Avalanche Advisory for Wednesday, December 31, 2014

This advisory expires tonight at 12:00 midnight. Happy New Year’s Eve, everyone!

All forecast areas of Tuckerman and Huntington Ravines have Low avalanche danger. Natural avalanches are very unlikely and human triggered avalanches are unlikely except in isolated terrain features. Unstable snow may exist in isolated terrain features – use caution in these locations.

AVALANCHE PROBLEM: Similar to yesterday, current avalanche problems are limited to small pockets of wind slab that developed early this week. There is a slight chance for enough snow to fall today that new wind slabs may develop in isolated areas, especially the well-protected leeward slopes in Tuckerman. In both ravines, the overall snowpack is looking rather sparse for the end of December. This means the locations where you may find unstable slab are relatively small and isolated from other areas of snow. This does not mean they are “safe” or that you should leave the beacon, shovel, and probe down in the car. In fact, given the consequences of a fall in the current conditions, any small pocket of unstable snow will be quite dangerous. On the whole, there is a lot of stable snow out there, but don’t let your guard down.

WEATHER: The cold weather has certainly settled in over the mountains. The summit of Mt. Washington has been below zero degrees F for about 40 hours now and may only go a few degrees above at some point tomorrow. A cold front will pass by this morning, providing a chance for some light snowfall accumulations of a trace – 2″ (tr-5cm). Winds will continue to be fairly strong, but may diminish somewhat after the front has passed by. Expect gusts up to 75mph (120kph) this morning. Once again, be prepared for arctic conditions above treeline. You may also face very limited visibility with clouds and blowing snow.

SNOWPACK: Throughout much of both ravines you will find snow with good to very good stability. Exposed crust and wind-packed hard slab are commonplace right now. Both of these surfaces can be very strong and make for good climbing conditions, and they can also make for very rapid descents if you were unable to quickly self-arrest a fall. There are two stability situations you should be watching out for. One is a slab resting on top of a layer of weak snow on top of crust. I saw this in one location beneath Pinnacle Buttress two days ago, and can envision other similar pockets existing elsewhere. The other is any new soft slabs created this morning from new snow and wind loading. I expect both of these to be limited in size and distribution. The true extent of the new slab problem will be determined by the amount of new snow received. If we reach or exceed the 2″ mark, this problem may push the boundaries of Low danger in favorable locations.

In other news, the Lion Head Summer Trail remains open and will be the preferred route until we get significantly more snow. The trail does cross an avalanche path in a couple locations, but there needs to be a lot more snow before this becomes a problem. The John Sherburne Ski Trail has fair coverage but is very hard-packed, icy, and very bumpy. And finally, we will be resuming the Eastern Snow and Avalanche Workshop (ESAW) Continuing Education Series this winter. The first session will be in mid-January. Stay tuned to our Facebook page for more details in the coming days.

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 7:30 a.m. December 31, 2014. A new advisory will be issued tomorrow.

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

2014-12-31

Avalanche Advisory for Tuesday, December 30, 2014

This advisory expires tonight at 12:00 midnight.

All forecast areas of Tuckerman and Huntington Ravines have Low avalanche danger. Natural avalanches are very unlikely and human triggered avalanches are unlikely except in isolated terrain features. Unstable snow may exist in isolated terrain features – use caution in these locations.

AVALANCHE PROBLEM: Avalanche problems today are limited to small pockets of wind slab that developed over the past couple days. In both ravines, the overall snowpack is looking rather sparse for the end of December. This means the locations where you may find unstable slab are relatively small and isolated from other areas of snow. This does not mean they are “safe” or that you should leave the beacon, shovel, and probe down in the car. In fact, given the consequences of a fall in the current conditions, any small pocket of unstable snow will be quite dangerous. On the whole, there is a lot of stable snow out there, but don’t let your guard down.

WEATHER: Today is going to be a sunny day on the mountain, albeit cold and windy. I don’t expect today’s winds to have much of an effect on the avalanche conditions. The snow that landed at upper elevations two days ago has largely reached its final destination already, or at least until we see a significant jump in wind speeds. If you are out in the Presidentials today, even just for a hike, be prepared for arctic conditions and gusty winds. Cover up exposed skin!

