Avalanche Advisory for Monday, March 5, 2018

Huntington Ravine has MODERATE and LOW avalanche danger. North, Damnation, and Yale have Moderate avalanche danger. Heightened avalanche conditions on specific terrain features. All other forecast areas have Low avalanche danger. Watch for unstable pockets of snow on isolated terrain features.

Tuckerman Ravine has MODERATE and LOW avalanche danger. Lobster Claw and Right Gully have Moderate avalanche danger. Heightened avalanche conditions on specific terrain features. All other forecast areas have Low avalanche danger. Watch for unstable pockets of snow on isolated terrain features. The Little Headwall is not rated due to a lack of snow.

 AVALANCHE PROBLEM: Wind slab is scattered through the terrain. This initially formed Friday into Saturday and likely developed further thanks to snow that fell overnight. Areas of largest wind slab development are expected in Moderate rated areas due to being lee of prevailing NE winds, though wind slab may still be navigable by staying on old surface.  While wind speed will be light by Mount Washington standards, the density of new snow (6% on the Summit and 7.7% at Hermit Lake) should still allow for wind transport and wind slab development in our terrain.

 WEATHER: After a clear start to yesterday, clouds moved in as snow showers began in the afternoon. As of this morning, 1.5” of snow fell on the Summit with 2” at Hermit Lake. Wind during the hours of snowfall began N with speeds under 20mph and shifted overnight to NE with a current speed between 30 and 40mph. Light freezing rain is falling at Pinkham and Hermit Lake, though not on the Summit. Approaching high pressure will end precipitation and may allow for periods of clearing today, though lingering lower elevation fog may persist. Temperatures should rise into the teens F and wind will remain from the NE between 30-45mph.

SNOWPACK: A stout melt/freeze crust is acting as the bed surface in all terrain. This crust is hard to penetrate even with a shovel and has also proven a difficult surface for new snow to adhere to. Easily identifiable pockets of wind slab were the result of Friday’s Nor’easter. Fog and new snow may make visually differentiating the wind slab from old surface more difficult today. While wind slab will be the avalanche problem and triggering a pocket may knock you off your feet, the inability to stop a fall due to the icy bed surface likely outweighs the risk of being buried in debris today. Crampons and an ice axe will be necessary tools to travel in avalanche terrain.

The Harvard Cabin will be open Monday night and reopen Thursday night. this week.

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, March 5, 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

2018-03-05

Avalanche Advisory for Sunday, March 4, 2018

Huntington and Tuckerman Ravines have LOW avalanche danger. All forecast areas have Low avalanche danger. Watch for unstable snow on isolated terrain features.

 AVALANCHE PROBLEM: Isolated and avoidable pockets of wind slab are scattered through our terrain, with the more dominant snow surface being old refrozen snow. A trace to 2” of new snow and wind late today could result in further development of wind slab in similarly isolated pockets. These relatively small wind slabs likely will remain sensitive to a human trigger but should be straightforward to avoid. The old, hard, and slick refrozen surface will appear distinctly grey in contrast to the white wind slab. Of equal or greater concern than avalanches today are long sliding falls on this old surface. A loss of footing on steep snow, be it from a stumble or even a small avalanche, is likely to result in a high speed slide on this particularly slick surface. Choose terrain carefully and consider the consequences of such a fall, as rocks and other hazards are in the fall line of many steep slopes. Self-arrest in the current conditions is unlikely to impossible.

WEATHER: Minimal flurries yesterday morning tapered early as skies became at least partly sunny for much of the day. A high temperature of 22F was recorded on the summit and Hermit Lake stayed just below freezing. NE summit winds around 40 mph resulted in little if any snow transportation on the ground. We will likely see at least a few snowflakes fall today, with peak precipitation late this evening resulting in up to 2” of snowfall. NE wind on the summit will increase slightly through the day from 30 mph to near 50 mph tonight. Temperatures should be steady, with low teens F forecast on the summit. Similar conditions with minimal if any snow accumulation are expected tomorrow.

SNOWPACK: The old refrozen surface is proving difficult for new snow to stick to. As a result, it is the primary snow surface in the Ravines. Pockets of wind slab do exist and we expect generally poor bonding to this icy bed surface, but with visibility you can navigate around these pockets and avoid today’s avalanche problem. Additional snow late today should behave similarly and be easily transported by wind to produce isolated new slabs and leave significant old surface exposed. The series of melt/freeze cycles which formed this icy surface also allowed the deeper snowpack to stabilize and limits avalanche concerns to slabs on the surface. Icy snow surfaces are not uncommon in our terrain, but be aware that this one is particularly hard and smooth which allows a sliding person to accelerate quickly and all but eliminates the possibility of self-arrest. Climbers will find good crampon purchase while skiers struggle to find many options to link turns in edge-able snow. The John Sherburne Ski Trail has improved over the past few days with reports of very thin cover in some sections by generally happy skiers and riders.

