Avalanche Advisory for Saturday, January 27, 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 MODERATE and LOW avalanche danger. Sluice, Lip, Center Bowl, Chute and Left Gully have Moderate avalanche danger. Heightened avalanche conditions exist on specific terrain features. Evaluate snow and terrain carefully. All other forecast areas have Low avalanche danger. Watch for unstable snow on isolated terrain features.  The Little Headwall is mostly open water or waterfall ice and not rated.

AVALANCHE PROBLEM: Lingering wind slabs are the primary avalanche problem today. These slabs are poorly bonded to the icy, rock hard snowpack though are limited in size and distribution. Today, these areas of wind slab will warm for the first time and likely become more sensitive to human triggers as they weaken. Ultimately the heating will bring some stability to these slabs but not before passing through a period of less stability. Evaluate snow for signs of instability and bonding to bed surface, especially since even a small avalanche or fall can have serious consequences on our icy slopes. Larger areas of wind slab have a moderate rating due to the possibility of a human-triggered avalanche.

WEATHER:  A warming trend began last night with southwest flow and warming temperatures. After two days of below zero temperatures, the summit has reached 23F and will warm to the upper 20’s today before a cold front brings moisture to the area. It’s likely that our forecast area will see a mix of wet snow and rain. Less than an inch of snow and a tenth of an inch of rain will fall starting around dark. Temperatures will fall tonight with upslope snowfall continuing through the day tomorrow. WSW winds today will blow in the 40 mph range today, slowly ramping up through the day.

SNOWPACK:  December brought over 8’ of snow to the summit, but two warm rain events have reduced the snowpack to a mostly solid frozen mass with drainage channels in the surface, glide cracks and a slick icy surface. During field observations Wednesday, much of the snowpack was found to be a hard, refrozen snow from previous rain events, but with many pockets of wind slab varying in size and depth scattered around. These slabs were firm (finger to pencil) and poorly bonded to the ice crust below failing on a weak layer of snow (four finger) at the bed surface. It’s likely that the continued cold temperatures since that time only weakened this bond to the icy crust. Limited settlement may have occurred yesterday on aspects with strong solar gain but not enough to feel confident that human-triggered avalanches are now unlikely. The old gray, icy surface remains a safer place to evaluate the new snow as long as you’re wearing crampons, carrying an ice axe and moving carefully in the terrain.

The large wet avalanche in the Lip is slowly starting to fill in, but the hole in the snowpack and 20’ crown face is far from gone.  Skiing has been better this year for sure, but snow and ice climbs are in great shape. The Sherburne Ski Trail is a refrozen mess and best left for the most hardy and desperate of skiers.

Please Remember:
• Safe travel in avalanche terrain requires training and experience. This bulletin 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., Saturday, January 27, 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

2018-1-27

Avalanche Advisory for Friday, January 26, 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 MODERATE and LOW avalanche danger. Sluice, Lip, Center Bowl, Chute and Left Gully have Moderate avalanche danger. Heightened avalanche conditions exist on specific terrain features. Evaluate snow and terrain carefully. All other forecast areas have Low avalanche danger. Watch for unstable snow on isolated terrain features.  The Little Headwall is mostly open water or waterfall ice and not rated.

AVALANCHE PROBLEM: The mountain received 2.5” of snow at the tail end of Tuesday’s low pressure system followed by strong winds from the west then north-west. Wind velocity was strong enough to scour the Alpine Garden above the ravines and deposit wind slab in our areas of concern. By and large, in good visibility, these wind slabs should not be difficult to avoid. In steep narrow gullies where route options are limited, venturing onto and triggering one of these slabs could result in a very nasty sliding fall on the icy bed surface. In the upper reaches of Left Gully and Chute, wind slab stretches wall to wall with no real option to avoid them. These wind slabs were poorly bonded to the ice crust beneath and sheared cleanly and easily. Be aware that low rated areas in our terrain may also be harboring these problematic wind slabs, though smaller in size with more options to avoid them altogether.

WEATHER:  Clear, cold and windy to start the day, with both temperature and wind hopefully moderating in the afternoon as the high pressure crests.  Current temperature at Hermit Lake is 3F and -9F on the summit.   Current summit wind is 62 mph from the NW.  Skies should remain clear for the forecast period with winds shifting west and diminishing to 20-35 mph by sunset. Summit temperatures will rise to the low teens.