SNOWPACK: We had been watching the weather closely over the last couple days, mostly because cloud cover on the mountain meant that was all we could see. Yesterday afternoon the clouds broke and Frank and I were able to get into both ravines to see what happened with the 5” of snow that fell on the summit Sunday and was followed by very strong winds. Much to our dismay, it did not appear as though 5” of snow had been loaded in. This could be due to a variety of factors, but the result is the same. We saw areas of old crust, areas of wind-hammered snow, and occasional pockets of slab with a weak layer of unconsolidated snow between the slab and the crust. These pockets were found only in very strong lee areas that were well protected from winds. If there are avalanche concerns out there today, they will be in these isolated pockets. Your best bet for finding them would be in the Lip (where the Tuckerman Ravine Trail crosses above the waterfall), under the ice in the Center Bowl, or perhaps in the middle section of Central Gully. Other locations may also harbor this problem, so keep your eyes open as you travel about, but generally you’ll be traveling through snow with good stability.

In other news, the Lion Head Summer Trail remains open and will be the preferred route until we get significantly more snow. The trail does cross an avalanche path in a couple locations, but there needs to be a lot more snow before this becomes a problem. The John Sherburne Ski Trail has fair coverage but is very hard-packed and icy. There are a lot of very abrupt waterbars, open patches of frozen turf, and some water ice. Extreme optimists say it’s still better than walking down, but you may disagree long before you reach the bottom. And finally, we will be resuming the Eastern Snow and Avalanche Workshop (ESAW) Continuing Education Series this winter. The first session will be in mid-January. Stay tuned to our Facebook page for more details in the coming days.

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 8:00 a.m. December 30, 2014. A new advisory will be issued tomorrow.

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

2014-12-30

 

Avalanche Advisory for Monday December 29, 2014

This advisory expires tonight at 12:00 midnight.

Tuckerman Ravine has CONSIDERABLE and MODERATE avalanche danger. The Sluice, Lip, Center Bowl, Chute, Left Gully, and Hillman’s have Considerable avalanche danger. Natural avalanches are possible and human-triggered avalanches are likely. Careful snowpack and weather evaluation, cautious route-finding, and conservative decision making are essential.  All other forecast areas have Moderate avalanche hazard. Natural avalanches are unlikely and human-triggered avalanches are possible. Evaluate snow, weather, and terrain carefully.

Huntington Ravine has CONSIDERABLE and MODERATE avalanche danger. North, Damnation, Yale, Central, Pinnacle, and Odell have Considerable avalanche danger. Natural avalanches are possible and human-triggered avalanches are likely. Careful snowpack and weather evaluation, cautious route-finding, and conservative decision making are essential. South Gully and the Escape Hatch have Moderate avalanche danger. Natural avalanches are unlikely and human triggered avalanches are possible. Evaluate snow, weather, and terrain carefully.

AVALANCHE PROBLEM: We have the potential for additional snowfall and strong consistent winds leading to the development of wind slab in lee areas. Winds today will remain quite strong, which should allow loading to continue throughout the day. This wind loading and subsequent slab development will keep the snowpack trending toward worse stability.

WEATHER: Since the thaw ended and snow began to fall, Mt. Washington Observatory has recorded 5.1″ (12.5cm) of roughly 11% density snow with winds holding strong from the W and NW. Due to temperature differences, elevations below Hermit Lake received wet snow and rain instead of the snow that landed in the alpine zone. After the bulk of the snow fell, there was a modest lull yesterday afternoon before winds cranked up again to 60-80mph (95-130kph). This morning the strong W and NW winds will continue and there are some snow squalls expected. This may bring another 1-3″ (2.5-7.5cm) of snow to upper elevations.

