Avalanche Advisory for Friday, April 13, 2018

Huntington Ravine has MODERATE and LOW avalanche danger. Central, Pinnacle, Odell, South, and Escape Hatch have 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.

Tuckerman Ravine has CONSIDERABLE, MODERATE, and LOW avalanche danger. The Lip has Considerable avalanche danger. All other forecast areas have Moderate avalanche danger. Evaluate snow and terrain carefully to identify features of concern. The Little Headwall is the exception with Low avalanche danger. Watch for unstable snow on isolated terrain features.

AVALANCHE PROBLEM: Wet slabs will become the primary avalanche problem today as prolonged above freezing temperatures continue to warm the recently dry upper snowpack. The sun may make an appearance today. If we see sunshine for an extended period, human triggered wet slab avalanches may push toward likely on southerly aspects. Without lengthy sun affect, the soft slabs that blanket much of our terrain should behave similarly on all terrain in the ravines. Loose-wet sluffs and point releases should be on your radar, and like wet slabs, will be possible to human trigger on many aspects. It’s worth noting that wet slab avalanches are notoriously difficult to forecast, with natural avalanches tricky to predict and the tipping point between unreactive and touchy to a human trigger often being a very fine line.

WEATHER: After a cloudy start to the day yesterday, skies cleared for the middle part of the day while wind speeds dropped to below 10mph. By mid-afternoon, summits fog developed as light snowfall began. This precipitation was capped by two hours of freezing rain around midnight. All told, the storm delivered just over 2″ of snow with a water equivalent of 0.24″. Unsettled weather with a degree of uncertainty will be the story of today. A warm front is moving into the region, creating warming temperatures as well as a drop from current wind speeds. Elevations under 4000′ are already above freezing at 7am and the higher summits should follow suit by mid-morning with highs reaching well into the 30sF all day. Current W wind at 60mph should decrease to the 30-45mph range early. Cloud cover for the day is a big question mark with the incoming warm front possibly allowing periods of clearing as it lifts over the White Mountains. By late afternoon, moisture will bring a return of fog and precipitation of some type, likely a mix of rain and freezing rain. Temperatures will dip below freezing on the summit tonight, allowing snow and sleet to enter the mix. All told, by tomorrow morning, 0.5″ of water should arrive in some form of mixed precipitation.

SNOWPACK: The past week has transformed our snow surface from predominantly refrozen crust to widespread new and soft snow. The crust, while present at the surface in very limited areas, is now buried under several layers of varying hardness though generally soft (4F-F) slab. Bonding between these slabs and to the buried crust was improving though continued to exhibit spatial variability across the terrain. Stability test results have illustrated this point, with varied loading amounts required to initiate a failure and mixed ability to propagate a crack. These layers of recent slabs, which we believe to be up to two feet thick, have been more consistently producing clean, even (Q1) shears. All told, this snowpack structure of layered soft slabs on a robust crust as a bed surface creates potential for a widespread wet slab avalanche cycle. We don’t expect likelihood to exceed “possible” today, but the gloppy snow may provide less than ideal skiing and riding conditions with heavily trafficked areas like the Sherburne being the exception.

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   8:00a.m., Friday, April 13, 2018. A new advisory will be issued tomorrow.

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

2018-04-13

Avalanche Advisory for Thursday, April 12, 2018

Huntington Ravine MODERATE and LOW avalanche danger. Central, Pinnacle, Odell, South and Escape Hatch have Moderate avalanche danger. Evaluate snow and terrain carefully. All other forecast areas have Low avalanche danger. Watch for unstable snow on isolated terrain features.

 Tuckerman Ravine has MODERATE and LOW avalanche danger. Sluice, Lip, Center Bowl, Chute, Left and Hillman’s Highway have 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.