SNOWPACK:  We had a great start to the season, but two warm rain events have reduced the snowpack to a mostly solid frozen mass. During field observations yesterday, it was clear that much of the snowpack is hard, refrozen snow from previous rain events, however there are many pockets of wind slab varying in size and depth scattered around. We found these slabs to be firm (finger to pencil) and poorly bonded to the ice crust below failing on a weak layer of snow (four finger) at the bed surface. It’s likely that cold temperatures overnight only weakened this bond to the icy crust.

The large wet avalanche in the Lip is slowly starting to fill in, but the hole in the snowpack and 20’ crown face is far from gone.  Skiing has been better this year for sure, but snow and ice climbs are in great shape. The Sherburne Ski Trail is a refrozen mess and best left for the most hardy and desperate of skiers.

Please Remember:
• Safe travel in avalanche terrain requires training and experience. This bulletin 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 7:15 a.m., Friday, January 26, 2018. A new advisory will be issued tomorrow.

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

2018-1-26

Avalanche Advisory for Thursday, January 25, 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 MODERATE and LOW avalanche danger. Lip, Center Bowl, Chute and Left Gully have Moderate avalanche danger. Heightened avalanche conditions exist on specific terrain features. Evaluate snow and terrain carefully. All other forecast areas have Low avalanche danger. Watch for unstable snow on isolated terrain features.  The Little Headwall is mostly open water or waterfall ice and not rated.

AVALANCHE PROBLEM: Lingering wind slabs will be the primary avalanche problem today. Areas of mostly firm but potentially unstable wind slab exist in steep, lee terrain sheltered by recent NW winds. These slabs are on the smaller side but the consequences of an avalanche on our slick bed surface could be severe. Evaluate the snow carefully. Most of the terrain consists of a hard, gray old surface of refrozen, rain saturated snow. This is especially true in low rated zones where most of the 2.5” of snow which fell in the past 48 hours was scoured off of the terrain by high winds. Still, areas with a low rating may contain pockets of wind slab on isolated terrain features so assess these slabs for signs of instability or avoid them altogether. In Tuckerman Ravine, the run in the headwall known as The Lip contains an unusually nasty fall potential due to the 20’ crown face in the middle of the run. The affected area is in the fall line of the Tuckerman Ravine Trail making the consequences of a fall on this slope particularly dangerous. The refrozen and hard nature of the existing snowpack makes crampons, ice axe and microspikes useful, if not required, to safely climb any route that takes you above treeline.

WEATHER: Currently, the temperature at Hermit Lake is 3F and -6F on the summit with winds from the NW at 60 mph. Cold, dry conditions will persist today with below normal temperatures around -10F on the summit and NW wind increasing from 50-70 mph to the 65-85 mph range. Gusts could reach 100 mph. About an inch of snow was recorded early yesterday morning bringing the total snowfall recorded since the most recent rain to 2.5”. The next opportunity for snow appears to be Sunday when a low pressure system moves up the coast. Until then, count on dry but warming weather on Friday and Saturday.

SNOWPACK: Two warm spells with copious amounts of rain this month have turned our deeper snowpack into a rock hard mass. The large wet avalanche that blew out the waterfall in the Lip area is reforming ice but remains mostly unchanged with a large debris pile filling the floor of the Bowl. Snow and ice climbs in Huntington are in fine shape with plenty of water around to form new ice.

The Sherburne Ski Trail is rideable but barely concealed rocks and other rain damaged sections exist.

Please Remember:
• Safe travel in avalanche terrain requires training and experience. This bulletin 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 7:45 a.m., Thursday, January 25, 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

2018-1-25

 

Avalanche Advisory for Wednesday, January 24, 2018

Huntington Ravine has MODERATE and LOW avalanche danger. Central Gully has Moderate avalanche danger. Heightened avalanche conditions exist on specific terrain features. 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. Sluice, Lip, Center Bowl, and Chute have Moderate avalanche danger. Heightened avalanche conditions exist on specific terrain features. Evaluate snow and terrain carefully. Lobster Claw, Right and Left Gully, Hillman’s Highway and Lower Snowfields have Low avalanche danger.  The Little Headwall is mostly open water or waterfall ice and not rated.