The Harvard Cabin will be closed Tuesday and Wednesday of this week. 

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., Sunday, March 4, 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

2018-3-4

Avalanche Advisory for Saturday, March 3, 2018

Huntington Ravine has MODERATE avalanche danger. All forecast areas have Moderate avalanche danger. Evaluate snow and terrain carefully.

Tuckerman Ravine has MODERATE and LOW avalanche danger. Lobster Claw and Right Gully have Moderate avalanche danger. Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully. Sluice, Lip, Center Bowl, Left, Hillman’s Highway and Lower Snowfields have Low avalanche danger. Watch for unstable snow on isolated terrain features. The Little Headwall is an open stream and is not rated.

AVALANCHE PROBLEM: Areas of new wind slab are the primary avalanche problem though the primary hazard remains the potential for taking a high-speed sliding fall from steep terrain on the frozen, icy snowpack. Brief windows of visibility into Tuckerman Ravine have confirmed suspicions that much of yesterday’s new snow was scoured off of windward facing forecast zones by high winds from the east-northeast. The high wind speed and easterly direction coupled with very limited fetch, or area of available snow for transport, leads us to our low rating in most areas. Forecast areas that face due east contain much more limited areas of wind slab. These areas should be assessed carefully for sensitivity to human-triggering and consequences of being swept off your feet. More sheltered areas like the long northern gullies in Huntington and Lobster Claw and Right Gully in Tucks will likely harbor larger and harder to avoid wind slab. Human triggered wind slabs are possible where they have developed in steep terrain. Up to an inch of new snow today on continued NE wind will add slightly to existing wind slab.

WEATHER: Wind from the northeast continues to blow this morning in the mid-50s mph and will remain from that direction through the day. Though temperatures will be on the mild side for this time of year, mid teen’s F will keep things feeling wintry. Yesterday’s highly elevation dependent snowfall brought 6.1” of snow to the summit and 2.4” of 20% density snow to Hermit Lake. Winds remained in the 60s and 70s mph during the storm which would have been an ideal loading speed had they blown from the west. Winds will continue to move some snow today as they blow in the 50 mph range from the northeast. Count on limited visibility through the day due to persistent summit fog, up to an inch of new snow, and a challenging headwind above treeline on a return trip on the Lion Head route.

SNOWPACK: An unusually warm February started to create hazards more typical of spring. Glide cracks, waterfall holes and ice that has gone through dramatic temperature swings are all in play now. The old, gray surface was saturated during earlier rain events and has now refrozen into a barely edge-able and slick surface. Three people have taken long sliding falls on this surface in the past week and though they were lucky to only receive minor injuries, history has shown the consequences of falls like this can lead to serious injuries and even death. Be sure to develop alternate plans if you or your group is strongly driven to get into steep terrain today, the consequences of pushing it are often much more severe than anticipated.

The John Sherburne Ski Trail was freshened up by a few inches of dense snow yesterday but still holds a wide variety of conditions, including exposed rocks, areas of water ice. Plenty of skiable snow remains but cautious and careful turns are advised.

The Harvard Cabin will be open Saturday night.  

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., Saturday, March 3, 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

2018-03-03

Avalanche Advisory for Friday, March 2, 2018

Huntington and Tuckerman Ravine will have CONSIDERABLE avalanche danger. Dangerous avalanche conditions may exist. Careful snow and weather evaluation, and cautious route-finding will be essential. The Little Headwall is an open stream and is not rated.

AVALANCHE PROBLEM: We are starting the morning with low avalanche danger in all forecast areas. The storm system passing by to the south will likely generate 4-8” of new snow in higher terrain. Easterly wind, shifting to the northeast, will ramp up through the day, building wind slabs that may avalanche naturally in many areas. While wind will eventually reach a velocity capable of scouring lots of the terrain, we will pass through a period of peak instability before we get there. If you choose to travel in avalanche terrain today, remember that the new wind slabs will be forming over an icy bed surface and will be touchy and may fail above you naturally. Due to the wind direction today, wind slab avalanches won’t be large, but they may be large enough to carry you over cliffs or into rocks. Dry loose avalanches may be plentiful as well and will contribute to the volume of wind slab at the base of steep areas. Forecast areas sheltered from NE winds may grow larger wind slabs than usual. Lobster Claw, Right Gully and Sluice in Tuckerman Ravine meet that criteria. The northern gullies in Huntington have limited bed surfaces but their sheltered location could allow wind slabs to grow quickly in steep, upper and mid elevation start zones.