AVALANCHE PROBLEM: Wind slabs remain the primary avalanche problem today. Small to medium sized wind slabs will become more of a threat later in the day as southwest wind increases and loads slopes further. Wind sheltered locations, especially Left and Chute in Tuckerman Ravine, yielded good powder skiing yesterday and also escaped the wrath of the hot April sun. These same aspects may receive more wind loading later today and become increasingly susceptible to triggering. If you are out in the afternoon, be on the lookout for increasing SW wind blowing and cross-loading snow from the alpine into start zones above. Wet loose avalanches may also become a problem, first as sun heats south facing slopes and later as slopes receive some rain or mixed precipitation. These smaller point release type avalanches can have remarkable pushing power as they entrain snow. Monitor your choice of slope for increasingly moist and dense snow and consider the consequences of a slide. Either avalanche type would occur over a bed surface which is icy and hard enough to be a challenge to arrest a fall on.

WEATHER: A trace of new snow fell in the past 24 hours with over 7” more in the past 48 hours. A west wind in the high 30 mph range blew again last night. Sunshine and warm conditions this morning will yield to cloud cover as low pressure moves towards the area. Temperatures in our forecast area should reach above freezing by mid-day. Warming temperatures will likely result in a mix of wet snow and rain in our forecast area with wind increasing from the 20 mph range at noon to the 40-60 mph range by sundown. The wind will shift from west to south and probably access some of the soft, recent snow remaining in our fetch in the process. A wide range of weather conditions will bring a wide range of changes to the snowpack through the day.

SNOWPACK: Avalanche activity Tuesday night and variable spring weather created a wide range of snow conditions consisting of older, stubborn wind slabs and a hard, icy crust hiding beneath the recent new snow, along with a thin sun crust on sunny aspects. There are areas of 2’ thick wind slab, especially in Central, the Lip and Center Bowl and other spots near the rollover where the old refrozen crust is lurking just beneath the new snow. While there were no signs of propagating cracks in these slabs yesterday, warming conditions could change that.  Our slopes are not at all the stable corn snow conditions that you might expect for mid-April. Continue to reduce your exposure in avalanche paths, carry avalanche rescue gear and manage your risk of long sliding falls carefully.

Be sure to check out our Instagram posts (@mwacenter) for up to date photos and videos. You don’t need an account to view them on your computer!

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., Thursday, April 12, 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

2018-04-12

Avalanche Advisory for Wednesday, April 11, 2018

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

Tuckerman Ravine has MODERATE and LOW avalanche danger. Lip, Center Bowl and Chute have 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.

AVALANCHE PROBLEM: Six to seven inches of very low density new snow fell yesterday on light winds. Overnight, west wind reached 37 mph with small, natural avalanches resulting. Wind slabs will be the primary avalanche concern today, with medium sized avalanches in moderate rated areas causing the most concern. If winds remain as light as forecast, our avalanche problem will be limited to small human-triggered, dry loose avalanches and small to medium sized wind slabs. Avalanche activity early this morning points to the fact that the new snow remains unstable and poorly bonded to older, firm wind slabs and ice crust. While likely to be small, avalanches today may occur on a bed surface which is icy and hard enough to be a challenge to arrest a fall on. Recent avalanche activity and variable spring weather is creating a wide range of snow conditions with older, stubborn wind slabs and a hard, icy crust hiding beneath the low density new snow. Our slopes are not at all the stable corn snow conditions that you might expect for mid-April so continue to reduce your exposure in avalanche paths, carry avalanche rescue gear and manage your risk of long sliding falls carefully. 

WEATHER: Today is starting out with blue skies and calm wind and 10F on the summit. Eleven centimeters (4.3”) of 6.1% density snow fell at Hermit Lake yesterday with 7” recorded on the summit. Summit wind speed is currently blowing at 9 mph and peaked at 37 mph from the west in the early hours of this morning which likely caused the avalanches observed in Duchess and Sluice. Wind is expected to remain light and shift southwest and blow 5-20 mph on the summit. Expect sunshine to continue this morning before clouds thicken this afternoon. More new snow is expected overnight before warmer temperatures and mixed precipitation arrives in our forecast area tomorrow.