SNOWPACK: We are still in recovery mode from the Christmas rain event. If we had a full mid-winter snowpack, 5″ of new snow with another 1-3″ on the way, coupled with these winds, would make for pretty simple forecasting and hazard assessment. It would scream “Danger! Danger!” with red lights flashing — or at least that’s how it would look to me. In the current situation, we have a more discontinuous snowpack and smaller bed surfaces. Avalanche tracks and runout paths are less developed. Many locations have numerous anchors still well exposed. The alpine zone in not fully encased in snow, so there are lots of locations for snow to get “trapped” instead of  blown into the ravines. All these factors do contribute to the nature of the avalanche potential being such that we expect relatively smaller sized avalanches and the likelihood of a naturally triggered avalanche falling somewhere on the line between Moderate and Considerable (i.e. unlikely vs. possible.) The primary factors that tipped the scale toward the Considerable ratings include the total amount of snow available for wind loading and the ability of the winds to move large quantities of snow in to the ravines. This data is difficult to ignore. Other factors come into play, such as the lull in winds and slight shifts in direction leading to variations and potential weak interfaces within the new slab. We believe that a savvy traveler who is very observant might be able to thread the needle through the terrain today, but it would not be without risk and uncertainty. If you intentionally seek to find softer snow, you won’t be threading the needle, you’d be sticking yourself right in the thumb with it, as you will be seeking the areas with the same new slab we are concerned about today. With a little luck, visibility will improve late today and more visual clues will help with decision making. Unless this happens, keep in mind that 8″ can translate to a lot of wind slab!

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 8:00 a.m. December 29, 2014. A new advisory will be issued tomorrow.

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

2014-12-29

Avalanche Advisory for Sunday, December 28, 2014

This advisory expires tonight at 12:00 midnight.

Tuckerman Ravine has CONSIDERABLE and MODERATE avalanche danger today. Sluice, Lip, Center Bowl Chute and  Left Gully have Considerable avalanche danger. Natural avalanches are possible and human-triggered avalanches are likely. Careful snowpack and weather evaluation, cautious route-finding and conservative decision making are essential.  All other forecast areas have Moderate avalanche hazard. Natural avalanches are unlikely and human-triggered avalanches are possible. Evaluate snow, weather and terrain carefully.

Huntington Ravine has CONSIDERABLE and MODERATE avalanche danger today. Yale, Central, Pinnacle, and Odell have Considerable avalanche danger. Natural avalanches are possible and human-triggered avalanches are likely.  Careful snowpack and weather evaluation, cautious route-finding and conservative decision making are essential. All other forecast areas have Moderate avalanche danger. Natural avalanches are unlikely and human triggered avalanches are possible. Evaluate snow, weather and terrain carefully.

AVALANCHE PROBLEM: Todays Wind Slab and Storm Slab problem is tied directly to wind speed and direction as well as total snowfall expected today. 2-4″ (5-10cm) of new snow is forecast and the current rate of precipitation at Pinkham and Hermit Lake is raising concerns that we may quickly reach the upper end of the forecast amount. The likelihood of natural avalanches will increase through the day as upslope snow showers accumulate and wind loading continues.

WEATHER:  Anticipate wind loading on east and southeast facing aspects as well as lee areas as wind shifts from the W to the NW at 60-80 mph (95-130kph). Lingering moisture will continue to generate upslope snow showers as the front passes which is creating our stability concerns as well as hamper visibility. Reduced visibility from fog and blowing snow may challenge your ability to assess the extent and size of potential wind and storm slabs. Though temperatures low on the mountain at this hour are allowing a copious drizzle to fall, anticipate temperatures to drop through the day to the lower teens F (-9 to -12C) tonight. Rain/snow line was at around 3700′ at 7:00am.