AVALANCHE PROBLEM: Areas of wind slab exist in Moderate rated forecast zones. Though small, these slabs are likely to be unstable enough to be triggered by a person traveling on them. Due to the small amount of snow which fell overnight, the size and distribution of these slabs is limited. Low rated areas contain isolated areas of wind slab and will likely receive more scouring and less deposition of new snow. Continued snow shower activity early today may contribute more snow to areas of instability. All of our terrain contains an abundance of stout, icy rain crust which creates a dangerous slide-for-life hazard. Unfortunately, avoiding the wind slabs puts you onto this hard crust. The most imminent threat that will remain constant for the next few days is the icy crust and the potential for a long sliding fall into rocks, stout bushes and holes melted into the snowpack. The Lip contains an unusually nasty fall potential due to the 20’ crown face in the middle of the run and in the fall line of the Tuckerman Ravine Trail.

  

WEATHER: 2 cm of new snow was recorded at Hermit Lake in the past 24 hours with about 2″ on the summit. Cold air is rushing into the area and replacing the warm moist air with a strong NW wind in the 60-80 mph range. The temperature on the summit has already fallen to 9F and will continue to fall through the day, reaching down to around 0F by dark. Sustained winds in the 70’s mph will also continue through the day and night with gusts to 95 mph. Summit fog will linger today but should clear overnight as the drier air mass takes hold. Anticipate temperatures down to -10F tonight and remain there tomorrow.

 

SNOWPACK: Another disappointing shot of snow fell in the terrain and failed to cover the icy surface that dominates the terrain following two June-uary thaws. The Alpine Garden and Bigelow Lawn which make up the typical fetch for our terrain have lost a lot of snow. Boulders fields and bushes have a way of holding onto the small snowfall events which can sometimes produce thick wind slabs in our terrain. Anticipate continued icy travel conditions with some drifted snow thrown in to make for engaging hiking and approaches to climbs. Microspikes, crampons and ice axes are all useful now given the firm and icy snowpack.

Please Remember:
• Safe travel in avalanche terrain requires training and experience. This bulletin 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, January 24, 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

2018-1-24

 

Avalanche Advisory for Tuesday, January 23, 2018

Huntington Ravine has LOW avalanche danger. Watch for unstable snow on isolated terrain features.

 Tuckerman Ravine has MODERATE and LOW avalanche danger. The Lip has Moderate avalanche danger. Evaluate snow and terrain carefully to identify features of concern. All other forecast areas have Low avalanche danger. Watch for unstable snow on isolated terrain features.  The Little Headwall is mostly open water or frozen waterfall ice and is not rated.

Due to the open waterfall hole and a 20’ high avalanche crown line, the Tuckerman Ravine Trail is closed in the Ravine between Lunch Rocks and the Alpine Garden Trail. Please use the Winter Lion Head Route if going to the summit from Pinkham Notch. Other routes to the summit from the east side are more significant mountaineering challenges.

 AVALANCHE PROBLEM: The relatively small wind slabs built since late last week will become wet slabs as significant rainfall occurs today. Remember that triggering a small avalanche in consequential terrain can still have dire consequences. That said, natural and human triggered avalanches are unlikely today. The exception to these small slabs is “hang fire” in the area of the large avalanche crown in the Lip. Your primary concern in this location should be moisture and warm temperatures today that will decrease stability in the unsupported snow above the crown, which is currently a vertical wall of snow up to 20’ in height. Cautious travelers will avoid terrain under the Lip today for the high consequence of a large though unlikely avalanche from above this crown line.

 WEATHER: Up to 1” of new snow fell in our terrain overnight before warmer temperatures brought a change to wetter precipitation early this morning. It’s already above freezing at both Hermit Lake and the Summit. Summit temperature is forecast to hit the mid-30’s F today and not drop below freezing until after dark. By tonight rainfall will likely total approximately 1”. Moderate SW wind will shift W and increase late tonight as precipitation shifts back to snow. 2-4” of new snow is expected late tonight and early tomorrow morning and will taper off with decreasing cloud cover forecast for tomorrow as temperatures remain below freezing.

SNOWPACK: Small snowfall totals and the scouring and drifting effect of wind over the past week has left us with isolated pockets of wind slab over an exposed or thinly veiled crust. This crust formed over a week ago and is thick and very firm. The slide for life nature of a fall on this firm surface will decrease through the day as rain and above freezing temperatures soften surface snow, though a long sliding fall will likely remain possible. The unique hazard of concern today is an unlikely though potentially large avalanche from unsupported snow above the crown line of the massive wet snow avalanche out of the Lip that occurred last week. Rain and above freezing temperatures will weaken the previously frozen snow and a large avalanche could occur in this location. Spending time in the fall line of the Lip is not advisable for this reason.