SNOWPACK: Yesterday’s new snow fell on the previous layers of wind slab formed since Friday and in some areas, the hard-refrozen crust.  This weekend’s wind events left us with 2-3 layers of wind slab of varying softness (4F-F).  The wind slab is quite spatially variable and will make snowpack observations challenging.  We expect there to be areas of 20” wind slab and spots where the old refrozen crust is lurking just beneath the new snow.   The old refrozen crust is no longer visible in our terrain but make no mistake, it still exists.  The bonding of this new snow to the varying surfaces it fell on will differ across the snowpack.  We are still experiencing a mid-winter snowpack and are by no means in a melt freeze cycle yet.

Be sure to check out our Instagram posts (@mwacenter) for up to date photos and videos. You don’t need an account to view them on your computer!

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., Wednesday, April 11, 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

2018-04-11

Avalanche Advisory for Tuesday, April 10, 2018

Huntington Ravine has MODERATE and LOW avalanche danger. Central Gully 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.

Tuckerman Ravine has MODERATE and LOW avalanche danger. Lobster Claw, Right Gully, Sluice, Lip, Center Bowl, and Chute have Moderate avalanche danger. Evaluate snow and terrain carefully to identify features of concern. Left Gully, Hillman’s Highway, the Lower Snowfields, and the Little Headwall have Low avalanche danger. Watch for unstable snow on isolated terrain features.

AVALANCHE PROBLEM: Wind slab formed since late Sunday is our primary avalanche problem. Generally on the thin side and thus not likely to produce large avalanches, this layer remains possible to human trigger. It will likely vary from stubborn to touchy across the terrain. A secondary avalanche problem is the older and now generally stubborn wind slabs which formed on Friday and Saturday nights, the culprit of our widespread cycle of somewhat small human triggered avalanches over the weekend. This layer is beneath the more recent slabs in some areas and at or near the snow surface in others. Low rated areas have significant old refrozen crust at the surface, presenting a long sliding fall hazard while still holding small pockets of wind slab. It’s certainly a “Low” doesn’t mean “No” avalanche danger kind of day. Moderate rated terrain holds more widespread wind slabs, though it will be difficult for travelers to visually discern thin from thicker slabs as well as the older and more stubborn slabs from the newer and touchier slabs.

 WEATHER: Wind decreased last night as temperatures rose to near 10F on the summit. It looks to be a pleasant, wintry morning, with W wind hovering around 20 mph and temperatures rising to the teens on the summit. Increasing clouds and a weak weather disturbance later today could bring a trace to 2” of additional snow, with scattered snow showers possibly giving us similarly small amounts through the end of the day tomorrow. Wind is forecast to remain under 30 mph on the summit for the next 36 hours, limiting concerns for new wind slab development from these small amounts of new snow.

SNOWPACK: Winter is back, with layers of wind slab formed since Friday night in much of our terrain. The thick and robust refrozen crust which is under this recent snow and still present at the surface in some areas limits stability concerns to slabs at or near the surface. Friday night, Saturday night, and Sunday night all had distinct wind events which coupled with the recent snowfall to ultimately result in the current 2-3 layers of wind slab in the terrain. These slabs are all relatively soft though vary slightly (4F-F), and the most recently formed layers should be most reactive. Where old refrozen crust is not present at the surface, the snowpack looks fairly uniform, but really is quite spatially variable. We suspect that visually similar snow will vary from dust on crust to possibly 20” total of layered wind slabs. Additionally, bonding to the old crust seems to vary across the terrain. This means that there will be a distinct element of uncertainty in your snowpack observations. Ask yourself, “What will happen if it avalanches?” as you carefully choose terrain, and you’ll likely find some good wintry turns on this April day.

 Boston folks: Join us on today from 7-10 pm at Arc’teryx Boston for a night of learning, socializing, and free gear! Free to attend, but space in limited, register at eventbrite.com.

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  8:10 a.m., Tuesday, April 10, 2018. A new advisory will be issued tomorrow.

Ryan Matz, Snow Ranger
USDA Forest Service
White Mountain National Forest
(603) 466-2713 TTY (603) 466-2858

2018-04-10

Avalanche Advisory for Monday, April 9, 2018

Huntington Ravine has MODERATE and LOW avalanche danger. Yale, Central, Pinnacle, Odell, South, and Escape Hatch gullies have Moderate avalanche danger. Evaluate snow and terrain carefully to identify features of concern. North and Damnation gullies have Low avalanche danger. Watch for unstable snow on isolated terrain features.

