Avalanche Advisory for Thursday, April 17, 2014

Tuckerman Ravine has Moderate and Low avalanche danger. Lip and Center Bowl have Moderate avalanche hazard. Natural avalanches are unlikely and human triggered avalanches are possible. All other forecast areas have Low avalanche hazard. Natural and human triggered avalanches are unlikely. Evaluate snow and terrain carefully!

Huntington Ravine is under a General Advisory. You will need to do your own snow stability assessments when traveling in avalanche terrain in Huntington. A danger of falling ice exists, and will persist until it all comes down.

AVALANCHE PROBLEM: Wind deposited snow across the Center Bowl and especially in the Lip area yesterday. These Wind Slabs will most likely be reactive to human triggering as they warm this morning before their energy is cooked out by the sunshine. The Open Book waterfall hole in the fall line of the Lip could make a sliding fall extremely consequential. Pockets of new wind slab also exist beneath Sluice ice, in Chute and below the narrow section, on skiers left, in Left Gully.

WEATHER: Two inches of snow yesterday blew into the Ravines on high, westerly winds. Light winds this morning coupled with clear skies will allow temperatures to push up into the 30’sF, if not into the 40’s, in Tuckerman today with upper 20’s F forecast for the summit. Scattered clouds could allow slopes to refreeze at times today with the temperature so close to freezing.

SNOWPACK: Snow surfaces not covered with new snow today will be very hard and icy this morning. Yesterday, winds from the west effectively transported the small amount of new snow into smooth wind slabs in the Lip, beneath the ice across the Headwall. Some of these drifts may be obscuring possibly deep slots that opened during recent heavy rain and warm temperatures. You are most likely to find these  on steep snow slopes beneath buttresses of rock or ice in the Headwall/Lip and Sluice areas. Be aware of the potential to punch through into these slots, especially when traveling on foot. The main waterfall hole marking the Lip/Center Bowl boundary opened but some thin ice and snow is now concealing the hazard from view. Choose your line carefully!

OTHER HAZARDS:  Recent rain and warm weather really melted out snow spanning streams like the one that flows out of Tuckerman. With our deep snowpack, the distance from snow surface to rushing streambed below could make it difficult to climb out of some of the holes should you fall in. Rain also weakened frozen waterfalls so keep this hazard on your radar. Lunch Rocks is still a roll of the dice in terms of this hazard.

Micro-spikes and other creeper style traction devices may be helpful on some lower angle trails, but they do not provide the security of crampons. Be prepared to handle steep, firm snow and fast, icy surfaces. A fall on steep terrain today would be next to impossible to self-arrest. Don’t fall today, especially above a crevasse or streambed.

The Sherburne ski trail is what you would expect after 2″ of rain followed by freezing temperatures. You can still make it to the parking lot but expect detours around ice, bare spots and open water drainages.

Please Remember:

  • Safe travel in avalanche terrain requires training and experience. This advisory is just one tool to help you make your own decisions in avalanche terrain. You control your own risk by choosing where, when, and how you travel.
  • Anticipate a changing avalanche danger when actual weather differs from the higher summits forecast.
  • For more information contact the Forest Service Snow Rangers, the AMC at the Pinkham Notch Visitor Center, or the caretakers at Hermit Lake Shelters.
  • Posted 7:45 a.m. 4-17-2014. 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

2014-04-17 Print friendly

Avalanche Advisory for Wednesday, April 16, 2014

Tuckerman Ravine has Low avalanche danger. Natural and human triggered avalanches are unlikely.

Huntington Ravine is under a General Advisory. You will need to do your own snow stability assessments when traveling in avalanche terrain in Huntington. A danger of falling ice exists, and will persist until it all comes down.

AVALANCHE PROBLEM: Plunging temperatures overnight are freezing our snow pack and beginning to lock up free water. A small amount of new snow (<1″) with continued upslope snow may create small pockets of unstable Wind Slab in lee areasThis morning, high winds are likely scouring high start zones and depositing snow lower in the Ravines. As winds slow later, look for the potential for wind slab development in higher start zones. Monitor the amount of new snow fall today and anticipate a potentially growing hazard, particularly if more upslope snow falls than is forecast.

