The Lip still contains a large void in the snowpack from the wet avalanche on January 12 or 13.

AVALANCHE PROBLEM: A firm and icy snowpack with some areas of mostly stubborn wind slab mark our terrain. These wind slabs are unlikely to produce an avalanche but are worth evaluating for signs of a weak bond to snow beneath and a tendency to sustain a crack along the surface. The wind slabs in question are easily visible and identified by contrast to the gray and dirtier looking, refrozen snow. You may find these slabs beneath steep pitches of ice and in other wind sheltered locations.

WEATHER: The temperature at Hermit Lake this morning is -2F and -10F on the summit with a NW wind in the low 60’s mph and gusting to 70 mph. Temps on the summit will warm to around 10F by nightfall as winds shift to the southwest. Wind speeds will diminish through mid-day before ramping up again as southwest flow brings clouds and light snow. Snow will start late in the day so is unlikely to create avalanche concerns though visibility may be reduced by snowfall and flat light. Scattered snow showers or light snow will continue through tomorrow and may refresh the snow coffers at higher elevations with up to 4-6” new snow by Friday morning. West winds combined with the new snow may create some unstable wind slabs tomorrow and Friday.

SNOWPACK: The dominant feature of the snowpack remains the widespread knife hard, ice glazed surface. Crampons are necessary to climb beyond low angle terrain due to this slick, hard surface. Stability tests and travel in Left Gully to the choke, about ¾ of the way up, last weekend showed that the older wind slab was well bonded to this icy surface. Nearer the surface, firmer (1F) wind slab over the thicker 4F slab created a clean shear at the interface between these two layers but neither layer showed any desire to propagate a crack much beyond your feet. No avalanche activity has been reported in these wind slabs. Elsewhere, the firm snow provides for quick and efficient cramponing but is an unforgivingly fast surface if you stumble so stay vigilant!

Microspikes and crampons are key tools for travel today. Crampons are needed on the steeper slopes and above treeline. Conditions on the Sherburne Ski Trail remain grim though passable for those desperate for a lap. Seems like the folks running to and from Hermit Lake and the summit yesterday had the right idea.

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 7:30 a.m., Wednesday, January 31, 2018. 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

2018-01-31

Avalanche Advisory for Tuesday, January 30, 2018

Huntington Ravine has LOW avalanche danger. All forecast areas have Low avalanche danger. Watch for unstable snow on isolated terrain features.

Tuckerman Ravine has LOW avalanche danger. All forecast areas have Low avalanche danger. Watch for unstable snow on isolated terrain features. The Little Headwall is not rated due to a lack of snow.  The Lip still contains a large void in the snowpack from the wet avalanche on January 12 or 13.

AVALANCHE PROBLEM: A firm and icy snowpack with some areas of wind slab summarize our terrain right now.  The wind slabs that are out there are unlikely to produce an avalanche but are worth evaluating for signs of a weak bond to snow beneath or a tendency to sustain a crack along the surface. These wind slabs are easily visible and identified by contrast to the gray and dirtier looking, refrozen snow.

WEATHER: A fairly benign day is in store for the mountains.  High temperatures on the summits will be in the single digits with a steady northerly wind.   Some light snow may come through tonight with a better chance on Wednesday night, which may bring a couple of inches of replenishment.  While we can rejoice at the forecast of colder air at the onset of the weekend, significant snows are not looking to turn this icy rock around anytime soon.

SNOWPACK: The Ravines are dominated by a very hard icy surface with sporadically distributed wind slabs discussed in above.  These wind slabs have not proven to be very reactive during our stability tests   which generally showed that the wind slab was well bonded to this icy surface. Nearer the surface, firmer (1F) wind slab over the thicker 4F slab created a clean shear at the interface between these two layers but neither layer showed any desire to propagate a crack much beyond your feet. Snow and ice climbs are in great shape now and today’s calm weather and good visibility provide a good opportunity to enjoy them.  The firm snow allow for efficient cramponing but self-arrest must occur immediately if you slip, otherwise a long sliding fall will likely ensue.

Microspikes and crampons are key tools for travel today. Crampons are needed on the steeper slopes and above treeline. Conditions on the Sherburne Ski Trail remain grim though passable for those desperate for a lap.

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 6:15 a.m., Tuesday, January 30, 2018. A new advisory will be issued tomorrow.

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

2018_01_30

Avalanche Advisory for Monday, January 29, 2018

Huntington Ravine has LOW avalanche danger. All forecast areas have Low avalanche danger. Watch for unstable snow on isolated terrain features.

Tuckerman Ravine has LOW avalanche danger. All forecast areas have Low avalanche danger. Watch for unstable snow on isolated terrain features. Little Headwall has not refrozen completely and is far from filled in with snow so is not rated. The Lip still contains a large void in the snowpack from the wet avalanche on January 12 or 13.