Tuckerman Ravine has MODERATE avalanche danger. All forecast areas have Moderate avalanche danger. Careful snowpack evaluation, cautious route finding, and conservative decision making are essential. The Little Headwall is the exception to this rating with Low avalanche danger and areas of open water.

 AVALANCHE PROBLEM: Wind slab formed Friday night is our primary avalanche problem, with a secondary problem of smaller wind slab formed from the few inches of new snow that fell on strong W wind last night. The older wind slab has been observed up to 14” thick. It varies in thickness and bonding to the old refrozen crust beneath it, but has gained some strength since Saturday’s widespread human-triggered avalanche cycle. Visibility is limited this morning, but we expect that the new wind slab exists in relatively small pockets throughout the terrain. Today is a “small avalanches in many areas” kind of Moderate rating. We don’t expect any terrain to produce particularly large avalanches, with the old wind slab showing variable stability and the new wind slab suspected to be small. Relatively small avalanches can still bury, injure, or kill a person, especially if they happen in high consequence terrain with rocks, cliffs, vegetation, or other hazards in the runout. If avalanches aren’t enough to make you choose lower consequence terrain, be aware that the refrozen crust which exists at the surface in areas is very hard and could easily allow a long sliding fall.

WEATHER: Three inches of snow was recorded last night at Hermit Lake, with just one inch recorded on the summit. This snow fell on 50-70 mph W wind that continues currently. Snowfall has subsided, beginning a trend towards clearing skies today as wind may briefly shift NW before diminishing to below 40 mph on the summit by midday. Temperatures will be cold, with a summit high in the single digits above zero F. Tonight and tomorrow are forecast to have mostly cloudy skies, slightly warmer temperatures, and W summit wind in the 10-30 mph range. We may receive a few inches from upslope snow showers late Tuesday as winter conditions in April continue.

SNOWPACK: The wind slab formed Friday night proved to be reactive over the weekend, with at least eight human triggered avalanches that were all relatively small. Though these slabs have gained some stability over the past two days, new slabs formed overnight should be touchy though small in size. The bed surface of concern is our old refrozen and thick crust from melt/freeze cycles over the past two weeks. We don’t expect deeper instabilities to be a concern currently. Spatial variability is high today, with inconsistent bonding of the older wind slab and pockets of new, touchy wind slab. Areas of exposed refrozen crust where you won’t trigger an avalanche will be visible once clearing occurs later today, but the new and old wind slabs will appear very similar visually. This spatial variability means that it will also be difficult to apply stability tests results across terrain, as is often the case with wind slab. Backcountry travelers exercising careful terrain selection should be able to find favorable conditions among our varied surface snow, and skiers and riders should still enjoy the John Sherburne Ski Trail.

 Boston folks: Join us on Tomorrow, April 10, from 7-10 pm at Arc’teryx Boston for a night of learning, socializing, and free gear! Free to attend, but space in limited, register at eventbrite.com.

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., Monday, April 9, 2018. A new advisory will be issued tomorrow.

Ryan Matz, Snow Ranger
USDA Forest Service
White Mountain National Forest
(603) 466-2713 TTY (603) 466-2858

2018-04-09

Avalanche Advisory for Sunday, April 8, 2018

Huntington Ravine has CONSIDERABLE, MODERATE, and LOW avalanche danger today. Central Gully has Considerable avalanche danger. Dangerous avalanche conditions. Careful snowpack evaluation, cautious route finding, and conservative decision making are essential. Yale, Pinnacle, Odell, South, and Escape Hatch have Moderate avalanche danger.  Evaluate snow and terrain carefully to identify features of concern. North and Damnation have Low avalanche danger. Watch for unstable snow on isolated terrain features.