Please Remember:
• Safe travel in avalanche terrain requires training and experience. This bulletin 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., Tuesday, January 23, 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

2018-1-23

Avalanche Advisory for Monday, January 22, 2018

Huntington and Tuckerman Ravines have LOW avalanche danger. Watch for unstable snow on isolated terrain features.  The Little Headwall is mostly open water or frozen waterfall ice.

Due to the open waterfall hole and a 20’ high avalanche crown line, the Tuckerman Ravine Trail is closed in the Ravine between Lunch Rocks and the Alpine Garden Trail. Please use the Winter Lion Head Route if going to the summit from Pinkham. Other routes to the summit from the east side are significant mountaineering challenges.

 AVALANCHE PROBLEM: Winter weather is inbound though the small amount of snowfall forecast today has minimal potential to elevate our avalanche danger. More isolated pockets of wind slab may develop from new snow on moderate winds today and tonight remain our primary avalanche problem. Small in size, if triggered these slabs aren’t likely to bury you but could cause a long sliding fall on our largely rock hard snow surface. Until more significant accumulation of snow and mixed precipitation late tonight and into tomorrow, sliding falls above numerous hazards remain a primary concern for travelers in steep terrain.

 WEATHER: A relatively warm low pressure system is moving in from the west, though we’re unlikely to see more than an inch of new snow before dark today. Summit temperature should peak in the lower 20’s F and wind will be out of the SW in the 15-30 mph range. Precipitation is forecast to continue tonight and tomorrow, transitioning to a mix of sleet, freezing rain, and rain as summit temperature pushes towards the freezing point by Tuesday morning. The few inches of snow that will likely fall tonight should see some amount of transport by southwesterly wind before warmer temperatures and wetter precipitation limits the wind’s ability to move snow on the ground.

SNOWPACK: The precipitation forecast to begin as snow today and transition to a wintry mix or possibly rain by tomorrow will fall on a largely rock hard surface. We don’t expect sufficient snow during daylight hours today to warrant new stability concerns. Depending on timing of more significant snowfall tonight as well as the forecast changeover to wetter precipitation, we could see greater wind slab development around the time this advisory expires at midnight tonight. The robust surface crust limits our concern for deeper instabilities, with one exception. Snow above the crown line at the top of the massive wet snow avalanche out of the Lip late last week is unsupported and could become unstable with wet and warm conditions tomorrow. We don’t expect this to occur today, with below freezing forecast temperatures that should keep our existing snow very firm. Long sliding falls should remain a key concern for travelers in the alpine.

Please Remember:
• Safe travel in avalanche terrain requires training and experience. This bulletin 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., Monday, January 22, 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

2018-1-22

Avalanche Advisory for Sunday, January 21, 2018

Huntington and Tuckerman Ravines 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 mostly open water or frozen waterfall ice.

Due to the open waterfall hole and 20’ crown line, the Tuckerman Ravine Trail is closed in the Ravine between Lunch Rocks and the Alpine Garden Trail. Please use the Winter Lion Head Route if going to the summit from Pinkham. Other routes to the summit from the east side are significant mountaineering challenges.

 AVALANCHE PROBLEM: Isolated pockets of wind slab exist in our terrain, though much of the snow surface is very hard and refrozen following the warm-up that occurred late last week. This very hard, icy snow will likely be your primary travel concern today for its potential to allow a long sliding fall. If you did trigger a small wind slab avalanche, it could easily knock you off your feet and cause such a fall. Realize that even those who are highly skilled in steep snow climbing with crampons and ice axe would have little chance of effectively self-arresting to stop this kind of slide. Additionally, melt out of rocks, trees, stream beds, and other hazards in the fall line of steep terrain make a traumatic outcome of a long sliding fall likely.

 WEATHER: It’s currently 13F on the summit and 22F at the Hermit Lake snow plot with a trace of new snow that has fallen early this morning. Yesterday was partially cloudy in the alpine with peak westerly wind near 100 mph. Temperatures pushed over 20F on the summit and just exceeded the freezing point at Hermit Lake. Today should be similar in temperature and cloud cover though slightly less windy, with current NW wind near 70 mph decreasing through the day. Despite the few flakes currently falling at Hermit Lake, we won’t see measurable snowfall. Tomorrow is forecast to be a few degrees warmer with wintry though possibly mixed precipitation beginning roughly in the middle of the day.

