Avalanche Advisory for Thursday, March 26, 2015

This advisory expires tonight at 12:00 midnight.

Tuckerman and Huntington Ravine have MODERATE avalanche danger.  Natural avalanches are unlikely and human triggered avalanches are possible in all forecast areas.  Evaluate weather, snow and terrain carefully to identify features of concern. Heightened avalanche conditions will develop on specific terrain features later today.

Mixed precipitation is expected to get started in the afternoon which will push us higher into the above ratings this afternoon. The ratings above most accurately reflect the daytime recreational period. Anticipate avalanche danger to increase, moving towards Considerable near sundown and more certainly in that rating after dark.

AVALANCHE PROBLEM: Existing stability is generally good to very good in most of the forecast area either because the upper snowpack is wind packed or wind scoured, or because it was exposed to strong solar heating yesterday. Some strong lee areas, like the Chute and the left side of Center Bowl as well as other lee pockets, harbor softer slabs. These softer slabs create the potential for Wet Slab avalanches later today as mixed precipitation falls. Wind Slabs may also develop later in the day. The degree to which these wind slabs will be problematic depends upon the type and timing of the precipitation’s changeover to snow.

WEATHER: The 1/3” of new snow yesterday evening did little to impact our stability. More precipitation is forecast for the afternoon with 1/4″ of water equivalent by dark and another 1/2″ or so through the night. The good news is that it will be getting colder with mixed precipitation on the summits turning to increasingly lighter snow overnight. The bad news is there is some chance for rain, in addition to freezing rain, sleet and snow, in our avalanche forecast area for a period this afternoon. Though not a tremendous amount of precipitation, it may be enough to weaken some existing softer surface slabs or penetrate thinner slabs. The type of precipitation is a wild card due to the position of the melt/freeze line within our forecast area.  Keep a close eye on temperature and incoming precipitation since they will directly impact stability today. As mentioned above, snow this afternoon and evening will increase and grow less dense as the cold front arrives with 2-4” expected to fall on diminishing winds overnight. Favorable conditions for upslope generated snow showers are forecast tomorrow with west winds potentially in the light range. Expect a new wind slab problem tomorrow and a return to wintry weather.

SNOWPACK: Generally firm or hard snow predominates in our terrain due the freeze/thaw cycle that started on Tuesday. Though summit temperatures that day never climbed to the mid-teens, the strong sunshine and dead calm wind in the forecast area allowed significant warming, even in shaded areas. Yesterday, it was apparent that south facing ice climbs in Huntington took a beating and slopes in Tuckerman developed peel away corn snow. Cooler temperatures overnight have no doubt hardened these aspects but the damage to ice features remains. Expect a hard surface requiring crampons and an ice axe in most areas today.  As a reminder, the warm temperatures over the past two days have not created a stable, isothermal spring snowpack.  Be wary of weak layers buried well down in the snowpack particularly in slightly lower elevation, lower angled terrain outside our forecast area.  Deeper weak layers in our terrain also exist but will most likely require more than today’s precipitation to activate.

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 the Harvard Cabin.
  • Posted 8:26 a.m. Thursday, March 26, 2015. A new advisory will be issued tomorrow.

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

2015-03-26 print friendly

Avalanche Advisory for Wednesday, March 25, 2015

This advisory expires tonight at 12:00 midnight.

Tuckerman Ravine has Moderate and Low avalanche danger. The Sluice, Lip, Center Bowl, and Chute have Moderate 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. Watch for unstable snow in isolated terrain features.

All forecast areas of Huntington Ravine have Low avalanche danger. Natural and human triggered avalanches are unlikely. Watch for unstable snow in isolated terrain features.

AVALANCHE PROBLEM: Aging wind slabs are the number one problem today. These began forming on Saturday night and didn’t stop growing until Monday morning when winds slowed. As with the past two days, the primary concerns are in the middle of Tuckerman, from the Sluice across to the Chute. The main issue is in the uppermost layer of the snowpack, which varies in depth but is generally at least 12” deep (30cm). Large avalanches can be produced from these locations. As you enter the floor of the bowl, you will be standing on old avalanche debris from previous avalanches that are smaller than what can be expected currently. Don’t assume the rocks in the floor are out of the range of the avalanche potential!