SNOWPACK: Our snowpack took a beating from recent warm temperatures and rainfall. Melt channels and signs of ice fall peppered the snow surface yesterday. Many areas are likely undermined and many frozen waterfalls are either detached or missing. Due to above average December snowfall, there remained ample bed surfaces in leeward slopes like Central Gully, Sluice, the Lip, Chute and Left. While certain factors  lead me to believe that we may not reach a Considerable rating, I wouldn’t bet my life on them. Warm incoming snow on a fairly coarse bed surface with abating winds may yield fair stability from a right side up slab configuration and reduce the likelihood of natural avalanches from possible to unlikely. Coupled with discontinuous bed surfaces in many areas like Center Bowl we may make it through the day without natural avalanche activity. Though our avalanche character may end up being on the small side, the nature of our terrain makes the outcome of an avalanche as dire as ever. The consequences of making the wrong stability assessment above rocky cliff bands and frozen waterfalls such as the Lip while on the Tuck trail, or anywhere in Yale or Pinnacle would be catastrophic. Other areas with larger potential bed surfaces like Central Gully or Chute will make the potential for a larger avalanche more likely and make the Considerable rating feel much more accurate if you find yourself in or below this terrain. Today is a day when you’ll want to use all of your strongest weather observation and snowpack evaluation skills if you venture into avalanche terrain.

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 8:20 a.m. December 28, 2014. A new advisory will be issued tomorrow.

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

2014-12-28 print friendly

Avalanche Advisory for Saturday, December 27, 2014

This advisory expires tonight at 12:00 midnight.

Tuckerman and Huntington Ravines have LOW avalanche danger.  Natural and human triggered avalanches are unlikely except in isolated terrain features.

AVALANCHE PROBLEM: The potential for isolated areas of Wind slab should be remembered today, but generally this should be a remote issue.  Since the thaw and rain on Tuesday and Wednesday we have only picked up a meager amount of new snow.  This may have given us a pocket or two behind some terrain features, but high winds have kept most areas scoured clean.  The water saturated snow from Wednesday has been re-freezing deeper each hour as cold air temperatures remain in place.  This continues to create a bridging eggshell over the snowpack causing any deep weaknesses to be inconsequential. Place your focus on new developing instabilities that may occur on top of the crust during upcoming precipitation events, such as tonight’s snow showers.
WEATHER: Yesterday, very high winds continued to pound the hill, peaking at 112mph (180kph).  Speeds have trended downward and the current winds, gusting to 75mph, are forecasted to continue falling to 30-45mph later today.  Expect sunshine and some clouds to give us a fairly reasonable day in the mountains.  Tonight snow showers will return expected to deliver 1-3″ (2.5-7.5cm) by Sunday morning.  This will be the first snow on the mountain since Thursday’s 0.4″ (1cm).  Winds will also increase once again, exceeding 100mph (160kph) from the W tonight and into tomorrow.  Temperatures will start moving down again, perhaps hitting 0F (-18C) Sunday night and early Monday morning.  Expect a very cold week ahead with temperatures deep into negative F territory.

SNOWPACK: The freewater from Wednesday’s wet event has been freezing from the surface down for about 48 hours. Snow temperatures will continue to fall with cold ambient air in place freezing and bonding round wet grains deeper by the hour. As already mentioned, this creates a bridge over any deeper weaknesses due to its strength.  Additionally, we have thin early season coverage so the freezing upper snowpack is also held in place by freezing around brush, trees, poking cliffbands, and rock anchors.  We’ll watch, as should you, for faceting/recrystalizing that will likely occur this week with very cold air settling in.  However, continued moderate to high wind speeds should keep this process from occurring too rapidly.  In the meantime, the big issue is more the slick surfaces that exist. As discussed yesterday, the current icy snow surface will lend itself more to a bobsled run than arresting a fall with an axe easily.  If a slip does cause a fall, an immediate self arrest is absolutely critical due to the potential for Mach speeds in a blink of an eye.  Unfortunately, history has shown that sliding falls into the rocks below is the most frequent accident when we have slick surface conditions. Microspikes and trekking poles are helpful on very low angle trails approaching the Ravines, but have no place in steep terrain.  Crampons, an ice ax, and the skill to use them effectively are all needed to travel safely on the upper mountain.  Ice climbers should expect the potential for ice dams struggling to hold back water pressure beneath the ice.  This is most common in narrow gullies, but is also common near bulges in more open terrain.  These have a history of causing accidents as their pressure becomes released by a swinging ax placement.  It goes without saying, but I’ll mention it anyway. Expect the Sherburne ski trail to be very challenging with hard rough terrain.