Tuckerman Ravine has CONSIDERABLE, MODERATE, and LOW avalanche danger today. Sluice, Lip, and Center Bowl have Considerable avalanche danger. Dangerous avalanche conditions. Careful snowpack evaluation, cautious route finding, and conservative decision making are essential. Right Gully, Chute, Left Gully and the Lower Snowfields have Moderate avalanche danger.  Evaluate snow and terrain carefully to identify features of concern. Lobster Claw, Hillman’s Highway, and the Little Headwall have Low avalanche Danger. Watch for unstable snow on isolated terrain features.

AVALANCHE PROBLEM: The 6” of snow that arrived Friday night on increasing west wind formed wind slab in all forecast areas. This wind slab proved touchy to human triggers yesterday with skier-triggered avalanches in Lobster Claw, Chute, Hillman’s Highway and the Little Headwall. Slab depths were up to 14” thick and while nobody was buried, enough snow was entrained to carry at least five people downhill in the Hillman’s avalanche. Size and distribution of this avalanche problem is aspect driven. East facing slopes (Considerable rated areas) contain more widespread wind slab capable of producing large avalanches. North and south-facing slopes (Moderate and Low rated slopes) contain smaller areas of wind slab that could produce a small avalanche. In addition to the avalanche problem, the exposed icy crust will make long, sliding falls a hazard today, particularly this morning before things warm.

WEATHER: Friday night into Saturday morning, the Hermit Lake snow plot recorded 6” of new snow while the summit received just under 5”. This was followed by clearing skies through the day on Saturday with a high temperature on the summit of 12F and an average wind speed of 50mph from the west. Last night, winds calmed to a current 15mph from the NW. Today, wind will remain from the NW and stay calm for the morning before beginning a gradual increase through the afternoon, reaching the 50-70mph tonight. Temperatures will increase to the teens on the summit. High clouds will be intermittent this morning with low and mid-level clouds developing in the early afternoon. There is also a chance for up to 1” of snow in the afternoon.

SNOWPACK: Wind slab sits on top of the icy melt-freeze crust that formed over the past week. Formed primarily Friday night with lesser wind loading continuing into last night, this wind slab has not bonded well to the bed surface and is reactive to human triggers. The bed surface will be icy this morning and may soften in the afternoon due to solar gain. The wind slab will remain reactive through the day. Safe travel techniques like not skiing or climbing under other people and traveling one at a time across a slope are key to getting home at the end of the day. The incident in Hillman’s Highway yesterday highlights this when a skier triggered avalanche in the looker’s left fork caught and carried multiple people below who were skiing and climbing. Other people on a slope do not mean the slope is safe, rather, they are potential triggers out of your control.

Check our Instagram for photo updates, we’ll post more specific information if we get any visibility today! You don’t need an account, just follow the link on our website.

 Boston folks: Join us on Tuesday, April 10, from 7-10 pm at Arc’teryx Boston for a night of learning, socializing, and free gear! Free to attend, but space in limited, register at eventbrite.com.

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  8:40 a.m., Sunday, April 8, 2018. A new advisory will be issued tomorrow.

Helon Hoffer, Snow Ranger
USDA Forest Service
White Mountain National Forest
(603) 466-2713 TTY (603) 466-2858

2018-04-08

Avalanche Advisory for Saturday, March 31, 2018

Huntington and Tuckerman Ravine have LOW avalanche danger today. All forecast areas have Low avalanche danger. Generally safe avalanche conditions exist.

AVALANCHE PROBLEM: Due to the melt-freeze cycle the mountain experienced over the past 48 hours, avalanche concerns have subsided for the day. A big drop in temperature following ¾” of rain has locked the surface of the snowpack and left avalanche terrain with a smooth, icy surface. Long, sliding falls will be the main concern today for skiers and climbers and will necessitate the skillful use of crampons and ice axes. In addition to this, other spring hazards are starting to appear, though weather today should prevent further development of undermined snow and keep most rock and ice in place rather than cascading down.  Climbers should be wary of ice dams as the cold snap will have trapped running water under a coating of ice that is waiting for pressure release in the form of a tool or screw placement. The Little Headwall is now open water and not recommended as an exit for those looking to ski out of Tuckerman Ravine.