WEATHER: There is some weather coming in starting tonight, but for most of today, the weather will not affect snow stability to any great degree. Expect winds to be shifting to the south and increasing in speeds. Some light snow or mixed precip may fall this afternoon and evening, but accumulations will be light. The fun stuff will come on Thursday as a warm front surges toward us, bringing rain all the way to the summits.

SNOWPACK: A good portion of the terrain in Tuckerman and Huntington is very firm wind-hammered surfaces. These offer good stability, but not great skiing or riding conditions. If you’re heading into one of these Low rated areas, the climbing will be easier and safer if you have an ice axe and crampons.

In the Moderate rated areas, the upper snowpack is predominantly 1F to 4F hardness windblown slab. Beneath this is a thin layer of new snow that fell prior to the winds ramping up in speeds on Sunday and loading the new slab on top. This weak layer is now buried under the aforementioned slab and waiting for a trigger. Fortunately, the upper slab does have a fair amount of strength to it, so we’re falling short of thinking human triggered avalanches are likely (which would warrant a Considerable rating.) In fact, these are the conditions where you could see several people ski or ride a slope without triggering an avalanche. This certainly does not imply the slope is stable, just that it’s not a hair-trigger Moderate. I can envision a situation where several people skiing the slope could actually be cutting apart the strength of the upper slab, making it a little less stable with every set of tracks. The snow quality in these areas is carvable and alluring, especially compared to the quality you’ll find in the Low rated areas, but don’t allow your desire to have fun influence your risk assessment. Make quality snow stability assessments, think hard about your decisions, and be prepared for the worst case scenario. In these conditions an avalanche could easily kill you, and that would certainly ruin the fun you and your buddies came for.

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 the Harvard Cabin.
  • Posted 6:30 a.m. Wednesday, March 25, 2015. A new advisory will be issued tomorrow.

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

2015-03-25

Avalanche Advisory for Tuesday, March 24, 2015

This advisory expires tonight at 12:00 midnight.

Tuckerman Ravine has Moderate and Low avalanche danger. The 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 and human triggered avalanches are unlikely. Watch for unstable snow in isolated terrain features.

All forecast areas of Huntington Ravine have Low avalanche danger. Natural and human triggered avalanches are unlikely. Watch for unstable snow in isolated terrain features.

AVALANCHE PROBLEM: Wind slab is the primary avalanche problem today. This problem is focused on the midsection of Tuckerman, from the Sluice through the Chute. As far as a Moderate rating goes, the likelihood of triggering a slide is on the lower end of the rating’s range, but not stable enough to warrant a different rating. Additionally, the stakes are raised quite a bit as we would expect the size of an avalanche here to be large and destructive. Other areas rated Low have good stability thanks to very strong winds hammering the slopes into submission. Be watchful for isolated unstable pockets in strongly sheltered areas such as the Lower Snowfields.

WEATHER: Very few people ventured up into the ravines yesterday, and for good reason. Temperatures spent much of the day below zero degrees Fahrenheit while summit winds blew strong throughout the day. From Sunday and into Monday morning, winds had been gusting over 100mph for more than 24 hours. They started to subside yesterday and have come down to near calm levels for this morning. Today you’ll have relatively light winds and sunshine but wintery temperatures will keep it from feeling too much like spring.

SNOWPACK: A good portion of the terrain in Tuckerman and Huntington is firm wind-hammered surfaces. These offer good stability, but not great skiing or riding conditions. If you’re heading into one of these Low rated areas, the climbing will be easier and safer if you have an ice axe and crampons. Speaking of wind-hammered surfaces, the Sherburne trail was scraped clean down to old hard snow for much of its length. My mountaineering boots barely scratch the surface when walking on it.