SNOWPACK: As you might already know, very hard refrozen snow dominates our terrain. Scattered pockets of wind slab do exist and should be respected, but avalanches are probably a secondary concern to long sliding falls today. The several inches of rain and prolonged warm temperatures that ultimately resulted in this hard surface “crust” of several inches to a foot or more in thickness also produced a massive wet snow avalanche out of the Lip. The crown line at the top of where this avalanche pulled out is up to 20 feet tall and vertical. Warmer temperatures forecast early this coming week could allow instabilities to develop in the unsupported snow above the vertical wall of this crown, creating potential to significantly increase overhead hazard in an area that has been stable over the past week. We don’t expect temperatures to warm to this degree today, but rather keep much or all of our snow a cold, hard surface that necessitates a high level of caution and skill in steep terrain to avoid a slide for life kind of fall.

Please Remember:
• Safe travel in avalanche terrain requires training and experience. This bulletin 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., Sunday, January 21, 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

2018-1-21

Avalanche Advisory for Saturday, January 20, 2018

Huntington and Tuckerman Ravines 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 mostly open water or frozen waterfall ice.

Due to the open waterfall hole and 20’ crown line, the Tuckerman Ravine Trail is closed in the Ravine between Lunch Rocks and the Alpine Garden Trail. Please use the Winter Lion Head Route if going to the summit from Pinkham. Other routes to the summit from the east side are significant mountaineering routes.

 AVALANCHE PROBLEM: Very widely scattered areas of wind slab may be found in avalanche terrain today though the majority of our forecast area is scoured down to a hard icy crust. This icy surface, combined with strong winds, will present significant travel challenges today. This surface creates the opportunity for long, sliding falls which can end in a pile of rocks, melted holes in stream beds or trees if not arrested immediately. Our snowpack took a beating in last week’s rain storm and what’s left in its wake requires crampons and careful footing in steep terrain. Some snow showers this afternoon will not likely create significant avalanche problems though may challenge visibility a bit and further obscure refrozen footprints and other trip hazards.

 WEATHER: The current temperature on the summit is 23F with a west wind blowing at 82 mph. It is just below freezing at the Hermit Lake with no new snow on the board.  Two tenths of an inch of snow fell on the summit during snow showers early yesterday but otherwise the dry spell and warmup continues this morning.  Early this afternoon, a cold front swings through and drops the mercury to the mid-teens. A bit of mixed precipitation associated with the frontal passage may occur this morning, though the strong winds will be the most notable weather factor today. Anticipate west winds around 80 mph to continue through the day with gusts over 100 mph. Snow showers seem likely this afternoon as a secondary cold front passes with up to an inch falling by dark. The wind will moderate overnight with temperatures in the mid-teens and a decreasing west wind in the 50 mph range tomorrow.

SNOWPACK: At the Hermit Lake snow plot, there is 86 cm of hard, refrozen snow at the stake. A prolonged warming spell with rain late last week turned the upper portion of the snowpack into a knife hardness crust. That warmup ended with a period of freezing rain that glazed trees and snow surfaces at our elevation with ice which created little bonding opportunities for the several inches of snow which has fallen since. Most of that snow has been scoured out of our avalanche terrain and redeposited at lower elevations or in a few scattered and sheltered pockets. What didn’t blow out of the terrain already will be scoured out today as winds reach 100 mph. The blown out portion of the Lip below the Tuckerman Ravine Trail and the hard, refrozen debris pile remain visible in Tucks. Overall, surface conditions are hard and icy, making crampons, an ice axe and careful movement in steep terrain necessary.

Please Remember:
• Safe travel in avalanche terrain requires training and experience. This bulletin 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., Saturday, January 20, 2018. A new advisory will be issued tomorrow.

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

2018-1-20

Avalanche Advisory for Friday, January 19, 2018

Huntington and Tuckerman Ravines have LOW avalanche danger. Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features. The Little Headwall is an open stream and is not rated.

 AVALANCHE PROBLEM: New snow in the last 48 hours has been pushed around by wind, leaving isolated pockets of wind slab where scouring to the old refrozen surface did not occur. Small avalanches in isolated areas might not have the potential to bury a person in the absence of a terrain trap, but such an avalanche could easily cause a long sliding fall. The hard surface that is still prevalent in our terrain would be difficult for even the most skilled to arrest a fall.