WEATHER: On Thursday morning, the summit of Mount Washington recorded above freezing temperatures that stayed above 32F for 30 hours. During this time period, the summit also recorded 0.75” of rain. At noon on Friday, temperatures began a downward trend that bottomed out at a current 3F on the summit and 14F at Hermit Lake. As today progresses, a ridge of high pressure over the region will keep skies clear until late in the day when upper level moisture will bring clouds in the evening. Temperature will be colder than it looks today with highs on the summit maybe reaching 20F by early afternoon. Wind is currently out of the NW at 65mph and will shift to the SW as high pressure moves out of the region late in the day. Wind speeds should drop to the 30-45mph midday and then increase again when the wind shifts to the SW.

SNOWPACK: As expected, our snowpack took a hit from yesterday’s rain. There is significantly less snow in the tops of gullies than earlier in the week. That being said, due to the porosity of the snow that arrived in early March, the snowpack was able to accept the rain well and we saw no drastic changes beyond the Little Headwall opening up. Today certainly has the appearance of spring, though those stepping out of their cars in the Pinkham parking lot at 7am might beg to differ. During our morning forecasters meeting, we discussed whether we thought the snow would soften today. Despite a combined give or take 45 years of experience, we struggled to say yes or no. If you are looking for spring skiing today, it might happen given the clear skies. That being said, cold temperatures and forecast wind speeds may prevent even south-facing slopes like Right Gully and Lobster Claw from softening. Wise skiers will carry crampons and an ice axe today and be prepared to down climb or wait and pray for the snow to soften.

The Sherburne still has full snow coverage from top to bottom, though ice is starting to appear in the usual places.

Tonight is the last night of operation for the Harvard Cabin, Starting tomorrow, the only place to camp in the Cutler River Drainage will be at Hermit Lake Shelters.

Please Remember:
• Safe travel in avalanche terrain requires training and experience. This advisory is just one tool to help you make your own decisions in avalanche terrain. You control your own risk by choosing where, when, and how you travel.
• Anticipate a changing avalanche danger when actual weather differs from the higher summits forecast. For more information contact the Forest Service Snow Rangers, the AMC at the Pinkham Notch Visitor Center, or the caretakers at Hermit Lake Shelters or Harvard Cabin.
• Posted  8:00 a.m., Saturday, March 31, 2018. A new advisory will be issued tomorrow.

Helon Hoffer, Snow Ranger
USDA Forest Service
White Mountain National Forest
(603) 466-2713 TTY (603) 466-2858

2018-03-31

Avalanche Advisory for Friday, March, 30, 2018

Huntington and Tuckerman Ravines have MODERATE avalanche danger. All forecast areas have Moderate avalanche danger. Heightened avalanche conditions on specific terrain features.

AVALANCHE PROBLEM: Rain on cold, dry layers of snow raises our avalanche danger today. Warm temperatures and rain overnight will continue into the early afternoon hours today, adding strain to the weak layers that exist in the snowpack. There is a good chance that no natural avalanches will occur today, but any avalanche, natural or human-triggered, could be large and destructive. If, for some reason, you venture out into avalanche terrain in the cold rain today, keep this low probability but high consequence avalanche problem in mind. Temperatures will fall to the freezing level this afternoon and continue to drop through the night bringing improved stability to the snowpack. It will also create a hard, icy surface layer that sunshine and cool temperatures tomorrow may have a hard time breaking down.

Spring hazards are becoming prominent and should be considered in your terrain decisions. Long sliding falls on the hard, icy snow will be possible. Given the rain and refreeze, don’t count on the firm Styrofoam snow to be around tomorrow. Ice climbers should be aware of potential for ice dams in many climbs which can rupture with the placement of a tool, crampon, or screw. Above freezing temperatures will result in water flowing beneath ice which will become brittle in places when temperatures drop tonight. Undermined snow in stream beds will make exiting the Bowl challenging.