The focus of the avalanche problems in Tuckerman are found under the ice in the Center Bowl and in the Lip area. The rim of the ravine was blown clean, and the lower angle transition to the floor is a mix of scoured and wind-hammered. It’s the elevation right in the middle where it’s most steep that you will want to be watching. You can expect firm surfaces and strong slabs in the upper layers, but what lurks beneath the surface is where the problem resides. Depending on your exact location, you may see weak interfaces between wind layers, faceting, or recently hidden ice, rocks, or bushes that have created shallower weak spots.

Sunshine may have an effect on steep south facing slopes, but I don’t expect this to be too great or have a significant effect on stability.

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 the Harvard Cabin.
  • Posted 7:45 a.m. Tuesday, March 24, 2015. A new advisory will be issued tomorrow.

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

2015-03-24

Avalanche Advisory for Monday, March 23, 2015

This advisory expires tonight at 12:00 midnight.

Tuckerman Ravine has MODERATE and LOW avalanche danger. Sluice, Lip, Center Bowl, Chute, and Little Headwall have Moderate avalanche danger. Natural avalanches are unlikely and human-triggered avalanches are possible. Evaluate snow and terrain carefully. Lobster Claw, Right Gully, Left Gully, Hillman’s Highway, and the Lower Snowfields have Low avalanche danger. Natural and human-triggered avalanches are unlikely. Watch for unstable snow on isolated terrain features.

All forecast areas in Huntington Ravine have LOW avalanche danger. Natural avalanches and human-triggered avalanches are unlikely. Watch for unstable snow on isolated terrain features.

 AVALANCHE PROBLEM:  It is no surprise that Wind Slab is the primary threat today. Hard and stubborn slabs of wind packed snow exist in Sluice, Lip and Center Bowl and probably on the approach to Yale and Diagonal and around areas near the Fan. More sensitive slabs likely exist in the most sheltered lee areas near terrain features and steep bushy areas that create natural wind drift fences. Thin, weak spots in firm slabs like we have now can serve as trigger points in an otherwise strong slab so use caution even in Low rated areas. Due to its low elevation and wind sheltered location, the Little Headwall has collected a lot of snow recently which has buried all the anchors and created a convex surface. Be careful if you are among the first few parties to ski the slope; the terrain traps below are nasty.

 WEATHER:  Again, the wind is raging on the mountain with a peak wind speed of 111 mph (179 km/h) recorded yesterday. Currently, NW winds are blowing at 88 mph (142 km/h) with the mercury standing at -22F (-30C). Temperatures will rise to near 0F (-18C) today as winds decrease to the 45-60 mph (70-95 km/h) range. Expect continued gusty conditions peaking at 105 mph (169 km/h) this morning as well as a challenging experience packing up in the parking lot at Pinkham, not to mention standing and walking above treeline. Conditions should moderate this afternoon but January-like weather will persist over the next couple of days. A warm front on Wednesday could bring a mixed bag of precipitation to the forecast area, the nature of which depends on the exact track of the front.

SNOWPACK: Wind speeds like we are having now created a long, sliding fall problem in addition to the avalanche concerns mentioned above. Though the pencil hard slabs on the surface will allow purchase from a hard boot or ski edge, most people would be comforted by the security of crampons. Persistent slabs are a distant threat on the horizon that may become more relevant this week as temperatures warm and the threat of rain increases. Though not a standout danger due to the strength of overlying slabs and their discontinuous nature, these weak layers of faceted snow are certainly present beneath old layers of wind slab.  In our forecast area, you will most likely find these layers near edges of avalanches paths that have not been swept out by previous avalanche activity or really deep in the snowpack. Other terrain around the White Mountains could also contain these weak layers near old buried crusts so you may want to look for this potentially problematic layer deeper than you would dig for a hand shear. A meter deep pit once in a while could help you make informed decisions and keep your risk acceptance discussions real.

 This last weekend saw an uptick in traffic in both Ravines. As we move into the spring season please remember that the party like atmosphere seems to distract folks from the hard of facts of mountain travel. Legitimate mountain hazards are abundant on, above and beneath our slopes and gullies so prepare carefully, stay alert and help others when you can.

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 the Harvard Cabin.
  • Posted 8:25 a.m. Monday, March 23, 2015. A new advisory will be issued tomorrow.