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 6:50 a.m. December 27, 2014. A new advisory will be issued tomorrow.

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

2014-12-27

Avalanche Advisory for December 26, 2014

Tuckerman and Huntington Ravines have LOW avalanche danger.  Natural and human triggered avalanches are unlikely except in isolated terrain features.

 AVALANCHE PROBLEMS: The potential for isolated areas of Wind slab is the problem to have eyes open for today.  Some scant snow yesterday and some isolated upslope snow showers today may be enough for high W winds to create thin pockets protected behind some terrain features.  This should be a remote issue. The dominate snow personality right now has been created by the recent rain and thaw event which is hitting the reset button in our mountain snowpack.  The saturated snow has been re-freezing deeper as overnight cold temperatures and extreme wind remove heat from the surface down. This is quickly making any older issues and problems that could have been categorized as persistent, moot.  Place your focus on newly developing instabilities that may occur on top of the crust during upcoming precipitation events.
WEATHER: Yesterday, very high winds pummeled the mountains as the front barreled through the region during Christmas morning.  Winds over 100mph (160kph) were common and the summit recorded a peak of 109mph (175kph) which made human outdoor observations difficult.  Nevertheless, the summit crew muscled the precipitation can back for melting and recorded 0.4″ of new snow yesterday, although they noted accurate collections were difficult. Very high winds will continue today, perhaps gusting to 110mph (176kph), along with some additional upslope snow.  Temperatures may rise a bit from the current of 14F (-10C), but not much.  Expect above treeline travel to be beyond difficult, to say extreme seems cliche, but it really describes it pretty well. We know you want to use that newly unwrapped winter parka in the alpine zone, but give it one more day.  Expect brutalizing winds to make it very difficult to deal with both icy surfaces and jumbled rocks, whether you’re on foot or crawling. One small problem could snowball into a desperate scenario when winds get to these levels.

SNOWPACK:  Well, the snow geek party is over for those inclined towards snow structure and crystal study. As the rain drains through the snowpack and and recent heat dissipates, the interesting layers (in 52.5″ total snowfall) from this month will be more or less pinned down by solid bonds leaving us an isothermal snowpack to start the new year. In the meantime, as winds lay down, enjoy the firm snow on the steep approach to climbs, but for goodness sake, don’t trip. The current icy snow surface will lend itself more to skeleton or luge racing than arresting a fall with an axe. Packed trails will demand micro-spikes and maybe a trekking pole or two but don’t forget that crampons are much more secure, both on your boot and on the ice, and may be needed on your chosen objective. Rain water and snow melt will most likely continue to flow in deeper channels of steep gullies so beware of increasing hydraulic pressure behind ice dams. On days like today, it is not unusual to see bloody paw prints on the trail so consider your dog’s pads when hiking on the chopped up, icy surface.

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 8:30 a.m. December 26, 2014. A new advisory will be issued tomorrow.

Chris Joosen/Frank Carus, Snow Rangers
USDA Forest Service
White Mountain National Forest
(603) 466-2713 TTY (603) 466-2856

2014-12-26 print friendly

Avalanche Advisory for Thursday, December 25, 2014

This advisory expires tonight at 12:00 midnight.

Tuckerman and Huntington Ravines have Considerable avalanche danger today. Natural avalanches are possible and human triggered avalanches are likely. Dangerous avalanche conditions exist and conservative decision making is essential.

AVALANCHE PROBLEM: Wet Slabs are the #1 avalanche problem today.  Record breaking heat coupled with rain continues to saturate our snowpack with free water, creating wet slabs of varying thickness depending on location.  A distant #2, is the potential for some wind slab to develop as the front moves through.  This will turn rain to snow, adding up to 1-3″ (2.5-7.5cm) later this afternoon.  If this accumulation occurs this will be a late day issue.