Potential for and consequences of a long sliding fall may be a greater concern as you travel in our terrain today. Microspikes are no substitute for crampons and ice axe. Your ability to travel in a controlled manner on steep snow using crampons and ice axe is a necessity in current conditions. A high speed slide towards rocks, cliffs, or other exposed hazards can easily have dire consequences.

 WEATHER: Temperatures pushed into the 20’s F on the summit yesterday under partial clouds and wind in the 20-40 mph range. Today looks largely the same regarding temperature and cloud cover, with wind that will increase to around 40 mph late today. We might see a trace of new snow. Wind will increase tonight and tomorrow, ultimately approaching 100 mph. Air temperature should approach 30F on the summit tomorrow, though the extreme wind will make it feel much colder.

SNOWPACK: New snow earlier this week struggled to stick to the hard refrozen surface as it was transported by wind. Pockets of new wind slab do exist but are largely small and avoidable. If you’ve tried to dig in our snow lately, you’ve noticed that the hard surface snow is tough to penetrate with any tool. Instability will be limited to snow above this refrozen layer for the foreseeable future. We’ve said it already today and have all week, but we continue to stress the hardness of the refrozen snow surface. It provides good purchase for crampons but is smooth enough to easily accelerate a small fall to a slide for life in steep terrain. You would be hard pressed to arrest such a fall.

The John Sherburne Ski Trail holds similarly hard conditions under a thin veil of newer snow and will only provide an enjoyable ski option for the most desperate skiers and riders.

Please Remember:
• Safe travel in avalanche terrain requires training and experience. This bulletin 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 7:45 a.m., Friday, January 19, 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

2018-1-19

Avalanche Advisory for Thursday, January 18, 2018

Huntington Ravine has MODERATE avalanche danger. All forecast areas have Moderate avalanche danger. Heightened avalanche conditions exist on specific terrain features. Evaluate snow and terrain carefully.

Tuckerman Ravine has MODERATE and LOW avalanche danger. All forecast areas have Moderate avalanche danger. Heightened avalanche conditions exist on specific terrain features. Evaluate snow and terrain carefully. Lobster Claw, Right Gully and Lower Snowfields have Low avalanche danger. Watch for unstable snow on isolated terrain features like the top of Lobster Claw and the choke of Right Gully.  The Little Headwall is mostly open water or a frozen waterfall.

 

AVALANCHE PROBLEM: Wind slab may develop today when gusty winds blow available snow into avalanche terrain. Limited amounts of new snow in the past 48 hours, along with moderate winds should limit wind slab development but stay tuned in to what’s happening at the ridge tops. As of this writing, upper start zones are mostly old surface with new snow generally pushed down to midslope through wind action or sluffing. Human triggering of these wind slabs is possible today though the resulting avalanche would be on the smaller side. Of equal or greater concern to avalanche issues today is the slide-for-life conditions camouflaged by the thin blanket of new snow. Any stumble or fall is likely to have serious consequences in any steep terrain due to the hard surface. Roping up early and not falling are your best protection on steep slopes.

  

WEATHER: In the past 24 hours, just 2” of new snow fell on the summit while 3cm (1.25”) fell at Hermit Lake. Roughly 3” of light density snow is lingering in the alpine fetch zone upwind of our terrain since the recent storm passed to our south. Yesterday, peak wind speed on the summit was just 42 mph out of the west though a 70 mph reading was taken at 7:00am this morning with winds expected to shift to the northwest. Today’s wind forecast holds the possibility for some transport of this snow but between moderate wind speeds, calming to the 40 mph range, and lots of nooks and crannies in the fetch to shelter the snow, sustained wind transport seems unlikely. Gusts from the northwest may move some snow around and create our primary avalanche concern today. Temperatures under clear skies will be in the 10-15F range on the summit through the day. Good visibility should remain through the day.

 

SNOWPACK: As mentioned above, the snowpack is hard. A prolonged warming spell with rain late last week turned the upper portion of the snowpack into a knife hardness crust. The recent warmup ended with a period of freezing rain that glazed trees and snow surfaces at our elevation with ice. While weaker snow exists deeper in the snowpack, it is not at all a player in current avalanche concerns. The blown out portion of the Lip below the Tuckerman Ravine Trail and the hard, refrozen debris pile remain visible in Tucks. Crampons and sure footedness are needed for travel any steep terrain today.

Please Remember:
• Safe travel in avalanche terrain requires training and experience. This bulletin 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., Thursday, January 18, 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

2018-1-18