WEATHER: The snowfall amounts forecast today remain uncertain due to our distance from the center of the low passing to our south. Snow has already begun on the mountain though valley locations are seeing rain and snow mixed. Snowfall totals today are dependent on bands of precipitation passing over and spawning periods of moderate or even heavy snow. Snow began earlier than expected making the increased MWObs snowfall forecast of 4-8” seem likely. Currently, a gusty northeast wind on the summit is blowing at 55 mph and will continue to increase through the day and really howl by the end of the day with gusts over 100 mph in the mid-afternoon. Descending from a morning summit attempt with that wind speed and direction may require crawling.

SNOWPACK: The result of multiple thaws in January and February is a stable snowpack to begin the month of March. Warm spells recently have reduced the overall snowpack, resulting in the snow study area at Hermit Lake losing close to 12” since mid-February. Glide cracks and small holes due to undermining appeared briefly, but never had the chance to fully develop. Snow that arrives today will likely cover these, though holes in the Little Headwall streambed will remain open and visible. Any exposed area of old surface today will be firm. Over the past week, we received several reports of people losing their footing and being unable to self-arrest due to the icy nature of the snowpack. Bear this in mind when moving around in steep terrain.

The John Sherburne Ski Trail holds a wide variety of conditions, including exposed rocks, areas of water ice, which is sometimes thinly veiled covered with the new snow that fell earlier this week. Plenty of skiable snow remains but cautious and careful turns are advised.

The Harvard Cabin will be open Friday and Saturday night this weekend.

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., Friday, March 2, 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

2018-03-02

Avalanche Advisory for March 1, 2018

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

AVALANCHE PROBLEM: Thin wind slabs, which formed earlier in the week, are scattered throughout northeast facing terrain. These have passed through their unstable phase and should not be of much concern except possibly in the very steepest locations. The old gray refrozen snowpack that makes up most of the travel surface in our forecast area, will be underfoot everywhere due to the thin coating of new snow on top. This surface will create the primary concern for climbing and riding due to its firm and icy nature. Any softening that occurs later in the day in the sun or with warming temperatures will likely be only at the surface. On days like today with temperatures around freezing, passing clouds can allow the snow to quickly refreeze and make arresting a fall difficult at best. Crampons, an ice axe and the ability to use them well will be useful to avoid a long sliding fall today. 

WEATHER: Warm and soggy conditions at Pinkham are kicking off another day of unseasonably warm weather. The temperature reached 41F (5C) yesterday at Hermit Lake before dipping back down to 28F (-2C) overnight. Currently the summit temperature is 22F, with 30F at Hermit Lake at 6:30 a.m. Thick fog currently cloaks the Ravines but will begin to clear with partly sunny and SW winds diminishing to 10-25 mph in the afternoon. The high temperature at the summit is forecast to be in the mid-20’s.

SNOWPACK: Last month, temperatures at the summit averaged 6.8 F above average. The 6.73” of SWE (snow water equivalent) that fell in February was close to average though warm spells allowed this precipitation to fall as rain, some of it heavy.  The summit received 51.6” of snow, which is about 12” above normal, but the snow took a beating by the warm temperatures and rain. Despite the warm temperatures, the ice has held up well in Huntington and the snowpack in Tuckerman seems set up for decent spring skiing, though the Lip has suffered from the large wet slab/waterfall blow out in January.

Fans of winter are no doubt keeping a close eye on the low pressure system moving across Pennsylvania on its way to Cape Cod. Though models are beginning to agree that the track will remain well south of the area, atmospheric conditions appear to be favorable for banding which may bring heavy snow to the Presidential Range. Snowfall totals will be variable by elevation but seems like there will be more than enough snow to bring elevated avalanche concerns tomorrow.  Saturday will likely have increased avalanche risks as well if wind wraps around to the west as it often does after a storm like this. Be sure to check the advisory before committing to your objectives over the weekend. 

The John Sherburne Ski Trail holds a wide variety of conditions, including exposed rocks, areas of water ice, which is sometimes thinly veiled covered with the new snow that fell earlier this week. Plenty of skiable snow remains but caution and careful turns are advised.

The Harvard Cabin will be open Thursday, Friday and Saturday night this week. 

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., Thursday, March 1, 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

2018-03-01