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

2015-03-23 print friendly

Avalanche Advisory for Sunday, March 22, 2015

This advisory expires at midnight.

Tuckerman Ravine has Considerable avalanche danger. Natural avalanches are possible and human triggered avalanches are likely in all forecast areas. Dangerous avalanche conditions exist.  

 Huntington Ravine has Moderate avalanche danger.  Natural avalanches are unlikely and human triggered avalanches are possible. Evaluate snow and terrain carefully to identify features of concern. Heightened avalanche conditions exist on specific terrain features.

 AVALANCHE PROBLEM: Wind slabs are our primary avalanche concern today. 5” of new snow fell since yesterday afternoon and is currently being deposited in our terrain in the sheltered lee of WNW and NW winds. Hard but stubborn wind slabs will be created by the strong winds today. Expect these slabs to build quickly this morning when peak avalanche instability is likely to occur. Huntington Ravine, being higher and in a more windward location, may see more scouring than loading this morning. Some locations like Central, Pinnacle and Odell may also be sluffing heavily this morning.

 WEATHER: Robins and crocus blooms are nowhere to be seen at Hermit Lake this morning. However, if you prefer wind drifted snow, rimed over conifers and biting arctic winds over the typical signs of spring, you won’t be disappointed. Wind speeds at the summit are gusting over 100 mph (160 km/h) this morning and are expected to hit 130 mph (210 km/h) later today.  Steady 90-110 mph (145-175 km/h) northwesterly winds will make a journey above treeline a fool’s errand even though velocities will abate later to the 80-100 mph (130-160 km/h) range. The 5” (13 cm) of new snow from yesterday is still airborne, along with dense fog, reducing visibility to a few hundred feet at Hermit Lake. Temperatures will continue to fall as the cold front passes, ultimately bottoming out at -25F (-32C) sometime later today.

 SNOWPACK: After the balmy but still winter-like conditions yesterday, the adventurous souls camping around Mount Washington are receiving a brutal wake-up call from weather concierge this morning. Tent flattening wind velocities and face numbing winds would push a quick journey to the nearest coffee shop to the top of my to-do list. Climbing and skiing conditions yesterday, and pretty good crowd of folks enjoyed the firm snow in both Ravines. Snow fall held off until around sundown and bumped new wind slab avalanches off the list of hazards to negotiate. Firm snow (pencil hard) dominated the scene with a few pockets of softer and harder snow here and there depending on aspect and the presence natural drift fences. Today’s wind event is creating similar conditions though I have no intention of venturing into avalanche terrain to verify this today. Expect peak instability sometime this morning, if it hasn’t peaked already, along with brutally challenging conditions for walking, much less for making careful snow stability assessments, group discussions on terrain selection and hazard mitigation.

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 the Harvard Cabin.
  • Posted 8:25 a.m. Sunday, March 22, 2015. A new advisory will be issued tomorrow.

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

2015-03-22 print version

Avalanche Advisory for Saturday, March 21, 2015

This advisory expires at midnight.

Tuckerman and Huntington Ravine have Moderate avalanche danger.  Natural avalanches are unlikely and human triggered avalanches are possible.   Evaluate weather, snow and terrain carefully to identify features of concern. Heightened avalanche conditions will develop on specific terrain features later today.

Snow and wind is expected to pick up late in the afternoon which should increase the above ratings very late in the day.  Both Ravines will be at the ceiling of their rating definitions in the afternoon. The ratings above most accurately reflect the recreational daylight period, however this is all based on the expectations that snow accumulations are limited until then. Anticipate avalanche danger to increase, moving towards Considerable, from dinner time towards midnight as snow increases in volume and intensity.

AVALANCHE PROBLEM: We are starting the day with a generally stable snowpack. Firm wind slabs with good stability are the predominate feature of our upper snowpack. Unstable new Wind Slabs will become the primary avalanche problem today. New snow this afternoon on increasing winds will build wind slabs in our start zones which will be reactive to human triggers and will potentially release naturally late this evening. Older Wind Slabs resting on the steepest slopes are the second concern to look out for. Though stubborn, these slabs could potentially crack and fail if you applied the right load in the right spot.