WEATHER: About a 0.4” (9.7mm) of rain fell overnight at Hermit Lake with more on the way today. The temperature is currently 39F on the summit and will slowly fall through the day, ultimately bottoming out at 8F on the summit at sunup tomorrow. West wind today will diminish a bit to 40-45 mph this afternoon but slowly ramp up and blow 65-70 mph tomorrow morning. Summit wind will diminish a bit tomorrow afternoon to 55-60 mph. Sunny skies are on tap and will likely seem appealing for a spring ski day but be prepared for borderline snow conditions which may struggle to soften even on sunny aspects.

SNOWPACK: Field time on the summit yesterday was a reminder of how important the direct sun and above freezing temperatures are to soften the snow surface. The more east facing snowfields were rock hard at 12 noon, despite sunlight filtered only by very thin, high clouds and temperatures at 34F. Wind from the west near 40 mph and indirect sunshine were enough to keep the snow from softening. Lower down the mountain, conditions improved on slopes facing directly into the sun but temperatures were quite warm there early on. Solar gain will be critical tomorrow. If you are choosing to come up on Saturday, remind yourself that the pressure that comes from a crowd of people is hard to withstand. Long-sliding falls often result in no injury whatsoever but have, on many occasions, resulted in life altering injuries and death. Look for sun softened snow, not the boot ladder with the most people.

Check our Instagram page, linked on our website, for conditions photos and additional updates. You don’t need an account to view our posts!

The Harvard Cabin will be open tonight and Saturday night and then close for the season.

Please Remember:
• Safe travel in avalanche terrain requires training and experience. This advisory is just one tool to help you make your own decisions in avalanche terrain. You control your own risk by choosing where, when, and how you travel.
• Anticipate a changing avalanche danger when actual weather differs from the higher summits forecast. For more information contact the Forest Service Snow Rangers, the AMC at the Pinkham Notch Visitor Center, or the caretakers at Hermit Lake Shelters or Harvard Cabin.
• Posted  8:00 a.m., Friday, March 30, 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) 466-2858

2018-03-30

 

Avalanche Advisory for Thursday, March 29, 2018

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

AVALANCHE PROBLEM: Temperatures will rise well above freezing today. So far, heating has been limited to the sunniest slopes and even then, wind and cool temperatures has limited heating to the surface. Today’s weather and snowpack trend is similar to the day a few years ago when a very large human triggered avalanche occurred on the summit cone. The warm temperatures that melt bonds between grains in the snowpack and create great skiing and riding conditions also melt bonds deeper in the snowpack. The first strong warming trend tests the strength of the snowpack, and in our case today, creates a low probability, high consequence avalanche problem. Natural and human-triggered avalanches are unlikely in most of our terrain but the threat of a large, hard slab makes it advisable to ski or ride a slope one at a time and to continue to carry your avalanche rescue gear. Large convexities or thin spots would be the most likely locations to trigger this type of avalanche. Wet loose avalanches could also occur in areas with strong solar gain or in the limited areas where soft snow remains. Low avalanche danger does not mean no avalanche danger!

WEATHER: A strong inversion this morning has valley locations slightly cooler than the summit which has already reached 30F. Tuesday night brought a trace amount of mixed precipitation to the mountain. Today looks clear and fairly calm though SW flow will bring clouds and eventually rain later this afternoon and evening. It looks as if these clouds won’t lower to become summit fog until nighttime though high clouds already developing this morning may reduce solar gain a bit this afternoon as they thicken. Temperatures should reach to the mid or high 30’s with 20-35 mph SW wind in the afternoon. Almost an inch of rain is forecast overnight and will further test our snowpack into tomorrow. Percolating rain in the snowpack will likely raise our avalanche concerns further tomorrow. 

SNOWPACK: The hard, icy melt-freeze crust that exists deep in the snowpack, beneath the firm wind slabs which developed March 17th, is one of the layers that will be a player in avalanche activity that occurs over the next couple of days. Rapid warming is one of the classic red flags signaling avalanche danger, along with heavy precipitation of any variety. The next 48 hours will bring changes to the snowpack which will ultimately reduce our avalanche concerns to the surface. Until then, we will continue to have the potential for a larger hard slab avalanche.