WEATHER: The summit temperature graph was bearish last night, to say the least. Temperatures dropped to -2F (-19C) from a steady 40F (4C) last night at 6pm. Cold frontal passages like the one we are experiencing often spawn upslope snow shower activity on the mountain, though the Obs is only calling for a trace to one inch (2.5cm) of new snow today. Winds are blowing pretty steadily around 90 mph (115 kph) this morning. NWS point forecast is for 115 mph (185 kph) gusts this morning. Either way, it is pretty darn windy out. NW winds should fall off to 30-45 mph (50-70 kph) by sunset with clearing skies and temperatures rebounding a bit to the mid-single digits F (+/-  -15C).

SNOWPACK: To sum it up, hard and icy everywhere and undermined in many areas. If weak layers deep in the snowpack remain intact after the warm spell, they will be thoroughly bridged over by a icy skin of frozen slush and cold hard slabs of melt forms in the upper layers. The 2.18″ of rain that fell in the past 36 hours have opened waterfall holes and crevasses and undermined snow bridges covering water channels. Despite the cold, water is still flowing and continuing this process so if you venture into the Ravines be aware of the potential for punching through into these voids which can be surprisingly deep. Some thin areas in Right Gully and Sluice and areas over high volume water courses like the Lip and Center Bowl could collapse. The Little Headwall is now a waterfall. The Lip/Center Bowl waterfall hole and a crevasse along the base of the ice opened up on Monday and likely grew yesterday. I wouldn’t be surprised to see a slot lower near the top of the Open Book when visibility improves later today.

OTHER HAZARDS:  Today, we are standing at the busy intersection of winter and spring hazards. Cold temps and high winds coupled with open waterfall holes and icy trails make travel in the mountains challenging. Recent rain and warm weather really melted out snow spanning streams like the one that flows out of Tuckerman. With our deep snowpack, the distance from snow surface to rushing streambed below could make it difficult to climb out of some of the holes.

Micro-spikes and other creeper style traction devices may be helpful on some lower angle trails, but they do not provide the security of crampons. Be prepared to handle steep, firm snow and fast, icy surfaces. A fall on steep terrain today would be next to impossible to self-arrest. Don’t fall today, especially above a crevasse or streambed.

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.
  • Posted 7:55 a.m. 4-16-2014. 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

2014-04-16 Print friendly

Avalanche Advisory for Tuesday, April 15, 2014

This advisory expires at 12:00 midnight.

Tuckerman Ravine has Considerable avalanche danger. Natural avalanches are possible and human triggered avalanches are likely. Dangerous avalanche conditions will exist after rainfall begins. Careful snowpack assessment, cautious route finding and conservative decision making are essential.

Huntington Ravine is under a General Advisory. You will need to do your own snow stability assessments when traveling in avalanche terrain in Huntington. A danger of falling ice exists, and will persist until it all comes down.

AVALANCHE PROBLEM: Potentially heavy rain today will create the potential for Wet Slab avalanches. The largest of these would be most likely to occur in the Sluice, Lip and Center Bowl area if the larger water courses overflow their channels and run out over deeper slabs or ice lenses. The greatest chance of these types of avalanches will be later in the day after the rain has penetrated more deeply through the snow and melt runoff increases beyond it’s already high levels. Most other forecast areas will share this problem so if skiing in the rain is your thing, consider lift service today.

WEATHER: Rain should begin this morning and pickup in intensity into the afternoon. An inch of rain will fall before changing over to snow late tonight and in the wee hours of Wednesday. Temperatures, now standing at 42F will start to decline in the late afternoon and evening to around freezing at sundown and then down to around 10F by morning. 1-3″ snow may fall by morning. SW Wind will ramp up a bit from it’s current 45 mph or so as rain increases in intensity before slowing a bit later in the day. Overnight wind will shift to the NW and crank up to the 80-100 mph range by morning. Expect temperatures well below normal tomorrow.

SNOWPACK: Todays rain will be falling on an already rotten, unsupportive snowpack. Even packed trails will have the potential for postholing as water channels beneath the melting bonds between snow grains. All the warm weather has weakened the snowpack and encouraged the inevitable downhill creep of the snowpack. Smaller crevasses near rocks were opening over the past several days but were minor compared to what you could expect to see today. The main waterfall hole that opened yesterday in the Lip/Center Bowl area makes a crossing of the Tuckerman Ravine trail a dangerous proposition.