WEATHER: Some snow flurries are falling at the moment with the temperature standing at a relatively balmy 20 F (-7 C) under an overcast sky. The cold front that is arriving today will bring 1-3″ (2.5-7.5 cm) of snow this afternoon with 2-4″ (5-10 cm) overnight followed by upslope showers tomorrow amounting to 1-2″ (2.5-5 cm). Winds are currently light from the west at 20-35 mph (30-55 km/h) but will increase through the day to the 35-50 mph (55-80 km/h) range and hit the 80-100 mph (130-160 km/h) range overnight. Today, winds speeds will be ideal for loading and will also contribute to diminished visibility. Temperatures will fall to around -15 F (-26 C) overnight. The timing of this incoming weather has the potential to spring a trap on the unwary or under prepared! Consider the consequences of delays in your travel plan today!

SNOWPACK: Very firm snow conditions exist throughout the Ravines with a mix of  just barely boot-able and edge-able firm newer wind slabs and more heavily textured snow (sastrugi) in windward areas like Hillman’s, Left Gully, South and Escape Hatch. The smooth pencil hard snow of gullies and slopes with a more southerly and easterly aspect allow passage without crampons but only with extreme care….consider wearing points particularly as new snow covers areas of the icier crust that exists on slopes that have caught sun lately. The firm, newer wind slab is resting on a much older, almost knife hard wind slab and an icier melt freeze crust. Field work in Right Gully, SLuice and Chute yesterday revealed that the firm, newer windslab was surprisingly well bonded with these harder layers below. Clean and smooth but slow and un-energetic Q2 shears broke in the upper wind slab layers rather than on the harder surface beneath. There was no sign of faceting at this interface yet but it is something to keep an eye on as temperatures plummet tomorrow. The firm wind slab in the upper snowpack is very strong and bridging well.

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 the Harvard Cabin.
  • Posted 8:35 a.m., Saturday, March 21, 2015. A new advisory will be issued tomorrow.

Frank Carus /Chris Joosen, Snow Ranger
USDA Forest Service
White Mountain National Forest
(603) 466-2713 TTY (603) 466-2713

2015-03-21

 

 

Avalanche Advisory for Friday, March 20, 2015

This advisory expires at midnight.

Tuckerman Ravine has Moderate and Low avalanche danger.  The Sluice, Lip, Center Bowl, Chute and the Lower Snowfields have Moderate avalanche danger. Natural avalanches are unlikely and human triggered avalanches are possible.  Heightened avalanche conditions on specific terrain features exist so evaluate snow conditions carefully to identify features of concern.  Lobster Claw, Right Gully, Left Gully, Hillmans Highway and the Little Headwall have Low avalanche danger. Natural and human-triggered avalanches are unlikely but watch for unstable snow on isolated terrain features.

Huntington Ravine has Low avalanche danger.  Natural and human triggered avalanches are unlikely except in isolated terrain.  These pockets of concern do exist is some locations.

AVALANCHE PROBLEM: Wind Slabs are the primary avalanche problem today. You will find firm and stubborn to trigger wind slabs scattered around our terrain with the greatest concentration of larger wind slabs in areas that are rated Moderate. The bull’s-eye for these wind slabs is in the Sluice, Lip and Center Bowl area where slopes have smoothed and grown much more continuous over the past week or so. Smaller, but still potentially unstable wind slabs, exist in some areas isolated areas within Low rated areas.  Assess these areas carefully from the relative safety of old hard surfaces. Consider the de-stabilizing contribution that some limited heat from the sun may have on south facing slopes, especially in Tuckerman where the recent wind slabs are more widespread.