AVALANCHE PROBLEM: A firm and icy snowpack with some areas of mostly stubborn wind slab mark our terrain. These wind slabs are unlikely to produce an avalanche but are worth evaluating for signs of a weak bond to snow beneath or a tendency to sustain a crack along the surface. The wind slabs in question are easily visible and identified by contrast to the gray and dirtier looking, refrozen snow.

WEATHER: It’s 15F at Hermit Lake this morning with calm winds, a few clouds and no precipitation recorded since January 24. Today, the summit will see partly cloudy conditions with a high of 13F and light winds in the 20-35 mph range. Summit fog is clearing this morning but high clouds will move in later today. Temperature and winds will remain mild and relatively calm today through Wednesday before shifting southwest as a bit of moisture arrives on Thursday. A better chance of more significant snowfall comes on Sunday.

SNOWPACK: The dominant feature of the snowpack in Tuckerman Ravine yesterday, in addition to the yard sale of refrigerator-sized blocks of ice from the wet avalanche, was the knife hard, ice glazed surface. Crampons were necessary to climb beyond the floor of Tuckerman Ravine due to this slick and hard surface with similar conditions in Huntington. Stability tests and travel in Left Gully to the choke, about ¾ of the way up, on Saturday showed that the older wind slab was well bonded to this icy surface. Nearer the surface, firmer (1F) wind slab over the thicker 4F slab created a clean shear at the interface between these two layers but neither layer showed any desire to propagate a crack much beyond your feet. Snow and ice climbs are in great shape now and looks as if we have a few days of calm weather and good visibility to enjoy them. The firm snow provides for quick and efficient cramponing but is an unforgivingly fast surface if you stumble so stay vigilant!

Microspikes and crampons are key tools for travel today. Crampons are needed on the steeper slopes and above treeline. Conditions on the Sherburne Ski Trail remain grim though passable for those desperate for a lap. Seems like the folks running to and from Hermit Lake and the summit yesterday had the right idea.

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 8:00 a.m., Monday, January 29, 2018. 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

2018-01-29

Avalanche Advisory for January 28, 2018

Huntington Ravine has MODERATE and LOW avalanche danger. Central Gully may rise to Moderate avalanche danger. Evaluate snow and terrain carefully. All other forecast areas have Low avalanche danger. Watch for unstable snow on isolated terrain features.

Tuckerman Ravine has MODERATE and LOW avalanche danger. All forecast areas may rise to Moderate avalanche danger today. Evaluate snow and terrain carefully. The exceptions to this rating are Lobster Claw, Right Gully and Lower Snowfields which have Low avalanche danger.  Watch for unstable snow on isolated terrain features there. Little Headwall has not refrozen completely and is far from filled in with snow. The Lip still contains a large void in the snowpack from the recent wet avalanche.

AVALANCHE PROBLEM: New wind slab may develop today if the mountain receives the upper end of forecast snowfall of a trace to two inches. The new snow could add stress to the scattered wind slabs that already exist in the terrain due to the inch or so that fell last night in higher terrain and blew into our forecast zones. Wind slabs scattered through these lee, sheltered areas may become sensitive to human triggering if the new snow forms more slabs on them. Yesterday, wind slabs showed no tendency to propagate a crack but additional snow load on top could make them more susceptible to human triggers. Evaluate snow carefully as you find your way through the terrain today.

WEATHER: Summit temperatures peaked at 28F late afternoon yesterday ahead of the passing cold front and have been steadily dropping. Current temperature on the summit is 21F and 30F at Hermit Lake. Expect temperatures to continue to decrease today with the summit reaching around 10F. West winds of 50 to 70 mph will moderate to 35 to 50 mph. Between lingering upslope snow showers and a secondary front passing this afternoon a trace to 2 inches of snow is possible.

SNOWPACK: The dominant feature of the snowpack in Tuckerman Ravine yesterday was the bullet hard, ice glazed surface. Crampons were necessary to climb beyond the floor of Tuckerman Ravine due to this slick and hard surface conditions with similar conditions reported in Huntington. Stability tests and travel in Left Gully to the choke showed that the older wind slab was well bonded to this icy surface. Nearer the surface, firmer (1F) wind slab over the thicker 4F slab created a clean shear at the interface between these two layers but neither layer showed any desire to propagate a crack much beyond your feet. These layers seemed to behave like the typical slabs that form here when legendary high winds and cold temperatures punish snow grains until they become complacent, lifeless rounds. Snow and ice climbing conditions have been stellar though today’s new snow may complicate route-finding.

Sharp edges, speed control and a willingness to sacrifice some P-tex to the snow gods is required to ski or ride the Sherburne Ski Trail today. Microspikes and crampons are key tools for travel 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 Harvard Cabin.
• Posted 7:50 a.m., Sunday, January 28, 2018. 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

2018-01-28