OTHER HAZARDS: Rain and more warm temperatures today continue to flood streams and undermine snow. Larger stream channels like the brook coming out of Tucks can be dangerous. Imagine falling into a treewell with water rushing through the bottom…..just as hard to get out of and with hypothermia and drowning a real possibility. To spice things up further, icefall potential will be on the rise today making Lunch Rocks an especially bad choice of places to hang out and enjoy the cold, wind driven rain.

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.
  • Posted 7:00 a.m. 4-15-2014. 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

2014-04-15 Print friendly

Avalanche Advisory for Monday, April 14, 2014

This advisory expires at 12:00 midnight.

Tuckerman Ravine has Low avalanche danger. Natural and human triggered avalanches are unlikely. Huntington Ravine is under a General Advisory. You will need to do your own snow stability assessments when traveling in avalanche terrain in Huntington. A danger of falling ice exists, and will persist until it all comes down.

AVALANCHE PROBLEM: The Low avalanche danger today is a result of multiple days of warm weather and cold nighttime temperatures. This diurnal cycle adds a lot of strength to the snow surfaces and reduces the potential for avalanche activity to a point where we are comfortable calling the danger level “Low.” Understand that predicting avalanches is not a perfect science. With this in mind, when traveling in avalanche terrain we always recommend carrying avalanche rescue equipment, practicing safe travel rituals, and keeping your awareness up for situations that could increase your risk.

WEATHER: If you’ve had any doubts about whether spring would ever arrive, today should be enough to erase them thoroughly. Valley temperatures may hit 70°F. The temperature sensors along the Auto Rd are already reading over 50°F at the 4300’ elevation! Higher summits forecasts for today call for the mountains to be in the clouds, but currently this is not the case. Even so, you should be ready for visibility to decrease if the cloud levels drop during the day.

Yesterday we received a surprise of about 2” of new snow at Hermit Lake before precipitation turned over to ice pellets and rain. At this point in the season, we will take whatever we can get to keep the existing snowpack fresh. It also highlights the ability of mountain weather to be somewhat unpredictable, so it’s best to be prepared for poor weather even if forecasts look promising.

SNOWPACK: We are certainly into a springtime snowpack. The ravines have spent far more time above freezing than they have below freezing over the last 24 hours. Today you should be expecting all surfaces to soften with the intense warming. Some slopes may turn into deep and unsupportive slop as well. Melt water may find its way to lower layers in the snow and produce a wet slab avalanche. My thoughts are that this will be more of a problem with Tuesday’s rain than with only melt water today.

OTHER HAZARDS: We are at the beginning of the icefall season, which means that there is a lot of ammunition perched high on the cliffs of the ravines. Sitting at Lunch Rocks is a lot like looking down the barrel of a loaded gun. You don’t want to be there when heat and sunshine pull the trigger. Other springtime hazards, such as undermined snow and crevasses, are emerging as well. If you’re planning a future trip to the ravine, do your homework about these issues in advance!

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.
  • Posted 7:45 a.m. 4-14-2014. A new advisory will be issued tomorrow.

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

2014-04-14 printable

Avalanche Advisory for Sunday, April 13, 2014

Tuckerman Ravine has Low avalanche danger. Natural and human triggered avalanches are unlikely.

Huntington Ravine is under a General Advisory. You will need to do your own snow stability assessments when traveling in avalanche terrain in Huntington. A danger of falling ice exists, and will persist until it all comes down.

AVALANCHE PROBLEM: Recent daily melt and freeze cycles have brought our avalanche hazard down to Low. Today’s small amount of rain and warming are unlikely to create much avalanche danger. That said, safe travel practices and avalanche safety equipment are still a good idea. Avalanches caused by rain and warming are notoriously hard to predict, so a savvy mountain traveler will respect this threat by minimizing exposure with careful route finding.