WEATHER: The windy weather of the past several days is well understood by valley residents. Branches and downed trees on the surface of the snow and wide spread wind scouring of slopes and gullies in many places testify to the protracted period of high winds that we have experienced on the mountain up until mid-day yesterday. Finally, the wind has abated as fair weather visits us briefly today. Summit temperatures have risen from 0F (-18C) last night at midnight to 16F (-9C) this morning where they are expected to remain though the day until the next arctic cold front approaches tonight. Clouds will build overhead this afternoon with new snow (Trace – 2” or 5cm) falling tonight. Calm winds from the west at 10-25mph (15-40 km/h) with some higher gusts to 40 mph (65km/h) will provide a nice break from the recent wicked winds. More snow, with winds blowing at an ideal rate for loading our forecast area, will probably elevate our avalanche danger Saturday and Sunday.  In addition, expect wind velocities to rage over 100mph and the mercury to dive deeply below 0F on Saturday night.  Keep a close eye on the Mount Washington Observatory weather forecast for more updates and check back for the latest avalanche advisory each morning.

SNOWPACK: Field time yesterday confirmed the hammering that our slopes received. Heavily sculpted snow (sastrugi) is the dominate feature of surface snow in many areas and in most areas of Huntington Ravine. Elsewhere, in the lee of northwest winds and at lower elevations in Huntington, wind transported snow grains packed into finger to pencil hard, smooth slabs which yields to boots and ski edges. In many areas, the older exposed surface is icy, so without crampons you would be forced to be a slope stability tester by travelling on the smoother and slightly softer wind slabs. Today seems to be the nice weather window for the weekend and will likely be the only day of the weekend with good stability. Remember that Low ratings carry with it the full weight of the North American Public Danger Scale, including travel advice and avalanche size and distribution. Don’t be bashful about reminding people that Low avalanche danger doesn’t mean no avalanche danger. We still have a dynamic winter snowpack, despite today being the first day of spring, so bring your avalanche skills and rescue gear if you want to play on the mountain.

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 the Harvard Cabin.
  • Posted 8:40 a.m. March 20, 2015. A new advisory will be issued tomorrow.

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

2015-03-20

Avalanche Advisory for Thursday, March 19, 2015

This advisory expires at midnight.

Tuckerman has Moderate and Low avalanche danger.  Lobster Claw, Right Gully, Sluice, Lip, Center Bowl, Chute and Lower Snowfields have Moderate avalanche danger. Natural avalanches are unlikely and human triggered avalanches are possible.  Heightened avalanche conditions on specific terrain features exist so evaluate snow conditions carefully to identify features of concern.  Left Gully, Hillmans Highway and the Little Headwall have Low avalanche danger. Natural and human-triggered avalanches are unlikely but watch for unstable snow on isolated terrain features.

Huntington Ravine has Low avalanche danger.  Natural and human triggered avalanches are unlikely except in isolated terrain.  These pockets of concern do exist is some locations.

AVALANCHE PROBLEM: Wind Slabs are the primary concern today.  Firm and stubborn wind slabs were built up during the last 36 hours of high wind. These slabs are largest in Moderate rated areas and most easily triggerable in the steepest or most wind protected areas of these gullies. Areas that fit this description are near the top out of Lobster Claw and Right Gully and in the Lower Snowfields at the convexities near the top of the “Christmas tree” feature and in the debris cone of Duchess. Sheltered areas near cliff walls and beneath steep pitches of ice may also harbor pockets of wind slab so stay alert in these areas as well. Larger areas of this wind slab in the Sluice, Lip and Center Bowl should have your hackles up due to the expansive nature of the slabs that exist there. Though stubborn, these areas hold the potential for larger and deeper avalanches.

WEATHER: Continued unseasonably bitter cold is on tap today with the NW wind finally diminishing a bit from the current 70-90 mph (115-145km/h) to the 50-70 mph (80-115 km/h) range later today. Since mid-day on Tuesday, gusts in excess of 100 mph (160 km/h) have been recorded 15 times in the past 36 hourly recordings with the period of highest peak wind speeds occurring from yesterday just after sun-up to around lunchtime. A cloud cap is still hanging around Tuckerman though Huntington is beginning to clear out. This clearing trend should continue through the day. The summit high temperature will reach all the way up to -5F (-20C) today after the mercury completes its downward journey to -20F (-29C) this morning.