WEATHER: Forecasts had difficulty with the precipitation amounts over the last 24 hours, as actual rain accumulations came in short of expectations.  As of midnight, the summit and Hermit Lake picked up about 0.7″ (1.8cm) of water during the previous 24 hours, with the general region getting a bit less.  Rain is expected to continue for a little longer before transitioning to snow as the frontal freight train draws cold air into the mountains.  1-3″ (2.5-7.5cm) of snow is expected, associated with a building wind from the West, smashing the 100mph (160kph) mark gusting over 120mph (192kph) late in the day. Temperatures peaked very late last night at 44F, crushing the previous daily high record for the Mount Washington summit.  Since then, the mercury has steadily been falling which will occur more rapidly as the front moves through this morning.   The Ravines are sitting in a mid-elevational warm band in the high 40’sF, trapped between the colder air above and below.  This will likely continue for a while this morning until mixing becomes more substantial with higher wind speeds.

SNOWPACK:  We feel very fortunate that rain totals did not match the earlier predictions of up to 4 times the actual observations.  That said, we are still dealing with a wet snowpack due to both the falling intermittent rain, as well as the melting snow already on the ground. Natural avalanches will continue to be possible due to wet slabs particularly during the first half of the day.   As the moisture moves out, temperatures will fall slowly, decreasing the potential for natural wet slab avalanches.  As this occurs, the water draining rate will exceed the melt rate and the wet surfaces will begin to refreeze, helping stability.  I would expect off trail travel to be arduous and slow because of the isothermal snowpack, inducing very deep boot penetration in most locations.  Climbers should expect the development of ice dam hazards particularly in the Huntington gullies and near ice bulges of the Tuckerman Headwall. This hydraulic pressure can release explosively with a tool placement as refreezing dams up water flow.

As the day progresses wet slab concerns will dissipate, but new thin dry slab concerns will be something to keep in mind.  Up to 3″ of new snow is forecasted which could add up to isolated problems created by a building W wind.  Based on the high velocities, look for pockets behind terrain features sheltered from the anticipated high winds. Extreme velocities are expected to build, gusting towards 130mph on the Washington summit late today.  Maximum winds should hit the highest mark yet for 2014. As high pressure moves in weather will improve over the next several days, but expect very hard surface conditions to exist.  The consequences of a slip and fall will likely be….. terminal velocity.  We’ll discuss more of this tomorrow.

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 8:20 a.m. December 25, 2014. A new advisory will be issued tomorrow.

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

2014-12-25

Avalanche Advisory for Wednesday, December 24, 2014

This advisory expires tonight at 12:00 midnight.

Tuckerman and Huntington Ravines will have HIGH avalanche danger today. Natural avalanches are likely and human triggered avalanches are very likely. Very dangerous avalanche conditions exist and travel in avalanche terrain is not recommended which includes runout paths.

AVALANCHE PROBLEM: Wet Slabs are the main avalanche problem today.  Several inches of new snow fell yesterday morning which has since transitioned to light rain, freezing rain and drizzle in the higher terrain.  Heavy rain today will rapidly increase instability pushing a number of slabs of varying density to their limit of strength causing some to fail. This will transition several problems to a singular wet slab issue. Expect natural wet slabs today.

WEATHER: The liquid gauntlet is about to begin.  A tropical system is setting it’s mass on the region expected to bring at least 1.5″ of rain to the mountains, much of it falling heavy at times.  Actual forecasted amounts (QPF) have been difficult due to the digital models having a history of trouble with this type of event.  Human forecasters are adding up to another inch to the potential amount and even more in isolated upsloping areas.  This makes the potential liquid window pretty large at 1.5″ to give or take 3″ over the next 24-30 hours.  Another question is wind speeds over the next 48 hours.  They will get ferocious, but forecasts differ on their level of violence.  Today we could see winds exceeding hurricane force on the higher summits gusting towards 90mph.  This upward moving trend will continue tonight, tomorrow and into Thursday evening when some meteorologists are discussing winds gusting to 140mph (224kph)!  Generally expect travel in alpine zones to be particularly horrific as temperatures drop tomorrow and the front moves in through the day.  Where the uncertainty stops is the question of precipitation type today.  The summit of Washington will be crawling towards its daily record with forecasted temperatures in the low 40’sF.  The mercury is anticipated to drift back below freezing after daylight tomorrow morning, changing precipitation back to snow.  Temperatures will continue to fall into the teensF after dark tomorrow night.