WEATHER: Current temperatures are hovering around freezing at Alpine Garden elevations this morning and in the mid-30’s at Hermit Lake. Freezing rain and then rain are likely today. Up to a 1/4″ of rain may fall with temperatures on the summit eventually reaching 40 F by afternoon. This morning, freezing rain is predicted with winds coming from the southwest at around 40 mph, increasing to around 60 mph with higher gusts this afternoon.

SNOWPACK:  The snow pack is really beginning to shows signs of spring. Folks enjoyed the heck out of Tuckerman yesterday. About 1800 folks. Friday nights freeze was not very deep so all it took to soften things up was some sunshine with sluff piles and moguls showing up in short order. Shady aspects near the rims refroze quickly as the sun began to set. A little rain and freezing rain today may help smooth things out a bit. While generally stable, the issues that keep us search and rescue ready are still out there. There are still potential weak interfaces between wind slabs deep in the snowpack that can be lubricated and weakened by water. We saw this last year on a busy day when a wet slab pulled out of the Lip/Center Bowl waterfall area and surprised a lot of people near Lunch Rocks. A flood watch has been issued until Wednesday for the region so this hazard, along with undermined snow, crevasses opening up and sketchy stream crossings are all coming. Huntington Ravine climbs will continue to be exposed to rock and ice fall hazard due to warming.

OTHER HAZARDS: Icefall from the Sluice onto Lunch Rocks is becoming a real threat. Some of the ice over the “Knife edge” ridge between Sluice and Right Gully looks like it could fall any day.  Continued melting has really softened snow spanning streams like the exit from Tuckerman. As the volume of running water increases so does the hazard. Micro-spikes and other creeper style traction devices may be helpful on some lower angle trails, but they do not provide the security of crampons. Be prepared to handle steep, firm snow and fast, icy surfaces.

Please Remember:

  • Safe travel in avalanche terrain requires training and experience. This advisory is just one tool to help you make your own decisions in avalanche terrain. You control your own risk by choosing where, when, and how you travel.
  • Anticipate a changing avalanche danger when actual weather differs from the higher summits forecast.
  • For more information contact the Forest Service Snow Rangers, the AMC at the Pinkham Notch Visitor Center, or the caretakers at Hermit Lake Shelters.
  • Posted 7:40 a.m. 4-13-2014. 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

2014-04-13 Print friendly

Avalanche Advisory for Saturday, April 12, 2014

This advisory expires at 12:00 midnight.

Tuckerman Ravine has Low avalanche danger. Natural and human triggered avalanches are unlikely. Huntington Ravine is under a General Advisory. You will need to do your own snow stability assessments when traveling in avalanche terrain in Huntington. A danger of falling ice exists, and will persist until it all comes down.

AVALANCHE PROBLEM: The Low avalanche danger today is a result of multiple days of warm weather and cold nighttime temperatures. This cycle adds a lot of strength to the snow surfaces and reduces the potential for avalanche activity to a point where we are comfortable calling the danger level “Low.” Understand that predicting avalanches is not a perfect science. With this in mind, when traveling in avalanche terrain we always recommend carrying avalanche rescue equipment, practicing safe travel rituals, and keeping your awareness up for situations that could increase your risk.

WEATHER: Today’s weather forecast is for generally pleasant weather, but don’t forget that safely spending time in the mountains requires more preparation and equipment than a pleasant day in the park. For example, bring some extra dry layers, a jacket, and don’t forget the sunblock! Temperatures are starting today down below freezing, but elevations all the way to the summit should rise up above the freezing mark before long. Cloud levels will be dropping late, so if you’re out on the mountain when this happens (intentionally or otherwise) be ready for poor visibility and maybe some icy surfaces.

SNOWPACK: Overnight, cold temperatures put a good freeze on the surface layers in the ravine. Icy surfaces should be expected both early today and late, after slopes become shaded temperatures start to fall. An ice axe and crampons are recommended for travel on steep slopes. Micro-spikes and other creeper style traction devices may be helpful on some lower angle trails, but they do not provide the security of crampons. Expect to find an isothermal snowpack to a significant depth. Deep beneath the surface, you may be able to find some buried weak layers or interfaces between cold wind slab. We don’t feel that these are major players in the avalanche danger at this time, but a heavy rain event or prolonged warm spell may bring them back to the forefront of our minds.