SNOWPACK: It was pretty clear that our snowpack has taken a pummeling from winds as we bobbed and weaved between large wind drifts, downed branches and pine boughs this morning on the Tuckerman Ravine trail. A few brave souls made the journey up to ski the Sherburne trail yesterday with many resorting to goggles while skinning to deal with the wind and cold. Unfortunately, today won’t offer much better conditions. Old hard surface and wind hammered slabs would be your reward for pushing through the high wind and cold weather to reach our steep terrain. I suppose good cramponing with little post-holing puts a checkmark in the climber’s plus column, but tomorrow looks like a much kinder day for climbing as far as the wind and cold goes. An inch or three of new snow (2.5-7.5 cm) is possible starting tomorrow afternoon and overnight Friday.

There are little technical details to share as far as the snowpack goes. Hopefully we’ll be able to get into the terrain today to have a look at the current snow structure and determine if any forecast areas are more scoured than we think. If venturing above tree-line today, anticipate hard going with large snow drifts and high wind gusts to contend with. Though weather conditions are improving slightly through the day, climbing Mount Washington is still the real deal. Be prepared for arctic conditions despite the proximity of the vernal equinox.

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 the Harvard Cabin.
  • Posted 8:05 a.m. March 18, 2015. A new advisory will be issued tomorrow.

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

2015-03-19 print friendly

Avalanche Advisory for Wednesday, March 18, 2015

This advisory expires at midnight.

Tuckerman Ravine has CONSIDERABLE and MODERATE avalanche danger. Lobster Claw, Right Gully, Sluice, the Lip, Center Bowl and the Chute have Considerable avalanche danger. Natural avalanches are possible and human-triggered avalanches are likely. Careful snowpack evaluation, cautious route-finding and conservative decision making are essential. Left Gully, Hillmans Highway, Lower Snowfields and the Little Headwall have Moderate avalanche danger. Natural avalanches are unlikely and human-triggered avalanches are possible.

All forecast areas in Huntington Ravine have MODERATE avalanche danger. Natural avalanches are unlikely and human-triggered avalanches are possible. Evaluate snow and terrain carefully to identify features of concern.

 AVALANCHE PROBLEM:  Wind velocities over the past 12 hours have reached past the century mark and scoured many of our start zones especially in higher elevation areas in Huntington.  Large but stubborn Wind Slabs in other areas protected from the NNW and NW wind are the primary concern. Look for these slabs lower in our slopes and gullies such as the approach to climbs in Huntington, the Lower Snowfields and mid slope in the Considerable rated terrain in Tuckerman. Another trace to 2” (TR to 5cm) of snow on somewhat diminishing winds is forecast later today. This new snow has the potential to create more wind slabs higher in start zones in the more typical places and add load to existing wind slabs.

WEATHER: Low visibility due to summit fog and continued blowing snow will create a significant challenge to snow and terrain assessment to anyone braving the wind and cold. Identifying your position relative to an avalanche path will be difficult, to put it mildly, so travel in the floor of either Ravine, and particularly Tuckerman’s, is probably not the best use of your time today. Even if you know the terrain intimately, wind velocity and cold will make travel near treeline a significant challenge with a razor’s edge safety margin. High temperatures around -15F (-26C) and winds gusting to 120 mph (190 km/h) will again delay the onset of spring skiing conditions.

SNOWPACK:  On Sunday and Monday, relatively small skier triggered avalanches in Hillmans (Sunday, R2) and Right Gully (Monday, R3) were a good reminder that spring skiing weather and good snow stability do not rely on the calendar to arrive. These wind slab avalanches failed on the interface between harder and softer wind slabs that developed over the weekend. This interface was thin but failed cleanly and easily in stability tests. Furthermore, a melt freeze crust from last Tuesday/Wednesday shelters another weak layer of snow in the upper snowpack. Though discontinuous, this melt freeze layer forms the upper slice of bread in a weak layer sandwich with the old, hard slab beneath. This layer of early facets is worth keeping in the back of your mind since it may be a player in areas where it still exists. It was swept out and no doubt contributed a volume of snow to the avalanche in Hillmans.

It is important to remember that hard slabs like the ones developing from today’s wind can be deceptive in that they may appear stable due to their firmness. However, this firmness can also be understood as brittleness, so this type of slab can crack a good distance on a steep slope as the slab weakens due to warming or stressed by an increasing load such as more slabs or skier/climber weight in the right spot.