SNOWPACK: Typically the snowpack discussion is the longest, but it takes a backseat to the weather today.  This is because issues will become very clear over the next several hours leaving little room for doubt.  Heavy rain intensity rates on a variety of slab densities and thickness will move the Ravines from a current Considerable rating at 730am to the forecasted High avalanche danger.  Natural avalanches will be likely due to wet slab development.  Rain adds weight, melts bonds decreasing slab strength and can lubricate impermeable or semi-impermeable layers such as buried water ice or crusts.  Will every slope naturally avalanche? No.  However a variety of paths criss-cross and the potential for some stream blow outs from under snow water flows such as in Tuckerman’s Lip or Sluice, and Huntington’s narrow gullies, is possible. Therefore, a prudent call is to stay out of avalanche terrain.

Based on the rain and extreme wind forecast a multi day Holiday alpine terrain trip starting this morning would be a horrendous idea. Looks like we’re generally getting a Holiday stocking of coal today, but we’ll talk about a few presents of whiteness in the advisory tomorrow.

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 7:50 a.m. December 24, 2014. A new advisory will be issued tomorrow.

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

2014-12-24

Avalanche Advisory for Tuesday, December 23, 2014

This advisory expires tonight at 12:00 midnight.

Tuckerman Ravine has Considerable and Moderate avalanche danger. The Sluice, Lip, Center Bowl, Chute, Left Gully, and Hillman’s Highway have Considerable danger. Natural avalanches are possible and human triggered avalanches are likely. Cautious route finding and conservative decision making are essential. The Lobster Claw and Right Gully have Moderate avalanche danger. Natural avalanches are unlikely and human triggered avalanches are possible. The Lower Snowfields and Little Headwall remain Not Posted due a lack of snow in these locations.

All forecast areas of Huntington Ravine have Considerable danger. Dangerous avalanche conditions exist. Natural avalanches are possible and human triggered avalanches are likely. Conservative decision making is essential.

AVALANCHE PROBLEM: You can take your pick of avalanche problems today. We’re looking at the potential for storm slabs, wet slabs, and/or wet loose avalanches today. These issues are coming as a result of new snow this morning which will likely transition to rain or freezing rain late today. Prior to today’s weather, we had been monitoring old wind slabs. These may become active again as the incoming weather system works to saturate the snowpack with liquid water. Keep this in mind, but for today you should focus your attention on the more immediate problems of new slab development and rain.

WEATHER: As of 8am, about 3″ (7.5cm) of new snow has fallen at Hermit Lake with slightly lower accumulations at Pinkham and the summit of Mt. Washington. The weather forecasters are calling for precipitation to change over to a mixed bag or freezing rain later today. In the ravines, the change is forecast to take place in the late afternoon or early evening. Until this happens, you should be expecting fresh snow falling on S or SW winds in the 25-40mph range (40-65kph). Temperatures will continue to rise through the night and into tomorrow.

The storm system that will be building over the next couple days is a significant one. If the worst-case scenarios play out, we may see upwards of 4″ of rain in favored upslope areas such as North Conway before Thursday morning. Needless to say, this is not a good situation for the snowpack anywhere in the North Country. Be sure to watch the avalanche advisory and weather forecasts carefully if you are planning to be out in the mountains over the next couple days.

SNOWPACK: With new snow falling on southerly winds, you should expect to see the most wind loading and slab development taking place in areas such as Hillman’s or Left Gully in Tuckerman and South and Odell in Huntington. Cross-loading will take place on slopes with a more easterly component, such as the Chute, Center Bowl, Pinnacle, and Central Gullies. All of these locations are prime candidates for avalanche activity to take place. On the northerly gullies of Huntington I would caution you to be aware of the potential for dry or wet loose snow avalanches, especially late in the day. Similar aspects in Tuckerman (i.e. Lobster Claw and Right Gully) are a lower concern due to their thin snow cover, as well as their aspect and lower slope angle.