OTHER HAZARDS: We are at the beginning of the icefall season. Smaller pieces of falling ice have been observed in a variety of locations in both Tuckerman and Huntington. Even small piece of falling ice can be very dangerous, so be alert for this hazard. Other springtime hazards, such as undermined snow and crevasses, are on the cusp of emerging, but so far have not been much of a threat.

FOR MORE INFORMATION ABOUT ANY OF THE POTENTIAL HAZARDS ON THE MOUNTAIN, CHECK IN WITH A SNOW RANGER OR SKI PATROL MEMBER.

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.
  • Posted 8:00 a.m. 4-12-2014. A new advisory will be issued tomorrow.

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

2014-04-12 Print Friendly

Avalanche Advisory for Friday, April 11, 2014

This advisory expires at midnight.

Tuckerman Ravine has Moderate and Low avalanche danger. Sluice, Lip, Center Bowl, Chute and Left Gully have Moderate avalanche danger. Natural avalanches are unlikely and human triggered avalanches are possible. All other forecast areas have Low avalanche danger. Natural and human triggered avalanches are unlikely.

Huntington Ravine is under a General Advisory. You will need to do your own snow stability assessments when traveling in avalanche terrain in Huntington. A danger of falling ice exists, and will persist until it all comes down.

AVALANCHE PROBLEM:  Heat penetrating into the snowpack, as well as some more rain, has the potential to weaken remaining deeper weak layers today. This means that Persistent Slabs are our primary avalanche problem. The Lip, Center Bowl, Chute and, to a lesser extent, Left Gully are the areas that carry the greatest risk. Though the probability of triggering one of these slabs is low, I would not want to be caught by the resulting debris. Minimize your exposure to this risk by traveling out of the fall line. Thin Wet Slabs from wind slabs which developed in the past 36-48 hrs in Moderate rated areas are also a potential concern though they carry less consequences than the deeper weak layers. Wet Loose sluffs are likely and will happen on most steeper terrain today.

WEATHER: The summit recorded .14″ of freezing rain last night with nothing in the collection can at Hermit Lake. Temperatures at Ravine elevations have been around 40F for the past 24 hours. Today’s forecast calls for more shower activity this morning before limited clearing begins this afternoon. West winds will drop from 50-70 mph to 30-45 mph through the day. Temperatures around 20F tonight will bring a good freeze up to restore the upper snowpack. Generally a warm but gloomy day is on tap.

SNOWPACK: Avalanches have mostly cleaned out the January 11 rain crust/facet layer but smaller areas still exist as do other deep wind slab interfaces. This 24 hr period of warm temperatures and rain is a pretty strong stressor so heat may reach these deeper layers for the first time. Shadier aspects have certainly not seen this degree of heating yet and many of the warm sunny days we have seen so far this year did not wet the snow much deeper than 40-50 cm down. This leads me to be suspicious of the Moderate rated slopes. This is the kind of hazard that can potentially reward a person who habitually practices safe travel techniques and minimizes exposure time. Skiing one at a time, climbing the extreme margins of gullies, and not waiting in the runout for others to descend are all wise choices.

OTHER HAZARDS: Slopes and gullies can change from soft and forgiving to icy and refrozen depending on subtle variations in aspect and snowpack. This can limit penetration of boots or skis therefore crampons and an ice axe are recommended for travel on steep slopes. Micro-spikes and other creeper style traction devices may be helpful on some lower angle trails, but they do not provide the security of crampons. Be prepared to handle steep, firm snow and fast, icy surfaces. Icefall can be a problem at times and though we are not into peak heating and associated icefall hazard yet, we are definitely seeing daily cycles of smaller icefall events. Huntington Gullies can spawn rockfall pretty readily with this amount of warmth and rain.

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. Posted 8:00 a.m. 4-11-2014. 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

2014-04-11 Print friendly

Avalanche Advisory for Thursday, April 10, 2014

This advisory expires at midnight.

Tuckerman Ravine has Moderate and Low avalanche danger.  Sluice, Lip, Center Bowl, and Chute have Moderate avalanche danger. Natural avalanches are unlikely and human triggered avalanches are possible. All other forecast areas have Low avalanche danger. Natural avalanches and human triggered avalanches are unlikely. Look out for small avalanches in isolated areas or extreme terrain.