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 the Harvard Cabin.
  • Posted 8:05 a.m. March 18, 2015. A new advisory will be issued tomorrow.

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

2015-03-18 print friendly

Avalanche Advisory for Tuesday March 17th, 2015

This advisory expires at midnight.

Tuckerman and Huntington Ravines will have Considerable avalanche danger.  Natural avalanches will be possible and human triggered avalanches will be likely.  Dangerous avalanche conditions will exist requiring conservative decision making.  The Little Headwall has Low avalanche danger.  Natural and human triggered avalanches are unlikely except in isolated terrain.

AVALANCHE PROBLEM: Wind Slabs are the primary concern today.   Unstable slabs left over from the weekend storm still exist, peppered across the Ravines.  This morning we are starting out with old wind slabs having fair to good stability depending on location.  Moderate winds early this morning will cause the start of new loading to occur.  This will begin with lower density soft slabs, moving towards denser slabs over initial layers as the day progresses.  Raging wind velocities, perhaps climbing to 130mph (210kph) late today, will move a tremendous amount of snow.  This will create a period of natural avalanche potential in both Ravines. As winds move through the century mark a number of locations will move towards scouring and stabilizing.  Peak instability will likely be through the midafternoon towards dinner time, but this will depend on how quickly wind speeds increase.

WEATHER: A somewhat tranquil morning will create what some call a “sucker hole”.  Drawing in the unaware tempting them to skip through the mountains.  However, as the day progresses the current summit temperature of 23F (-5C) and a wind speed of 31mph (50kph) will seem like another world. Big wind will rule by this afternoon eventually gusting way over 100mph (160kph).  This evening a peak velocity may reach between 130-140mph (210-226kph) as temperatures fall to -20F (-29C).  What’s that in wind chill? Too cold!  Snow is expected up to 2” (5cm) today and again tonight, with some localized higher amounts due to a developing trough.

SNOWPACK: The wind slabs that were created during the weekend storm still hold some instabilities as we head into the next loading event today.  Two human triggered avalanches over the past couple of days were good indicators of the reactivity to skier weight and loading.  Solar gain helped some direct south facing slopes stabilize a bit yesterday, although nearby snow pointing slightly towards SE or SW retained their cold properties and was less affected.  Today, a building wind will likely create an upside down snow pack with light low density snow developing this morning, followed by denser layers through the day.  As the freight train winds move snow from the alpine zone and the other side of the range, particles will become smaller, beat up, and will pack into denser slabs.  This scenario develops a classic instability of dense harder snow over newly developed softer slabs, leaning towards a propensity to fracture and fail.  The timing of the developing wind ramp up is the key ingredient to this recipe.  Forecast models are showing a shifting wind from the W to the NW up to 50mph (80kph) this morning, 50-70mph (80-112kph) during the early afternoon, climbing towards 100 late in the afternoon, gusting much higher.  By late today into the evening 110, 120, 130, 140mph are all a possibility so expect treeline travel to be less than inviting.  If tonight’s conditions were a high school band they’d be billed as “Extreme Insanity”.  Be conservative in your travels and plan to get out of alpine zones early today.  Although it seems fine now, it won’t be later.  These winds will eventually scour many slopes turning them back towards more stability.  This may occur as early as later this afternoon for Huntington Ravine, but between poor climbing weather and occurring late in the day this won’t be too helpful for mountain travelers today.

Please Remember:

  • Safe travel in avalanche terrain requires training and experience. This advisory is just one tool to help you make your own decisions in avalanche terrain. You control your own risk by choosing where, when, and how you travel.
  • Anticipate a changing avalanche danger when actual weather differs from the higher summits forecast.
  • For more information contact the Forest Service Snow Rangers, the AMC at the Pinkham Notch Visitor Center, or the caretakers at Hermit Lake Shelters or the Harvard Cabin.
  • Posted 8:40 a.m. March 17, 2015. A new advisory will be issued tomorrow.

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

2015-03-17