There are a lot of variables at play today, such as snow totals, timing of the snow-rain transition, temperatures, etc. Each has its own influence on the hazard you’ll face if you’re in avalanche terrain. You’ll do well to focus on the fundamentals. New snow, winds at a favorable direction and speed for loading, and a change to rain or mixed precip should all be commanding your attention and influencing your decision making 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 8:25 a.m. December 23, 2014. A new advisory will be issued tomorrow.

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

2014-12-23

Avalanche Advisory for December 22, 2014

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. Evaluate snow and terrain carefully to identify heightened avalanche conditions and features of concern. All other forecast areas have Low avalanche danger where natural and human triggered avalanches are unlikely. Watch for unstable snow in isolated terrain features.

Huntington Ravine has MODERATE and LOW avalanche danger. North, Damnation, Yale, and Central have Moderate avalanche danger. Natural avalanches are unlikely and human triggered avalanches are possible. Evaluate the snow and terrain carefully. Pinnacle, Odell, South Gully, and the Escape Hatch have Low avalanche danger. Natural and human triggered avalanches are unlikely. Watch for unstable snow in isolated terrain features.

AVALANCHE PROBLEM: Wind slab from last Thursday’s wind event continue to be our primary concern. Piles of sluff or point release debris from steep terrain run a very close second. Though both types of slab offer moderate to good stability, a weak layer exists within reach of a human trigger on the surface in enough places in our Ravines to maintain the Moderate rating. Continue to evaluate snow carefully when moving around our terrain. Avalanches on this wind slab could be on the large side in Central Gully, and in the hangfire in parts of the Lip, Center Bowl and Chute with other smaller areas remaining a problem in many other areas such as the top of Yale and Damnation.

WEATHER: Light winds will continue today, though clouds and fog will challenge visual assessment of our snow surfaces. While not frigid, or even very cold by Mount Washington standards, overnight temperatures have been cold enough the last two nights to preserve the weaker layers in our snowpack which are creating our current instability. Calm winds, cloud cover and a high near 20F today won’t change much about the snowpack or avalanche conditions again today and will help preserve our weak layers for Wednesday’s rain on snow event.

SNOWPACK: Jeff and I split up with volunteers yesterday and made some observations in Huntington and Tuckerman yesterday. The changes that 98 mph winds last Thursday brought to the remaining snow was immediately obvious while climbing around on slopes beneath the steeper parts of gullies. Scouring action left a widely variable surface of refrozen wet snow and ice crust but with pencil hard wind slab the predominate surface.  Our snowpack is pretty shallow, given our position on the calendar, so depth hoar and collapsing snow over rocks, holes and shrubs added to the fun. Stability tests confirmed suspicions that pencil hard wind slabs are still potentially active with moderate results on clean (Q2) shears on multiple layers with the upper 50cm. One ECT did not propagate, but I wouldn’t bank on this result in all areas due to the variability in depth and strength of the weak layers. Most disconcerting is the interface between Thursday’s wind slab and the refrozen wet snow crust. This layer is widely variable in depth and in many places has avalanched already (beneath the choke in Chute, low in Lip) or has been scoured out by the wind (top of Left Gully). In some places this layer is likely nearer the surface and here the overlying pencil hard wind slab may be thin enough to crack and avalanche. Central Gully, the mid-section of Chute and the bowl-like section of Sluice are areas I would avoid due to this issue and the expanse of wind slab. I would approach other areas like the top pitches of Yale, Damnation and Pinnacle cautiously and take the time to protect myself and my belayer. Sluff piles which have reloaded the bed surface in many areas are best avoided and left for Wednesday’s rain to clean out. Last Saturday allowed for sunshine and warmer temperatures in the Ravines but solar gain in the snowpack was limited to very particular locations with the most direct southerly aspect near shrubs and rocks. Lately, night-time clear skies and calm winds have treated snow geeks to a really nice surface hoar display with frost feathers up to 10mm in places.

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. December 22, 2014. A new advisory will be issued tomorrow.

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

2014-12-22 print friendly