Huntington Ravine is under a General Advisory. You will need to do your own snow stability assessments when travelling in avalanche terrain in Huntington. A danger of falling ice exists, and will persist until it all comes down.

AVALANCHE PROBLEM: New Wind Slab formed high in the lee areas from snow that fell yesterday. High in the Chute, as well as just above and below the ice in the Center Bowl and Lip are where these slabs could exist in a potentially dangerous thickness. Though unlikely to bury you, they could hurt you if you triggered one and were pushed into rocks or over an ice cliff. These wind slabs could turn into Wet Slabs later. Incoming heat energy and later in the day, rain and mixed precipitation could add to instability by weakening and adding mass to the slabs. A distant third problem should still be considered. Though settlement has occurred with the recent warming trends, the steepest areas, especially those near watercourses, could heat enough to avalanche on deeper (>4′) weak layers. The top of Left Gully springs to mind due to a cornice and wind affected hang fire from earlier avalanche cycles. It is the kind of hazard that can potentially reward a person who habitually practices safe travel techniques and minimizes exposure time.

WEATHER:  Clear skies through mid-day should warm things up in the Ravines before clouds thicken and the latest round of precipitation moves in. Hermit Lake temperatures are edging towards the freezing mark from a low somewhere in the mid-twenties. Winds are currently out of the north around 40 mph and should slow further, warm and shift southwest. Later in the day they will ramp up into the 60-80 mph range on the summit  as the next cold front approaches, bringing with it another mixed bag of precipitation.

SNOWPACK:  Surface snow conditions are solidly refrozen following recent warming and last nights cold temperatures. Ambient air temperatures are predicted to rise through the day. Cloud cover will slow snowpack temperature gain so timing is everything today. NWS and MWOBs aren’t entirely in sync with the timing of incoming precipitation but my money is on some snowpack warming today as the high April sun can work pretty quickly. We are still at a crossroads with winter and spring hazards both showing their teeth depending on the time of day and quick blasts of wintry precipitation. A savvy traveller will account for this and be flexible with travel plans and pay close attention to snowpack details and changeable weather conditions and how the two play together.

OTHER HAZARDS: Slopes and gullies can change from soft and forgiving to icy and refrozen depending on subtle variations in aspect and snowpack. This can limit penetration of boots or skis therefore crampons and an ice axe are recommended for travel on steep slopes. Micro-spikes and other creeper style traction devices may be helpful on some lower angle trails, but they do not provide the security of crampons. Be prepared to handle steep, firm snow and fast, icy surfaces. Icefall can be a problem at times and though we are not into peak heating and associated icefall hazard yet, we are definitely seeing daily cycles of smaller icefall events. South facing Huntington Gullies can spawn rockfall pretty readily this time of year.

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. Posted 8:30 a.m. 4-10-2014. 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

2014-04-10 Print friendly

Avalanche Advisory for Wednesday April 9, 2014

This advisory expires at midnight

Tuckerman and Huntington Ravine have Moderate avalanche danger.  Natural avalanches are unlikely and human triggered avalanches are possible.

AVALANCHE PROBLEM: New Wind Slabs are the primary avalanche problem today.  Yesterday snow generally ended during the morning followed by a rapid rise in temperature pushing a good deal of avalanche terrain close to 50F in the afternoon.  Following this warm fog the mercury fell with new snow showers beginning overnight, which is forecasted to continue this morning. This is causing new cold dry snow, on a NW wind, to load into slopes with an E facing component, hence the Wind Slab problem.

WEATHER:  The summit recorded 4.1” of snow and frozen forms, melting to 1.22” of water, in the past 24 hours.  Temperatures hit 38F, the 2nd highest mark of the season so far, which did a good job settling new wet snow from yesterday morning. The new snow overnight, coupled with a freefall of the mercury, will continue this morning. Eventually, ambient air temperatures will settle around 10F on the summit with any additional moisture being limited.  NW winds will increase all day gusting over 80mph late in the forecast period.