The Sherburne Ski Trail has good coverage top to bottom and should soften through the day. The usual scoured areas may start to reveal some rocks.

Check our Instagram page, linked on our website, for conditions photos and additional updates. You don’t need an account to view our posts!

The Harvard Cabin will be open all nights this week.

Please Remember:
• Safe travel in avalanche terrain requires training and experience. This advisory is just one tool to help you make your own decisions in avalanche terrain. You control your own risk by choosing where, when, and how you travel.
• Anticipate a changing avalanche danger when actual weather differs from the higher summits forecast. For more information contact the Forest Service Snow Rangers, the AMC at the Pinkham Notch Visitor Center, or the caretakers at Hermit Lake Shelters or Harvard Cabin.
• Posted  7:45 a.m., Thursday, March 29, 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) 466-2858

2018-03-29

Avalanche Advisory for Wednesday, March 28, 2018

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

 AVALANCHE PROBLEM: Snow on sun exposed slopes yesterday saw at least some degree of softening, which was followed by a quick refreeze in the afternoon. Areas seeing less direct sun continued to hold dry snow. Avalanche concerns are limited to small loose dry sluffs in this dry snow and loose wet sluffs when the refrozen snow warms again. The snowpack is exhibiting good stability and the current wintry mix of precipitation will not significantly change this. That said, we’re still far from a spring snowpack and it remains wise to travel one at a time in avalanche terrain while carrying a beacon, probe, and shovel.

 Spring hazards are becoming prominent and should be considered in your terrain decisions. Long sliding falls on the hard snow, which essentially all steep terrain holds, is a key concern today. If you brave the weather to travel in the alpine, crampons and an ice axe will be crucial equipment. Ice climbers should be aware of potential for ice dams in many climbs which can rupture with the placement of a tool, crampon, or screw. Recent above freezing temperatures has resulted in water flowing beneath ice and can create this hazard.

 WEATHER: A sunny and above freezing day yesterday gave way to increasing clouds which ultimately brought a wintry mix of precipitation to the mountain. Under an inch of mixed precipitation fell overnight and precipitation has tapered off this morning. Summit temperatures will hover around freezing as NW wind blows around 20 mph. Cloud cover should decrease to partly cloudy conditions by late today before increasing again by late tomorrow, bringing another round of precipitation that is currently forecast to fall as rain on the higher summits.

SNOWPACK: The nor’easters of two weeks ago ultimately built a firm upper snowpack which has exhibited good stability. Warming over the last two days did not penetrate deeply into this firm snow, though did allow softening yesterday to allow 4-6” of boot penetration on areas seeing greatest solar heating. These areas refroze quickly. Terrain which remained shaded or saw less direct sun continued to hold dry, cold, and firm snow. The mix of snow and sleet which fell overnight totaled less than a half inch at Hermit Lake. It has likely created additional variability in our snow surface but is not posing a stability concern. Avalanches are unlikely in the current conditions but the limited freeze-thaw action in recent weeks means that we still have a winter-like snowpack structure. The transition to an isothermal spring snowpack will likely occur in the coming weeks and is a time to begin planning for a variety of mountain hazards.

Check our Instagram page, linked on our website, for conditions photos and additional updates. You don’t need an account to view our posts!

The Harvard Cabin will be open all nights this week.

Please Remember:
• Safe travel in avalanche terrain requires training and experience. This advisory is just one tool to help you make your own decisions in avalanche terrain. You control your own risk by choosing where, when, and how you travel.
• Anticipate a changing avalanche danger when actual weather differs from the higher summits forecast. For more information contact the Forest Service Snow Rangers, the AMC at the Pinkham Notch Visitor Center, or the caretakers at Hermit Lake Shelters or Harvard Cabin.
• Posted  8:00 a.m., Wednesday, March 27, 2018. A new advisory will be issued tomorrow.

Ryan Matz, Snow Ranger
USDA Forest Service
White Mountain National Forest
(603) 466-2713 TTY (603) 466-2858

2018-03-28