SNOWPACK:  In the past couple of days the summit has picked up 7.4” of frozen forms melting to 1.66” of water.  Following this dense, wet, mixed accumulation the temperatures soared to around 50F in avalanche terrain Tuesday afternoon.  Falling temperatures last night began the process of locking up this wet blanket by penetrating deeper into warm snow by the hour. Meanwhile, some light snow began intermittently bringing some new cold snow to E facing slopes, thinly covering some of the previous refreezing slabs.  This light snowfall is expected to continue this morning before a clearing trend begins.  The main issue today is any new cold slabs that may be developing in the two ravines.  This concern has caused us to issue today’s rating of Moderate.  There is some uncertainty exactly how this morning will play out due to the amount of light snow yet to come, an increasing wind, thick fog and blowing snow encapsulating the mountain.  A Moderate rating may be a conservative call for some areas, so anticipate hard crust, potentially breakable, to be as much of a safety issue as avalanches today.  Therefore, expect both a falling hazard, of both you and those above you, as well as new snow instabilities.  A likely scenario is hard conditions down low with areas of new snow in the highest strongest lee slopes.

OTHER HAZARDS: A falling hazard on frozen wind swept slopes is a real concern today so as always an ice ax and crampons are required to travel safely.  Also being ready for winter conditions with a temperature of 10F and hurricane force winds.  Despite the calendar, it is not spring in the mountains today.  Quality winter clothing should be part of your repertoire to avoid hypothermia.

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.Posted 7:55a.m. 4-9-2014. A new advisory will be issued tomorrow.

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

2014-04-09 Print

Avalanche Advisory for Tuesday, April 8, 2014

This advisory expires at 12:00 midnight.

Tuckerman and Huntington Ravine have Moderate avalanche danger. Heightened avalanche conditions exist on specific terrain features. Natural avalanches are unlikely and human triggered avalanches are possible.

AVALANCHE PROBLEM: Wet Loose Avalanches are the primary threat today. The standard definition of Moderate danger says that naturally triggered avalanches are unlikely. With today’s loose wet problem, this is not the case. Expect rain today to trigger small wet loose avalanches across many different aspects. Steeper slopes will be more susceptible to this problem. The expected size of these allows the danger rating to be Moderate, whereas Considerable is usually the more appropriate rating when naturally triggered avalanches are possible.

If rain falls heavier than we currently are expecting, avalanche danger may rise further due to the threat of wet slab avalanches. You need to be your own weather observer for this one. If you see heavy rain and not so much frozen precipitation today, consider recreating outside of avalanche terrain.

WEATHER: As one former Snow Ranger used to say…today is a good day to be wearing a house. It’s currently 37°F at Pinkham Notch. The summit is several degrees below freezing, and Hermit Lake sits right at the freezing mark. So the upper portions of the mountain are receiving mixed frozen precipitation, at least for now. Temperatures are expected to rise this morning which will bring rain to all elevations. In the afternoon, precipitation will transition from steady to showery. Temperatures will be falling during this time, so we will begin to see snow showers again in the afternoon. Overnight the summit has received a few inches of heavy dense snow and ice pellets. We will need to wait to see how much more falls before a transition to rain showers.

SNOWPACK: The last two days have turned out to offer good snow conditions for skiing and riding. Yesterday’s warm temperatures helped the snowpack continue on its path to being fully isothermal. However, last night the temperatures only slightly dipped below freezing, so there is going to be some refrozen snow grains near the surface but deeper in the snowpack you would likely still find warm moist snow.

Today’s primary avalanche problem stems from rain landing on two different snow layers. The older one fell on Saturday night with strong NW winds which landed on slopes with an easterly or southeasterly component. Much of this has been skied over, so wet slab concerns are minimal in these locations, but the loose snow that remains can still get moving enough to be a concern. The more recent layer is 3” or so of wet snow and sleet that fell overnight and early this morning. Winds were from the SSE, but the wetness of this snow leaves me thinking it’s blanketing all aspects, not only those in the lee of SSE winds.

OTHER HAZARDS: Swollen streams today may increase the hazard of undermined snow. We’re also beginning to think about falling ice as a potential concern.

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.
  • Posted 7:45 a.m. 4-8-2014. A new advisory will be issued tomorrow.

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

2014-04-08 Printable